1
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Hulett RE, Rivera-López C, Gehrke AR, Gompers A, Srivastava M. A wound-induced differentiation trajectory for neurons. Proc Natl Acad Sci U S A 2024; 121:e2322864121. [PMID: 38976727 DOI: 10.1073/pnas.2322864121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2023] [Accepted: 05/03/2024] [Indexed: 07/10/2024] Open
Abstract
Animals capable of whole-body regeneration can replace any missing cell type and regenerate fully functional new organs, including new brains, de novo. The regeneration of a new brain requires the formation of diverse neural cell types and their assembly into an organized structure with correctly wired circuits. Recent work in various regenerative animals has revealed transcriptional programs required for the differentiation of distinct neural subpopulations, however, how these transcriptional programs are initiated in response to injury remains unknown. Here, we focused on the highly regenerative acoel worm, Hofstenia miamia, to study wound-induced transcriptional regulatory events that lead to the production of neurons and subsequently a functional brain. Footprinting analysis using chromatin accessibility data on a chromosome-scale genome assembly revealed that binding sites for the Nuclear Factor Y (NFY) transcription factor complex were significantly bound during regeneration, showing a dynamic increase in binding within one hour upon amputation specifically in tail fragments, which will regenerate a new brain. Strikingly, NFY targets were highly enriched for genes with neuronal function. Single-cell transcriptome analysis combined with functional studies identified soxC+ stem cells as a putative progenitor population for multiple neural subtypes. Further, we found that wound-induced soxC expression is likely under direct transcriptional control by NFY, uncovering a mechanism for the initiation of a neural differentiation pathway by early wound-induced binding of a transcriptional regulator.
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Affiliation(s)
- Ryan E Hulett
- Department of Organismic and Evolutionary Biology, Museum of Comparative Zoology, Harvard University, Cambridge, MA 02138
| | - Carlos Rivera-López
- Department of Organismic and Evolutionary Biology, Museum of Comparative Zoology, Harvard University, Cambridge, MA 02138
- Department of Molecular and Cell Biology, Harvard University, Cambridge, MA 02138
| | - Andrew R Gehrke
- Department of Organismic and Evolutionary Biology, Museum of Comparative Zoology, Harvard University, Cambridge, MA 02138
| | - Annika Gompers
- Department of Organismic and Evolutionary Biology, Museum of Comparative Zoology, Harvard University, Cambridge, MA 02138
| | - Mansi Srivastava
- Department of Organismic and Evolutionary Biology, Museum of Comparative Zoology, Harvard University, Cambridge, MA 02138
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2
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Collins EMS, Hessel EVS, Hughes S. How neurobehavior and brain development in alternative whole-organism models can contribute to prediction of developmental neurotoxicity. Neurotoxicology 2024; 102:48-57. [PMID: 38552718 PMCID: PMC11139590 DOI: 10.1016/j.neuro.2024.03.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 03/01/2024] [Accepted: 03/23/2024] [Indexed: 04/12/2024]
Abstract
Developmental neurotoxicity (DNT) is not routinely evaluated in chemical risk assessment because current test paradigms for DNT require the use of mammalian models which are ethically controversial, expensive, and resource demanding. Consequently, efforts have focused on revolutionizing DNT testing through affordable novel alternative methods for risk assessment. The goal is to develop a DNT in vitro test battery amenable to high-throughput screening (HTS). Currently, the DNT in vitro test battery consists primarily of human cell-based assays because of their immediate relevance to human health. However, such cell-based assays alone are unable to capture the complexity of a developing nervous system. Whole organismal systems that qualify as 3 R (Replace, Reduce and Refine) models are urgently needed to complement cell-based DNT testing. These models can provide the necessary organismal context and be used to explore the impact of chemicals on brain function by linking molecular and/or cellular changes to behavioural readouts. The nematode Caenorhabditis elegans, the planarian Dugesia japonica, and embryos of the zebrafish Danio rerio are all suited to low-cost HTS and each has unique strengths for DNT testing. Here, we review the strengths and the complementarity of these organisms in a novel, integrative context and highlight how they can augment current cell-based assays for more comprehensive and robust DNT screening of chemicals. Considering the limitations of all in vitro test systems, we discuss how a smart combinatory use of these systems will contribute to a better human relevant risk assessment of chemicals that considers the complexity of the developing brain.
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Affiliation(s)
- Eva-Maria S Collins
- Swarthmore College, Biology, 500 College Avenue, Swarthmore, PA 19081, USA; Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA; Center of Excellence in Environmental Toxicology, University of Pennsylvania, Philadelphia, PA, USA.
| | - Ellen V S Hessel
- Centre for Health Protection, National Institute for Public Health and the Environment (RIVM), Antonie van Leeuwenhoeklaan 9, Bilthoven, 3721 MA, the Netherlands
| | - Samantha Hughes
- Department of Environmental Health and Toxicology, A-LIFE, Vrije Universiteit Amsterdam, de Boelelaan 1085, Amsterdam, 1081 HV, the Netherlands.
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3
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McMillen P, Levin M. Collective intelligence: A unifying concept for integrating biology across scales and substrates. Commun Biol 2024; 7:378. [PMID: 38548821 PMCID: PMC10978875 DOI: 10.1038/s42003-024-06037-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Accepted: 03/11/2024] [Indexed: 04/01/2024] Open
Abstract
A defining feature of biology is the use of a multiscale architecture, ranging from molecular networks to cells, tissues, organs, whole bodies, and swarms. Crucially however, biology is not only nested structurally, but also functionally: each level is able to solve problems in distinct problem spaces, such as physiological, morphological, and behavioral state space. Percolating adaptive functionality from one level of competent subunits to a higher functional level of organization requires collective dynamics: multiple components must work together to achieve specific outcomes. Here we overview a number of biological examples at different scales which highlight the ability of cellular material to make decisions that implement cooperation toward specific homeodynamic endpoints, and implement collective intelligence by solving problems at the cell, tissue, and whole-organism levels. We explore the hypothesis that collective intelligence is not only the province of groups of animals, and that an important symmetry exists between the behavioral science of swarms and the competencies of cells and other biological systems at different scales. We then briefly outline the implications of this approach, and the possible impact of tools from the field of diverse intelligence for regenerative medicine and synthetic bioengineering.
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Affiliation(s)
- Patrick McMillen
- Department of Biology, Tufts University, Medford, MA, 02155, USA
- Allen Discovery Center at Tufts University, Medford, MA, 02155, USA
| | - Michael Levin
- Department of Biology, Tufts University, Medford, MA, 02155, USA.
- Allen Discovery Center at Tufts University, Medford, MA, 02155, USA.
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, 02115, USA.
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4
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Sun Y, Huang Y, Hao Z, Zhang S, Tian Q. MRLC controls apoptotic cell death and functions to regulate epidermal development during planarian regeneration and homeostasis. Cell Prolif 2024; 57:e13524. [PMID: 37357415 PMCID: PMC10771114 DOI: 10.1111/cpr.13524] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Revised: 06/02/2023] [Accepted: 06/13/2023] [Indexed: 06/27/2023] Open
Abstract
Adult stem cells (ASCs) are pluripotent cells with the capacity to self-renew and constantly replace lost cells due to physiological turnover or injury. Understanding the molecular mechanisms of the precise coordination of stem cell proliferation and proper cell fate decision is important to regeneration and organismal homeostasis. The planarian epidermis provides a highly tractable model to study ASC complex dynamic due to the distinct spatiotemporal differentiation stages during lineage development. Here, we identified the myosin regulatory light chain (MRLC) homologue in the Dugesia japonica transcriptome. We found high expression levels of MRLC in wound region during regeneration and also expressed in late epidermal progenitors as an essential regulator of the lineage from neoblasts to mature epidermal cells. We investigated the function of MRLC using in situ hybridization, real-time polymerase chain reaction and double fluorescent and uncovered the potential mechanism. Knockdown of MRLC leads to a remarkable increase in cell death, causes severe abnormalities during regeneration and homeostasis and eventually leads to animal death. The global decrease in epidermal cell in MRLC RNAi animals induces accelerated epidermal proliferation and differentiation. Additionally, we find that MRLC is co-expressed with cdc42 and acts cooperatively to control the epidermal lineage development by affecting cell death. Our results uncover an important role of MRLC, as an inhibitor of apoptosis, involves in epidermal development.
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Affiliation(s)
- Yujia Sun
- School of Life SciencesZhengzhou UniversityZhengzhouHenanChina
| | - Yongding Huang
- School of Life SciencesZhengzhou UniversityZhengzhouHenanChina
| | - Zhitai Hao
- Department of Biochemistry and Molecular PharmacologyNew York University, School of MedicineNew YorkUSA
| | - Shoutao Zhang
- School of Life SciencesZhengzhou UniversityZhengzhouHenanChina
- Longhu Laboratory of Advanced ImmunologyZhengzhouHenanChina
| | - Qingnan Tian
- School of Life SciencesZhengzhou UniversityZhengzhouHenanChina
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5
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Molina MD, Abduljabbar D, Guixeras A, Fraguas S, Cebrià F. LIM-HD transcription factors control axial patterning and specify distinct neuronal and intestinal cell identities in planarians. Open Biol 2023; 13:230327. [PMID: 38086422 PMCID: PMC10715919 DOI: 10.1098/rsob.230327] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Accepted: 11/01/2023] [Indexed: 12/18/2023] Open
Abstract
Adult planarians can regenerate the gut, eyes and even a functional brain. Proper identity and patterning of the newly formed structures require signals that guide and commit their adult stem cells. During embryogenesis, LIM-homeodomain (LIM-HD) transcription factors act in a combinatorial 'LIM code' to control cell fate determination and differentiation. However, our understanding about the role these genes play during regeneration and homeostasis is limited. Here, we report the full repertoire of LIM-HD genes in Schmidtea mediterranea. We found that lim homeobox (lhx) genes appear expressed in complementary patterns along the cephalic ganglia and digestive system of the planarian, with some of them being co-expressed in the same cell types. We have identified that Smed-islet1, -lhx1/5-1, -lhx2/9-3, -lhx6/8, -lmx1a/b-2 and -lmx1a/b-3 are essential to pattern and size the planarian brain as well as for correct regeneration of specific subpopulations of dopaminergic, serotonergic, GABAergic and cholinergic neurons, while Smed-lhx1/5.2 and -lhx2/9.2 are required for the proper expression of intestinal cell type markers, specifically the goblet subtype. LIM-HD are also involved in controlling axonal pathfinding (lhx6/8), axial patterning (islet1, lhx1/5-1, lmx1a/b-3), head/body proportions (islet2) and stem cell proliferation (lhx3/4, lhx2/9-3, lmx1a/b-2, lmx1a/b-3). Altogether, our results suggest that planarians might present a combinatorial LIM code that controls axial patterning and axonal growing and specifies distinct neuronal and intestinal cell identities.
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Affiliation(s)
- M. Dolores Molina
- Department of Genetics, Microbiology and Statistics, Faculty of Biology, University of Barcelona, Barcelona, Spain
- Institute of Biomedicine of the University of Barcelona (IBUB), Barcelona, Spain
| | - Dema Abduljabbar
- Department of Genetics, Microbiology and Statistics, Faculty of Biology, University of Barcelona, Barcelona, Spain
| | - Anna Guixeras
- Department of Genetics, Microbiology and Statistics, Faculty of Biology, University of Barcelona, Barcelona, Spain
- Institute of Biomedicine of the University of Barcelona (IBUB), Barcelona, Spain
| | - Susanna Fraguas
- Department of Genetics, Microbiology and Statistics, Faculty of Biology, University of Barcelona, Barcelona, Spain
- Institute of Biomedicine of the University of Barcelona (IBUB), Barcelona, Spain
| | - Francesc Cebrià
- Department of Genetics, Microbiology and Statistics, Faculty of Biology, University of Barcelona, Barcelona, Spain
- Institute of Biomedicine of the University of Barcelona (IBUB), Barcelona, Spain
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6
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Hulett RE, Gehrke AR, Gompers A, Rivera-López C, Srivastava M. A wound-induced differentiation trajectory for neurons. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.10.540286. [PMID: 37214981 PMCID: PMC10197691 DOI: 10.1101/2023.05.10.540286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Animals capable of whole-body regeneration can replace any missing cell type and regenerate fully-functional new organs, de novo . The regeneration of a new brain requires the formation of diverse neuronal cell types and their assembly into an organized structure and correctly-wired circuits. Recent work in various regenerative animals has revealed transcriptional programs required for the differentiation of distinct neuronal subpopulations, however how these transcriptional programs are initiated upon amputation remains unknown. Here, we focused on the highly regenerative acoel worm, Hofstenia miamia , to study wound-induced transcriptional regulatory events that lead to the production of neurons. Footprinting analysis using chromatin accessibility data on an improved genome assembly revealed that binding sites for the NFY transcription factor complex were significantly bound during regeneration, showing a dynamic increase in binding within one hour upon amputation specifically in tail fragments, which will regenerate a new brain. Strikingly, NFY targets were highly enriched for genes with neuronal functional. Single-cell transcriptome analysis combined with functional studies identified sox4 + stem cells as the likely progenitor population for multiple neuronal subtypes. Further, we found that wound-induced sox4 expression is likely under direct transcriptional control by NFY, uncovering a mechanism for how early wound-induced binding of a transcriptional regulator results in the initiation of a neuronal differentiation pathway. Highlights A new chromosome-scale assembly for Hofstenia enables comprehensive analysis of transcription factor binding during regeneration NFY motifs become dynamically bound by 1hpa in regenerating tail fragments, particularly in the loci of neural genes A sox4 + neural-specialized stem cell is identified using scRNA-seq sox4 is wound-induced and required for differentiation of multiple neural cell types NFY regulates wound-induced expression of sox4 during regeneration.
