151
|
He Y, Li J, Chen J, Miao X, Li G, He Q, Xu H, Li H, Wei Y. Cytotoxic effects of polystyrene nanoplastics with different surface functionalization on human HepG2 cells. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 723:138180. [PMID: 32224412 DOI: 10.1016/j.scitotenv.2020.138180] [Citation(s) in RCA: 106] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Revised: 03/04/2020] [Accepted: 03/23/2020] [Indexed: 06/10/2023]
Abstract
Nanoplastics in the environment lead to the human exposure to these particles. However, the consequences of this exposure are not yet fully understood. Here, the cytotoxicity of polystyrene nanoparticles (PS-NPs) with a uniform size (50 nm) but distinct surface functionalization (pristine polystyrene, PS; carboxy and amino functionalized, PS-COOH and PS-NH2, respectively), and at an exposure dosage of 10, 50 and 100 μg/mL, were assessed in the human hepatocellular carcinoma (HepG2) cell line. Although all PS-NPs could be internalized by the HepG2 cells, according to the fluorescent intensities, more of PS-COOH and PS-NH2 than PS, accumulated in the cells. The cell viability was significantly affected in a positively dose-related manner. Functionalized PS-NPs exhibited greater inhibition of cell viability than PS, and the viability inhibition peaked (46%) at 100 μg/mL of PS-NH2 exposure. Superoxide dismutase (SOD) activity was maximum when HepG2 cells were exposed to 10 μg/mL of PS-COOH (1.8 folds higher than that without PS-COOH exposure). The glutathione (GSH) content was maximum when the cells were treated with 50 μg/mL of PS (3.75 fold increase compared to untreated cells). Although the difference in inhibition of cell viability was not significant between PS-NH2 and PS-COOH exposure, 100 μg/mL of PS-NH2 exposure caused the most severe oxidative stress due to dramatically increased accumulation of malondialdehyde (MDA); however, a decrease in the antioxidants levels as the SOD activity and GSH content were also found. The results demonstrated that the cellular oxidative damage occurred and that the antioxidation enzymes may not be able to maintain the balance between the generation of oxidant species and the antioxidant defense. Consequently, 100 μg/mL of PS-NH2 exposure triggered the destruction of antioxidant structures. This study defines the cytotoxic effects of PS-NPs on HepG2 cells and emphasizes the significance of investigating the cytotoxic outcomes of nanoplastics in humans.
Collapse
Affiliation(s)
- Yixin He
- Key Laboratory of Eco-Environment of Three Gorges Region, Ministry of Education, Chongqing University, Chongqing 400044, China
| | - Jing Li
- Hunan Provincial Key Laboratory of Shale Gas Resource Exploitation, Hunan University of Science and Technology, Xiangtan 411201, China
| | - Jiancheng Chen
- Cultivation Base of Guangxi Key Laboratory for Agro-Environment and Agro-Products Safety, College of Agriculture, Guangxi University, Nanning 530004, China
| | - Xiaojun Miao
- Key Laboratory of Eco-Environment of Three Gorges Region, Ministry of Education, Chongqing University, Chongqing 400044, China
| | - Guo Li
- Key Laboratory of Eco-Environment of Three Gorges Region, Ministry of Education, Chongqing University, Chongqing 400044, China
| | - Qiang He
- Key Laboratory of Eco-Environment of Three Gorges Region, Ministry of Education, Chongqing University, Chongqing 400044, China
| | - Haizhao Xu
- Cultivation Base of Guangxi Key Laboratory for Agro-Environment and Agro-Products Safety, College of Agriculture, Guangxi University, Nanning 530004, China
| | - Hong Li
- Key Laboratory of Eco-Environment of Three Gorges Region, Ministry of Education, Chongqing University, Chongqing 400044, China.
| | - Yanyan Wei
- Cultivation Base of Guangxi Key Laboratory for Agro-Environment and Agro-Products Safety, College of Agriculture, Guangxi University, Nanning 530004, China.
| |
Collapse
|
152
|
Cupo RR, Shorter J. Skd3 (human ClpB) is a potent mitochondrial protein disaggregase that is inactivated by 3-methylglutaconic aciduria-linked mutations. eLife 2020; 9:e55279. [PMID: 32573439 PMCID: PMC7343390 DOI: 10.7554/elife.55279] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2020] [Accepted: 06/22/2020] [Indexed: 12/14/2022] Open
Abstract
Cells have evolved specialized protein disaggregases to reverse toxic protein aggregation and restore protein functionality. In nonmetazoan eukaryotes, the AAA+ disaggregase Hsp78 resolubilizes and reactivates proteins in mitochondria. Curiously, metazoa lack Hsp78. Hence, whether metazoan mitochondria reactivate aggregated proteins is unknown. Here, we establish that a mitochondrial AAA+ protein, Skd3 (human ClpB), couples ATP hydrolysis to protein disaggregation and reactivation. The Skd3 ankyrin-repeat domain combines with conserved AAA+ elements to enable stand-alone disaggregase activity. A mitochondrial inner-membrane protease, PARL, removes an autoinhibitory peptide from Skd3 to greatly enhance disaggregase activity. Indeed, PARL-activated Skd3 solubilizes α-synuclein fibrils connected to Parkinson's disease. Human cells lacking Skd3 exhibit reduced solubility of various mitochondrial proteins, including anti-apoptotic Hax1. Importantly, Skd3 variants linked to 3-methylglutaconic aciduria, a severe mitochondrial disorder, display diminished disaggregase activity (but not always reduced ATPase activity), which predicts disease severity. Thus, Skd3 is a potent protein disaggregase critical for human health.
Collapse
Affiliation(s)
- Ryan R Cupo
- Department of Biochemistry and Biophysics, Perelman School of Medicine at the University of PennsylvaniaPhiladelphiaUnited States
- Pharmacology Graduate Group, Perelman School of Medicine at the University of PennsylvaniaPhiladelphiaUnited States
| | - James Shorter
- Department of Biochemistry and Biophysics, Perelman School of Medicine at the University of PennsylvaniaPhiladelphiaUnited States
- Pharmacology Graduate Group, Perelman School of Medicine at the University of PennsylvaniaPhiladelphiaUnited States
| |
Collapse
|
153
|
Kumler WE, Jorge J, Kim PM, Iftekhar N, Koehl MAR. Does Formation of Multicellular Colonies by Choanoflagellates Affect Their Susceptibility to Capture by Passive Protozoan Predators? J Eukaryot Microbiol 2020; 67:555-565. [PMID: 32455487 DOI: 10.1111/jeu.12808] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 04/17/2020] [Accepted: 05/14/2020] [Indexed: 01/20/2023]
Abstract
Microbial eukaryotes, critical links in aquatic food webs, are unicellular, but some, such as choanoflagellates, form multicellular colonies. Are there consequences to predator avoidance of being unicellular vs. forming larger colonies? Choanoflagellates share a common ancestor with animals and are used as model organisms to study the evolution of multicellularity. Escape in size from protozoan predators is suggested as a selective factor favoring evolution of multicellularity. Heterotrophic protozoans are categorized as suspension feeders, motile raptors, or passive predators that eat swimming prey which bump into them. We focused on passive predation and measured the mechanisms responsible for the susceptibility of unicellular vs. multicellular choanoflagellates, Salpingoeca helianthica, to capture by passive heliozoan predators, Actinosphaerium nucleofilum, which trap prey on axopodia radiating from the cell body. Microvideography showed that unicellular and colonial choanoflagellates entered the predator's capture zone at similar frequencies, but a greater proportion of colonies contacted axopodia. However, more colonies than single cells were lost during transport by axopodia to the cell body. Thus, feeding efficiency (proportion of prey entering the capture zone that were engulfed in phagosomes) was the same for unicellular and multicellular prey, suggesting that colony formation is not an effective defense against such passive predators.
Collapse
Affiliation(s)
- William E Kumler
- Department of Integrative Biology, University of California, Berkeley, California, 94720-3140.,School of Oceanography, University of Washington, Seattle, Washington, 98105
| | - Justin Jorge
- Department of Integrative Biology, University of California, Berkeley, California, 94720-3140.,Department of Biology, Duke University, Durham, North Carolina, 27708-0338
| | - Paul M Kim
- Department of Integrative Biology, University of California, Berkeley, California, 94720-3140
| | - Noama Iftekhar
- Department of Integrative Biology, University of California, Berkeley, California, 94720-3140
| | - M A R Koehl
- Department of Integrative Biology, University of California, Berkeley, California, 94720-3140
| |
Collapse
|
154
|
Cardoso JCR, Garcia MG, Power DM. Tracing the Origins of the Pituitary Adenylate-Cyclase Activating Polypeptide (PACAP). Front Neurosci 2020; 14:366. [PMID: 32508559 PMCID: PMC7251081 DOI: 10.3389/fnins.2020.00366] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Accepted: 03/25/2020] [Indexed: 11/13/2022] Open
Abstract
Pituitary adenylate cyclase activating polypeptide (PACAP) is a well-conserved neuropeptide characteristic of vertebrates. This pluripotent hypothalamic neuropeptide regulates neurotransmitter release, intestinal motility, metabolism, cell division/differentiation, and immunity. In vertebrates, PACAP has a specific receptor (PAC1) but it can also activate the Vasoactive Intestinal Peptide receptors (VPAC1 and VPAC2). The evolution of the vertebrate PACAP ligand - receptor pair has been well-described. In contrast, the situation in invertebrates is much less clear. The PACAP ligand - receptor pair in invertebrates has mainly been studied using heterologous antibodies raised against mammalian peptides. A few partial PACAP cDNA clones sharing >87% aa identity with vertebrate PACAP have been isolated from a cnidarian, several protostomes and tunicates but no gene has been reported. Moreover, current evolutionary models of the peptide and receptors using molecular data from phylogenetically distinct invertebrate species (mostly nematodes and arthropods) suggests the PACAP ligand and receptors are exclusive to vertebrate genomes. A basal deuterostome, the cephalochordate amphioxus (Branchiostoma floridae), is the only invertebrate in which elements of a PACAP-like system exists but the peptides and receptor share relatively low sequence conservation with the vertebrate homolog system and are a hybrid with the vertebrate glucagon system. In this study, the evolution of the PACAP system is revisited taking advantage of the burgeoning sequence data (genome and transcriptomes) available for invertebrates to uncover clues about when it first appeared. The results suggest that elements of the PACAP system are absent from protozoans, non-bilaterians, and protostomes and they only emerged after the protostome-deuterostome divergence. PACAP and its receptors appeared in vertebrate genomes and they probably shared a common ancestral origin with the cephalochordate PACAP/GCG-like system which after the genome tetraploidization events that preceded the vertebrate radiation generated the PACAP ligand and receptor pair and also the other members of the Secretin family peptides and their receptors.
Collapse
Affiliation(s)
- João C R Cardoso
- Comparative Molecular and Integrative Biology, Centre of Marine Sciences, University of Algarve, Faro, Portugal
| | - Manuel G Garcia
- Comparative Molecular and Integrative Biology, Centre of Marine Sciences, University of Algarve, Faro, Portugal
| | - Deborah M Power
- Comparative Molecular and Integrative Biology, Centre of Marine Sciences, University of Algarve, Faro, Portugal
| |
Collapse
|
155
|
Booth DS, King N. Genome editing enables reverse genetics of multicellular development in the choanoflagellate Salpingoeca rosetta. eLife 2020; 9:56193. [PMID: 32496191 PMCID: PMC7314544 DOI: 10.7554/elife.56193] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Accepted: 06/03/2020] [Indexed: 12/20/2022] Open
Abstract
In a previous study, we established a forward genetic screen to identify genes required for multicellular development in the choanoflagellate, Salpingoeca rosetta (Levin et al., 2014). Yet, the paucity of reverse genetic tools for choanoflagellates has hampered direct tests of gene function and impeded the establishment of choanoflagellates as a model for reconstructing the origin of their closest living relatives, the animals. Here we establish CRISPR/Cas9-mediated genome editing in S. rosetta by engineering a selectable marker to enrich for edited cells. We then use genome editing to disrupt the coding sequence of a S. rosetta C-type lectin gene, rosetteless, and thereby demonstrate its necessity for multicellular rosette development. This work advances S. rosetta as a model system in which to investigate how genes identified from genetic screens and genomic surveys function in choanoflagellates and evolved as critical regulators of animal biology.
