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Olson PD, Zarowiecki M, James K, Baillie A, Bartl G, Burchell P, Chellappoo A, Jarero F, Tan LY, Holroyd N, Berriman M. Genome-wide transcriptome profiling and spatial expression analyses identify signals and switches of development in tapeworms. EvoDevo 2018; 9:21. [PMID: 30455861 PMCID: PMC6225667 DOI: 10.1186/s13227-018-0110-5] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Accepted: 10/05/2018] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Tapeworms are agents of neglected tropical diseases responsible for significant health problems and economic loss. They also exhibit adaptations to a parasitic lifestyle that confound comparisons of their development with other animals. Identifying the genetic factors regulating their complex ontogeny is essential to understanding unique aspects of their biology and for advancing novel therapeutics. Here we use RNA sequencing to identify up-regulated signalling components, transcription factors and post-transcriptional/translational regulators (genes of interest, GOI) in the transcriptomes of Larvae and different regions of segmented worms in the tapeworm Hymenolepis microstoma and combine this with spatial gene expression analyses of a selection of genes. RESULTS RNA-seq reads collectively mapped to 90% of the > 12,000 gene models in the H. microstoma v.2 genome assembly, demonstrating that the transcriptome profiles captured a high percentage of predicted genes. Contrasts made between the transcriptomes of Larvae and whole, adult worms, and between the Scolex-Neck, mature strobila and gravid strobila, resulted in 4.5-30% of the genes determined to be differentially expressed. Among these, we identified 190 unique GOI up-regulated in one or more contrasts, including a large range of zinc finger, homeobox and other transcription factors, components of Wnt, Notch, Hedgehog and TGF-β/BMP signalling, and post-transcriptional regulators (e.g. Boule, Pumilio). Heatmap clusterings based on overall expression and on select groups of genes representing 'signals' and 'switches' showed that expression in the Scolex-Neck region is more similar to that of Larvae than to the mature or gravid regions of the adult worm, which was further reflected in large overlap of up-regulated GOI. CONCLUSIONS Spatial expression analyses in Larvae and adult worms corroborated inferences made from quantitative RNA-seq data and in most cases indicated consistency with canonical roles of the genes in other animals, including free-living flatworms. Recapitulation of developmental factors up-regulated during larval metamorphosis suggests that strobilar growth involves many of the same underlying gene regulatory networks despite the significant disparity in developmental outcomes. The majority of genes identified were investigated in tapeworms for the first time, setting the stage for advancing our understanding of developmental genetics in an important group of flatworm parasites.
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Affiliation(s)
- Peter D. Olson
- Division of Parasites and Vectors, Department of Life Sciences, The Natural History Museum, Cromwell Road, London, SW7 5BD UK
| | - Magdalena Zarowiecki
- Division of Parasites and Vectors, Department of Life Sciences, The Natural History Museum, Cromwell Road, London, SW7 5BD UK
- Parasite Genomics, Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 1SA UK
| | - Katherine James
- Division of Parasites and Vectors, Department of Life Sciences, The Natural History Museum, Cromwell Road, London, SW7 5BD UK
| | - Andrew Baillie
- Division of Parasites and Vectors, Department of Life Sciences, The Natural History Museum, Cromwell Road, London, SW7 5BD UK
| | - Georgie Bartl
- Division of Parasites and Vectors, Department of Life Sciences, The Natural History Museum, Cromwell Road, London, SW7 5BD UK
| | - Phil Burchell
- Division of Parasites and Vectors, Department of Life Sciences, The Natural History Museum, Cromwell Road, London, SW7 5BD UK
| | - Azita Chellappoo
- Division of Parasites and Vectors, Department of Life Sciences, The Natural History Museum, Cromwell Road, London, SW7 5BD UK
| | - Francesca Jarero
- Division of Parasites and Vectors, Department of Life Sciences, The Natural History Museum, Cromwell Road, London, SW7 5BD UK
| | - Li Ying Tan
- Division of Parasites and Vectors, Department of Life Sciences, The Natural History Museum, Cromwell Road, London, SW7 5BD UK
| | - Nancy Holroyd
- Parasite Genomics, Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 1SA UK
| | - Matt Berriman
- Parasite Genomics, Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 1SA UK
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Kerbl A, Conzelmann M, Jékely G, Worsaae K. High diversity in neuropeptide immunoreactivity patterns among three closely related species of Dinophilidae (Annelida). J Comp Neurol 2017; 525:3596-3635. [PMID: 28744909 DOI: 10.1002/cne.24289] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Revised: 06/23/2017] [Accepted: 07/07/2017] [Indexed: 12/31/2022]