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7
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Bray SR, Wyss LS, Chai C, Lozada ME, Wang B. Adaptive robustness through incoherent signaling mechanisms in a regenerative brain. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.20.523817. [PMID: 36711454 PMCID: PMC9882340 DOI: 10.1101/2023.01.20.523817] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Animal behavior emerges from collective dynamics of interconnected neurons, making it vulnerable to connectome damage. Paradoxically, many organisms maintain significant behavioral output after large-scale neural injury. Molecular underpinnings of this extreme robustness remain largely unknown. Here, we develop a quantitative behavioral analysis pipeline to measure previously uncharacterized long-lasting latent memory states in planarian flatworms during whole-brain regeneration. By combining >20,000 animal trials with neural population dynamic modeling, we show that long-range volumetric peptidergic signals allow the planarian to rapidly reestablish latent states and restore coarse behavior after large structural perturbations to the nervous system, while small-molecule neuromodulators gradually refine the precision. The different time and length scales of neuropeptide and small-molecule transmission generate incoherent patterns of neural activity which competitively regulate behavior and memory. Controlling behavior through opposing communication mechanisms creates a more robust system than either alone and may serve as a generic approach to construct robust neural networks.
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Affiliation(s)
- Samuel R. Bray
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Livia S. Wyss
- Department of Biology, Stanford University, Stanford, CA, USA
| | - Chew Chai
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Maria E. Lozada
- Department of Bioengineering, Stanford University, Stanford, CA, USA
- Department of Biomedical Engineering, University of Miami, Coral Gables, FL, USA
| | - Bo Wang
- Department of Bioengineering, Stanford University, Stanford, CA, USA
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8
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Gambino G, Rossi L, Iacopetti P, Ghezzani C, Guidi P, Linsalata S, Ippolito C, Salvetti A. Microtubule-associated protein 1B is implicated in stem cell commitment and nervous system regeneration in planarians. PLoS One 2022; 17:e0278966. [PMID: 36508441 PMCID: PMC9744283 DOI: 10.1371/journal.pone.0278966] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Accepted: 11/24/2022] [Indexed: 12/14/2022] Open
Abstract
Microtubule-associated 1B (MAP1B) proteins are expressed at the nervous system level where they control cytoskeleton activity and regulate neurotransmitter release. Here, we report about the identification of a planarian MAP1B factor (DjMap1B) that is enriched in cephalic ganglia and longitudinal nerve cords but not in neoblasts, the plentiful population of adult stem cells present in planarians, thanks to which these animals can continuously cell turnover and regenerate any lost body parts. DjMap1B knockdown induces morphological anomalies in the nervous system and affects neoblast commitment. Our data put forward a correlation between a MAP1B factor and stem cells and suggest a function of the nervous system in non-cell autonomous control of planarian stem cells.
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Affiliation(s)
- Gaetana Gambino
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Leonardo Rossi
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Paola Iacopetti
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Claudio Ghezzani
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Patrizia Guidi
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Stefania Linsalata
- Medical Physics Unit, Azienda Ospedaliera Universitaria Pisana, Pisa, Italy
| | - Chiara Ippolito
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Alessandra Salvetti
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
- * E-mail:
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9
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Ireland D, Rabeler C, Gong T, Collins EMS. Bioactivation and detoxification of organophosphorus pesticides in freshwater planarians shares similarities with humans. Arch Toxicol 2022; 96:3233-3243. [PMID: 36173421 PMCID: PMC10729609 DOI: 10.1007/s00204-022-03387-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Accepted: 09/21/2022] [Indexed: 11/02/2022]
Abstract
Organophosphorus pesticides (OPs) are a chemically diverse class of insecticides that inhibit acetylcholinesterase (AChE). Many OPs require bioactivation to their active oxon form via cytochrome P450 to effectively inhibit AChE. OP toxicity can be mitigated by detoxification reactions performed by carboxylesterase and paraoxonase. The relative extent of bioactivation to detoxification varies among individuals and between species, leading to differential susceptibility to OP toxicity. Because of these species differences, it is imperative to characterize OP metabolism in model systems used to assess OP toxicity. We have shown that the asexual freshwater planarian Dugesia japonica is a suitable model to assess OP neurotoxicity and developmental neurotoxicity via rapid, automated testing of adult and developing organisms in parallel using morphological and behavioral endpoints. D. japonica has two cholinesterase enzymes with intermediate properties between AChE and butyrylcholinesterase that are sensitive to OP inhibition. Here, we demonstrate that D. japonica contains the major OP metabolic machinery to be a relevant model for OP neurotoxicity studies. Adult and regenerating D. japonica can bioactivate chlorpyrifos and diazinon into their respective oxons. Significant AChE inhibition was only observed after in vivo metabolic activation but not when the parent OPs were directly added to planarian homogenate using the same concentrations and timing. Using biochemical assays, we found that D. japonica has both carboxylesterase (24 nmol/(min*mg protein)) and paraoxonase (60 pmol/(min*mg protein)) activity. We show that planarian carboxylesterase activity is distinct from cholinesterase activity using benzil and tacrine. These results further support the use of D. japonica for OP toxicity studies.
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Affiliation(s)
| | | | - TaiXi Gong
- Department of Biology, Swarthmore College, Swarthmore, PA, USA
| | - Eva-Maria S Collins
- Department of Biology, Swarthmore College, Swarthmore, PA, USA.
- Department of Physics and Astronomy, Swarthmore College, Swarthmore, PA, USA.
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
- Center of Excellence in Environmental Toxicology, University of Pennsylvania, Philadelphia, PA, USA.
- Department of Physics, University of California San Diego, La Jolla, CA, USA.
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Ireland D, Zhang S, Bochenek V, Hsieh JH, Rabeler C, Meyer Z, Collins EMS. Differences in neurotoxic outcomes of organophosphorus pesticides revealed via multi-dimensional screening in adult and regenerating planarians. FRONTIERS IN TOXICOLOGY 2022; 4:948455. [PMID: 36267428 PMCID: PMC9578561 DOI: 10.3389/ftox.2022.948455] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Accepted: 08/25/2022] [Indexed: 11/07/2022] Open
Abstract
Organophosphorus pesticides (OPs) are a chemically diverse class of commonly used insecticides. Epidemiological studies suggest that low dose chronic prenatal and infant exposures can lead to life-long neurological damage and behavioral disorders. While inhibition of acetylcholinesterase (AChE) is the shared mechanism of acute OP neurotoxicity, OP-induced developmental neurotoxicity (DNT) can occur independently and/or in the absence of significant AChE inhibition, implying that OPs affect alternative targets. Moreover, different OPs can cause different adverse outcomes, suggesting that different OPs act through different mechanisms. These findings emphasize the importance of comparative studies of OP toxicity. Freshwater planarians are an invertebrate system that uniquely allows for automated, rapid and inexpensive testing of adult and developing organisms in parallel to differentiate neurotoxicity from DNT. Effects found only in regenerating planarians would be indicative of DNT, whereas shared effects may represent neurotoxicity. We leverage this unique feature of planarians to investigate potential differential effects of OPs on the adult and developing brain by performing a comparative screen to test 7 OPs (acephate, chlorpyrifos, dichlorvos, diazinon, malathion, parathion and profenofos) across 10 concentrations in quarter-log steps. Neurotoxicity was evaluated using a wide range of quantitative morphological and behavioral readouts. AChE activity was measured using an Ellman assay. The toxicological profiles of the 7 OPs differed across the OPs and between adult and regenerating planarians. Toxicological profiles were not correlated with levels of AChE inhibition. Twenty-two "mechanistic control compounds" known to target pathways suggested in the literature to be affected by OPs (cholinergic neurotransmission, serotonin neurotransmission, endocannabinoid system, cytoskeleton, adenyl cyclase and oxidative stress) and 2 negative controls were also screened. When compared with the mechanistic control compounds, the phenotypic profiles of the different OPs separated into distinct clusters. The phenotypic profiles of adult vs. regenerating planarians exposed to the OPs clustered differently, suggesting some developmental-specific mechanisms. These results further support findings in other systems that OPs cause different adverse outcomes in the (developing) brain and build the foundation for future comparative studies focused on delineating the mechanisms of OP neurotoxicity in planarians.
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Affiliation(s)
- Danielle Ireland
- Department of Biology, Swarthmore College, Swarthmore, PA, United States
| | - Siqi Zhang
- Department of Bioengineering, University of California San Diego, La Jolla, CA, United States
| | - Veronica Bochenek
- Department of Biology, Swarthmore College, Swarthmore, PA, United States
| | - Jui-Hua Hsieh
- Division of the National Toxicology Program, National Institute of Environmental Health Sciences, Durham, NC, United States
| | - Christina Rabeler
- Department of Biology, Swarthmore College, Swarthmore, PA, United States
| | - Zane Meyer
- Department of Engineering, Swarthmore College, Swarthmore, PA, United States,Department of Computer Science, Swarthmore College, Swarthmore, PA, United States
| | - Eva-Maria S. Collins
- Department of Biology, Swarthmore College, Swarthmore, PA, United States,Department of Physics and Astronomy, Swarthmore College, Swarthmore, PA, United States,Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States,Center of Excellence in Environmental Toxicology, University of Pennsylvania, Philadelphia, PA, United States,Department of Physics, University of California San Diego, La Jolla, CA, United States,*Correspondence: Eva-Maria S. Collins,
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11
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Reho G, Lelièvre V, Cadiou H. Planarian nociception: Lessons from a scrunching flatworm. Front Mol Neurosci 2022; 15:935918. [PMID: 35959107 PMCID: PMC9362985 DOI: 10.3389/fnmol.2022.935918] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Accepted: 07/08/2022] [Indexed: 11/20/2022] Open
Abstract
In addition to being studied for their exceptional regeneration abilities, planarians (i.e., flatworms) have also been extensively used in the context of pharmacological experiments during the past century. Many researchers used planarians as a model system for the study of drug abuse because they display high similarities with the nervous system of vertebrates at cellular and molecular levels (e.g., neuronal morphology, neurotransmitter ligands, and receptor function). This research field recently led to the discovery of causal relationships between the expression of Transient Receptor Potential ion channels in planarians and their behavioral responses to noxious stimuli such as heat, cold or pharmacological analogs such as TRP agonists, among others. It has also been shown that some antinociceptive drugs modulate these behaviors. However, among the few authors that tried to implement a full behavior analysis, none reached a consensual use of the terms used to describe planarian gaits yet, nor did they establish a comprehensive description of a potential planarian nociceptive system. The aim of this review is therefore to aggregate the ancient and the most recent evidence for a true nociceptive behavior in planarians. It also highlights the convenience and relevance of this invertebrate model for nociceptive tests and suggests further lines of research. In regards to past pharmacological studies, this review finally discusses the opportunities given by the model to extensively screen for novel antinociceptive drugs.
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12
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Majid S, Van Belleghem F, Ploem JP, Wouters A, Blust R, Smeets K. Interactive toxicity of copper and cadmium in regenerating and adult planarians. CHEMOSPHERE 2022; 297:133819. [PMID: 35114265 DOI: 10.1016/j.chemosphere.2022.133819] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2021] [Revised: 12/31/2021] [Accepted: 01/28/2022] [Indexed: 06/14/2023]
Abstract
In a polluted environment, metals are present as complex mixtures. As a result, organisms are exposed to different metals at the same time, which affects both metal-specific as well as overall toxicity. Detailed information about the molecular mechanisms underlying the adverse effects of combined exposures remains limited in terms of different life stages. In this study, the freshwater planarian Schmidtea mediterranea was used to investigate developmental and physiological responses associated with a combined exposure to Cu and Cd. In addition, the cellular and molecular mechanisms underlying the provoked adverse effects were studied in different exposure scenarios. Mixed exposure resulted in a decline in survival, diverse non-lethal morphological changes, neuroregenerative impairments, altered behaviour and a limited repair capacity. Underlying to these effects, the cellular redox state was altered in all exposure conditions. In adult animals, this led to DNA damage and corresponding transcriptional changes in cell cycle and DNA repair genes. In regenerating animals, changes in hydrogen peroxide and glutathione contents led to regenerative defects. Overall, our results demonstrate that (1) developing organisms are more susceptible to metal exposures, and (2) the toxicity of an individual metal increases significantly in a mixed exposure scenario. These aspects have to be included in current risk assessment strategies.
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Affiliation(s)
- Sanah Majid
- Laboratory of Toxicology, Centre for Environmental Sciences (CMK), Hasselt University, Diepenbeek, 3590, Belgium; Systemic Physiological & Eco-toxicological Research (SPHERE), Department of Biology, University of Antwerp, Groenenborgerlaan, 2020, Belgium
| | - Frank Van Belleghem
- Laboratory of Toxicology, Centre for Environmental Sciences (CMK), Hasselt University, Diepenbeek, 3590, Belgium; Department of Environmental Sciences, Faculty of Science, Open University of the Netherlands, Heerlen, 6419, AT, the Netherlands
| | - Jan-Pieter Ploem
- Laboratory of Toxicology, Centre for Environmental Sciences (CMK), Hasselt University, Diepenbeek, 3590, Belgium
| | - Annelies Wouters
- Laboratory of Toxicology, Centre for Environmental Sciences (CMK), Hasselt University, Diepenbeek, 3590, Belgium
| | - Ronny Blust
- Systemic Physiological & Eco-toxicological Research (SPHERE), Department of Biology, University of Antwerp, Groenenborgerlaan, 2020, Belgium
| | - Karen Smeets
- Laboratory of Toxicology, Centre for Environmental Sciences (CMK), Hasselt University, Diepenbeek, 3590, Belgium.