Collapse
Affiliation(s)
- David S Booth
- Howard Hughes Medical Institute and Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
| | - Nicole King
- Howard Hughes Medical Institute and Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
| |
Collapse
|
156
|
Kuncha SK, Venkadasamy VL, Amudhan G, Dahate P, Kola SR, Pottabathini S, Kruparani SP, Shekar PC, Sankaranarayanan R. Genomic innovation of ATD alleviates mistranslation associated with multicellularity in Animalia. eLife 2020; 9:58118. [PMID: 32463355 PMCID: PMC7302879 DOI: 10.7554/elife.58118] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 05/27/2020] [Indexed: 12/26/2022] Open
Abstract
The emergence of multicellularity in Animalia is associated with increase in ROS and expansion of tRNA-isodecoders. tRNA expansion leads to misselection resulting in a critical error of L-Ala mischarged onto tRNAThr, which is proofread by Animalia-specific-tRNA Deacylase (ATD) in vitro. Here we show that in addition to ATD, threonyl-tRNA synthetase (ThrRS) can clear the error in cellular scenario. This two-tier functional redundancy for translation quality control breaks down during oxidative stress, wherein ThrRS is rendered inactive. Therefore, ATD knockout cells display pronounced sensitivity through increased mistranslation of threonine codons leading to cell death. Strikingly, we identify the emergence of ATD along with the error inducing tRNA species starting from Choanoflagellates thus uncovering an important genomic innovation required for multicellularity that occurred in unicellular ancestors of animals. The study further provides a plausible regulatory mechanism wherein the cellular fate of tRNAs can be switched from protein biosynthesis to non-canonical functions. The first animals evolved around 750 million years ago from single-celled ancestors that were most similar to modern-day organisms called the Choanoflagellates. As animals evolved they developed more complex body plans consisting of multiple cells organized into larger structures known as tissues and organs. Over time cells also evolved increased levels of molecules called reactive oxygen species, which are involved in many essential cell processes but are toxic at high levels. Animal cells also contain more types of molecules known as transfer ribonucleic acids, or tRNAs for short, than Choanoflagellate cells and other single-celled organisms. These molecules deliver building blocks known as amino acids to the machinery that produces new proteins. To ensure the proteins are made correctly, it is important that tRNAs deliver specific amino acids to the protein-building machinery in the right order. Each type of tRNA usually only pairs with a specific type of amino acid, but sometimes the enzymes involved in this process can make mistakes. Therefore, cells contain proofreading enzymes that help remove incorrect amino acids on tRNAs. One such enzyme – called ATD – is only found in animals. Experiments in test tubes reported that ATD removes an amino acid called alanine from tRNAs that are supposed to carry threonine, but its precise role in living cells remained unclear. To address this question, Kuncha et al. studied proofreading enzymes in human kidney cells. The experiments showed that, in addition to ATD, a second enzyme known as ThrRS was also able to correct alanine substitutions for threonines on tRNAs. However, reactive oxygen species inactivated the proofreading ability of ThrRS, suggesting ATD plays an essential role in correcting errors in cells containing high levels of reactive oxygen species. These findings suggest that as organisms evolved multiple cells and the levels of tRNA and oxidative stress increased, this led to the appearance of a new proofreading enzyme. Further studies found that ATD originated around 900 million years ago, before Choanoflagellates and animals diverged, indicating these enzymes might have helped to shape the evolution of animals. The next step following on from this work will be to understand the role of ATD in the cells of organs that are known to have particularly high levels of reactive oxygen species, such as testis and ovaries.
Collapse
Affiliation(s)
- Santosh Kumar Kuncha
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
| | | | | | - Priyanka Dahate
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India
| | - Sankara Rao Kola
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India
| | | | | | - P Chandra Shekar
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India
| | | |
Collapse
|
157
|
Cole DB, Mills DB, Erwin DH, Sperling EA, Porter SM, Reinhard CT, Planavsky NJ. On the co-evolution of surface oxygen levels and animals. GEOBIOLOGY 2020; 18:260-281. [PMID: 32175670 DOI: 10.1111/gbi.12382] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 01/04/2020] [Accepted: 01/22/2020] [Indexed: 05/22/2023]
Abstract
Few topics in geobiology have been as extensively debated as the role of Earth's oxygenation in controlling when and why animals emerged and diversified. All currently described animals require oxygen for at least a portion of their life cycle. Therefore, the transition to an oxygenated planet was a prerequisite for the emergence of animals. Yet, our understanding of Earth's oxygenation and the environmental requirements of animal habitability and ecological success is currently limited; estimates for the timing of the appearance of environments sufficiently oxygenated to support ecologically stable populations of animals span a wide range, from billions of years to only a few million years before animals appear in the fossil record. In this light, the extent to which oxygen played an important role in controlling when animals appeared remains a topic of debate. When animals originated and when they diversified are separate questions, meaning either one or both of these phenomena could have been decoupled from oxygenation. Here, we present views from across this interpretive spectrum-in a point-counterpoint format-regarding crucial aspects of the potential links between animals and surface oxygen levels. We highlight areas where the standard discourse on this topic requires a change of course and note that several traditional arguments in this "life versus environment" debate are poorly founded. We also identify a clear need for basic research across a range of fields to disentangle the relationships between oxygen availability and emergence and diversification of animal life.
Collapse
Affiliation(s)
- Devon B Cole
- School of Earth and Atmospheric Science, Georgia Institute of Technology, Atlanta, Georgia
| | - Daniel B Mills
- Department of Geological Sciences, Stanford University, Stanford, California
| | - Douglas H Erwin
- Department of Paleobiology, National Museum of Natural History, Washington, District of Columbia
- Santa Fe Institute, Santa Fe, New Mexico
| | - Erik A Sperling
- Department of Geological Sciences, Stanford University, Stanford, California
| | - Susannah M Porter
- Department of Earth Science, University of California Santa Barbara, Santa Barbara, California
| | - Christopher T Reinhard
- School of Earth and Atmospheric Science, Georgia Institute of Technology, Atlanta, Georgia
| | - Noah J Planavsky
- Department of Geology and Geophysics, Yale University, New Haven, Connecticut
| |
Collapse
|
158
|
Metabolic Heterogeneity and Cross-Feeding in Bacterial Multicellular Systems. Trends Microbiol 2020; 28:732-743. [PMID: 32781027 DOI: 10.1016/j.tim.2020.03.008] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Accepted: 03/25/2020] [Indexed: 01/19/2023]
Abstract
Cells in assemblages differentiate and perform distinct roles. Though many pathways of differentiation are understood at the molecular level in multicellular eukaryotes, the elucidation of similar processes in bacterial assemblages is recent and ongoing. Here, we discuss examples of bacterial differentiation, focusing on cases in which distinct metabolisms coexist and those that exhibit cross-feeding, with one subpopulation producing substrates that are metabolized by a second subpopulation. We describe several studies of single-species systems, then segue to studies of multispecies metabolic heterogeneity and cross-feeding in the clinical setting. Many of the studies described exemplify the application of new techniques and modeling approaches that provide insights into metabolic interactions relevant for bacterial growth outside the laboratory.
Collapse
|
159
|
Hua QY, Zhang MH, Wang L, Bai LL, Li L, He H, Mustafa A, Liu HH, Song CL. Temperature-sensitive pathways may be involved in duck embryonic developmental recovery from blastoderm dormancy during hatching. Br Poult Sci 2020; 61:366-374. [PMID: 32290702 DOI: 10.1080/00071668.2020.1752910] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
1. Birds' newly oviposited blastoderms can survive several weeks in a dormant state during low-temperature storage. Previous studies demonstrated that there is a critical temperature range from 19 to 27°C for chicken embryos. Within this range, the embryo will diapause in a dormant state; once the temperature rises above this range, the blastoderm will break dormancy. 2. Clarifying the mechanism that initiates duck embryo developmental recovery from blastoderm dormancy will be helpful to change temperature control to improve hatching in poultry production. It was hypothesised that there might be some temperature-sensitive genes involved in initiating duck embryo developmental recovery from blastoderm dormancy. 3. To test this hypothesis, the transcriptome of the newly oviposited duck blastoderm and duck embryo (incubated for 48 hours) were sequenced to screen for differentially expressed genes with functions that had been predicted by bioinformatics. 4. The results showed that there were 2416 differentially expressed genes between the two groups, 53 of which were involved in temperature-sensitive pathways. The protein-protein interaction network combined these 53 temperature-sensitive genes and another group of 65 genes, which enriched the development pathway. These results suggested that temperature-sensitive genes may be involved in growth and development related pathways.
Collapse
Affiliation(s)
- Q Y Hua
- Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University , Chengdu, Sichuan, P.R China
| | - M H Zhang
- Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University , Chengdu, Sichuan, P.R China
| | - L Wang
- Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University , Chengdu, Sichuan, P.R China
| | - L L Bai
- Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University , Chengdu, Sichuan, P.R China
| | - L Li
- Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University , Chengdu, Sichuan, P.R China
| | - H He
- Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University , Chengdu, Sichuan, P.R China
| | - A Mustafa
- Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University , Chengdu, Sichuan, P.R China
| | - H H Liu
- Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University , Chengdu, Sichuan, P.R China
| | - C L Song
- Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University , Chengdu, Sichuan, P.R China
| |
Collapse
|
160
|
Tikhonenkov DV, Hehenberger E, Esaulov AS, Belyakova OI, Mazei YA, Mylnikov AP, Keeling PJ. Insights into the origin of metazoan multicellularity from predatory unicellular relatives of animals. BMC Biol 2020; 18:39. [PMID: 32272915 PMCID: PMC7147346 DOI: 10.1186/s12915-020-0762-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2019] [Accepted: 03/02/2020] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND The origin of animals from their unicellular ancestor was one of the most important events in evolutionary history, but the nature and the order of events leading up to the emergence of multicellular animals are still highly uncertain. The diversity and biology of unicellular relatives of animals have strongly informed our understanding of the transition from single-celled organisms to the multicellular Metazoa. Here, we analyze the cellular structures and complex life cycles of the novel unicellular holozoans Pigoraptor and Syssomonas (Opisthokonta), and their implications for the origin of animals. RESULTS Syssomonas and Pigoraptor are characterized by complex life cycles with a variety of cell types including flagellates, amoeboflagellates, amoeboid non-flagellar cells, and spherical cysts. The life cycles also include the formation of multicellular aggregations and syncytium-like structures, and an unusual diet for single-celled opisthokonts (partial cell fusion and joint sucking of a large eukaryotic prey), all of which provide new insights into the origin of multicellularity in Metazoa. Several existing models explaining the origin of multicellular animals have been put forward, but these data are interestingly consistent with one, the "synzoospore hypothesis." CONCLUSIONS The feeding modes of the ancestral metazoan may have been more complex than previously thought, including not only bacterial prey, but also larger eukaryotic cells and organic structures. The ability to feed on large eukaryotic prey could have been a powerful trigger in the formation and development of both aggregative (e.g., joint feeding, which also implies signaling) and clonal (e.g., hypertrophic growth followed by palintomy) multicellular stages that played important roles in the emergence of multicellular animals.
Collapse
Affiliation(s)
- Denis V Tikhonenkov
- Papanin Institute for Biology of Inland Waters, Russian Academy of Sciences, Borok, Russia, 152742.