Abstract
Neuropeptides are conserved metazoan signaling molecules, and represent useful markers for comparative investigations on the morphology and function of the nervous system. However, little is known about the variation of neuropeptide expression patterns across closely related species in invertebrate groups other than insects. In this study, we compare the immunoreactivity patterns of 14 neuropeptides in three closely related microscopic dinophilid annelids (Dinophilus gyrociliatus, D. taeniatus and Trilobodrilus axi). The brains of all three species were found to consist of around 700 somata, surrounding a central neuropil with 3-5 ventral and 2-5 dorsal commissures. Neuropeptide immunoreactivity was detected in the brain, the ventral cords, stomatogastric nervous system, and additional nerves. Different neuropeptides are expressed in specific, non-overlapping cells in the brain in all three species. FMRFamide, MLD/pedal peptide, allatotropin, RNamide, excitatory peptide, and FVRIamide showed a broad localization within the brain, while calcitonin, SIFamide, vasotocin, RGWamide, DLamide, FLamide, FVamide, MIP, and serotonin were present in fewer cells in demarcated regions. The different markers did not reveal ganglionic subdivisions or physical compartmentalization in any of these microscopic brains. The non-overlapping expression of different neuropeptides may indicate that the regionalization in these uniform, small brains is realized by individual cells, rather than cell clusters, representing an alternative to the lobular organization observed in several macroscopic annelids. Furthermore, despite the similar gross brain morphology, we found an unexpectedly high variation in the expression patterns of neuropeptides across species. This suggests that neuropeptide expression evolves faster than morphology, representing a possible mechanism for the evolutionary divergence of behaviors.
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Affiliation(s)
- Alexandra Kerbl
- Marine Biological Section - Department of Biology, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | | | - Gáspár Jékely
- Max Planck Institute for Developmental Biology, Tübingen, Germany
| | - Katrine Worsaae
- Marine Biological Section - Department of Biology, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
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Kerbl A, Martín-Durán JM, Worsaae K, Hejnol A. Molecular regionalization in the compact brain of the meiofaunal annelid Dinophilus gyrociliatus (Dinophilidae). EvoDevo 2016; 7:20. [PMID: 27583125 PMCID: PMC5006589 DOI: 10.1186/s13227-016-0058-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Accepted: 08/17/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Annelida is a morphologically diverse animal group that exhibits a remarkable variety in nervous system architecture (e.g., number and location of longitudinal cords, architecture of the brain). Despite this heterogeneity of neural arrangements, the molecular profiles related to central nervous system patterning seem to be conserved even between distantly related annelids. In particular, comparative molecular studies on brain and anterior neural region patterning genes have focused so far mainly on indirect-developing macrofaunal taxa. Therefore, analyses on microscopic, direct-developing annelids are important to attain a general picture of the evolutionary events underlying the vast diversity of annelid neuroanatomy. RESULTS We have analyzed the expression domains of 11 evolutionarily conserved genes involved in brain and anterior neural patterning in adult females of the direct-developing meiofaunal annelid Dinophilus gyrociliatus. The small, compact brain shows expression of dimmed, foxg, goosecoid, homeobrain, nk2.1, orthodenticle, orthopedia, pax6, six3/6 and synaptotagmin-1. Although most of the studied markers localize to specific brain areas, the genes six3/6 and synaptotagmin-1 are expressed in nearly all perikarya of the brain. All genes except for goosecoid, pax6 and nk2.2 overlap in the anterior brain region, while the respective expression domains are more separated in the posterior brain. CONCLUSIONS Our findings reveal that the expression patterns of the genes foxg, orthodenticle, orthopedia and six3/6 correlate with those described in Platynereis dumerilii larvae, and homeobrain, nk2.1, orthodenticle and synaptotagmin-1 resemble the pattern of late larvae of Capitella teleta. Although data on other annelids are limited, molecular similarities between adult Dinophilus and larval Platynereis and Capitella suggest an overall conservation of molecular mechanisms patterning the anterior neural regions, independent from developmental and ecological strategies, or of the size and configuration of the nervous system.