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13
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Transcription Factors Active in the Anterior Blastema of Schmidtea mediterranea. Biomolecules 2021; 11:biom11121782. [PMID: 34944426 PMCID: PMC8698962 DOI: 10.3390/biom11121782] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Revised: 11/22/2021] [Accepted: 11/23/2021] [Indexed: 12/28/2022] Open
Abstract
Regeneration, the restoration of body parts after injury, is quite widespread in the animal kingdom. Species from virtually all Phyla possess regenerative abilities. Human beings, however, are poor regenerators. Yet, the progress of knowledge and technology in the fields of bioengineering, stem cells, and regenerative biology have fostered major advancements in regenerative medical treatments, which aim to regenerate tissues and organs and restore function. Human induced pluripotent stem cells can differentiate into any cell type of the body; however, the structural and cellular complexity of the human tissues, together with the inability of our adult body to control pluripotency, require a better mechanistic understanding. Planarians, with their capacity to regenerate lost body parts thanks to the presence of adult pluripotent stem cells could help providing such an understanding. In this paper, we used a top-down approach to shortlist blastema transcription factors (TFs) active during anterior regeneration. We found 44 TFs—31 of which are novel in planarian—that are expressed in the regenerating blastema. We analyzed the function of half of them and found that they play a role in the regeneration of anterior structures, like the anterior organizer, the positional instruction muscle cells, the brain, the photoreceptor, the intestine. Our findings revealed a glimpse of the complexity of the transcriptional network governing anterior regeneration in planarians, confirming that this animal model is the perfect playground to study in vivo how pluripotency copes with adulthood.
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14
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Brodrick E, Jékely G. Flatworm behaviour: Pieces behaving like wholes. Curr Biol 2021; 31:R1472-R1474. [PMID: 34813750 DOI: 10.1016/j.cub.2021.09.065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Planarians can regenerate from severed body parts. A new study shows that very soon after amputation and before regeneration can happen each piece behaves as a whole organism with distinct responses between head, middle, and tail regions.
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Affiliation(s)
- Emelie Brodrick
- Living Systems Institute, University of Exeter, Stocker Road, Exeter EX4 4QD, UK.
| | - Gáspár Jékely
- Living Systems Institute, University of Exeter, Stocker Road, Exeter EX4 4QD, UK.
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15
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Le D, Sabry Z, Chandra A, Kristan WB, Collins EMS, Kristan WB. Planarian fragments behave as whole animals. Curr Biol 2021; 31:5111-5117.e4. [PMID: 34624209 DOI: 10.1016/j.cub.2021.09.056] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 09/08/2021] [Accepted: 09/22/2021] [Indexed: 12/11/2022]
Abstract
Behavioral responses of freshwater planarians have been studied for over a century.1 In recent decades, behavior has been used as a readout to study planarian development and regeneration,2-6 wound healing,7,8 molecular evolution,4,9,10 neurotoxicology,11-13 and learning and memory.14-17The planarian nervous system is among the simplest of the bilaterally symmetric animals,18 with an anterior brain attached to two ventral nerve cords interconnected by multiple commissures. We found that, in response to mechanical and near-UV stimulation, head stimulation produces turning, tail stimulation produces contraction, and trunk stimulation produces midbody elongation in the planarian Dugesia japonica. When cut into two or three pieces, the anterior end of each headless piece switched its behavior to turning instead of elongation; i.e., it responded as though it were the head. In addition, posterior ends of the head and midbody pieces sometimes produced contraction instead of elongation. Thus, each severed piece acts like an intact animal, with each midbody region having nearly complete behavioral capabilities. These observations show that each midbody region reads the global state of the organism and adapts its response to incoming signals from the remaining tissue. Selective lateral incisions showed that the changes in behavior are not due to nonselective pain responses and that the ventral nerve cords and cross-connectives are responsible for coordinating local behaviors. Our findings highlight a fast functional reorganization of the planarian nervous system that complements the slower repairs provided by regeneration. This reorganization provides needed behavioral responses for survival as regeneration proceeds.
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Affiliation(s)
- Dylan Le
- Section of Neurobiology, Division of Biological Sciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Ziad Sabry
- Department of Biology, Swarthmore College, 500 College Avenue, Swarthmore, PA 19081, USA
| | - Aarav Chandra
- The Bishop's School, 7607 La Jolla Boulevard, La Jolla, CA 92037, USA
| | - William B Kristan
- Department of Biological Sciences, California State University San Marcos, 333 South Twin Oaks Valley Road, San Marcos, CA 92096, USA
| | - Eva-Maria S Collins
- Department of Biology, Swarthmore College, 500 College Avenue, Swarthmore, PA 19081, USA; Department of Physics and Astronomy, 500 College Avenue, Swarthmore College, Swarthmore, PA 19081, USA; Department of Physics, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA; Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, 415 Curie Boulevard, Philadelphia, PA, USA.
| | - William B Kristan
- Section of Neurobiology, Division of Biological Sciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA.
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16
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Morris J, Bealer EJ, Souza IDS, Repmann L, Bonelli H, Stanzione JF, Staehle MM. Chemical Exposure-Induced Developmental Neurotoxicity in Head-Regenerating Schmidtea Mediterranea. Toxicol Sci 2021; 185:220-231. [PMID: 34791476 DOI: 10.1093/toxsci/kfab132] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The growing number of commercially-used chemicals that are under-evaluated for developmental neurotoxicity (DNT) combined with the difficulty in describing the etiology of exposure-related neurodevelopmental toxicity has created a reticent threat to human health. Current means of screening chemicals for DNT are limited to expensive, time-consuming, and labor-intensive traditional laboratory animal models. In this study, we hypothesize that exposed head regenerating planarian flatworms can effectively and efficiently categorize DNT in known developmental neurotoxins (ethanol and bisphenol A (BPA)). Planarian flatworms are an established alternative animal model for neurodevelopmental studies and have remarkable regenerative abilities allowing neurodevelopment to be induced via head resection. Here, we observed changes in photophobic behavior and central nervous system (CNS) morphology to evaluate the impact of exposure to low concentrations of ethanol, BPA, and BPA industry alternatives bisphenol F (BPF), and bisguaiacol (BG) on neurodevelopment. Our studies show that exposure to 1% v/v ethanol during regeneration induces a recoverable 48-hour delay in the development of proper CNS integrity, which aligns with behavioral assessments of cognitive ability. Exposure to BPA and its alternatives induced deviations to neurodevelopment in a range of severities, distinguished by suppressions, delays, or a combination of the two. These results suggest that quick and inexpensive behavioral assessments are a viable surrogate for tedious and costly immunostaining studies, equipping more utility and resolution to the planarian model for neurodevelopmental toxicity in the future of mass chemical screening. These studies demonstrate that behavioral phenotypes observed following chemical exposure are classifiable and also temporally correlated to the anatomical development of the central nervous system in planaria. This will facilitate and accelerate toxicological screening assays with this alternative animal model.
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Affiliation(s)
- J Morris
- Department of Biomedical Engineering, Rowan University, Glassboro, NJ
| | - E J Bealer
- Department of Biomedical Engineering, Rowan University, Glassboro, NJ
| | - I D S Souza
- Department of Chemical Engineering, Rowan University, Glassboro, NJ
| | - L Repmann
- Department of Biomedical Engineering, Rowan University, Glassboro, NJ
| | - H Bonelli
- Department of Biomedical Engineering, Rowan University, Glassboro, NJ
| | - J F Stanzione
- Department of Chemical Engineering, Rowan University, Glassboro, NJ
| | - M M Staehle
- Department of Biomedical Engineering, Rowan University, Glassboro, NJ
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17
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Dong Z, Huo J, Liang A, Chen J, Chen G, Liu D. Gamma-Secretase Inhibitor (DAPT), a potential therapeutic target drug, caused neurotoxicity in planarian regeneration by inhibiting Notch signaling pathway. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 781:146735. [PMID: 33812110 DOI: 10.1016/j.scitotenv.2021.146735] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/25/2020] [Revised: 02/28/2021] [Accepted: 03/21/2021] [Indexed: 06/12/2023]
Abstract
DAPT (N-[N-(3, 5-difluorophenacetyl)-l-alanyl]-s-phenylglycinet-butyl ester) is a γ-secretase inhibitor that indirectly blocks the activity of Notch pathway. It is a potential therapeutic target drug for many diseases, such as cancer, neurological, cardiovascular, and cerebrovascular diseases. However, the pharmacological action and specific mechanisms of DAPT are not clear. Planarians have strong regenerative capacity and can regenerate a new individual with a complete nervous system in one week. Thus, they are used as an ideal indicator of environmental toxicants and a novel model for studying neurodevelopmental toxicology. In this study, different concentrations and treatment times of DAPT are used to analyze the gene expression levels of major components in Notch pathway. The results show that the optimal concentration and exposure time of DAPT is 100 nM for 10 days in planarians and indicate that the inhibitory of DAPT treatment on Notch pathway is time- and concentration-dependent. The potential impact of DAPT is effectively analyzed by qPCR, WISH, and Immunofluorescence. The results indicate that DAPT exposure causes intact planarian wavy or swollen, and regenerative planarians asymmetric growth or muti-eye. Moreover, DAPT exposure increases cell proliferation and apoptosis, results in neurodevelopmental defects and dynamic changes of some marker genes. These results suggest that the balance of proliferation and apoptosis is disturbed, and then, affecting tissue homeostasis and differentiation. These findings demonstrate that DAPT has serious side effects in organisms and relies on Notch pathway to determine cell fate, it is cautious in the use of DAPT as a potential therapeutic approach for the disease in clinical trials.
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Affiliation(s)
- Zimei Dong
- College of Life Science, Henan Normal University, Xinxiang 453007, Henan, China
| | - Jinrui Huo
- College of Life Science, Henan Normal University, Xinxiang 453007, Henan, China
| | - Ang Liang
- College of Life Science, Henan Normal University, Xinxiang 453007, Henan, China
| | - Jinzi Chen
- College of Life Science, Henan Normal University, Xinxiang 453007, Henan, China
| | - Guangwen Chen
- College of Life Science, Henan Normal University, Xinxiang 453007, Henan, China.
| | - Dezeng Liu
- College of Life Science, Henan Normal University, Xinxiang 453007, Henan, China.
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18
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Grosbusch AL, Bertemes P, Egger B. The serotonergic nervous system of prolecithophorans shows a closer similarity to fecampiids than to triclads (Platyhelminthes). J Morphol 2021; 282:574-587. [PMID: 33569841 PMCID: PMC7986211 DOI: 10.1002/jmor.21332] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 02/03/2021] [Accepted: 02/06/2021] [Indexed: 11/11/2022]
Abstract
Prolecithophora is a poorly studied flatworm order belonging to the adiaphanidan clade, together with Tricladida and Fecampiida. The phylogenetic position of the three orders within this clade is not yet resolved. Additionally, no obvious synapomorphy other than an opaque epidermis could be found so far. In this study, the serotonergic nervous system of six different prolecithophoran species has been studied for the first time with a fluorescent immunocytochemical technique. We found that all six species show a similar pattern of the serotonergic nervous system. The typical prolecithophoran serotonergic nervous system consists of a cephalic ganglion in the anterior body part from which a pair of dorsal, ventral, and lateral longitudinal nerve cords originate. Furthermore, the three longitudinal nerve cords of one body side are connected to each other at the posterior body part by a conspicuous commissure. The ventral cords, which we consider the main cords, are most prominent and show double brain roots. A comparison of the nervous system within Adiaphanida shows clearly that prolecithophorans and fecampiids are much more similar in this regard than prolecithophorans and triclads.
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Affiliation(s)
- Alexandra L. Grosbusch
- Research Unit, Evolutionary Developmental BiologyInstitute of Zoology, University of InnsbruckInnsbruckAustria
| | - Philip Bertemes
- Research Unit, Evolutionary Developmental BiologyInstitute of Zoology, University of InnsbruckInnsbruckAustria
| | - Bernhard Egger
- Research Unit, Evolutionary Developmental BiologyInstitute of Zoology, University of InnsbruckInnsbruckAustria
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19
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Abstract
Freshwater planarians are free-living flatworms known for their regenerative ability. Being easily cultured under laboratory conditions, they are recognized test model organisms in regeneration, developmental biology, and neuropharmacological research. Also, they have been recently employed in toxicity testing where they displayed an array of sensitive and reliable responses to environmental stressors. Here, we outline simple and easy-to-follow protocols to evaluate effects of environmental contaminants and other stressors on survival, behavior (feeding and locomotor activity), and regeneration of freshwater planarians. These endpoints are comparable with responses of well-established ecotoxicological model species.
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Affiliation(s)
| | - Pearl Ugochi Ofoegbu
- Department of Biology & CESAM, University of Aveiro, Aveiro, Portugal
- Department of Biology, Federal University of Technology Owerri, Owerri, Nigeria
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20
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A novel RhoA-related gene, DjRhoA, contributes to the regeneration of brain and intestine in planarian Dugesia japonica. Biochem Biophys Res Commun 2020; 533:1359-1365. [PMID: 33059921 DOI: 10.1016/j.bbrc.2020.10.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Accepted: 10/08/2020] [Indexed: 11/23/2022]
Abstract
A small GTPase, RhoA, plays a variety of functions in the regulation of cellular and developmental events via its downstream effectors, including cytokinesis, cell migration, and phagocytosis. In this study, a novel RhoA-related gene from the planarian Dugesia japonica, DjRhoA, was cloned and characterized. The full-length cDNA of DjRhoA is 869 bp, and the open reading frame encodes a poly-peptide of 194 amino acids. Phylogenetic analysis revealed that DjRhoA clustered with another RhoA-related protein, DjRho2, and located on the base of phylogenetic tree. Whole-mount in situ hybridization results indicated that DjRhoA was expressed in the brain primordia and intestine during regeneration. Knockdown of DjRhoA induces defects in the brain and intestine. These results suggested that DjRhoA was responsible for the regeneration of brain and intestine in Dugesia japonica.