- Department of Botany, University of British Columbia, Vancouver, British Columbia, V6T 1Z4, Canada.
| | - Elisabeth Hehenberger
- Ocean EcoSystems Biology Unit, RD3, GEOMAR Helmholtz Centre for Ocean Research Kiel, Duesternbrookerweg 20, 24105, Kiel, Germany
| | | | | | | | - Alexander P Mylnikov
- Papanin Institute for Biology of Inland Waters, Russian Academy of Sciences, Borok, Russia, 152742
| | - Patrick J Keeling
- Department of Botany, University of British Columbia, Vancouver, British Columbia, V6T 1Z4, Canada.
| |
Collapse
|
161
|
Hehenberger E, Eitel M, Fortunato SAV, Miller DJ, Keeling PJ, Cahill MA. Early eukaryotic origins and metazoan elaboration of MAPR family proteins. Mol Phylogenet Evol 2020; 148:106814. [PMID: 32278076 DOI: 10.1016/j.ympev.2020.106814] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Revised: 03/24/2020] [Accepted: 04/01/2020] [Indexed: 01/01/2023]
Abstract
The membrane-associated progesterone receptor (MAPR) family consists of heme-binding proteins containing a cytochrome b5 (cytb5) domain characterized by the presence of a MAPR-specific interhelical insert region (MIHIR) between helices 3 and 4 of the canonical cytb5-domain fold. Animals possess three MAPR genes (PGRMC-like, Neuferricin and Neudesin). Here we show that all three animal MAPR genes were already present in the common ancestor of the opisthokonts (comprising animals and fungi as well as related single-celled taxa). All three MAPR genes acquired extensions C-terminal to the cytb5 domain, either before or with the evolution of animals. The archetypical MAPR protein, progesterone receptor membrane component 1 (PGRMC1), contains phosphorylated tyrosines Y139 and Y180. The combination of Y139/Y180 appeared in the common ancestor of cnidarians and bilaterians, along with an early embryological organizer and synapsed neurons, and is strongly conserved in all bilaterian animals. A predicted protein interaction motif in the PGRMC1 MIHIR is potentially regulated by Y139 phosphorylation. A multilayered model of animal MAPR function acquisition includes some pre-metazoan functions (e.g., heme binding and cytochrome P450 interactions) and some acquired animal-specific functions that involve regulation of strongly conserved protein interaction motifs acquired by animals (Metazoa). This study provides a conceptual framework for future studies, against which especially PGRMC1's multiple functions can perhaps be stratified and functionally dissected.
Collapse
Affiliation(s)
- Elisabeth Hehenberger
- Department of Botany, University of British Columbia, 3529-6270 University Boulevard, Vancouver, BC V6T 1Z4, Canada
| | - Michael Eitel
- Department of Earth and Environmental Sciences, Paleontology and Geobiology, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Sofia A V Fortunato
- ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, QLD 4811, Australia
| | - David J Miller
- ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, QLD 4811, Australia
| | - Patrick J Keeling
- Department of Botany, University of British Columbia, 3529-6270 University Boulevard, Vancouver, BC V6T 1Z4, Canada
| | - Michael A Cahill
- School of Biomedical Sciences, Charles Sturt University, Wagga Wagga, NSW 2678, Australia; ACRF Department of Cancer Biology and Therapeutics, The John Curtin School of Medical Research, Canberra, ACT 2601, Australia.
| |
Collapse
|
162
|
Weiss GL, Kieninger AK, Maldener I, Forchhammer K, Pilhofer M. Structure and Function of a Bacterial Gap Junction Analog. Cell 2020; 178:374-384.e15. [PMID: 31299201 PMCID: PMC6630896 DOI: 10.1016/j.cell.2019.05.055] [Citation(s) in RCA: 56] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Revised: 03/04/2019] [Accepted: 05/29/2019] [Indexed: 11/29/2022]
Abstract
Multicellular lifestyle requires cell-cell connections. In multicellular cyanobacteria, septal junctions enable molecular exchange between sister cells and are required for cellular differentiation. The structure of septal junctions is poorly understood, and it is unknown whether they are capable of controlling intercellular communication. Here, we resolved the in situ architecture of septal junctions by electron cryotomography of cryo-focused ion beam-milled cyanobacterial filaments. Septal junctions consisted of a tube traversing the septal peptidoglycan. Each tube end comprised a FraD-containing plug, which was covered by a cytoplasmic cap. Fluorescence recovery after photobleaching showed that intercellular communication was blocked upon stress. Gating was accompanied by a reversible conformational change of the septal junction cap. We provide the mechanistic framework for a cell junction that predates eukaryotic gap junctions by a billion years. The conservation of a gated dynamic mechanism across different domains of life emphasizes the importance of controlling molecular exchange in multicellular organisms. The in situ architecture of septal junctions reveals cap, plug, and tube modules Septal junctions reversibly control cell-cell communication upon stress FraD is a structural element of the septal junction plug module Bacterial septal junctions are mechanistically analogous to metazoan gap junctions
Collapse
Affiliation(s)
- Gregor L Weiss
- Department of Biology, Institute of Molecular Biology & Biophysics, Eidgenössische Technische Hochschule Zürich, Otto-Stern-Weg 5, 8093 Zürich, Switzerland
| | - Ann-Katrin Kieninger
- Interfaculty Institute of Microbiology and Infection Medicine Tübingen, Organismic Interactions, University of Tübingen, Auf der Morgenstelle 28, 72076 Tübingen, Germany
| | - Iris Maldener
- Interfaculty Institute of Microbiology and Infection Medicine Tübingen, Organismic Interactions, University of Tübingen, Auf der Morgenstelle 28, 72076 Tübingen, Germany.
| | - Karl Forchhammer
- Interfaculty Institute of Microbiology and Infection Medicine Tübingen, Organismic Interactions, University of Tübingen, Auf der Morgenstelle 28, 72076 Tübingen, Germany
| | - Martin Pilhofer
- Department of Biology, Institute of Molecular Biology & Biophysics, Eidgenössische Technische Hochschule Zürich, Otto-Stern-Weg 5, 8093 Zürich, Switzerland.
| |
Collapse
|
163
|
Brunet T, Larson BT, Linden TA, Vermeij MJA, McDonald K, King N. Light-regulated collective contractility in a multicellular choanoflagellate. Science 2020; 366:326-334. [PMID: 31624206 DOI: 10.1126/science.aay2346] [Citation(s) in RCA: 74] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Accepted: 09/16/2019] [Indexed: 12/11/2022]
Abstract
Collective cell contractions that generate global tissue deformations are a signature feature of animal movement and morphogenesis. However, the origin of collective contractility in animals remains unclear. While surveying the Caribbean island of Curaçao for choanoflagellates, the closest living relatives of animals, we isolated a previously undescribed species (here named Choanoeca flexa sp. nov.) that forms multicellular cup-shaped colonies. The colonies rapidly invert their curvature in response to changing light levels, which they detect through a rhodopsin-cyclic guanosine monophosphate pathway. Inversion requires actomyosin-mediated apical contractility and allows alternation between feeding and swimming behavior. C. flexa thus rapidly converts sensory inputs directly into multicellular contractions. These findings may inform reconstructions of hypothesized animal ancestors that existed before the evolution of specialized sensory and contractile cells.
Collapse
Affiliation(s)
- Thibaut Brunet
- Howard Hughes Medical Institute and the Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
| | - Ben T Larson
- Howard Hughes Medical Institute and the Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA.,Biophysics Graduate Group, University of California, Berkeley, CA, USA
| | - Tess A Linden
- Howard Hughes Medical Institute and the Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
| | - Mark J A Vermeij
- Department of Aquatic Microbiology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, CARMABI, Piscaderabaai z/n Willemstad, Curaçao
| | - Kent McDonald
- Electron Microscopy Laboratory, University of California, Berkeley, CA, USA
| | - Nicole King
- Howard Hughes Medical Institute and the Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA.
| |
Collapse
|
164
|
Koehl MAR. Selective factors in the evolution of multicellularity in choanoflagellates. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2020; 336:315-326. [PMID: 32198827 DOI: 10.1002/jez.b.22941] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Revised: 02/12/2020] [Accepted: 02/17/2020] [Indexed: 11/10/2022]
Abstract
Choanoflagellates, unicellular eukaryotes that can form multicellular colonies by cell division and that share a common ancestor with animals, are used as a model system to study functional consequences of being unicellular versus colonial. This review examines performance differences between unicellular and multicellular choanoflagellates in swimming, feeding, and avoiding predation, to provide insights about possible selective advantages of being multicellular for the protozoan ancestors of animals. Each choanoflagellate cell propels water by beating a single flagellum and captures bacterial prey on a collar of microvilli around the flagellum. Formation of multicellular colonies does not improve the swimming performance, but the flux of prey-bearing water to the collars of some of the cells in colonies of certain configurations can be greater than for single cells. Colony geometry appears to affect whether cells in colonies catch more prey per cell per time than do unicellular choanoflagellates. Although multicellular choanoflagellates show chemokinetic behavior in response to oxygen, only the unicellular dispersal stage (fast swimmers without collars) use pH signals to aggregate in locations where bacterial prey might be abundant. Colonies produce larger hydrodynamic signals than do single cells, and raptorial protozoan predators capture colonies while ignoring single cells. In contrast, ciliate predators entrain both single cells and colonies in their feeding currents, but reject larger colonies, whereas passive heliozoan predators show no preference. Thus, the ability of choanoflagellate cells to differentiate into different morphotypes, including multicellular forms, in response to variable aquatic environments might have provided a selective advantage to the ancestors of animals.
Collapse
Affiliation(s)
- M A R Koehl
- Department of Integrative Biology, University of California, Berkeley, California
| |
Collapse
|
165
|
Erwin DH. The origin of animal body plans: a view from fossil evidence and the regulatory genome. Development 2020; 147:147/4/dev182899. [DOI: 10.1242/dev.182899] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
ABSTRACT
The origins and the early evolution of multicellular animals required the exploitation of holozoan genomic regulatory elements and the acquisition of new regulatory tools. Comparative studies of metazoans and their relatives now allow reconstruction of the evolution of the metazoan regulatory genome, but the deep conservation of many genes has led to varied hypotheses about the morphology of early animals and the extent of developmental co-option. In this Review, I assess the emerging view that the early diversification of animals involved small organisms with diverse cell types, but largely lacking complex developmental patterning, which evolved independently in different bilaterian clades during the Cambrian Explosion.
Collapse
Affiliation(s)
- Douglas H. Erwin
- Department of Paleobiology, MRC-121, National Museum of Natural History, PO Box 37012, Washington, DC 20013-7012, USA
- Santa Fe Institute, 1399 Hyde Park Road, Santa Fe, NM 87501, USA
| |
Collapse
|
166
|
van Gestel J. Slow lane to collectivity. Nat Ecol Evol 2020; 4:292-293. [PMID: 32042120 DOI: 10.1038/s41559-020-1116-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Jordi van Gestel
- Department of Evolutionary Biology and Environmental Studies, University of Zürich, Zürich, Switzerland. .,Department of Environmental Systems Science, ETH Zürich, Zürich, Switzerland. .,Department of Environmental Microbiology, Swiss Federal Institute of Aquatic Science and Technology (Eawag), Dübendorf, Switzerland. .,Swiss Institute of Bioinformatics, Lausanne, Switzerland.
| |
Collapse
|
167
|
Abstract
Inspired by the patterns of multicellularity in choanoflagellates, the closest living relatives of animals, we quantify the biophysical processes underlying the morphogenesis of rosette colonies in the choanoflagellate Salpingoeca rosetta We find that rosettes reproducibly transition from an early stage of 2-dimensional (2D) growth to a later stage of 3D growth, despite the underlying variability of the cell lineages. Our perturbative experiments demonstrate the fundamental importance of a basally secreted extracellular matrix (ECM) for rosette morphogenesis and show that the interaction of the ECM with cells in the colony physically constrains the packing of proliferating cells and, thus, controls colony shape. Simulations of a biophysically inspired model that accounts for the size and shape of the individual cells, the fraction of ECM, and its stiffness relative to that of the cells suffices to explain our observations and yields a morphospace consistent with observations across a range of multicellular choanoflagellate colonies. Overall, our biophysical perspective on rosette development complements previous genetic perspectives and, thus, helps illuminate the interplay between cell biology and physics in regulating morphogenesis.