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Affiliation(s)
- Alexandra Kerbl
- Marine Biology Section, Department of Biology, Faculty of Science, University of Copenhagen, Universitetsparken 4, 2100 Copenhagen, Denmark
| | - José M Martín-Durán
- Sars International Centre for Marine Molecular Biology, University of Bergen, Thormøhlensgate, 55, 5006 Bergen, Norway
| | - Katrine Worsaae
- Marine Biology Section, Department of Biology, Faculty of Science, University of Copenhagen, Universitetsparken 4, 2100 Copenhagen, Denmark
| | - Andreas Hejnol
- Sars International Centre for Marine Molecular Biology, University of Bergen, Thormøhlensgate, 55, 5006 Bergen, Norway
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Yaguchi J, Takeda N, Inaba K, Yaguchi S. Cooperative Wnt-Nodal Signals Regulate the Patterning of Anterior Neuroectoderm. PLoS Genet 2016; 12:e1006001. [PMID: 27101101 PMCID: PMC4839626 DOI: 10.1371/journal.pgen.1006001] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Accepted: 03/30/2016] [Indexed: 11/18/2022] Open
Abstract
When early canonical Wnt is experimentally inhibited, sea urchin embryos embody the concept of a Default Model in vivo because most of the ectodermal cell fates are specified as anterior neuroectoderm. Using this model, we describe here how the combination of orthogonally functioning anteroposterior Wnt and dorsoventral Nodal signals and their targeting transcription factors, FoxQ2 and Homeobrain, regulates the precise patterning of normal neuroectoderm, of which serotonergic neurons are differentiated only at the dorsal/lateral edge. Loss-of-function experiments revealed that ventral Nodal is required for suppressing the serotonergic neural fate in the ventral side of the neuroectoderm through the maintenance of foxQ2 and the repression of homeobrain expression. In addition, non-canonical Wnt suppressed homeobrain in the anterior end of the neuroectoderm, where serotonergic neurons are not differentiated. Canonical Wnt, however, suppresses foxQ2 to promote neural differentiation. Therefore, the three-dimensionally complex patterning of the neuroectoderm is created by cooperative signals, which are essential for the formation of primary and secondary body axes during embryogenesis.