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21
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Zhen H, Deng H, Song Q, Zheng M, Yuan Z, Cao Z, Pang Q, Zhao B. The Wnt/Ca 2+ signaling pathway is essential for the regeneration of GABAergic neurons in planarian Dugesia japonica. FASEB J 2020; 34:16567-16580. [PMID: 33094857 DOI: 10.1096/fj.201903040rr] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 09/17/2020] [Accepted: 10/13/2020] [Indexed: 11/11/2022]
Abstract
The growth and differentiation of neurons are critical events in the establishment of proper neuron connectivity and function. Planarians have a remarkable ability to completely regenerate a functional nervous system from a pluripotent stem cell population. Thus, planarians provide a powerful model to identify genes required for neuronal differentiation in vivo. The Wnt/Ca2+ signaling pathway is crucial for cancer development, arousing inflammatory responses, and neurodegeneration. We analyzed the expression patterns and RNAi phenotypes for members of the Wnt/Ca2+ signaling pathway in the planarian, Dugesia japonica. The expression of DjWnt5a, DjPLC-β, DjCamKII, and DjCaln during regeneration was surprisingly similar and revealing in the regenerated brain. RNAi knockdown of DjWnt5a, DjPLC-β, DjCamKII, and DjCaln led to defects in regenerated brains including brain partial deletions, incompact phenotypes at the posterior of the new brain, and lateral branches, which could not regenerate. Furthermore, the expressions of GAD and the number of GABAergic neurons decreased. Together, these results suggest that the Wnt/Ca2+ signaling pathway is required for GABAergic neuron regeneration.
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Affiliation(s)
- Hui Zhen
- Laboratory of Developmental and Evolutionary Biology, Shandong University of Technology, Shandong, China
| | - Hongkuan Deng
- Laboratory of Developmental and Evolutionary Biology, Shandong University of Technology, Shandong, China.,School of Life Sciences, Shandong University of Technology, Shandong, China
| | - Qian Song
- Laboratory of Developmental and Evolutionary Biology, Shandong University of Technology, Shandong, China
| | - Mingyue Zheng
- College of Marine Life Sciences, Ocean University of China, Qingdao, China
| | - Zuoqing Yuan
- Laboratory of Developmental and Evolutionary Biology, Shandong University of Technology, Shandong, China.,School of Life Sciences, Shandong University of Technology, Shandong, China
| | - Zhonghong Cao
- Laboratory of Developmental and Evolutionary Biology, Shandong University of Technology, Shandong, China.,School of Life Sciences, Shandong University of Technology, Shandong, China
| | - Qiuxiang Pang
- School of Life Sciences, Shandong University of Technology, Shandong, China
| | - Bosheng Zhao
- Laboratory of Developmental and Evolutionary Biology, Shandong University of Technology, Shandong, China
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22
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Zhang J, Shao X, Zhao B, Zhai L, Liu N, Gong F, Ma X, Pan X, Zhao B, Yuan Z, Zhang X. Neurotoxicity of perfluorooctanoic acid and post-exposure recovery due to blueberry anthocyanins in the planarians Dugesia japonica. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2020; 263:114471. [PMID: 32268227 DOI: 10.1016/j.envpol.2020.114471] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 03/13/2020] [Accepted: 03/25/2020] [Indexed: 06/11/2023]
Abstract
Perfluorooctanoic acid (PFOA) is a widely used synthetic industrial chemical which accumulates in ecosystems and organisms. Our study have investigated the neurobehavioral effects of PFOA and the alleviation effects of PFOA-induced neurotoxicity by blueberry anthocyanins (ANT) in Dugesia japonica. The planarians were exposed to PFOA and ANT for ten days. Researchs showed that exposure to PFOA affected locomotor behavior and ANT significantly alleviated the reduction in locomotion induced by PFOA. The regeneration of eyespots and auricles was suppressed by PFOA and was promoted by ANT. Following exposure to PFOA, acetylcholinesterase activity continually decreased and was unaffected in the ANT group, but was elevated after combined administration of PFOA and ANT. Oxidative DNA damage was found in planarians exposed to PFOA and was attenuated after administration of ANT by the alkaline comet assay. Concentrations of three neurotransmitters increased following exposure to PFOA and decreased after administration of ANT. Furthermore, ANT promoted and PFOA inhibited neuronal regeneration. DjotxA, DjotxB, DjFoxG, DjFoxD and Djnlg associated with neural processes were up-regulated following exposure to PFOA. Our findings indicate that PFOA is a neurotoxicant while ANT can attenuate these detrimental effects.
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Affiliation(s)
- Jianyong Zhang
- School of Life Sciences, Shandong University of Technology, Zibo, Shandong, 255000, China.
| | - Xinxin Shao
- School of Life Sciences, Shandong University of Technology, Zibo, Shandong, 255000, China.
| | - Baoying Zhao
- School of Life Sciences, Shandong University of Technology, Zibo, Shandong, 255000, China.
| | - Liming Zhai
- School of Life Sciences, Shandong University of Technology, Zibo, Shandong, 255000, China.
| | - Na Liu
- School of Life Sciences, Shandong University of Technology, Zibo, Shandong, 255000, China.
| | - Fangbin Gong
- School of Life Sciences, Shandong University of Technology, Zibo, Shandong, 255000, China.
| | - Xue Ma
- School of Life Sciences, Shandong University of Technology, Zibo, Shandong, 255000, China.
| | - Xiaolu Pan
- School of Life Sciences, Shandong University of Technology, Zibo, Shandong, 255000, China.
| | - Bosheng Zhao
- School of Life Sciences, Shandong University of Technology, Zibo, Shandong, 255000, China.
| | - Zuoqing Yuan
- School of Life Sciences, Shandong University of Technology, Zibo, Shandong, 255000, China.
| | - Xiufang Zhang
- School of Life Sciences, Shandong University of Technology, Zibo, Shandong, 255000, China.
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23
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Abstract
One of the most important aspects of the scientific endeavour is the definition of specific concepts as precisely as possible. However, it is also important not to lose sight of two facts: (i) we divide the study of nature into manageable parts in order to better understand it owing to our limited cognitive capacities and (ii) definitions are inherently arbitrary and heavily influenced by cultural norms, language, the current political climate, and even personal preferences, among many other factors. As a consequence of these facts, clear-cut definitions, despite their evident importance, are oftentimes quite difficult to formulate. One of the most illustrative examples about the difficulty of articulating precise scientific definitions is trying to define the concept of a brain. Even though the current thinking about the brain is beginning to take into account a variety of organisms, a vertebrocentric bias still tends to dominate the scientific discourse about this concept. Here I will briefly explore the evolution of our 'thoughts about the brain', highlighting the difficulty of constructing a universally (or even a generally) accepted formal definition of it and using planarians as one of the earliest examples of organisms proposed to possess a 'traditional', vertebrate-style brain. I also suggest that the time is right to attempt to expand our view of what a brain is, going beyond exclusively structural and taxa-specific criteria. Thus, I propose a classification that could represent a starting point in an effort to expand our current definitions of the brain, hopefully to help initiate conversations leading to changes of perspective on how we think about this concept. This article is part of the theme issue 'Liquid brains, solid brains: How distributed cognitive architectures process information'.
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Affiliation(s)
- Oné R Pagán
- Department of Biology, West Chester University , West Chester, PA 19383 , USA
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24
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Zhang S, Hagstrom D, Hayes P, Graham A, Collins EMS. Multi-Behavioral Endpoint Testing of an 87-Chemical Compound Library in Freshwater Planarians. Toxicol Sci 2019; 167:26-44. [PMID: 29893936 DOI: 10.1093/toxsci/kfy145] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
There is an increased recognition in the field of toxicology of the value of medium-to-high-throughput screening methods using in vitro and alternative animal models. We have previously introduced the asexual freshwater planarian Dugesia japonica as a new alternative animal model and proposed that it is particularly well-suited for the study of developmental neurotoxicology. In this article, we discuss how we have expanded and automated our screening methodology to allow for fast screening of multiple behavioral endpoints, developmental toxicity, and mortality. Using an 87-compound library provided by the National Toxicology Program, consisting of known and suspected neurotoxicants, including drugs, flame retardants, industrial chemicals, polycyclic aromatic hydrocarbons (PAHs), pesticides, and presumptive negative controls, we further evaluate the benefits and limitations of the system for medium-throughput screening, focusing on the technical aspects of the system. We show that, in the context of this library, planarians are the most sensitive to pesticides with 16/16 compounds causing toxicity and the least sensitive to PAHs, with only 5/17 causing toxicity. Furthermore, while none of the presumptive negative controls were bioactive in adult planarians, 2/5, acetaminophen and acetylsalicylic acid, were bioactive in regenerating worms. Notably, these compounds were previously reported as developmentally toxic in mammalian studies. Through parallel screening of adults and developing animals, planarians are thus a useful model to detect such developmental-specific effects, which was observed for 13 chemicals in this library. We use the data and experience gained from this screen to propose guidelines for best practices when using planarians for toxicology screens.
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Affiliation(s)
| | | | | | | | - Eva-Maria S Collins
- Division of Cell and Developmental Biology.,Department of Physics, University of California San Diego, La Jolla California 92093.,Department of Biology, Swarthmore College, Swarthmore, Pennsylvania 19081
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25
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Ivankovic M, Haneckova R, Thommen A, Grohme MA, Vila-Farré M, Werner S, Rink JC. Model systems for regeneration: planarians. Development 2019; 146:146/17/dev167684. [PMID: 31511248 DOI: 10.1242/dev.167684] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Planarians are a group of flatworms. Some planarian species have remarkable regenerative abilities, which involve abundant pluripotent adult stem cells. This makes these worms a powerful model system for understanding the molecular and evolutionary underpinnings of regeneration. By providing a succinct overview of planarian taxonomy, anatomy, available tools and the molecular orchestration of regeneration, this Primer aims to showcase both the unique assets and the questions that can be addressed with this model system.
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Affiliation(s)
- Mario Ivankovic
- Max Planck Institute for Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Radmila Haneckova
- Max Planck Institute for Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany.,Department of Tissue Dynamics and Regeneration, Max Planck Institute for Biophysical Chemistry, am Fassberg 11, 37077 Göttingen, Germany
| | - Albert Thommen
- Max Planck Institute for Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany.,The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Markus A Grohme
- Max Planck Institute for Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Miquel Vila-Farré
- Max Planck Institute for Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany.,Department of Tissue Dynamics and Regeneration, Max Planck Institute for Biophysical Chemistry, am Fassberg 11, 37077 Göttingen, Germany
| | - Steffen Werner
- FOM Institute AMOLF, Department of Systems Biology, Science Park 104, 1098 XG, Amsterdam, The Netherlands
| | - Jochen C Rink
- Max Planck Institute for Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany .,Department of Tissue Dynamics and Regeneration, Max Planck Institute for Biophysical Chemistry, am Fassberg 11, 37077 Göttingen, Germany
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26
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Shao X, Zhao B, Wang B, Zhao B, Zhu Y, Yuan Z, Zhang J. Neuroprotective effects of blueberry anthocyanins against perfluorooctanoic sulfonate on planarian Dugesia japonica. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2019; 175:39-47. [PMID: 30884343 DOI: 10.1016/j.ecoenv.2019.03.023] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 03/04/2019] [Accepted: 03/06/2019] [Indexed: 06/09/2023]
Abstract
In this study, the planarian Dugesia japonica was exposed to perfluorooctane sulfonate (PFOS) and blueberry anthocyanins (ANT) for 1-10 days to investigate the protective effects of ANT on neurotoxicity and DNA damage induced by PFOS. The expression of neural related genes (Djnlg, DjFoxD, DjFoxG, DjotxA, and DjotxB) in D. japonica following exposure was determined using quantitative real-time PCR (qPCR). Immunofluorescence was performed to determine the alterations in neural morphology. In addition, ELISA kits were used to measure level of the neurotransmitters Dopamine (DA), serotonin (5-HT) and γ-aminobutyric acid (GABA). Furthermore, single cell gel electrophoresis was measured to analyze DNA damage. In this study, PFOS treatment induced neural morphology defects, alterations in neural-related gene expression, alterations in neurotransmitter levels, and DNA damage. However, co-exposure to ANT and PFOS mitigated the damage to D. japonica induced by PFOS. Restoration of neurotransmitter contents and neural related genes expression were observed in planarians following co-application of ANT and PFOS, immunofluorescence showed that nerve morphology almost recovered, and DNA damage was decreased. The results of this study showed that ANT may have a protective effect against PFOS induced neurotoxicity and DNA damage.
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Affiliation(s)
- Xinxin Shao
- School of Life Sciences, Shandong University of Technology, No. 266 Xincun West Road, 255000 Zibo, Shandong, China
| | - Baoying Zhao
- School of Life Sciences, Shandong University of Technology, No. 266 Xincun West Road, 255000 Zibo, Shandong, China
| | - Bin Wang
- School of Life Sciences, Shandong University of Technology, No. 266 Xincun West Road, 255000 Zibo, Shandong, China
| | - Bosheng Zhao
- School of Life Sciences, Shandong University of Technology, No. 266 Xincun West Road, 255000 Zibo, Shandong, China
| | - Yi Zhu
- School of Life Sciences, Shandong University of Technology, No. 266 Xincun West Road, 255000 Zibo, Shandong, China
| | - Zuoqing Yuan
- School of Life Sciences, Shandong University of Technology, No. 266 Xincun West Road, 255000 Zibo, Shandong, China.
| | - Jianyong Zhang
- School of Life Sciences, Shandong University of Technology, No. 266 Xincun West Road, 255000 Zibo, Shandong, China.