Collapse
|
168
|
Liang Z, Geng Y, Ji C, Du H, Wong CE, Zhang Q, Zhang Y, Zhang P, Riaz A, Chachar S, Ding Y, Wen J, Wu Y, Wang M, Zheng H, Wu Y, Demko V, Shen L, Han X, Zhang P, Gu X, Yu H. Mesostigma viride Genome and Transcriptome Provide Insights into the Origin and Evolution of Streptophyta. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2020; 7:1901850. [PMID: 31921561 PMCID: PMC6947507 DOI: 10.1002/advs.201901850] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Revised: 10/10/2019] [Indexed: 05/02/2023]
Abstract
The Streptophyta include unicellular and multicellular charophyte green algae and land plants. Colonization of the terrestrial habitat by land plants is a major evolutionary event that has transformed the planet. So far, lack of genome information on unicellular charophyte algae hinders the understanding of the origin and the evolution from unicellular to multicellular life in Streptophyta. This work reports the high-quality reference genome and transcriptome of Mesostigma viride, a single-celled charophyte alga with a position at the base of Streptophyta. There are abundant segmental duplications and transposable elements in M. viride, which contribute to a relatively large genome with high gene content compared to other algae and early diverging land plants. This work identifies the origin of genetic tools that multicellular Streptophyta have inherited and key genetic innovations required for the evolution of land plants from unicellular aquatic ancestors. The findings shed light on the age-old questions of the evolution of multicellularity and the origin of land plants.
Collapse
Affiliation(s)
- Zhe Liang
- Department of Biological SciencesNational University of SingaporeSingapore117543Singapore
| | - Yuke Geng
- Biotechnology Research InstituteChinese Academy of Agricultural SciencesBeijing100081China
| | - Changmian Ji
- Biomarker TechnologiesBeijing101300China
- Institute of Tropical Bioscience and BiotechnologyChinese Academy of Tropical Agricultural SciencesHaikou571101China
| | - Hai Du
- College of Agronomy and BiotechnologySouthwest UniversityChongqing400715China
| | - Chui Eng Wong
- Department of Biological SciencesNational University of SingaporeSingapore117543Singapore
| | - Qian Zhang
- Biotechnology Research InstituteChinese Academy of Agricultural SciencesBeijing100081China
| | - Ye Zhang
- Biotechnology Research InstituteChinese Academy of Agricultural SciencesBeijing100081China
| | - Pingxian Zhang
- Biotechnology Research InstituteChinese Academy of Agricultural SciencesBeijing100081China
| | - Adeel Riaz
- Biotechnology Research InstituteChinese Academy of Agricultural SciencesBeijing100081China
| | - Sadaruddin Chachar
- Biotechnology Research InstituteChinese Academy of Agricultural SciencesBeijing100081China
| | - Yike Ding
- Department of EntomologyUniversity of California RiversideRiversideCA92521USA
| | - Jing Wen
- College of Agronomy and BiotechnologySouthwest UniversityChongqing400715China
| | - Yunwen Wu
- Biotechnology Research InstituteChinese Academy of Agricultural SciencesBeijing100081China
- College of Agronomy and BiotechnologySouthwest UniversityChongqing400715China
| | | | | | - Yanmin Wu
- College of Agronomy and BiotechnologySouthwest UniversityChongqing400715China
| | - Viktor Demko
- Department of Plant PhysiologyFaculty of Natural SciencesComenius University in BratislavaBratislava84215Slovakia
| | - Lisha Shen
- Temasek Life Sciences LaboratoryNational University of SingaporeSingapore117604Singapore
| | - Xiao Han
- College of Biological Science and EngineeringFuzhou UniversityFuzhou350108China
| | - Pengpeng Zhang
- Biotechnology Research InstituteChinese Academy of Agricultural SciencesBeijing100081China
| | - Xiaofeng Gu
- Biotechnology Research InstituteChinese Academy of Agricultural SciencesBeijing100081China
| | - Hao Yu
- Department of Biological SciencesNational University of SingaporeSingapore117543Singapore
- Temasek Life Sciences LaboratoryNational University of SingaporeSingapore117604Singapore
| |
Collapse
|
169
|
|
170
|
Fields C, Bischof J, Levin M. Morphological Coordination: A Common Ancestral Function Unifying Neural and Non-Neural Signaling. Physiology (Bethesda) 2020; 35:16-30. [DOI: 10.1152/physiol.00027.2019] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Nervous systems are traditionally thought of as providing sensing and behavioral coordination functions at the level of the whole organism. What is the evolutionary origin of the mechanisms enabling the nervous systems’ information processing ability? Here, we review evidence from evolutionary, developmental, and regenerative biology suggesting a deeper, ancestral function of both pre-neural and neural cell-cell communication systems: the long-distance coordination of cell division and differentiation required to create and maintain body-axis symmetries. This conceptualization of the function of nervous system activity sheds new light on the evolutionary transition from the morphologically rudimentary, non-neural Porifera and Placazoa to the complex morphologies of Ctenophores, Cnidarians, and Bilaterians. It further allows a sharp formulation of the distinction between long-distance axis-symmetry coordination based on external coordinates, e.g., by whole-organism scale trophisms as employed by plants and sessile animals, and coordination based on body-centered coordinates as employed by motile animals. Thus we suggest that the systems that control animal behavior evolved from ancient mechanisms adapting preexisting ionic and neurotransmitter mechanisms to regulate individual cell behaviors during morphogenesis. An appreciation of the ancient, non-neural origins of bioelectrically mediated computation suggests new approaches to the study of embryological development, including embryological dysregulation, cancer, regenerative medicine, and synthetic bioengineering.
Collapse
Affiliation(s)
- Chris Fields
- 23 Rue des Lavandières, Caunes Minervois, France
| | - Johanna Bischof
- Allen Discovery Center at Tufts University, Medford, Massachusetts
| | - Michael Levin
- Allen Discovery Center at Tufts University, Medford, Massachusetts
| |
Collapse
|
171
|
Khan RB, Goult BT. Adhesions Assemble!-Autoinhibition as a Major Regulatory Mechanism of Integrin-Mediated Adhesion. Front Mol Biosci 2019; 6:144. [PMID: 31921890 PMCID: PMC6927945 DOI: 10.3389/fmolb.2019.00144] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Accepted: 11/26/2019] [Indexed: 01/14/2023] Open
Abstract
The advent of cell-cell and cell-extracellular adhesion enabled cells to interact in a coherent manner, forming larger structures and giving rise to the development of tissues, organs and complex multicellular life forms. The development of such organisms required tight regulation of dynamic adhesive structures by signaling pathways that coordinate cell attachment. Integrin-mediated adhesion to the extracellular matrix provides cells with support, survival signals and context-dependent cues that enable cells to run different cellular programs. One mysterious aspect of the process is how hundreds of proteins assemble seemingly spontaneously onto the activated integrin. An emerging concept is that adhesion assembly is regulated by autoinhibition of key proteins, a highly dynamic event that is modulated by a variety of signaling events. By enabling precise control of the activation state of proteins, autoinhibition enables localization of inactive proteins and the formation of pre-complexes. In response to the correct signals, these proteins become active and interact with other proteins, ultimately leading to development of cell-matrix junctions. Autoinhibition of key components of such adhesion complexes—including core components integrin, talin, vinculin, and FAK and important peripheral regulators such as RIAM, Src, and DLC1—leads to a view that the majority of proteins involved in complex assembly might be regulated by intramolecular interactions. Autoinhibition is relieved via multiple different signals including post-translation modification and proteolysis. More recently, mechanical forces have been shown to stabilize and increase the lifetimes of active conformations, identifying autoinhibition as a means of encoding mechanosensitivity. The complexity and scope for nuanced adhesion dynamics facilitated via autoinhibition provides numerous points of regulation. In this review, we discuss what is known about this mode of regulation and how it leads to rapid and tightly controlled assembly and disassembly of cell-matrix adhesion.
Collapse
Affiliation(s)
- Rejina B Khan
- School of Biosciences, University of Kent, Canterbury, United Kingdom
| | - Benjamin T Goult
- School of Biosciences, University of Kent, Canterbury, United Kingdom
| |
Collapse
|
172
|
Abstract
Two unicellular relatives of animals reveal that coordinated contractions of groups of cells using actomyosin predated animal multicellularity during evolution.
Collapse
Affiliation(s)
- Mukund Thattai
- Simons Centre for the Study of Living Machines, National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India
| |
Collapse
|
173
|
Dudin O, Ondracka A, Grau-Bové X, Haraldsen AA, Toyoda A, Suga H, Bråte J, Ruiz-Trillo I. A unicellular relative of animals generates a layer of polarized cells by actomyosin-dependent cellularization. eLife 2019; 8:49801. [PMID: 31647412 PMCID: PMC6855841 DOI: 10.7554/elife.49801] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2019] [Accepted: 10/23/2019] [Indexed: 12/30/2022] Open
Abstract
In animals, cellularization of a coenocyte is a specialized form of cytokinesis that results in the formation of a polarized epithelium during early embryonic development. It is characterized by coordinated assembly of an actomyosin network, which drives inward membrane invaginations. However, whether coordinated cellularization driven by membrane invagination exists outside animals is not known. To that end, we investigate cellularization in the ichthyosporean Sphaeroforma arctica, a close unicellular relative of animals. We show that the process of cellularization involves coordinated inward plasma membrane invaginations dependent on an actomyosin network and reveal the temporal order of its assembly. This leads to the formation of a polarized layer of cells resembling an epithelium. We show that this stage is associated with tightly regulated transcriptional activation of genes involved in cell adhesion. Hereby we demonstrate the presence of a self-organized, clonally-generated, polarized layer of cells in a unicellular relative of animals.
Collapse
Affiliation(s)
- Omaya Dudin
- Institut de Biologia Evolutiva (CSIC-Universitat Pompeu Fabra), Barcelona, Spain
| | - Andrej Ondracka
- Institut de Biologia Evolutiva (CSIC-Universitat Pompeu Fabra), Barcelona, Spain
| | - Xavier Grau-Bové
- Institut de Biologia Evolutiva (CSIC-Universitat Pompeu Fabra), Barcelona, Spain.,Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Arthur Ab Haraldsen
- Section for Genetics and Evolutionary Biology (EVOGENE), Department of Biosciences, University of Oslo, Oslo, Norway
| | - Atsushi Toyoda
- Department of Genomics and Evolutionary Biology, National Institute of Genetics, Mishima, Japan
| | - Hiroshi Suga
- Faculty of Life and Environmental Sciences, Prefectural University of Hiroshima, Hiroshima, Japan
| | - Jon Bråte
- Section for Genetics and Evolutionary Biology (EVOGENE), Department of Biosciences, University of Oslo, Oslo, Norway
| | - Iñaki Ruiz-Trillo
- Institut de Biologia Evolutiva (CSIC-Universitat Pompeu Fabra), Barcelona, Spain.,Departament de Genètica, Microbiologia i Estadística, Universitat de Barcelona, Barcelona, Spain.,ICREA, Barcelona, Spain
| |
Collapse
|
174
|
Murphy DP, Hughes AEO, Lawrence KA, Myers CA, Corbo JC. Cis-regulatory basis of sister cell type divergence in the vertebrate retina. eLife 2019; 8:e48216. [PMID: 31633482 PMCID: PMC6802965 DOI: 10.7554/elife.48216] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2019] [Accepted: 09/19/2019] [Indexed: 12/27/2022] Open
Abstract
Multicellular organisms evolved via repeated functional divergence of transcriptionally related sister cell types, but the mechanisms underlying sister cell type divergence are not well understood. Here, we study a canonical pair of sister cell types, retinal photoreceptors and bipolar cells, to identify the key cis-regulatory features that distinguish them. By comparing open chromatin maps and transcriptomic profiles, we found that while photoreceptor and bipolar cells have divergent transcriptomes, they share remarkably similar cis-regulatory grammars, marked by enrichment of K50 homeodomain binding sites. However, cell class-specific enhancers are distinguished by enrichment of E-box motifs in bipolar cells, and Q50 homeodomain motifs in photoreceptors. We show that converting K50 motifs to Q50 motifs represses reporter expression in bipolar cells, while photoreceptor expression is maintained. These findings suggest that partitioning of Q50 motifs within cell type-specific cis-regulatory elements was a critical step in the evolutionary divergence of the bipolar transcriptome from that of photoreceptors.