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Affiliation(s)
- Junko Yaguchi
- Shimoda Marine Research Center, University of Tsukuba, Shizuoka, Japan
| | - Noriyo Takeda
- Shimoda Marine Research Center, University of Tsukuba, Shizuoka, Japan
| | - Kazuo Inaba
- Shimoda Marine Research Center, University of Tsukuba, Shizuoka, Japan
| | - Shunsuke Yaguchi
- Shimoda Marine Research Center, University of Tsukuba, Shizuoka, Japan
- * E-mail:
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Wollesen T, Rodríguez Monje SV, McDougall C, Degnan BM, Wanninger A. The ParaHox gene Gsx patterns the apical organ and central nervous system but not the foregut in scaphopod and cephalopod mollusks. EvoDevo 2015; 6:41. [PMID: 26715985 PMCID: PMC4693441 DOI: 10.1186/s13227-015-0037-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Accepted: 12/17/2015] [Indexed: 11/21/2022] Open
Abstract
Background It has been hypothesized that the ParaHox gene Gsx patterned the foregut of the last common bilaterian ancestor. This notion was corroborated by Gsx expression in three out of four lophotrochozoan species, several ecdysozoans, and some deuterostomes. Remarkably, Gsx is also expressed in the bilaterian anterior-most central nervous system (CNS) and the gastropod and annelid apical organ. To infer whether these findings are consistent with other mollusks or even lophotrochozoans, we investigated Gsx expression in developmental stages of representatives of two other molluscan classes, the scaphopod Antalis entalis and the cephalopod Idiosepius notoides. Results Gsx is not expressed in the developing digestive tract of Antalis entalis and Idiosepius notoides. Instead, it is expressed in cells of the apical organ in the scaphopod trochophore and in two cells adjacent to this organ. Late-stage trochophores express Aen-Gsx in cells of the developing cerebral and pedal ganglia and in cells close to the pavilion, mantle, and foot. In postmetamorphic specimens, Aen-Gsx is expressed in the cerebral and pedal ganglia, the foot, and the nascent captacula. In early squid embryos, Ino-Gsx is expressed in the cerebral, palliovisceral, and optic ganglia. In late-stage embryos, Ino-Gsx is additionally expressed close to the eyes and in the supraesophageal and posterior subesophageal masses and optic lobes. Developmental stages close to hatching express Ino-Gsx only close to the eyes. Conclusions Our results suggest that Gsx expression in the foregut might not be a plesiomorphic trait of the Lophotrochozoa as insinuated previously. Since neither ecdysozoans nor deuterostomes express Gsx in their gut, a role in gut formation in the last common bilaterian ancestor appears unlikely. Gsx is consistently expressed in the bilaterian anterior-most CNS and the apical organ of lophotrochozoan larvae, suggesting a recruitment of Gsx into the formation of this organ in the Lophotrochozoa. The cephalopod posterior subesophageal mass and optic ganglia and the scaphopod pedal ganglia also express Gsx. In summary, Gsx expression only appears to be conserved in the anterior-most brain region during evolution. Accordingly, Gsx appears to have been recruited into the formation of other expression domains, e.g., the apical organ or the foregut, in some lophotrochozoans.
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Affiliation(s)
- Tim Wollesen
- Department of Integrative Zoology, Faculty of Life Sciences, University of Vienna, 1090 Vienna, Austria
| | | | - Carmel McDougall
- School of Biological Sciences, The University of Queensland, Brisbane, QLD 4072 Australia
| | - Bernard M Degnan
- School of Biological Sciences, The University of Queensland, Brisbane, QLD 4072 Australia
| | - Andreas Wanninger
- Department of Integrative Zoology, Faculty of Life Sciences, University of Vienna, 1090 Vienna, Austria
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Hibsh D, Schori H, Efroni S, Shefi O. Spatial regulation dominates gene function in the ganglia chain. ACTA ACUST UNITED AC 2013; 30:310-6. [PMID: 24085568 DOI: 10.1093/bioinformatics/btt570] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
MOTIVATION To understand the molecular mechanisms of neurons, it is imperative to identify genomic dissimilarities within the heterogeneity of the neural system. This is especially true for neuronal disorders in which spatial considerations are of critical nature. For this purpose, Hirudo medicinalis provides here an ideal system in which we are able to follow gene expression along the central nervous system, to affiliate location with gene behavior. RESULTS In all, 221.1 million high-quality short reads were sequenced on the Illumina Hiseq2000 platform at the single ganglion level. Thereafter, a de novo assembly was performed using two state-of-the-art assemblers, Trinity and Trans-ABySS, to reconstruct a comprehensive de novo transcriptome. Classification of Trinity and Trans-ABySS transcripts produced a non-redundant set of 76 845 and 268 355 transcripts (>200 bp), respectively. Remarkably, using Trinity, 82% of the published medicinal leech messenger RNAs was identified. For the innexin family, all of the 21 recently reported genes were identified. Spatial regulation analysis across three ganglia throughout the entire central nervous system revealed distinct patterns of gene expression. These transcriptome data were combined with expression distribution to produce a spatio-transcripto map along the ganglia chain. This study provides a resource for gene discovery and gene regulation in future studies.