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Zhang S, Ireland D, Sipes NS, Behl M, Collins EMS. Screening for neurotoxic potential of 15 flame retardants using freshwater planarians. Neurotoxicol Teratol 2019; 73:54-66. [PMID: 30943442 DOI: 10.1016/j.ntt.2019.03.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Revised: 03/22/2019] [Accepted: 03/25/2019] [Indexed: 10/27/2022]
Abstract
Asexual freshwater planarians are an attractive invertebrate model for high-throughput neurotoxicity screening, because they possess multiple quantifiable behaviors to assess distinct neuronal functions. Planarians uniquely allow direct comparisons between developing and adult animals to distinguish developmentally selective effects from general neurotoxicity. In this study, we used our automated planarian screening platform to compare the neurotoxicity of 15 flame retardants (FRs), consisting of representative phased-out brominated (BFRs) and replacement organophosphorus FRs (OPFRs). OPFRs have emerged as a proposed safer alternative to BFRs; however, limited information is available on their health effects. We found 11 of the 15 FRs (3/6 BFRs, 7/8 OPFRs, and Firemaster 550) caused adverse effects in both adult and developing planarians with similar nominal lowest-effect-levels for BFRs and OPFRs. This suggests that replacement OPFRs are comparably neurotoxic to the phased-out compounds. BFRs were primarily systemically toxic, whereas OPFRs, except Tris(2-chloroethyl) phosphate, shared a behavioral phenotype in response to noxious heat at sublethal concentrations, indicating specific neurotoxic effects. We found this behavioral phenotype was correlated with cholinesterase inhibition, thus linking behavioral outcomes to molecular targets. By directly comparing effects on adult and developing planarians, we further found that one BFR (3,3',5,5'-Tetrabromobisphenol A) caused a developmental selective defect. Together, these results demonstrate that our planarian screening platform yields high content data from various behavioral and morphological endpoints, allowing us to distinguish selective neurotoxic effects and effects specific to the developing nervous system. Ten of these 11 bioactive FRs were previously found to be bioactive in other models, including cell culture and alternative animal models (nematodes and zebrafish). This level of concordance across different platforms emphasizes the urgent need for further evaluation of OPFRs in mammalian systems.
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Affiliation(s)
- Siqi Zhang
- Department of Bioengineering, University of California San Diego, La Jolla, CA 92093, USA
| | - Danielle Ireland
- Division of Cell and Developmental Biology, University of California San Diego, La Jolla, CA 92093, USA; Department of Biology, Swarthmore College Swarthmore, PA 19081, USA
| | - Nisha S Sipes
- Division of the National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, NC, 27709, USA
| | - Mamta Behl
- Division of the National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, NC, 27709, USA
| | - Eva-Maria S Collins
- Division of Cell and Developmental Biology, University of California San Diego, La Jolla, CA 92093, USA; Department of Physics, University of California San Diego, La Jolla, CA 92093, USA; Department of Biology, Swarthmore College Swarthmore, PA 19081, USA.
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Durant F, Bischof J, Fields C, Morokuma J, LaPalme J, Hoi A, Levin M. The Role of Early Bioelectric Signals in the Regeneration of Planarian Anterior/Posterior Polarity. Biophys J 2019; 116:948-961. [PMID: 30799071 DOI: 10.1016/j.bpj.2019.01.029] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Revised: 01/11/2019] [Accepted: 01/16/2019] [Indexed: 01/14/2023] Open
Abstract
Axial patterning during planarian regeneration relies on a transcriptional circuit that confers distinct positional information on the two ends of an amputated fragment. The earliest known elements of this system begin demarcating differences between anterior and posterior wounds by 6 h postamputation. However, it is still unknown what upstream events break the axial symmetry, allowing a mutual repressor system to establish invariant, distinct biochemical states at the anterior and posterior ends. Here, we show that bioelectric signaling at 3 h is crucial for the formation of proper anterior-posterior polarity in planaria. Briefly manipulating the endogenous bioelectric state by depolarizing the injured tissue during the first 3 h of regeneration alters gene expression by 6 h postamputation and leads to a double-headed phenotype upon regeneration despite confirmed washout of ionophores from tissue. These data reveal a primary functional role for resting membrane potential taking place within the first 3 h after injury and kick-starting the downstream pattern of events that elaborate anatomy over the following 10 days. We propose a simple model of molecular-genetic mechanisms to explain how physiological events taking place immediately after injury regulate the spatial distribution of downstream gene expression and anatomy of regenerating planaria.
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Affiliation(s)
- Fallon Durant
- Allen Discovery Center at Tufts University, Department of Biology, Tufts University, Medford, Massachusetts
| | - Johanna Bischof
- Allen Discovery Center at Tufts University, Department of Biology, Tufts University, Medford, Massachusetts
| | - Chris Fields
- Allen Discovery Center at Tufts University, Department of Biology, Tufts University, Medford, Massachusetts
| | - Junji Morokuma
- Allen Discovery Center at Tufts University, Department of Biology, Tufts University, Medford, Massachusetts
| | - Joshua LaPalme
- Allen Discovery Center at Tufts University, Department of Biology, Tufts University, Medford, Massachusetts
| | - Alison Hoi
- Allen Discovery Center at Tufts University, Department of Biology, Tufts University, Medford, Massachusetts
| | - Michael Levin
- Allen Discovery Center at Tufts University, Department of Biology, Tufts University, Medford, Massachusetts.
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Hagstrom D, Truong L, Zhang S, Tanguay R, Collins EMS. Comparative Analysis of Zebrafish and Planarian Model Systems for Developmental Neurotoxicity Screens Using an 87-Compound Library. Toxicol Sci 2019; 167:15-25. [PMID: 30011007 PMCID: PMC6317421 DOI: 10.1093/toxsci/kfy180] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
There is a clear need to establish and validate new methodologies to more quickly and efficiently screen chemicals for potential toxic effects, particularly on development. The emergence of alternative animal systems for rapid toxicology screens presents valuable opportunities to evaluate how systems complement each other. In this article, we compare a chemical library of 87-compounds in 2 such systems, developing zebrafish and freshwater planarians, by screening for developmental neurotoxic effects. We show that the systems' toxicological profiles are complementary to each other, with zebrafish yielding more detailed morphological endpoints and planarians more behavioral endpoints. Overall, zebrafish was more sensitive to this chemical library, yielding 86/87 hits, compared with 50/87 hits in planarians. The difference in sensitivity could not be attributed to molecular weight, log Kow, or the bioconcentration factor. Of the 87 chemicals, 28 had previously been evaluated in mammalian developmental neuro- (DNT), neuro-, or developmental toxicity studies. Of the 28, 20 were hits in the planarian, and 27 were hits in zebrafish. Eighteen of the 28 had previously been identified as DNT hits in mammals and were highly associated with activity in zebrafish and planarian behavioral assays in this study. Only 1 chemical (of 28) was a false negative in both zebrafish and planarian systems. The differences in endpoint coverage and system sensitivity illustrate the value of a dual systems approach to rapidly query a large chemical-bioactivity space and provide weight-of-evidence for prioritization of chemicals for further testing.
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Affiliation(s)
- Danielle Hagstrom
- Division of Cell and Developmental Biology, University of California San Diego, La Jolla, California 92093
| | - Lisa Truong
- Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, Oregon 97331
| | | | - Robert Tanguay
- Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, Oregon 97331
| | - Eva-Maria S Collins
- Division of Cell and Developmental Biology, University of California San Diego, La Jolla, California 92093
- Department of Physics, University of California San Diego, La Jolla, California 92093
- Department of Biology, Swarthmore College, Swarthmore, Pennsylvania 19081
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30
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Walker SE, Spencer GE, Necakov A, Carlone RL. Identification and Characterization of microRNAs during Retinoic Acid-Induced Regeneration of a Molluscan Central Nervous System. Int J Mol Sci 2018; 19:E2741. [PMID: 30217012 PMCID: PMC6163488 DOI: 10.3390/ijms19092741] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Revised: 09/06/2018] [Accepted: 09/08/2018] [Indexed: 12/11/2022] Open
Abstract
Retinoic acid (RA) is the biologically active metabolite of vitamin A and has become a well-established factor that induces neurite outgrowth and regeneration in both vertebrates and invertebrates. However, the underlying regulatory mechanisms that may mediate RA-induced neurite sprouting remain unclear. In the past decade, microRNAs have emerged as important regulators of nervous system development and regeneration, and have been shown to contribute to processes such as neurite sprouting. However, few studies have demonstrated the role of miRNAs in RA-induced neurite sprouting. By miRNA sequencing analysis, we identify 482 miRNAs in the regenerating central nervous system (CNS) of the mollusc Lymnaeastagnalis, 219 of which represent potentially novel miRNAs. Of the remaining conserved miRNAs, 38 show a statistically significant up- or downregulation in regenerating CNS as a result of RA treatment. We further characterized the expression of one neuronally-enriched miRNA upregulated by RA, miR-124. We demonstrate, for the first time, that miR-124 is expressed within the cell bodies and neurites of regenerating motorneurons. Moreover, we identify miR-124 expression within the growth cones of cultured ciliary motorneurons (pedal A), whereas expression in the growth cones of another class of respiratory motorneurons (right parietal A) was absent in vitro. These findings support our hypothesis that miRNAs are important regulators of retinoic acid-induced neuronal outgrowth and regeneration in regeneration-competent species.
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Affiliation(s)
- Sarah E Walker
- Department of Biological Sciences, Brock University, St. Catharines, ON L2S 3A1, Canada.
| | - Gaynor E Spencer
- Department of Biological Sciences, Brock University, St. Catharines, ON L2S 3A1, Canada.
| | - Aleksandar Necakov
- Department of Biological Sciences, Brock University, St. Catharines, ON L2S 3A1, Canada.
| | - Robert L Carlone
- Department of Biological Sciences, Brock University, St. Catharines, ON L2S 3A1, Canada.
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31
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Yuan Z, Shao X, Miao Z, Zhao B, Zheng Z, Zhang J. Perfluorooctane sulfonate induced neurotoxicity responses associated with neural genes expression, neurotransmitter levels and acetylcholinesterase activity in planarians Dugesia japonica. CHEMOSPHERE 2018; 206:150-156. [PMID: 29738904 DOI: 10.1016/j.chemosphere.2018.05.011] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Revised: 04/30/2018] [Accepted: 05/02/2018] [Indexed: 06/08/2023]
Abstract
As a persistent and widespread toxic organic pollutant in the environment, perfluorooctane sulfonate (PFOS) has the potential to cause great harm to wildlife. In our study, the effects of PFOS on neurodevelopment gene expression, neurotransmitter content, neuronal morphology, acetylcholinesterase (AChE) activity were examined, and the potential neurotoxicity mechanisms of PFOS were also investigated in planarians, Dugesia japonica. Using quantitative real-time PCR analysis, five neurodevelopmental related genes were measured, among which, DjotxA, DjotxB, DjFoxD, and DjFoxG were found to be down-regulated, while Djnlg was found to be up-regulated, following exposure to PFOS for 10 days compared with control groups. In addition, the neurotransmitters including dopamine, serotonin, and γ-aminobutyricacid as well as the acitivity of AChE were altered by PFOS exposure. Furthermore, PFOS exposure altered brain morphology as well as smaller cephalic ganglia which displayed reduced nerve fiber density decreased brain branches compared to controls. Our results demonstrate that neurotransmission was disturbed after exposure to PFOS and that exposure to this pollutant can cause neurotoxic defects. Results from this study provide valuable information regarding the neuro- and ecological toxicity of PFOS in aquatic animals and aquatic environments.
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Affiliation(s)
- Zuoqing Yuan
- School of Life Sciences, Shandong University of Technology, No. 266 Xincun West Road, Zibo 255000, China
| | - Xinxin Shao
- School of Life Sciences, Shandong University of Technology, No. 266 Xincun West Road, Zibo 255000, China
| | - Zili Miao
- School of Life Sciences, Shandong University of Technology, No. 266 Xincun West Road, Zibo 255000, China
| | - Bosheng Zhao
- School of Life Sciences, Shandong University of Technology, No. 266 Xincun West Road, Zibo 255000, China
| | - Ziyang Zheng
- School of Life Sciences, Shandong University of Technology, No. 266 Xincun West Road, Zibo 255000, China
| | - Jianyong Zhang
- School of Life Sciences, Shandong University of Technology, No. 266 Xincun West Road, Zibo 255000, China.
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32
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Felix DA, Gutiérrez-Gutiérrez Ó, Espada L, Thems A, González-Estévez C. It is not all about regeneration: Planarians striking power to stand starvation. Semin Cell Dev Biol 2018; 87:169-181. [PMID: 29705301 DOI: 10.1016/j.semcdb.2018.04.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Revised: 04/11/2018] [Accepted: 04/25/2018] [Indexed: 12/12/2022]
Abstract
All living forms, prokaryotes as eukaryotes, have some means of adaptation to food scarcity, which extends the survival chances under extreme environmental conditions. Nowadays we know that dietary interventions, including fasting, extends lifespan of many organisms and can also protect against age-related diseases including in humans. Therefore, the capacity of adapting to periods of food scarcity may have evolved billions of years ago not only to allow immediate organismal survival but also to be able to extend organismal lifespan or at least to lead to a healthier remaining lifespan. Planarians have been the center of attention since more than two centuries because of their astonishing power of full body regeneration that relies on a large amount of adult stem cells or neoblasts. However, they also present an often-overlooked characteristic. They are able to stand long time starvation. Planarians have adapted to periods of fasting by shrinking or degrowing. Here we will review the published data about starvation in planarians and conclude with the possibility of starvation being one of the processes that rejuvenate the planarian, thus explaining the historical notion of non-ageing planarians.