Collapse
Affiliation(s)
- Daniel P Murphy
- Department of Pathology and ImmunologyWashington University School of MedicineSt. LouisUnited States
| | - Andrew EO Hughes
- Department of Pathology and ImmunologyWashington University School of MedicineSt. LouisUnited States
| | - Karen A Lawrence
- Department of Pathology and ImmunologyWashington University School of MedicineSt. LouisUnited States
| | - Connie A Myers
- Department of Pathology and ImmunologyWashington University School of MedicineSt. LouisUnited States
| | - Joseph C Corbo
- Department of Pathology and ImmunologyWashington University School of MedicineSt. LouisUnited States
| |
Collapse
|
175
|
Naumann B, Burkhardt P. Spatial Cell Disparity in the Colonial Choanoflagellate Salpingoeca rosetta. Front Cell Dev Biol 2019; 7:231. [PMID: 31681764 PMCID: PMC6803389 DOI: 10.3389/fcell.2019.00231] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Accepted: 09/26/2019] [Indexed: 11/13/2022] Open
Abstract
Choanoflagellates are the closest unicellular relatives of animals (Metazoa). These tiny protists display complex life histories that include sessile as well as different pelagic stages. Some choanoflagellates have the ability to form colonies as well. Up until recently, these colonies have been described to consist of mostly identical cells showing no spatial cell differentiation, which supported the traditional view that spatial cell differentiation, leading to the co-existence of specific cell types in animals, evolved after the split of the last common ancestor of the Choanoflagellata and Metazoa. The recent discovery of single cells in colonies of the choanoflagellate Salpingoeca rosetta that exhibit unique cell morphologies challenges this traditional view. We have now reanalyzed TEM serial sections, aiming to determine the degree of similarity of S. rosetta cells within a rosette colony. We investigated cell morphologies and nuclear, mitochondrial, and food vacuole volumes of 40 individual cells from four different S. rosetta rosette colonies and compared our findings to sponge choanocytes. Our analysis shows that cells in a choanoflagellate colony differ from each other in respect to cell morphology and content ratios of nuclei, mitochondria, and food vacuoles. Furthermore, cell disparity within S. rosetta colonies is slightly higher compared to cell disparity within sponge choanocytes. Moreover, we discovered the presence of plasma membrane contacts between colonial cells in addition to already described intercellular bridges and filo-/pseudopodial contacts. Our findings indicate that the last common ancestor of Choanoflagellata and Metazoa might have possessed plasma membrane contacts and spatial cell disparity during colonial life history stages.
Collapse
Affiliation(s)
- Benjamin Naumann
- Institute of Zoology and Evolutionary Research, Friedrich Schiller University Jena, Jena, Germany
| | - Pawel Burkhardt
- Sars International Centre for Marine Molecular Biology, University of Bergen, Bergen, Norway
| |
Collapse
|
176
|
Keeling PJ. Combining morphology, behaviour and genomics to understand the evolution and ecology of microbial eukaryotes. Philos Trans R Soc Lond B Biol Sci 2019; 374:20190085. [PMID: 31587641 DOI: 10.1098/rstb.2019.0085] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Microbial eukaryotes (protists) are structurally, developmentally and behaviourally more complex than their prokaryotic cousins. This complexity makes it more difficult to translate genomic and metagenomic data into accurate functional inferences about systems ranging all the way from molecular and cellular levels to global ecological networks. This problem can be traced back to the advent of the cytoskeleton and endomembrane systems at the origin of eukaryotes, which endowed them with a range of complex structures and behaviours that still largely dominate how they evolve and interact within microbial communities. But unlike the diverse metabolic properties that evolved within prokaryotes, the structural and behavioural characteristics that strongly define how protists function in the environment cannot readily be inferred from genomic data, since there is generally no simple correlation between a gene and a discrete activity or function. A deeper understanding of protists at both cellular and ecological levels, therefore, requires not only high-throughput genomics but also linking such data to direct observations of natural history and cell biology. This is challenging since these observations typically require cultivation, which is lacking for most protists. Potential remedies with current technology include developing a more phylogenetically diverse range of model systems to better represent the diversity, as well as combining high-throughput, single-cell genomics with microscopic documentation of the subject cells to link sequence with structure and behaviour. This article is part of a discussion meeting issue 'Single cell ecology'.
Collapse
Affiliation(s)
- Patrick J Keeling
- Botany Department, University of British Columbia, Vancouver, British Columbia, Canada V6T1Z4
| |
Collapse
|
177
|
Gilbert SF. Evolutionary transitions revisited: Holobiont evo-devo. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2019; 332:307-314. [PMID: 31565856 DOI: 10.1002/jez.b.22903] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 08/07/2019] [Accepted: 08/10/2019] [Indexed: 12/14/2022]
Abstract
John T. Bonner lists four essential transformations in the evolution of life: the emergence of the eukaryotic cell, meiosis, multicellularity, and the nervous system. This paper analyses the mechanisms for those transitions in light of three of Dr. Bonner's earlier hypotheses: (a) that the organism is its life cycle, (b) that evolution consists of alterations of the life cycle, and (c) that development extends beyond the body and into interactions with other organisms. Using the notion of the holobiont life cycle, this paper attempts to show that these evolutionary transitions can be accomplished through various means of symbiosis. Perceiving the organism both as an interspecies consortium and as a life cycle supports a twofold redefinition of the organism as a holobiont constructed by integrating together the life cycles of several species. These findings highlight the importance of symbiosis and the holobiont development in analyses of evolution.
Collapse
Affiliation(s)
- Scott F Gilbert
- Department of Biology, Swarthmore College, Swarthmore, Pennsylvania
| |
Collapse
|
178
|
Bich L, Pradeu T, Moreau JF. Understanding Multicellularity: The Functional Organization of the Intercellular Space. Front Physiol 2019; 10:1170. [PMID: 31620013 PMCID: PMC6759637 DOI: 10.3389/fphys.2019.01170] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Accepted: 08/29/2019] [Indexed: 01/08/2023] Open
Abstract
The aim of this paper is to provide a theoretical framework to understand how multicellular systems realize functionally integrated physiological entities by organizing their intercellular space. From a perspective centered on physiology and integration, biological systems are often characterized as organized in such a way that they realize metabolic self-production and self-maintenance. The existence and activity of their components rely on the network they realize and on the continuous management of the exchange of matter and energy with their environment. One of the virtues of the organismic approach focused on organization is that it can provide an understanding of how biological systems are functionally integrated into coherent wholes. Organismic frameworks have been primarily developed by focusing on unicellular life. Multicellularity, however, presents additional challenges to our understanding of biological systems, related to how cells are capable to live together in higher-order entities, in such a way that some of their features and behaviors are constrained and controlled by the system they realize. Whereas most accounts of multicellularity focus on cell differentiation and increase in size as the main elements to understand biological systems at this level of organization, we argue that these factors are insufficient to provide an understanding of how cells are physically and functionally integrated in a coherent system. In this paper, we provide a new theoretical framework to understand multicellularity, capable to overcome these issues. Our thesis is that one of the fundamental theoretical principles to understand multicellularity, which is missing or underdeveloped in current accounts, is the functional organization of the intercellular space. In our view, the capability to be organized in space plays a central role in this context, as it enables (and allows to exploit all the implications of) cell differentiation and increase in size, and even specialized functions such as immunity. We argue that the extracellular matrix plays a crucial active role in this respect, as an evolutionary ancient and specific (non-cellular) control subsystem that contributes as a key actor to the functional specification of the multicellular space and to modulate cell fate and behavior. We also analyze how multicellular systems exert control upon internal movement and communication. Finally, we show how the organization of space is involved in some of the failures of multicellular organization, such as aging and cancer.
Collapse
Affiliation(s)
- Leonardo Bich
- Department of Logic and Philosophy of Science, IAS-Research Centre for Life, Mind and Society, University of the Basque Country (UPV/EHU), Donostia-San Sebastian, Spain
| | - Thomas Pradeu
- ImmunoConcept, CNRS UMR 5164, Bordeaux University, Bordeaux, France.,CNRS UMR8590, Institut d'Histoire et de Philosophie des Sciences et des Techniques, Pantheon-Sorbonne University, Paris, France
| | - Jean-François Moreau
- ImmunoConcept, CNRS UMR 5164, Bordeaux University, Bordeaux, France.,CHU Bordeaux, Bordeaux, France
| |
Collapse
|
179
|
Comparative genomics reveals the origin of fungal hyphae and multicellularity. Nat Commun 2019; 10:4080. [PMID: 31501435 PMCID: PMC6733946 DOI: 10.1038/s41467-019-12085-w] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Accepted: 08/20/2019] [Indexed: 02/01/2023] Open
Abstract
Hyphae represent a hallmark structure of multicellular fungi. The evolutionary origins of hyphae and of the underlying genes are, however, hardly known. By systematically analyzing 72 complete genomes, we here show that hyphae evolved early in fungal evolution probably via diverse genetic changes, including co-option and exaptation of ancient eukaryotic (e.g. phagocytosis-related) genes, the origin of new gene families, gene duplications and alterations of gene structure, among others. Contrary to most multicellular lineages, the origin of filamentous fungi did not correlate with expansions of kinases, receptors or adhesive proteins. Co-option was probably the dominant mechanism for recruiting genes for hypha morphogenesis, while gene duplication was apparently less prevalent, except in transcriptional regulators and cell wall - related genes. We identified 414 novel gene families that show correlated evolution with hyphae and that may have contributed to its evolution. Our results suggest that hyphae represent a unique multicellular organization that evolved by limited fungal-specific innovations and gene duplication but pervasive co-option and modification of ancient eukaryotic functions.
Collapse
|
180
|
Steinmetz PRH. A non-bilaterian perspective on the development and evolution of animal digestive systems. Cell Tissue Res 2019; 377:321-339. [PMID: 31388768 PMCID: PMC6733828 DOI: 10.1007/s00441-019-03075-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Accepted: 07/08/2019] [Indexed: 12/14/2022]
Abstract
Digestive systems and extracellular digestion are key animal features, but their emergence during early animal evolution is currently poorly understood. As the last common ancestor of non-bilaterian animal groups (sponges, ctenophores, placozoans and cnidarians) dates back to the beginning of animal life, their study and comparison provides important insights into the early evolution of digestive systems and functions. Here, I have compiled an overview of the development and cell biology of digestive tissues in non-bilaterian animals. I will highlight the fundamental differences between extracellular and intracellular digestive processes, and how these are distributed among animals. Cnidarians (e.g. sea anemones, corals, jellyfish), the phylogenetic outgroup of bilaterians (e.g. vertebrates, flies, annelids), occupy a key position to reconstruct the evolution of bilaterian gut evolution. A major focus will therefore lie on the development and cell biology of digestive tissues in cnidarians, especially sea anemones, and how they compare to bilaterian gut tissues. In that context, I will also review how a recent study on the gastrula fate map of the sea anemone Nematostella vectensis challenges our long-standing conceptions on the evolution of cnidarian and bilaterian germ layers and guts.
Collapse
Affiliation(s)
- Patrick R H Steinmetz
- Sars International Centre for Marine Molecular Biology, University of Bergen, Thormøhlensgt. 55, 5006, Bergen, Norway.
| |
Collapse
|
181
|
Modelling the early evolution of extracellular matrix from modern Ctenophores and Sponges. Essays Biochem 2019; 63:389-405. [DOI: 10.1042/ebc20180048] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Revised: 07/29/2019] [Accepted: 08/01/2019] [Indexed: 12/14/2022]
Abstract
AbstractAnimals (metazoans) include some of the most complex living organisms on Earth, with regard to their multicellularity, numbers of differentiated cell types, and lifecycles. The metazoan extracellular matrix (ECM) is well-known to have major roles in the development of tissues during embryogenesis and in maintaining homoeostasis throughout life, yet insight into the ECM proteins which may have contributed to the transition from unicellular eukaryotes to multicellular animals remains sparse. Recent phylogenetic studies place either ctenophores or poriferans as the closest modern relatives of the earliest emerging metazoans. Here, we review the literature and representative genomic and transcriptomic databases for evidence of ECM and ECM-affiliated components known to be conserved in bilaterians, that are also present in ctenophores and/or poriferans. Whereas an extensive set of related proteins are identifiable in poriferans, there is a strikingly lack of conservation in ctenophores. From this perspective, much remains to be learnt about the composition of ctenophore mesoglea. The principal ECM-related proteins conserved between ctenophores, poriferans, and bilaterians include collagen IV, laminin-like proteins, thrombospondin superfamily members, integrins, membrane-associated proteoglycans, and tissue transglutaminase. These are candidates for a putative ancestral ECM that may have contributed to the emergence of the metazoans.