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Affiliation(s)
- Daniel A Felix
- Leibniz Institute on Aging - Fritz Lipmann Institute (FLI), Beutenbergstraße 11, 07745 Jena, Germany
| | - Óscar Gutiérrez-Gutiérrez
- Leibniz Institute on Aging - Fritz Lipmann Institute (FLI), Beutenbergstraße 11, 07745 Jena, Germany
| | - Lilia Espada
- Leibniz Institute on Aging - Fritz Lipmann Institute (FLI), Beutenbergstraße 11, 07745 Jena, Germany
| | - Anne Thems
- Leibniz Institute on Aging - Fritz Lipmann Institute (FLI), Beutenbergstraße 11, 07745 Jena, Germany
| | - Cristina González-Estévez
- Leibniz Institute on Aging - Fritz Lipmann Institute (FLI), Beutenbergstraße 11, 07745 Jena, Germany.
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33
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Insight into stem cell regulation from sub-lethally irradiated worms. Gene 2018; 662:37-45. [PMID: 29627527 DOI: 10.1016/j.gene.2018.04.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Revised: 03/24/2018] [Accepted: 04/05/2018] [Indexed: 12/30/2022]
Abstract
Despite the significant advances in the comprehension of stem cell control network, the nature of extrinsic signals regulating their dynamic remains to be understood. In this paper, we take advantage of the stem cell repopulation process that follows low-dose X-ray treatment in planarians to identify genes, preferentially enriched in differentiated cells, whose expression is activated during the process. Genetic silencing of some of them impaired the stem cell repopulation, suggesting a tight extrinsic control of stem cell activity.
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34
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Castillo-Lara S, Abril JF. PlanNET: homology-based predicted interactome for multiple planarian transcriptomes. Bioinformatics 2018; 34:1016-1023. [PMID: 29186384 PMCID: PMC5860622 DOI: 10.1093/bioinformatics/btx738] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Revised: 10/24/2017] [Accepted: 11/23/2017] [Indexed: 01/30/2023] Open
Abstract
Motivation Planarians are emerging as a model organism to study regeneration in animals. However, the little available data of protein-protein interactions hinders the advances in understanding the mechanisms underlying its regenerating capabilities. Results We have developed a protocol to predict protein-protein interactions using sequence homology data and a reference Human interactome. This methodology was applied on 11 Schmidtea mediterranea transcriptomic sequence datasets. Then, using Neo4j as our database manager, we developed PlanNET, a web application to explore the multiplicity of networks and the associated sequence annotations. By mapping RNA-seq expression experiments onto the predicted networks, and allowing a transcript-centric exploration of the planarian interactome, we provide researchers with a useful tool to analyse possible pathways and to design new experiments, as well as a reproducible methodology to predict, store, and explore protein interaction networks for non-model organisms. Availability and implementation The web application PlanNET is available at https://compgen.bio.ub.edu/PlanNET. The source code used is available at https://compgen.bio.ub.edu/PlanNET/downloads. Contact jabril@ub.edu. Supplementary information Supplementary data are available at Bioinformatics online.
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Affiliation(s)
- S Castillo-Lara
- Computational Genomics Laboratory, Genetics, Microbiology and Statistics Department, Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Catalonia, Spain
| | - J F Abril
- Computational Genomics Laboratory, Genetics, Microbiology and Statistics Department, Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Catalonia, Spain
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35
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Rossi L, Salvetti A. Planarian stem cell niche, the challenge for understanding tissue regeneration. Semin Cell Dev Biol 2018. [PMID: 29534938 DOI: 10.1016/j.semcdb.2018.03.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Stem cell fate depends on surrounding microenvironment, the so called niche. For this reason, understanding stem cell niche is one of the most challenging target in cell biology field and need to be unraveled with in vivo studies. Planarians offer this unique opportunity, as their stem cells, the neoblasts, are abundant, highly characterized and genetically modifiable by RNA interference in alive animals. However, despite impressive advances have been done in the understanding planarian stem cells and regeneration, only a few information is available in defining signals from differentiated tissues, which affect neoblast stemness and fate. Here, we review on molecular factors that have been found activated in differentiated tissues and directly or indirectly affect neoblast behavior, and we suggest future directions for unravelling this challenge in understanding planarian stem cells.
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Affiliation(s)
- Leonardo Rossi
- Departement of Clinical and Experimental Medicine, Unit of Experimental Biology and Genetics, University of Pisa, Via Volta 4 Pisa, Italy
| | - Alessandra Salvetti
- Departement of Clinical and Experimental Medicine, Unit of Experimental Biology and Genetics, University of Pisa, Via Volta 4 Pisa, Italy.
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36
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Stamatis SA, Worsaae K, Garm A. Regeneration of the Rhopalium and the Rhopalial Nervous System in the Box Jellyfish Tripedalia cystophora. THE BIOLOGICAL BULLETIN 2018; 234:22-36. [PMID: 29694798 DOI: 10.1086/697071] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Cubozoans have the most intricate visual apparatus within Cnidaria. It comprises four identical sensory structures, the rhopalia, each of which holds six eyes of four morphological types. Two of these eyes are camera-type eyes that are, in many ways, similar to the vertebrate eye. The visual input is used to control complex behaviors, such as navigation and obstacle avoidance, and is processed by an elaborate rhopalial nervous system. Several studies have examined the rhopalial nervous system, which, despite a radial symmetric body plan, is bilaterally symmetrical, connecting the two sides of the rhopalium through commissures in an extensive neuropil. The four rhopalia are interconnected by a nerve ring situated in the oral margin of the bell, and together these structures constitute the cubozoan central nervous system. Cnidarians have excellent regenerative capabilities, enabling most species to regenerate large body areas or body parts, and some species can regenerate completely from just a few hundred cells. Here we test whether cubozoans are capable of regenerating the rhopalia, despite the complexity of the visual system and the rhopalial nervous system. The results show that the rhopalia are readily regrown after amputation and have developed most, if not all, neural elements within two weeks. Using electrophysiology, we investigated the functionality of the regrown rhopalia and found that they generated pacemaker signals and that the lens eyes showed a normal response to light. Our findings substantiate the amazing regenerative ability in Cnidaria by showing here the complex sensory system of Cubozoa, a model system proving to be highly applicable in studies of neurogenesis.
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Key Words
- CNS, central nervous system
- DAPI, 4′,6-diamidino-2-phenylindole
- EdU, 5-ethynyl-2′-deoxyuridine
- FMRF-LIR, FMRFamide-like immunoreactive
- I-cells, interstitial cells
- PFA, paraformaldehyde
- PNS, peripheral nervous system
- RF-LIR, RFamide-like immunoreactive
- RNS, rhopalial nervous system
- α-tubulin LIR, α-tubulin-like immunoreactions
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37
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Brown DDR, Molinaro AM, Pearson BJ. The planarian TCF/LEF factor Smed-tcf1 is required for the regeneration of dorsal-lateral neuronal subtypes. Dev Biol 2017; 433:374-383. [PMID: 29291981 DOI: 10.1016/j.ydbio.2017.08.024] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2017] [Revised: 08/18/2017] [Accepted: 08/21/2017] [Indexed: 10/18/2022]
Abstract
The adult brain of the planarian Schmidtea mediterranea (a freshwater flatworm) is a dynamic structure with constant cell turnover as well as the ability to completely regenerate de novo. Despite this, function and pattern is achieved in a reproducible manner from individual to individual in terms of the correct spatial and temporal production of specific neuronal subtypes. Although several signaling molecules have been found to be key to scaling and cell turnover, the mechanisms by which specific neural subtypes are specified remain largely unknown. Here we performed a 6 day RNAseq time course on planarians that were regenerating either 0, 1, or 2 heads in order to identify novel regulators of brain regeneration. Focusing on transcription factors, we identified a TCF/LEF factor, Smed-tcf1, which was required to correctly pattern the dorsal-lateral cell types of the regenerating brain. The most severely affected neurons in Smed-tcf1(RNAi) animals were the dorsal GABAergic neurons, which failed to regenerate, leading to an inability of the animals to phototaxis away from light. Together, Smed-tcf1 is a critical regulator, required to pattern the dorsal-lateral region of the regenerating planarian brain.
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Affiliation(s)
- David D R Brown
- Hospital for Sick Children, Program in Developmental and Stem Cell Biology, Toronto, ON, Canada M5G0A4; Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada M5G0A4
| | - Alyssa M Molinaro
- Hospital for Sick Children, Program in Developmental and Stem Cell Biology, Toronto, ON, Canada M5G0A4; Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada M5G0A4
| | - Bret J Pearson
- Hospital for Sick Children, Program in Developmental and Stem Cell Biology, Toronto, ON, Canada M5G0A4; Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada M5G0A4; Ontario Institute for Cancer Research, Toronto, ON, Canada M5G0A4.
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38
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Yang X, Kaj KJ, Schwab DJ, Collins EMS. Coordination of size-control, reproduction and generational memory in freshwater planarians. Phys Biol 2017; 14:036003. [PMID: 28467318 DOI: 10.1088/1478-3975/aa70c4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Uncovering the mechanisms that control size, growth, and division rates of organisms reproducing through binary division means understanding basic principles of their life cycle. Recent work has focused on how division rates are regulated in bacteria and yeast, but this question has not yet been addressed in more complex, multicellular organisms. We have, over the course of several years, assembled a unique large-scale data set on the growth and asexual reproduction of two freshwater planarian species, Dugesia japonica and Girardia tigrina, which reproduce by transverse fission and succeeding regeneration of head and tail pieces into new planarians. We show that generation-dependent memory effects in planarian reproduction need to be taken into account to accurately capture the experimental data. To achieve this, we developed a new additive model that mixes multiple size control strategies based on planarian size, growth, and time between divisions. Our model quantifies the proportions of each strategy in the mixed dynamics, revealing the ability of the two planarian species to utilize different strategies in a coordinated manner for size control. Additionally, we found that head and tail offspring of both species employ different mechanisms to monitor and trigger their reproduction cycles. Thus, we find a diversity of strategies not only between species but between heads and tails within species. Our additive model provides two advantages over existing 2D models that fit a multivariable splitting rate function to the data for size control: firstly, it can be fit to relatively small data sets and can thus be applied to systems where available data is limited. Secondly, it enables new biological insights because it explicitly shows the contributions of different size control strategies for each offspring type.
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Affiliation(s)
- Xingbo Yang
- Department of Physics and Astronomy, Northwestern University, Evanston, IL, United States of America. These authors contributed equally to this work
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Brown DDR, Pearson BJ. A Brain Unfixed: Unlimited Neurogenesis and Regeneration of the Adult Planarian Nervous System. Front Neurosci 2017; 11:289. [PMID: 28588444 PMCID: PMC5441136 DOI: 10.3389/fnins.2017.00289] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Accepted: 05/08/2017] [Indexed: 11/25/2022] Open
Abstract
Powerful genetic tools in classical laboratory models have been fundamental to our understanding of how stem cells give rise to complex neural tissues during embryonic development. In contrast, adult neurogenesis in our model systems, if present, is typically constrained to one or a few zones of the adult brain to produce a limited subset of neurons leading to the dogma that the brain is primarily fixed post-development. The freshwater planarian (flatworm) is an invertebrate model system that challenges this dogma. The planarian possesses a brain containing several thousand neurons with very high rates of cell turnover (homeostasis), which can also be fully regenerated de novo from injury in just 7 days. Both homeostasis and regeneration depend on the activity of a large population of adult stem cells, called neoblasts, throughout the planarian body. Thus, much effort has been put forth to understand how the flatworm can continually give rise to the diversity of cell types found in the adult brain. Here we focus on work using single-cell genomics and functional analyses to unravel the cellular hierarchies from stem cell to neuron. In addition, we will review what is known about how planarians utilize developmental signaling to maintain proper tissue patterning, homeostasis, and cell-type diversity in their brains. Together, planarians are a powerful emerging model system to study the dynamics of adult neurogenesis and regeneration.
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Affiliation(s)
- David D R Brown
- Program in Developmental and Stem Cell Biology, The Hospital for Sick ChildrenToronto, ON, Canada.,Department of Molecular Genetics, University of TorontoToronto, ON, Canada
| | - Bret J Pearson
- Program in Developmental and Stem Cell Biology, The Hospital for Sick ChildrenToronto, ON, Canada.,Department of Molecular Genetics, University of TorontoToronto, ON, Canada.,Ontario Institute for Cancer ResearchToronto, ON, Canada
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Wu S, Liu B, Yuan Z, Zhang X, Liu H, Pang Q, Zhao B. Planarian homolog of puromycin-sensitive aminopeptidase DjPsa is required for brain regeneration. INVERTEBRATE NEUROSCIENCE 2017; 17:3. [PMID: 28324191 DOI: 10.1007/s10158-017-0196-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Accepted: 03/10/2017] [Indexed: 12/19/2022]
Abstract
Puromycin-sensitive aminopeptidase (PSA) belongs to the M1 zinc metallopeptidase family. PSA is the most abundant aminopeptidase in the brain and plays a role in the metabolism of neuropeptides including those involved in neurodegeneration. A cDNA DjPsa was identified from the planarian Dugesia japonica cDNA library. It contains a 639-bp open reading frame corresponding to a deduced protein of 212 amino acids. Whole mount in situ hybridization revealed that DjPsa is expressed in the brain and ventral nerve cords of intact and regenerating animals and demonstrates a tissue and stage-specific expression pattern of DjPsa in developing embryos and larvae. Knocking down DjPsa gene expression with RNA interference during planarian regeneration inhibits the brain reformation completely. The results suggest that DjPsa is required for planarian brain regeneration.