Collapse
|
182
|
Winklbauer R. Dynamic cell–cell adhesion mediated by pericellular matrix interaction – a hypothesis. J Cell Sci 2019; 132:132/16/jcs231597. [DOI: 10.1242/jcs.231597] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
ABSTRACT
Cell–cell adhesion strength, measured as tissue surface tension, spans an enormous 1000-fold range when different cell types are compared. However, the examination of basic mechanical principles of cell adhesion indicates that cadherin-based and related mechanisms are not able to promote the high-strength adhesion experimentally observed in many late embryonic or malignant tissues. Therefore, the hypothesis is explored that the interaction of the pericellular matrices of cells generates strong adhesion by a mechanism akin to the self-adhesion/self-healing of dynamically cross-linked hydrogels. Quantitative data from biofilm matrices support this model. The mechanism links tissue surface tension to pericellular matrix stiffness. Moreover, it explains the wide, matrix-filled spaces around cells in liquid-like, yet highly cohesive, tissues, and it rehabilitates aspects of the original interpretation of classical cell sorting experiments, as expressed in Steinberg's differential adhesion hypothesis: that quantitative differences in adhesion energies between cells are sufficient to drive sorting.
Collapse
Affiliation(s)
- Rudolf Winklbauer
- Department of Cell and Systems Biology, University of Toronto, 25 Harbord Street, Toronto, Ontario, M5S 3G5, Canada
| |
Collapse
|
183
|
Mayorova TD, Hammar K, Winters CA, Reese TS, Smith CL. The ventral epithelium of Trichoplax adhaerens deploys in distinct patterns cells that secrete digestive enzymes, mucus or diverse neuropeptides. Biol Open 2019; 8:bio045674. [PMID: 31366453 PMCID: PMC6737977 DOI: 10.1242/bio.045674] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Accepted: 07/23/2019] [Indexed: 01/11/2023] Open
Abstract
The disk-shaped millimeter-sized marine animal, Trichoplax adhaerens, is notable because of its small number of cell types and primitive mode of feeding. It glides on substrates propelled by beating cilia on its lower surface and periodically pauses to feed on underlying microorganisms, which it digests externally. Here, a combination of advanced electron and light microscopic techniques are used to take a closer look at its secretory cell types and their roles in locomotion and feeding. We identify digestive enzymes in lipophils, a cell type implicated in external digestion and distributed uniformly throughout the ventral epithelium except for a narrow zone near its edge. We find three morphologically distinct types of gland cell. The most prevalent contains and secretes mucus, which is shown to be involved in adhesion and gliding. Half of the mucocytes are arrayed in a tight row around the edge of the ventral epithelium while the rest are scattered further inside, in the region containing lipophils. The secretory granules in mucocytes at the edge label with an antibody against a neuropeptide that was reported to arrest ciliary beating during feeding. A second type of gland cell is arrayed in a narrow row just inside the row of mucocytes while a third is located more centrally. Our maps of the positions of the structurally distinct secretory cell types provide a foundation for further characterization of the multiple peptidergic cell types in Trichoplax and the microscopic techniques we introduce provide tools for carrying out these studies.
Collapse
Affiliation(s)
- Tatiana D Mayorova
- Laboratory of Neurobiology, National Institute of Neurological Disorders and Stroke, National Institutes of Health, 49 Convent Drive, Bethesda, MD 20892, USA
| | - Katherine Hammar
- Central Microscopy Facility, Marine Biological Laboratory, 7 MBL Street, Woods Hole, MA 02543, USA
| | - Christine A Winters
- Laboratory of Neurobiology, National Institute of Neurological Disorders and Stroke, National Institutes of Health, 49 Convent Drive, Bethesda, MD 20892, USA
| | - Thomas S Reese
- Laboratory of Neurobiology, National Institute of Neurological Disorders and Stroke, National Institutes of Health, 49 Convent Drive, Bethesda, MD 20892, USA
| | - Carolyn L Smith
- Light Imaging Facility, National Institute of Neurological Disorders and Stroke, National Institutes of Health, 35 Convent Drive, Bethesda, MD 20892, USA
| |
Collapse
|
184
|
Colgren J, Nichols SA. The significance of sponges for comparative studies of developmental evolution. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2019; 9:e359. [PMID: 31352684 DOI: 10.1002/wdev.359] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 05/27/2019] [Accepted: 06/27/2019] [Indexed: 12/31/2022]
Abstract
Sponges, ctenophores, placozoans, and cnidarians have key evolutionary significance in that they bracket the time interval during which organized animal tissues were first assembled, fundamental cell types originated (e.g., neurons and myocytes), and developmental patterning mechanisms evolved. Sponges in particular have often been viewed as living surrogates for early animal ancestors, largely due to similarities between their feeding cells (choanocytes) with choanoflagellates, the unicellular/colony-forming sister group to animals. Here, we evaluate these claims and highlight aspects of sponge biology with comparative value for understanding developmental evolution, irrespective of the purported antiquity of their body plan. Specifically, we argue that sponges strike a different balance between patterning and plasticity than other animals, and that environmental inputs may have prominence over genetically regulated developmental mechanisms. We then present a case study to illustrate how contractile epithelia in sponges can help unravel the complex ancestry of an ancient animal cell type, myocytes, which sponges lack. Sponges represent hundreds of millions of years of largely unexamined evolutionary experimentation within animals. Their phylogenetic placement lends them key significance for learning about the past, and their divergent biology challenges current views about the scope of animal cell and developmental biology. This article is characterized under: Comparative Development and Evolution > Evolutionary Novelties Comparative Development and Evolution > Body Plan Evolution.
Collapse
Affiliation(s)
- Jeffrey Colgren
- Department of Biological Sciences, University of Denver, Denver, Colorado
| | - Scott A Nichols
- Department of Biological Sciences, University of Denver, Denver, Colorado
| |
Collapse
|
185
|
Fields C, Levin M. Somatic multicellularity as a satisficing solution to the prediction-error minimization problem. Commun Integr Biol 2019; 12:119-132. [PMID: 31413788 PMCID: PMC6682261 DOI: 10.1080/19420889.2019.1643666] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Revised: 07/04/2019] [Accepted: 07/07/2019] [Indexed: 11/26/2022] Open
Abstract
Adaptive success in the biosphere requires the dynamic ability to adjust physiological, transcriptional, and behavioral responses to environmental conditions. From chemical networks to organisms to whole communities, biological entities at all levels of organization seek to optimize their predictive power. Here, we argue that this fundamental drive provides a novel perspective on the origin of multicellularity. One way for unicellular organisms to minimize surprise with respect to external inputs is to be surrounded by reproductively-disabled, i.e. somatic copies of themselves – highly predictable agents which in effect reduce uncertainty in their microenvironments. We show that the transition to multicellularity can be modeled as a phase transition driven by environmental threats. We present modeling results showing how multicellular bodies can arise if non-reproductive somatic cells protect their reproductive parents from environmental lethality. We discuss how a somatic body can be interpreted as a Markov blanket around one or more reproductive cells, and how the transition to somatic multicellularity can be represented as a transition from exposure of reproductive cells to a high-uncertainty environment to their protection from environmental uncertainty by this Markov blanket. This is, effectively, a transition by the Markov blanket from transparency to opacity for the variational free energy of the environment. We suggest that the ability to arrest the cell cycle of daughter cells and redirect their resource utilization from division to environmental threat amelioration is the key innovation of obligate multicellular eukaryotes, that the nervous system evolved to exercise this control over long distances, and that cancer is an escape by somatic cells from the control of reproductive cells. Our quantitative model illustrates the evolutionary dynamics of this system, provides a novel hypothesis for the origin of multicellular animal bodies, and suggests a fundamental link between the architectures of complex organisms and information processing in proto-cognitive cellular agents.
Collapse
Affiliation(s)
| | - Michael Levin
- Allen Discovery Center at Tufts University, Medford, MA USA
| |
Collapse
|
186
|
Staps M, van Gestel J, Tarnita CE. Emergence of diverse life cycles and life histories at the origin of multicellularity. Nat Ecol Evol 2019; 3:1197-1205. [PMID: 31285576 DOI: 10.1038/s41559-019-0940-0] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Accepted: 06/04/2019] [Indexed: 02/07/2023]
Abstract
The evolution of multicellularity has given rise to a remarkable diversity of multicellular life cycles and life histories. Whereas some multicellular organisms are long-lived, grow through cell division, and repeatedly release single-celled propagules (for example, animals), others are short-lived, form by aggregation, and propagate only once, by generating large numbers of solitary cells (for example, cellular slime moulds). There are no systematic studies that explore how diverse multicellular life cycles can come about. Here, we focus on the origin of multicellularity and develop a mechanistic model to examine the primitive life cycles that emerge from a unicellular ancestor when an ancestral gene is co-opted for cell adhesion. Diverse life cycles readily emerge, depending on ecological conditions, group-forming mechanism, and ancestral constraints. Among these life cycles, we recapitulate both extremes of long-lived groups that propagate continuously and short-lived groups that propagate only once, with the latter type of life cycle being particularly favoured when groups can form by aggregation. Our results show how diverse life cycles and life histories can easily emerge at the origin of multicellularity, shaped by ancestral constraints and ecological conditions. Beyond multicellularity, this finding has similar implications for other major transitions, such as the evolution of sociality.
Collapse
Affiliation(s)
- Merlijn Staps
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ, USA
| | - Jordi van Gestel
- Department of Evolutionary Biology and Environmental Studies, University of Zürich, Zürich, Switzerland. .,Swiss Institute of Bioinformatics, Lausanne, Switzerland. .,Department of Environmental Systems Science, ETH Zürich, Zürich, Switzerland. .,Department of Environmental Microbiology, Swiss Federal Institute of Aquatic Science and Technology (EAWAG), Dübendorf, Switzerland.
| | - Corina E Tarnita
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ, USA.
| |
Collapse
|
187
|
|
188
|
Smith CL, Mayorova TD. Insights into the evolution of digestive systems from studies of Trichoplax adhaerens. Cell Tissue Res 2019; 377:353-367. [PMID: 31270610 DOI: 10.1007/s00441-019-03057-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Accepted: 06/09/2019] [Indexed: 01/01/2023]
Abstract
Trichoplax, a member of the phylum Placozoa, is a tiny ciliated marine animal that glides on surfaces feeding on algae and cyanobacteria. It stands out from other animals in that it lacks an internal digestive system and, instead, digests food trapped under its lower surface. Here we review recent work on the phenotypes of its six cell types and their roles in digestion and feeding behavior. Phylogenomic analyses place Placozoa as sister to Eumetazoa, the clade that includes Cnidaria and Bilateria. Comparing the phenotypes of cells in Trichoplax to those of cells in the digestive epithelia of Eumetazoa allows us to make inferences about the cell types and mode of feeding of their ancestors. From our increasingly mechanistic understanding of feeding in Trichoplax, we get a glimpse into how primitive animals may have hunted and consumed food prior to the evolution of neurons, muscles, and internal digestive systems.
Collapse
Affiliation(s)
- Carolyn L Smith
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, 20892, USA.
| | - Tatiana D Mayorova
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, 20892, USA
| |
Collapse
|
189
|
Nielsen C. Early animal evolution: a morphologist's view. ROYAL SOCIETY OPEN SCIENCE 2019; 6:190638. [PMID: 31417759 PMCID: PMC6689584 DOI: 10.1098/rsos.190638] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Accepted: 07/04/2019] [Indexed: 05/15/2023]
Abstract
Two hypotheses for the early radiation of the metazoans are vividly discussed in recent phylogenomic studies, the 'Porifera-first' hypothesis, which places the poriferans as the sister group of all other metazoans, and the 'Ctenophora-first' hypothesis, which places the ctenophores as the sister group to all other metazoans. It has been suggested that an analysis of morphological characters (including specific molecules) could throw additional light on the controversy, and this is the aim of this paper. Both hypotheses imply independent evolution of nervous systems in Planulozoa and Ctenophora. The Porifera-first hypothesis implies no homoplasies or losses of major characters. The Ctenophora-first hypothesis shows no important synapomorphies of Porifera, Planulozoa and Placozoa. It implies either independent evolution, in Planulozoa and Ctenophora, of a new digestive system with a gut with extracellular digestion, which enables feeding on larger organisms, or the subsequent loss of this new gut in the Poriferans (and the re-evolution of the collar complex). The major losses implied in the Ctenophora-first theory show absolutely no adaptational advantages. Thus, morphology gives very strong support for the Porifera-first hypothesis.