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Affiliation(s)
- Suge Wu
- Laboratory of Developmental and Evolutionary Biology, Shandong University of Technology, Zibo, 255049, People's Republic of China
| | - Bin Liu
- Laboratory of Developmental and Evolutionary Biology, Shandong University of Technology, Zibo, 255049, People's Republic of China
| | - Zuoqing Yuan
- Laboratory of Developmental and Evolutionary Biology, Shandong University of Technology, Zibo, 255049, People's Republic of China.,School of Life Sciences, Shandong University of Technology, 266 Xincun Western Road, Zibo, 255049, People's Republic of China
| | - Xiufang Zhang
- Laboratory of Developmental and Evolutionary Biology, Shandong University of Technology, Zibo, 255049, People's Republic of China.,School of Life Sciences, Shandong University of Technology, 266 Xincun Western Road, Zibo, 255049, People's Republic of China
| | - Hong Liu
- School of Life Sciences, Shandong University of Technology, 266 Xincun Western Road, Zibo, 255049, People's Republic of China
| | - Qiuxiang Pang
- Laboratory of Developmental and Evolutionary Biology, Shandong University of Technology, Zibo, 255049, People's Republic of China.,School of Life Sciences, Shandong University of Technology, 266 Xincun Western Road, Zibo, 255049, People's Republic of China
| | - Bosheng Zhao
- Laboratory of Developmental and Evolutionary Biology, Shandong University of Technology, Zibo, 255049, People's Republic of China. .,School of Life Sciences, Shandong University of Technology, 266 Xincun Western Road, Zibo, 255049, People's Republic of China.
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Currie KW, Molinaro AM, Pearson BJ. Neuronal sources of hedgehog modulate neurogenesis in the adult planarian brain. eLife 2016; 5:19735. [PMID: 27864883 PMCID: PMC5153250 DOI: 10.7554/elife.19735] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2016] [Accepted: 11/18/2016] [Indexed: 12/13/2022] Open
Abstract
The asexual freshwater planarian is a constitutive adult, whose central nervous system (CNS) is in a state of constant homeostatic neurogenesis. However, very little is known about the extrinsic signals that act on planarian stem cells to modulate rates of neurogenesis. We have identified two planarian homeobox transcription factors, Smed-nkx2.1 and Smed-arx, which are required for the maintenance of cholinergic, GABAergic, and octopaminergic neurons in the planarian CNS. These very same neurons also produce the planarian hedgehog ligand (Smed-hh), which appears to communicate with brain-adjacent stem cells to promote normal levels of neurogenesis. Planarian stem cells nearby the brain express core hh signal transduction genes, and consistent hh signaling levels are required to maintain normal production of neural progenitor cells and new mature cholinergic neurons, revealing an important mitogenic role for the planarian hh signaling molecule in the adult CNS. DOI:http://dx.doi.org/10.7554/eLife.19735.001 Most animals can continue to generate and add new neurons in their nervous system into adulthood, though the process is often tightly regulated. In adult humans, only a small number of neurons are made or lost, such that the fewer than 2% of the neurons in the nervous will change over, or “turnover”, the course of a year. The turnover of neurons in some other animals is much higher than it is in humans. A freshwater flatworm, called Schmidtea mediterranea, is one example of such an animal that can even regenerate an entirely new brain if its head is decapitated. These flatworms have a large population of adult stem cells, which makes these high rates of neuron production and regeneration possible. However, it is largely unknown if this population contains stem cells that can only become new neurons, in other words “dedicated neuronal stem cells”. Moreover, it is also not clear what kinds of signals communicate with these stem cells to promote the production of new neurons. In animals from flies to humans, a signaling molecule encoded by a gene called hedgehog forms part of a signaling pathway that can promote neuron production during development. Therefore, Currie et al. asked if the hedgehog signaling molecule might communicate with the stem cells in adult flatworms to control how many new neurons they produce. The experiments revealed that the hedgehog signaling molecule is almost exclusively produced by the flatworm’s brain and the pair of nerve cords that run the length of the flatworm. Currie et al. then found a smaller group of cells close to the flatworm’s brain that looked like dedicated neural stem cells. These cells can receive the hedgehog signals, and further experiments showed that flatworm’s brain requires hedgehog signaling to be able to produce new neurons at its normal level. The hedgehog signaling molecule is likely only one of many signaling molecules that regulate the production of new neurons in flatworms. It will be important to uncover these additional signals and understand how they work in concert. In the future, a better understanding of this process will help efforts to devise ways to induce humans to replace neurons that are lost following injury or neurodegenerative diseases. DOI:http://dx.doi.org/10.7554/eLife.19735.002
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Affiliation(s)
- Ko W Currie
- Program in Developmental and Stem Cell Biology, Hospital for Sick Children, Toronto, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, Canada
| | - Alyssa M Molinaro
- Program in Developmental and Stem Cell Biology, Hospital for Sick Children, Toronto, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, Canada
| | - Bret J Pearson
- Program in Developmental and Stem Cell Biology, Hospital for Sick Children, Toronto, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, Canada.,Ontario Institute for Cancer Research, Toronto, Canada
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Chan JD, Zhang D, Liu X, Zarowiecki M, Berriman M, Marchant JS. Utilizing the planarian voltage-gated ion channel transcriptome to resolve a role for a Ca 2+ channel in neuromuscular function and regeneration. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1864:1036-1045. [PMID: 27771293 DOI: 10.1016/j.bbamcr.2016.10.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Revised: 10/13/2016] [Accepted: 10/17/2016] [Indexed: 12/22/2022]
Abstract
The robust regenerative capacity of planarian flatworms depends on the orchestration of signaling events from early wounding responses through the stem cell enacted differentiative outcomes that restore appropriate tissue types. Acute signaling events in excitable cells play an important role in determining regenerative polarity, rationalized by the discovery that sub-epidermal muscle cells express critical patterning genes known to control regenerative outcomes. These data imply a dual conductive (neuromuscular signaling) and instructive (anterior-posterior patterning) role for Ca2+ signaling in planarian regeneration. Here, to facilitate study of acute signaling events in the excitable cell niche, we provide a de novo transcriptome assembly from the planarian Dugesia japonica allowing characterization of the diverse ionotropic portfolio of this model organism. We demonstrate the utility of this resource by proceeding to characterize the individual role of each of the planarian voltage-operated Ca2+ channels during regeneration, and demonstrate that knockdown of a specific voltage operated Ca2+ channel (Cav1B) that impairs muscle function uniquely creates an environment permissive for anteriorization. Provision of the full transcriptomic dataset should facilitate further investigations of molecules within the planarian voltage-gated channel portfolio to explore the role of excitable cell physiology on regenerative outcomes. This article is part of a Special Issue entitled: ECS Meeting edited by Claus Heizmann, Joachim Krebs and Jacques Haiech.
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Affiliation(s)
- John D Chan
- Department of Pharmacology, University of Minnesota Medical School, MN 55455, United States
| | - Dan Zhang
- Department of Pharmacology, University of Minnesota Medical School, MN 55455, United States
| | - Xiaolong Liu
- Department of Pharmacology, University of Minnesota Medical School, MN 55455, United States
| | - Magdalena Zarowiecki
- Parasite Genomics Group, Wellcome Trust Sanger Institute, Hinxton, United Kingdom
| | - Matthew Berriman
- Parasite Genomics Group, Wellcome Trust Sanger Institute, Hinxton, United Kingdom
| | - Jonathan S Marchant
- Department of Pharmacology, University of Minnesota Medical School, MN 55455, United States; The Stem Cell Institute, University of Minnesota Medical School, MN 55455, United States.
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Cochet-Escartin O, Carter JA, Chakraverti-Wuerthwein M, Sinha J, Collins EMS. Slo1 regulates ethanol-induced scrunching in freshwater planarians. Phys Biol 2016; 13:055001. [DOI: 10.1088/1478-3975/13/5/055001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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Molinaro AM, Pearson BJ. In silico lineage tracing through single cell transcriptomics identifies a neural stem cell population in planarians. Genome Biol 2016; 17:87. [PMID: 27150006 PMCID: PMC4858873 DOI: 10.1186/s13059-016-0937-9] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Accepted: 04/08/2016] [Indexed: 12/01/2022] Open
Abstract
Background The planarian Schmidtea mediterranea is a master regenerator with a large adult stem cell compartment. The lack of transgenic labeling techniques in this animal has hindered the study of lineage progression and has made understanding the mechanisms of tissue regeneration a challenge. However, recent advances in single-cell transcriptomics and analysis methods allow for the discovery of novel cell lineages as differentiation progresses from stem cell to terminally differentiated cell. Results Here we apply pseudotime analysis and single-cell transcriptomics to identify adult stem cells belonging to specific cellular lineages and identify novel candidate genes for future in vivo lineage studies. We purify 168 single stem and progeny cells from the planarian head, which were subjected to single-cell RNA sequencing (scRNAseq). Pseudotime analysis with Waterfall and gene set enrichment analysis predicts a molecularly distinct neoblast sub-population with neural character (νNeoblasts) as well as a novel alternative lineage. Using the predicted νNeoblast markers, we demonstrate that a novel proliferative stem cell population exists adjacent to the brain. Conclusions scRNAseq coupled with in silico lineage analysis offers a new approach for studying lineage progression in planarians. The lineages identified here are extracted from a highly heterogeneous dataset with minimal prior knowledge of planarian lineages, demonstrating that lineage purification by transgenic labeling is not a prerequisite for this approach. The identification of the νNeoblast lineage demonstrates the usefulness of the planarian system for computationally predicting cellular lineages in an adult context coupled with in vivo verification. Electronic supplementary material The online version of this article (doi:10.1186/s13059-016-0937-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Alyssa M Molinaro
- Hospital for Sick Children, Program in Developmental and Stem Cell Biology, Toronto, ON, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Bret J Pearson
- Hospital for Sick Children, Program in Developmental and Stem Cell Biology, Toronto, ON, Canada. .,Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada. .,Ontario Institute for Cancer Research, Toronto, ON, M5G0A4, Canada.
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Hagstrom D, Cochet-Escartin O, Collins EMS. Planarian brain regeneration as a model system for developmental neurotoxicology. ACTA ACUST UNITED AC 2016; 3:65-77. [PMID: 27499880 PMCID: PMC4895328 DOI: 10.1002/reg2.52] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Revised: 01/14/2016] [Accepted: 01/18/2016] [Indexed: 12/12/2022]
Abstract
Freshwater planarians, famous for their regenerative prowess, have long been recognized as a valuable in vivo animal model to study the effects of chemical exposure. In this review, we summarize the current techniques and tools used in the literature to assess toxicity in the planarian system. We focus on the planarian's particular amenability for neurotoxicology and neuroregeneration studies, owing to the planarian's unique ability to regenerate a centralized nervous system. Zooming in from the organismal to the molecular level, we show that planarians offer a repertoire of morphological and behavioral readouts while also being amenable to mechanistic studies of compound toxicity. Finally, we discuss the open challenges and opportunities for planarian brain regeneration to become an important model system for modern toxicology.
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Affiliation(s)
- Danielle Hagstrom
- Division of Biological Sciences University of California San Diego, La Jolla California 92093 USA
| | | | - Eva-Maria S Collins
- Division of Biological Sciences University of California San Diego, La Jolla California 92093 USA; Department of Physics University of California San Diego, La Jolla California 92093 USA
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Bezerra da Silva C, Pott A, Elifio-Esposito S, Dalarmi L, Fialho do Nascimento K, Moura Burci L, de Oliveira M, de Fátima Gaspari Dias J, Warumby Zanin SM, Gomes Miguel O, Dallarmi Miguel M. Effect of Donepezil, Tacrine, Galantamine and Rivastigmine on Acetylcholinesterase Inhibition in Dugesia tigrina. Molecules 2016; 21:53. [PMID: 26760993 PMCID: PMC6273381 DOI: 10.3390/molecules21010053] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2015] [Revised: 07/26/2015] [Accepted: 09/15/2015] [Indexed: 01/02/2023] Open
Abstract
Dugesia tigrina is a non-parasitic platyhelminth, which has been recently utilized in pharmacological models, regarding the nervous system, as it presents a wide sensitivity to drugs. Our trials aimed to propose a model for an in vivo screening of substances with inhibitory activity of the enzyme acetylcholinesterase. Trials were performed with four drugs commercialized in Brazil: donepezil, tacrine, galantamine and rivastigmine, utilized in the control of Alzheimer's disease, to inhibit the activity of acetylcholinesterase. We tested five concentrations of the drugs, with an exposure of 24 h, and the mortality and the inhibition of acetylcholinesterase planarian seizure-like activity (pSLA) and planarian locomotor velocity (pLMV) were measured. Galantamine showed high anticholinesterasic activity when compared to the other drugs, with a reduction of 0.05 μmol·min(-1) and 63% of convulsant activity, presenting screw-like movement and hypokinesia, with pLMV of 65 crossed lines during 5 min. Our results showed for the first time the anticholinesterasic and convulsant effect, in addition to the decrease in locomotion induced by those drugs in a model of invertebrates. The experimental model proposed is simple and low cost and could be utilized in the screening of substances with anticholinesterasic action.