Collapse
Affiliation(s)
- Claus Nielsen
- The Natural History Museum of Denmark, University of Copenhagen, Zoological Museum, Universitetsparken 15, DK-2100 Copenhagen, Denmark
| |
Collapse
|
190
|
Newman SA. Inherency of Form and Function in Animal Development and Evolution. Front Physiol 2019; 10:702. [PMID: 31275153 PMCID: PMC6593199 DOI: 10.3389/fphys.2019.00702] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Accepted: 05/20/2019] [Indexed: 12/11/2022] Open
Abstract
I discuss recent work on the origins of morphology and cell-type diversification in Metazoa – collectively the animals – and propose a scenario for how these two properties became integrated, with the help of a third set of processes, cellular pattern formation, into the developmental programs seen in present-day metazoans. Inherent propensities to generate familiar forms and cell types, in essence a parts kit for the animals, are exhibited by present-day organisms and were likely more prominent in primitive ones. The structural motifs of animal bodies and organs, e.g., multilayered, hollow, elongated and segmented tissues, internal and external appendages, branched tubes, and modular endoskeletons, can be accounted for by the properties of mesoscale masses of metazoan cells. These material properties, in turn, resulted from the recruitment of “generic” physical forces and mechanisms – adhesion, contraction, polarity, chemical oscillation, diffusion – by toolkit molecules that were partly conserved from unicellular holozoan antecedents and partly novel, distributed in the different metazoan phyla in a fashion correlated with morphological complexity. The specialized functions of the terminally differentiated cell types in animals, e.g., contraction, excitability, barrier function, detoxification, excretion, were already present in ancestral unicellular organisms. These functions were implemented in metazoan differentiation in some cases using the same transcription factors as in single-celled ancestors, although controlled by regulatory mechanisms that were hybrids between earlier-evolved processes and regulatory innovations, such as enhancers. Cellular pattern formation, mediated by released morphogens interacting with biochemically responsive and excitable tissues, drew on inherent self-organizing processes in proto-metazoans to transform clusters of holozoan cells into animal embryos and organs.
Collapse
Affiliation(s)
- Stuart A Newman
- Department of Cell Biology and Anatomy, New York Medical College, Valhalla, NY, United States
| |
Collapse
|
191
|
Pluripotency and the origin of animal multicellularity. Nature 2019; 570:519-522. [PMID: 31189954 DOI: 10.1038/s41586-019-1290-4] [Citation(s) in RCA: 69] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Accepted: 05/16/2019] [Indexed: 01/01/2023]
Abstract
A widely held-but rarely tested-hypothesis for the origin of animals is that they evolved from a unicellular ancestor, with an apical cilium surrounded by a microvillar collar, that structurally resembled modern sponge choanocytes and choanoflagellates1-4. Here we test this view of animal origins by comparing the transcriptomes, fates and behaviours of the three primary sponge cell types-choanocytes, pluripotent mesenchymal archaeocytes and epithelial pinacocytes-with choanoflagellates and other unicellular holozoans. Unexpectedly, we find that the transcriptome of sponge choanocytes is the least similar to the transcriptomes of choanoflagellates and is significantly enriched in genes unique to either animals or sponges alone. By contrast, pluripotent archaeocytes upregulate genes that control cell proliferation and gene expression, as in other metazoan stem cells and in the proliferating stages of two unicellular holozoans, including a colonial choanoflagellate. Choanocytes in the sponge Amphimedon queenslandica exist in a transient metastable state and readily transdifferentiate into archaeocytes, which can differentiate into a range of other cell types. These sponge cell-type conversions are similar to the temporal cell-state changes that occur in unicellular holozoans5. Together, these analyses argue against homology of sponge choanocytes and choanoflagellates, and the view that the first multicellular animals were simple balls of cells with limited capacity to differentiate. Instead, our results are consistent with the first animal cell being able to transition between multiple states in a manner similar to modern transdifferentiating and stem cells.
Collapse
|
192
|
Stahl PD, Raposo G. Extracellular Vesicles: Exosomes and Microvesicles, Integrators of Homeostasis. Physiology (Bethesda) 2019; 34:169-177. [PMID: 30968753 DOI: 10.1152/physiol.00045.2018] [Citation(s) in RCA: 210] [Impact Index Per Article: 42.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Extracellular vesicles (EVs), cell-derived membrane structures, are secreted after fusion of endosomes with the plasma membrane (exosomes) or shed from the plasma membrane (microvesicles). EVs play a key role both in physiological balance and homeostasis and in disease processes by their ability to participate in intercellular signaling and communication.
Collapse
Affiliation(s)
- Philip D Stahl
- Department of Cell Biology and Physiology, Washington University School of Medicine , St. Louis, Missouri
| | - Graca Raposo
- Institut Curie, PSL Research University, CNRS, Paris , France.,Sorbonne Universités, UPMC CNRS, Paris , France
| |
Collapse
|
193
|
Shoemark DK, Ziegler B, Watanabe H, Strompen J, Tucker RP, Özbek S, Adams JC. Emergence of a Thrombospondin Superfamily at the Origin of Metazoans. Mol Biol Evol 2019; 36:1220-1238. [PMID: 30863851 PMCID: PMC6526912 DOI: 10.1093/molbev/msz060] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Extracellular matrix (ECM) is considered central to the evolution of metazoan multicellularity; however, the repertoire of ECM proteins in nonbilaterians remains unclear. Thrombospondins (TSPs) are known to be well conserved from cnidarians to vertebrates, yet to date have been considered a unique family, principally studied for matricellular functions in vertebrates. Through searches utilizing the highly conserved C-terminal region of TSPs, we identify undisclosed new families of TSP-related proteins in metazoans, designated mega-TSP, sushi-TSP, and poriferan-TSP, each with a distinctive phylogenetic distribution. These proteins share the TSP C-terminal region domain architecture, as determined by domain composition and analysis of molecular models against known structures. Mega-TSPs, the only form identified in ctenophores, are typically >2,700 aa and are also characterized by N-terminal leucine-rich repeats and central cadherin/immunoglobulin domains. In cnidarians, which have a well-defined ECM, Mega-TSP was expressed throughout embryogenesis in Nematostella vectensis, with dynamic endodermal expression in larvae and primary polyps and widespread ectodermal expression in adult Nematostella vectensis and Hydra magnipapillata polyps. Hydra Mega-TSP was also expressed during regeneration and siRNA-silencing of Mega-TSP in Hydra caused specific blockade of head regeneration. Molecular phylogenetic analyses based on the conserved TSP C-terminal region identified each of the TSP-related groups to form clades distinct from the canonical TSPs. We discuss models for the evolution of the newly defined TSP superfamily by gene duplications, radiation, and gene losses from a debut in the last metazoan common ancestor. Together, the data provide new insight into the evolution of ECM and tissue organization in metazoans.
Collapse
Affiliation(s)
| | - Berenice Ziegler
- Centre for Organismal Studies, Department of Molecular Evolution and Genomics, University of Heidelberg, Heidelberg, Germany
| | - Hiroshi Watanabe
- Evolutionary Neurobiology Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
| | - Jennifer Strompen
- Centre for Organismal Studies, Department of Molecular Evolution and Genomics, University of Heidelberg, Heidelberg, Germany
| | - Richard P Tucker
- Department of Cell Biology and Human Anatomy, University of California at Davis, Davis, CA
| | - Suat Özbek
- Centre for Organismal Studies, Department of Molecular Evolution and Genomics, University of Heidelberg, Heidelberg, Germany
| | - Josephine C Adams
- School of Biochemistry, University of Bristol, Bristol, United Kingdom
| |
Collapse
|
194
|
The Vav GEF Family: An Evolutionary and Functional Perspective. Cells 2019; 8:cells8050465. [PMID: 31100928 PMCID: PMC6562523 DOI: 10.3390/cells8050465] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Revised: 05/10/2019] [Accepted: 05/15/2019] [Indexed: 02/07/2023] Open
Abstract
Vav proteins play roles as guanosine nucleotide exchange factors for Rho GTPases and signaling adaptors downstream of protein tyrosine kinases. The recent sequencing of the genomes of many species has revealed that this protein family originated in choanozoans, a group of unicellular organisms from which animal metazoans are believed to have originated from. Since then, the Vav family underwent expansions and reductions in its members during the evolutionary transitions that originated the agnates, chondrichthyes, some teleost fish, and some neoaves. Exotic members of the family harboring atypical structural domains can be also found in some invertebrate species. In this review, we will provide a phylogenetic perspective of the evolution of the Vav family. We will also pay attention to the structure, signaling properties, regulatory layers, and functions of Vav proteins in both invertebrate and vertebrate species.
Collapse
|
195
|
Rodríguez-Pascual F. How evolution made the matrix punch at the multicellularity party. J Biol Chem 2019; 294:770-771. [PMID: 30659161 DOI: 10.1074/jbc.h118.006972] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The basement membrane is a specialized sheet-like form of the extracellular matrix that provides structural support to epithelial cells and tissues, while influencing multiple biological functions, and was essential in the transition to multicellularity. By exploring a variety of genomes, Darris et al. provide evidence that the emergence and divergence of a multifunctional Goodpasture antigen-binding protein (GPBP), a basement membrane constituent, played a role in this transition. These findings help to explain how GPBP contributed to the formation of these extracellular matrices and to more precisely define the transition to multicellular organisms.
Collapse
Affiliation(s)
- Fernando Rodríguez-Pascual
- From the Centro de Biología Molecular "Severo Ochoa," Consejo Superior de Investigaciones Científicas (C.S.I.C.), Universidad Autónoma de Madrid (U.A.M.), Nicolás Cabrera 1, Madrid, E28049 Spain
| |
Collapse
|
196
|
The architecture of cell differentiation in choanoflagellates and sponge choanocytes. PLoS Biol 2019; 17:e3000226. [PMID: 30978201 PMCID: PMC6481868 DOI: 10.1371/journal.pbio.3000226] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Revised: 04/24/2019] [Accepted: 03/27/2019] [Indexed: 11/19/2022] Open
Abstract
Although collar cells are conserved across animals and their closest relatives, the choanoflagellates, little is known about their ancestry, their subcellular architecture, or how they differentiate. The choanoflagellate Salpingoeca rosetta expresses genes necessary for animal development and can alternate between unicellular and multicellular states, making it a powerful model for investigating the origin of animal multicellularity and mechanisms underlying cell differentiation. To compare the subcellular architecture of solitary collar cells in S. rosetta with that of multicellular ‘rosette’ colonies and collar cells in sponges, we reconstructed entire cells in 3D through transmission electron microscopy on serial ultrathin sections. Structural analysis of our 3D reconstructions revealed important differences between single and colonial choanoflagellate cells, with colonial cells exhibiting a more amoeboid morphology consistent with higher levels of macropinocytotic activity. Comparison of multiple reconstructed rosette colonies highlighted the variable nature of cell sizes, cell–cell contact networks, and colony arrangement. Importantly, we uncovered the presence of elongated cells in some rosette colonies that likely represent a distinct and differentiated cell type, pointing toward spatial cell differentiation. Intercellular bridges within choanoflagellate colonies displayed a variety of morphologies and connected some but not all neighbouring cells. Reconstruction of sponge choanocytes revealed ultrastructural commonalities but also differences in major organelle composition in comparison to choanoflagellates. Together, our comparative reconstructions uncover the architecture of cell differentiation in choanoflagellates and sponge choanocytes and constitute an important step in reconstructing the cell biology of the last common ancestor of animals. 3D electron microscopy of choanoflagellates and sponge choanocytes reveals a remarkable variety of cell architecture and suggests that cell type differentiation may have been present in the stem lineage leading to the animals. Choanoflagellates are microscopic aquatic organisms that can alternate between single-celled and multicellular states, and sequencing of their genomes has revealed that choanoflagellates are the closest single-celled relatives of animals. Moreover, choanoflagellates are a form of ‘collar cell’—a cell type crowned by an array of finger-like microvilli and a single, whip-like flagellum. This cell type is also found throughout the animal kingdom; therefore, studying the structure of the choanoflagellate collar cell can shed light on how this cell type and animal multicellularity might have evolved. We used electron microscopy to reconstruct in 3D the total subcellular composition of single-celled and multicellular choanoflagellates as well as the collar cells from a marine sponge, which represents an early-branching animal lineage. We found differences between single-celled and multicellular choanoflagellates in structures associated with cellular energetics, membrane trafficking, and cell morphology. Likewise, we describe a complex system of cell–cell connections associated with multicellular choanoflagellates. Finally, comparison of choanoflagellates and sponge collar cells revealed subcellular differences associated with feeding and cellular energetics. Taken together, this study is an important step forward in reconstructing the biology of the last common ancestor of the animals.