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Affiliation(s)
- Cristiane Bezerra da Silva
- Department of Pharmacy, Federal University of Paraná (UFPR), Av. Pref. Lothário Meissner 3400, Jardim Botânico, Curitiba 80210-170, Brazil.
| | - Arnildo Pott
- Department of Biology, Federal University of Mato Grosso do Sul (UFMS), Av. Senador Filinto Müller, Campo Grande 79046-460, Brazil.
| | - Selene Elifio-Esposito
- Post-Graduation in Health Sciences, Pontíficia Universidade Católica do Paraná, Imaculada Conceição, 1155, Prado Velho, Curitiba 80215-901, Brazil.
| | - Luciane Dalarmi
- Department of Pharmacy, Federal University of Paraná (UFPR), Av. Pref. Lothário Meissner 3400, Jardim Botânico, Curitiba 80210-170, Brazil.
| | - Kátia Fialho do Nascimento
- Department of Celular Biology, Federal University of Paraná (UFPR), Centro Politécnico, Jardim das Américas, Curitiba 81530-900, Brazil.
| | - Ligia Moura Burci
- Department of Pharmacy, Federal University of Paraná (UFPR), Av. Pref. Lothário Meissner 3400, Jardim Botânico, Curitiba 80210-170, Brazil.
| | - Maislian de Oliveira
- Department of Pharmacy, Federal University of Paraná (UFPR), Av. Pref. Lothário Meissner 3400, Jardim Botânico, Curitiba 80210-170, Brazil.
| | - Josiane de Fátima Gaspari Dias
- Department of Pharmacy, Federal University of Paraná (UFPR), Av. Pref. Lothário Meissner 3400, Jardim Botânico, Curitiba 80210-170, Brazil.
| | - Sandra Maria Warumby Zanin
- Department of Pharmacy, Federal University of Paraná (UFPR), Av. Pref. Lothário Meissner 3400, Jardim Botânico, Curitiba 80210-170, Brazil.
| | - Obdulio Gomes Miguel
- Department of Pharmacy, Federal University of Paraná (UFPR), Av. Pref. Lothário Meissner 3400, Jardim Botânico, Curitiba 80210-170, Brazil.
| | - Marilis Dallarmi Miguel
- Department of Pharmacy, Federal University of Paraná (UFPR), Av. Pref. Lothário Meissner 3400, Jardim Botânico, Curitiba 80210-170, Brazil.
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Emmons-Bell M, Durant F, Hammelman J, Bessonov N, Volpert V, Morokuma J, Pinet K, Adams DS, Pietak A, Lobo D, Levin M. Gap Junctional Blockade Stochastically Induces Different Species-Specific Head Anatomies in Genetically Wild-Type Girardia dorotocephala Flatworms. Int J Mol Sci 2015; 16:27865-96. [PMID: 26610482 PMCID: PMC4661923 DOI: 10.3390/ijms161126065] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2015] [Revised: 11/06/2015] [Accepted: 11/10/2015] [Indexed: 12/13/2022] Open
Abstract
The shape of an animal body plan is constructed from protein components encoded by the genome. However, bioelectric networks composed of many cell types have their own intrinsic dynamics, and can drive distinct morphological outcomes during embryogenesis and regeneration. Planarian flatworms are a popular system for exploring body plan patterning due to their regenerative capacity, but despite considerable molecular information regarding stem cell differentiation and basic axial patterning, very little is known about how distinct head shapes are produced. Here, we show that after decapitation in G. dorotocephala, a transient perturbation of physiological connectivity among cells (using the gap junction blocker octanol) can result in regenerated heads with quite different shapes, stochastically matching other known species of planaria (S. mediterranea, D. japonica, and P. felina). We use morphometric analysis to quantify the ability of physiological network perturbations to induce different species-specific head shapes from the same genome. Moreover, we present a computational agent-based model of cell and physical dynamics during regeneration that quantitatively reproduces the observed shape changes. Morphological alterations induced in a genomically wild-type G. dorotocephala during regeneration include not only the shape of the head but also the morphology of the brain, the characteristic distribution of adult stem cells (neoblasts), and the bioelectric gradients of resting potential within the anterior tissues. Interestingly, the shape change is not permanent; after regeneration is complete, intact animals remodel back to G. dorotocephala-appropriate head shape within several weeks in a secondary phase of remodeling following initial complete regeneration. We present a conceptual model to guide future work to delineate the molecular mechanisms by which bioelectric networks stochastically select among a small set of discrete head morphologies. Taken together, these data and analyses shed light on important physiological modifiers of morphological information in dictating species-specific shape, and reveal them to be a novel instructive input into head patterning in regenerating planaria.
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Affiliation(s)
- Maya Emmons-Bell
- Center for Regenerative and Developmental Biology and Department of Biology, Tufts University, 200 Boston Avenue, Suite 4600, Medford, MA 02155, USA; (M.E.-B.); (F.D.); (J.H.); (J.M.); (K.P.); (D.S.A.)
| | - Fallon Durant
- Center for Regenerative and Developmental Biology and Department of Biology, Tufts University, 200 Boston Avenue, Suite 4600, Medford, MA 02155, USA; (M.E.-B.); (F.D.); (J.H.); (J.M.); (K.P.); (D.S.A.)
| | - Jennifer Hammelman
- Center for Regenerative and Developmental Biology and Department of Biology, Tufts University, 200 Boston Avenue, Suite 4600, Medford, MA 02155, USA; (M.E.-B.); (F.D.); (J.H.); (J.M.); (K.P.); (D.S.A.)
| | - Nicholas Bessonov
- Institute of Problems of Mechanical Engineering, Russian Academy of Sciences, Saint Petersburg 199178, Russia;
| | - Vitaly Volpert
- Institut Camille Jordan, UMR 5208 CNRS, University Lyon 1, Villeurbanne 69622, France;
| | - Junji Morokuma
- Center for Regenerative and Developmental Biology and Department of Biology, Tufts University, 200 Boston Avenue, Suite 4600, Medford, MA 02155, USA; (M.E.-B.); (F.D.); (J.H.); (J.M.); (K.P.); (D.S.A.)
| | - Kaylinnette Pinet
- Center for Regenerative and Developmental Biology and Department of Biology, Tufts University, 200 Boston Avenue, Suite 4600, Medford, MA 02155, USA; (M.E.-B.); (F.D.); (J.H.); (J.M.); (K.P.); (D.S.A.)
| | - Dany S. Adams
- Center for Regenerative and Developmental Biology and Department of Biology, Tufts University, 200 Boston Avenue, Suite 4600, Medford, MA 02155, USA; (M.E.-B.); (F.D.); (J.H.); (J.M.); (K.P.); (D.S.A.)
| | | | - Daniel Lobo
- Department of Biological Sciences, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA;
| | - Michael Levin
- Center for Regenerative and Developmental Biology and Department of Biology, Tufts University, 200 Boston Avenue, Suite 4600, Medford, MA 02155, USA; (M.E.-B.); (F.D.); (J.H.); (J.M.); (K.P.); (D.S.A.)
- Correspondence: ; Tel.: +1-617-627-6161; Fax: +1-617-627-6121
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48
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Hill EM, Petersen CP. Wnt/Notum spatial feedback inhibition controls neoblast differentiation to regulate reversible growth of the planarian brain. Development 2015; 142:4217-29. [PMID: 26525673 DOI: 10.1242/dev.123612] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Accepted: 10/27/2015] [Indexed: 12/20/2022]
Abstract
Mechanisms determining final organ size are poorly understood. Animals undergoing regeneration or ongoing adult growth are likely to require sustained and robust mechanisms to achieve and maintain appropriate sizes. Planarians, well known for their ability to undergo whole-body regeneration using pluripotent adult stem cells of the neoblast population, can reversibly scale body size over an order of magnitude by controlling cell number. Using quantitative analysis, we showed that after injury planarians perfectly restored brain:body proportion by increasing brain cell number through epimorphosis or decreasing brain cell number through tissue remodeling (morphallaxis), as appropriate. We identified a pathway controlling a brain size set-point that involves feedback inhibition between wnt11-6/wntA/wnt4a and notum, encoding conserved antagonistic signaling factors expressed at opposite brain poles. wnt11-6/wntA/wnt4a undergoes feedback inhibition through canonical Wnt signaling but is likely to regulate brain size in a non-canonical pathway independently of beta-catenin-1 and APC. Wnt/Notum signaling tunes numbers of differentiated brain cells in regenerative growth and tissue remodeling by influencing the abundance of brain progenitors descended from pluripotent stem cells, as opposed to regulating cell death. These results suggest that the attainment of final organ size might be accomplished by achieving a balance of positional signaling inputs that regulate the rates of tissue production.
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Affiliation(s)
- Eric M Hill
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA
| | - Christian P Petersen
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA Robert Lurie Comprehensive Cancer Center, Northwestern University, Evanston, IL 60208, USA
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49
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Hagstrom D, Cochet-Escartin O, Zhang S, Khuu C, Collins EMS. Freshwater Planarians as an Alternative Animal Model for Neurotoxicology. Toxicol Sci 2015; 147:270-85. [PMID: 26116028 PMCID: PMC4838007 DOI: 10.1093/toxsci/kfv129] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Traditional toxicology testing has relied on low-throughput, expensive mammalian studies; however, timely testing of the large number of environmental toxicants requires new in vitro and in vivo platforms for inexpensive medium- to high-throughput screening. Herein, we describe the suitability of the asexual freshwater planarian Dugesia japonica as a new animal model for the study of developmental neurotoxicology. As these asexual animals reproduce by binary fission, followed by regeneration of missing body structures within approximately 1 week, development and regeneration occur through similar processes allowing us to induce neurodevelopment "at will" through amputation. This short time scale and the comparable sizes of full and regenerating animals enable parallel experiments in adults and developing worms to determine development-specific aspects of toxicity. Because the planarian brain, despite its simplicity, is structurally and molecularly similar to the mammalian brain, we are able to ascertain neurodevelopmental toxicity that is relevant to humans. As a proof of concept, we developed a 5-step semiautomatic screening platform to characterize the toxicity of 9 known neurotoxicants (consisting of common solvents, pesticides, and detergents) and a neutral agent, glucose, and quantified effects on viability, stimulated and unstimulated behavior, regeneration, and brain structure. Comparisons of our findings with other alternative toxicology animal models, such as zebrafish larvae and nematodes, demonstrated that planarians are comparably sensitive to the tested chemicals. In addition, we found that certain compounds induced adverse effects specifically in developing animals. We thus conclude that planarians offer new complementary opportunities for developmental neurotoxicology animal models.
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Affiliation(s)
- Danielle Hagstrom
- *Division of Biological Sciences, University of California, San Diego, La Jolla, California 92093
| | | | - Siqi Zhang
- Department of Bioengineering, University of California, San Diego, La Jolla, California 92093
| | - Cindy Khuu
- *Division of Biological Sciences, University of California, San Diego, La Jolla, California 92093
| | - Eva-Maria S Collins
- *Division of Biological Sciences, University of California, San Diego, La Jolla, California 92093; Physics Department, University of California, San Diego, La Jolla, California 92093; and
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Zhu SJ, Hallows SE, Currie KW, Xu C, Pearson BJ. A mex3 homolog is required for differentiation during planarian stem cell lineage development. eLife 2015; 4. [PMID: 26114597 PMCID: PMC4507787 DOI: 10.7554/elife.07025] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2015] [Accepted: 06/25/2015] [Indexed: 12/30/2022] Open
Abstract
Neoblasts are adult stem cells (ASCs) in planarians that sustain cell replacement during homeostasis and regeneration of any missing tissue. While numerous studies have examined genes underlying neoblast pluripotency, molecular pathways driving postmitotic fates remain poorly defined. In this study, we used transcriptional profiling of irradiation-sensitive and irradiation-insensitive cell populations and RNA interference (RNAi) functional screening to uncover markers and regulators of postmitotic progeny. We identified 32 new markers distinguishing two main epithelial progenitor populations and a planarian homolog to the MEX3 RNA-binding protein (Smed-mex3-1) as a key regulator of lineage progression. mex3-1 was required for generating differentiated cells of multiple lineages, while restricting the size of the stem cell compartment. We also demonstrated the utility of using mex3-1(RNAi) animals to identify additional progenitor markers. These results identified mex3-1 as a cell fate regulator, broadly required for differentiation, and suggest that mex3-1 helps to mediate the balance between ASC self-renewal and commitment. DOI:http://dx.doi.org/10.7554/eLife.07025.001 Adult tissues constantly replace the millions of cells they lose on a daily basis. This is made possible by adult stem cells. But how is a stable population of stem cells maintained throughout the life of the organism with constant cell division? One way this can be accomplished is if at every stem cell division, only one of the daughter cells remains a stem cell, while the other becomes specialized. For humans, if this balance is disturbed, cancers may result from too many stem cells, and early aging may result from too few stem cells. A freshwater flatworm called Schmidtea mediterranea is known for its ability to regenerate nearly every part of its body after injury. This flatworm possesses stem cells called neoblasts that can form all of the flatworm's different cell types both during regeneration and during normal tissue turnover. Evidence suggests that the number of neoblasts and the number of specialized cells that neoblasts produce are finely balanced, similar to adult human tissues. However, little is known about the mechanism that controls whether a neoblast takes on a more specialized form. To express a gene, it must first be copied or ‘transcribed’ into an RNA molecule. Identifying the RNA molecules that are enriched in the non-stem cells that develop from neoblasts could therefore indicate which genes regulate the cell specialization process. These RNA molecules could also be used as markers that identify which cells have taken on a more specialized form. Using techniques called transcriptional profiling and RNA interference, Zhu et al. identified 32 new markers that indicate that the neoblasts have started to specialize into epithelial cells: cells that line the surfaces of many structures in the body. Further investigation revealed that one gene, called mex3-1, is needed for many specialized cell types—not just epithelial cells—to mature from neoblasts in the flatworms. In doing so, mex3-1 also limits the size of the stem cell population. Equivalents of mex3-1 are found in many different species including humans, and so Zhu et al.'s results may help us to understand how other animals regenerate and control the size of their stem cell populations. Mutant flatworms that cannot express mex3-1 could also be used to study other genes that help neoblasts to specialize. DOI:http://dx.doi.org/10.7554/eLife.07025.002
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Affiliation(s)
- Shu Jun Zhu
- Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, Toronto, Canada
| | - Stephanie E Hallows
- Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, Toronto, Canada
| | - Ko W Currie
- Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, Toronto, Canada
| | - ChangJiang Xu
- Terrence Donnelly Centre for Cellular and Biomedical Research, Toronto, Canada
| | - Bret J Pearson
- Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, Toronto, Canada
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