Collapse
|
197
|
Sperling EA, Stockey RG. The Temporal and Environmental Context of Early Animal Evolution: Considering All the Ingredients of an "Explosion". Integr Comp Biol 2019; 58:605-622. [PMID: 30295813 DOI: 10.1093/icb/icy088] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Animals originated and evolved during a unique time in Earth history-the Neoproterozoic Era. This paper aims to discuss (1) when landmark events in early animal evolution occurred, and (2) the environmental context of these evolutionary milestones, and how such factors may have affected ecosystems and body plans. With respect to timing, molecular clock studies-utilizing a diversity of methodologies-agree that animal multicellularity had arisen by ∼800 million years ago (Ma) (Tonian period), the bilaterian body plan by ∼650 Ma (Cryogenian), and divergences between sister phyla occurred ∼560-540 Ma (late Ediacaran). Most purported Tonian and Cryogenian animal body fossils are unlikely to be correctly identified, but independent support for the presence of pre-Ediacaran animals is recorded by organic geochemical biomarkers produced by demosponges. This view of animal origins contrasts with data from the fossil record, and the taphonomic question of why animals were not preserved (if present) remains unresolved. Neoproterozoic environments demanding small, thin, body plans, and lower abundance/rarity in populations may have played a role. Considering environmental conditions, geochemical data suggest that animals evolved in a relatively low-oxygen ocean. Here, we present new analyses of sedimentary total organic carbon contents in shales suggesting that the Neoproterozoic ocean may also have had lower primary productivity-or at least lower quantities of organic carbon reaching the seafloor-compared with the Phanerozoic. Indeed, recent modeling efforts suggest that low primary productivity is an expected corollary of a low-O2 world. Combined with an inability to inhabit productive regions in a low-O2 ocean, earliest animal communities would likely have been more food limited than generally appreciated, impacting both ecosystem structure and organismal behavior. In light of this, we propose the "fire triangle" metaphor for environmental influences on early animal evolution. Moving toward consideration of all environmental aspects of the Cambrian radiation (fuel, heat, and oxidant) will ultimately lead to a more holistic view of the event.
Collapse
Affiliation(s)
- Erik A Sperling
- Department of Geological Sciences, Stanford University, 450 Serra Mall, Building 320, Stanford, CA 94305, USA
| | - Richard G Stockey
- Department of Geological Sciences, Stanford University, 450 Serra Mall, Building 320, Stanford, CA 94305, USA
| |
Collapse
|
198
|
Fernandez-Valverde SL, Aguilera F, Ramos-Díaz RA. Inference of Developmental Gene Regulatory Networks Beyond Classical Model Systems: New Approaches in the Post-genomic Era. Integr Comp Biol 2019; 58:640-653. [PMID: 29917089 DOI: 10.1093/icb/icy061] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The advent of high-throughput sequencing (HTS) technologies has revolutionized the way we understand the transformation of genetic information into morphological traits. Elucidating the network of interactions between genes that govern cell differentiation through development is one of the core challenges in genome research. These networks are known as developmental gene regulatory networks (dGRNs) and consist largely of the functional linkage between developmental control genes, cis-regulatory modules, and differentiation genes, which generate spatially and temporally refined patterns of gene expression. Over the last 20 years, great advances have been made in determining these gene interactions mainly in classical model systems, including human, mouse, sea urchin, fruit fly, and worm. This has brought about a radical transformation in the fields of developmental biology and evolutionary biology, allowing the generation of high-resolution gene regulatory maps to analyze cell differentiation during animal development. Such maps have enabled the identification of gene regulatory circuits and have led to the development of network inference methods that can recapitulate the differentiation of specific cell-types or developmental stages. In contrast, dGRN research in non-classical model systems has been limited to the identification of developmental control genes via the candidate gene approach and the characterization of their spatiotemporal expression patterns, as well as to the discovery of cis-regulatory modules via patterns of sequence conservation and/or predicted transcription-factor binding sites. However, thanks to the continuous advances in HTS technologies, this scenario is rapidly changing. Here, we give a historical overview on the architecture and elucidation of the dGRNs. Subsequently, we summarize the approaches available to unravel these regulatory networks, highlighting the vast range of possibilities of integrating multiple technical advances and theoretical approaches to expand our understanding on the global gene regulation during animal development in non-classical model systems. Such new knowledge will not only lead to greater insights into the evolution of molecular mechanisms underlying cell identity and animal body plans, but also into the evolution of morphological key innovations in animals.
Collapse
Affiliation(s)
- Selene L Fernandez-Valverde
- CONACYT, Unidad de Genómica Avanzada, Laboratorio Nacional de Genómica para la Biodiversidad (Langebio), Centro de Investigación y de Estudios Avanzados del IPN, Irapuato, Guanajuato, Mexico
| | - Felipe Aguilera
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Chile
| | - René Alexander Ramos-Díaz
- CONACYT, Unidad de Genómica Avanzada, Laboratorio Nacional de Genómica para la Biodiversidad (Langebio), Centro de Investigación y de Estudios Avanzados del IPN, Irapuato, Guanajuato, Mexico
| |
Collapse
|
199
|
Raza Q, Choi JY, Li Y, O’Dowd RM, Watkins SC, Chikina M, Hong Y, Clark NL, Kwiatkowski AV. Evolutionary rate covariation analysis of E-cadherin identifies Raskol as a regulator of cell adhesion and actin dynamics in Drosophila. PLoS Genet 2019; 15:e1007720. [PMID: 30763317 PMCID: PMC6375579 DOI: 10.1371/journal.pgen.1007720] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Accepted: 12/07/2018] [Indexed: 12/17/2022] Open
Abstract
The adherens junction couples the actin cytoskeletons of neighboring cells to provide the foundation for multicellular organization. The core of the adherens junction is the cadherin-catenin complex that arose early in the evolution of multicellularity to link actin to intercellular adhesions. Over time, evolutionary pressures have shaped the signaling and mechanical functions of the adherens junction to meet specific developmental and physiological demands. Evolutionary rate covariation (ERC) identifies proteins with correlated fluctuations in evolutionary rate that can reflect shared selective pressures and functions. Here we use ERC to identify proteins with evolutionary histories similar to the Drosophila E-cadherin (DE-cad) ortholog. Core adherens junction components α-catenin and p120-catenin displayed positive ERC correlations with DE-cad, indicating that they evolved under similar selective pressures during evolution between Drosophila species. Further analysis of the DE-cad ERC profile revealed a collection of proteins not previously associated with DE-cad function or cadherin-mediated adhesion. We then analyzed the function of a subset of ERC-identified candidates by RNAi during border cell (BC) migration and identified novel genes that function to regulate DE-cad. Among these, we found that the gene CG42684, which encodes a putative GTPase activating protein (GAP), regulates BC migration and adhesion. We named CG42684 raskol (“to split” in Russian) and show that it regulates DE-cad levels and actin protrusions in BCs. We propose that Raskol functions with DE-cad to restrict Ras/Rho signaling and help guide BC migration. Our results demonstrate that a coordinated selective pressure has shaped the adherens junction and this can be leveraged to identify novel components of the complexes and signaling pathways that regulate cadherin-mediated adhesion. The establishment of intercellular adhesions facilitated the genesis of multicellular organisms. The adherens junction, which links the actin cytoskeletons of neighboring cells, arose early in the evolution of multicellularity and selective pressures have shaped its function and molecular composition over time. In this study, we used evolutionary rate covariation (ERC) analysis to examine the evolutionary history of the adherens junction and to identify proteins that coevolved with the core adherens junction protein Drosophila E-cadherin (DE-cad). ERC analysis of DE-cad revealed a collection of proteins with similar evolutionary histories. We then tested the role of ERC-identified candidates in border cell migration in the fly egg chamber, a process that requires the coordinated regulation of cell-cell adhesion and cell motility. Among these, we found that a previously uncharacterized gene CG42684, which encodes a putative GTPase activating protein (GAP), regulates the collective cell migration of border cells, stabilizes cell-cell adhesions and regulates the actin dynamics. Our results demonstrate that components of the adherens junction share an evolutionary history and that ERC analysis is a powerful method to identify novel components of cell adhesion complexes in Drosophila.
Collapse
Affiliation(s)
- Qanber Raza
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Jae Young Choi
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, New York, United States of America
| | - Yang Li
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Roisin M. O’Dowd
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Simon C. Watkins
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
- Center for Biologic Imaging, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Maria Chikina
- Department of Computational and Systems Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Yang Hong
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Nathan L. Clark
- Department of Computational and Systems Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Adam V. Kwiatkowski
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
- * E-mail:
| |
Collapse
|
200
|
Junqueira Alves C, Yotoko K, Zou H, Friedel RH. Origin and evolution of plexins, semaphorins, and Met receptor tyrosine kinases. Sci Rep 2019; 9:1970. [PMID: 30760850 PMCID: PMC6374515 DOI: 10.1038/s41598-019-38512-y] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Accepted: 12/28/2018] [Indexed: 12/20/2022] Open
Abstract
The transition from unicellular to multicellular organisms poses the question as to when genes that regulate cell-cell interactions emerged during evolution. The receptor and ligand pairing of plexins and semaphorins regulates cellular interactions in a wide range of developmental and physiological contexts. We surveyed here genomes of unicellular eukaryotes and of non-bilaterian and bilaterian Metazoa and performed phylogenetic analyses to gain insight into the evolution of plexin and semaphorin families. Remarkably, we detected plexins and semaphorins in unicellular choanoflagellates, indicating their evolutionary origin in a common ancestor of Choanoflagellida and Metazoa. The plexin domain structure is conserved throughout all clades; in contrast, semaphorins are structurally diverse. Choanoflagellate semaphorins are transmembrane proteins with multiple fibronectin type III domains following the N-terminal Sema domain (termed Sema-FN). Other previously not yet described semaphorin classes include semaphorins of Ctenophora with tandem immunoglobulin domains (Sema-IG) and secreted semaphorins of Echinoderamata (Sema-SP, Sema-SI). Our study also identified Met receptor tyrosine kinases (RTKs), which carry a truncated plexin extracellular domain, in several bilaterian clades, indicating evolutionary origin in a common ancestor of Bilateria. In addition, a novel type of Met-like RTK with a complete plexin extracellular domain was detected in Lophotrochozoa and Echinodermata (termed Met-LP RTK). Our findings are consistent with an ancient function of plexins and semaphorins in regulating cytoskeletal dynamics and cell adhesion that predates their role as axon guidance molecules.
Collapse
Affiliation(s)
- Chrystian Junqueira Alves
- Fishberg Department of Neuroscience, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, New York, 10029, USA
| | - Karla Yotoko
- Biology Department, Universidade Federal de Viçosa, Viçosa, Minas Gerais, 36570-900, Brazil
| | - Hongyan Zou
- Fishberg Department of Neuroscience, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, New York, 10029, USA.,Department of Neurosurgery, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, New York, 10029, USA
| | - Roland H Friedel
- Fishberg Department of Neuroscience, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, New York, 10029, USA. .,Department of Neurosurgery, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, New York, 10029, USA.
| |
Collapse
|