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Affiliation(s)
- Dror Hibsh
- Faculty of Life Sciences, Faculty of Engineering and Institute of Nanotechnologies and Advanced Materials, Bar Ilan University, Ramat Gan, Israel 52900
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Helm RR, Siebert S, Tulin S, Smith J, Dunn CW. Characterization of differential transcript abundance through time during Nematostella vectensis development. BMC Genomics 2013; 14:266. [PMID: 23601508 PMCID: PMC3680055 DOI: 10.1186/1471-2164-14-266] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2012] [Accepted: 03/14/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Nematostella vectensis, a burrowing sea anemone, has become a popular species for the study of cnidarian development. In previous studies, the expression of a variety of genes has been characterized during N. vectensis development with in situ mRNA hybridization. This has provided detailed spatial resolution and a qualitative perspective on changes in expression. However, little is known about broad transcriptome-level patterns of gene expression through time. Here we examine the expression of N. vectensis genes through the course of development with quantitative RNA-seq. We provide an overview of changes in the transcriptome through development, and examine the maternal to zygotic transition, which has been difficult to investigate with other tools. RESULTS We measured transcript abundance in N. vectensis with RNA-seq at six time points in development: zygote (2 hours post fertilization (HPF)), early blastula (7 HPF), mid-blastula (12 HPF), gastrula (24 HPF), planula (5 days post fertilization (DPF)) and young polyp (10 DPF). The major wave of zygotic expression appears between 7-12 HPF, though some changes occur between 2-7 HPF. The most dynamic changes in transcript abundance occur between the late blastula and early gastrula stages. More transcripts are upregulated between the gastrula and planula than downregulated, and a comparatively lower number of transcripts significantly change between planula and polyp. Within the maternal to zygotic transition, we identified a subset of maternal factors that decrease early in development, and likely play a role in suppressing zygotic gene expression. Among the first genes to be expressed zygotically are genes whose proteins may be involved in the degradation of maternal RNA. CONCLUSIONS The approach presented here is highly complementary to prior studies on spatial patterns of gene expression, as it provides a quantitative perspective on a broad set of genes through time but lacks spatial resolution. In addition to addressing the problems identified above, our work provides an annotated matrix that other investigators can use to examine genes and developmental events that we do not examine in detail here.
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Affiliation(s)
- Rebecca Rae Helm
- Ecology and Evolutionary Biology, Brown University, 80 Waterman Street, Providence, RI 02912, USA.
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Simakov O, Marletaz F, Cho SJ, Edsinger-Gonzales E, Havlak P, Hellsten U, Kuo DH, Larsson T, Lv J, Arendt D, Savage R, Osoegawa K, de Jong P, Grimwood J, Chapman JA, Shapiro H, Aerts A, Otillar RP, Terry AY, Boore JL, Grigoriev IV, Lindberg DR, Seaver EC, Weisblat DA, Putnam NH, Rokhsar DS. Insights into bilaterian evolution from three spiralian genomes. Nature 2012; 493:526-31. [PMID: 23254933 PMCID: PMC4085046 DOI: 10.1038/nature11696] [Citation(s) in RCA: 453] [Impact Index Per Article: 37.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2012] [Accepted: 10/24/2012] [Indexed: 12/18/2022]
Abstract
Current genomic perspectives on animal diversity neglect two prominent phyla, the molluscs and annelids, that together account for nearly one-third of known marine species and are important both ecologically and as experimental systems in classical embryology1–3. Here we describe the draft genomes of the owl limpet (Lottia gigantea), a marine polychaete (Capitella teleta) and a freshwater leech (Helobdella robusta), and compare them with other animal genomes to investigate the origin and diversification of bilaterians from a genomic perspective. We find that the genome organization, gene structure and functional content of these species are more similar to those of some invertebrate deuterostome genomes (for example, amphioxus and sea urchin) than those of other protostomes that have been sequenced to date (flies, nematodes and flatworms). The conservation of these genomic features enables us to expand the inventory of genes present in the last common bilaterian ancestor, establish the tripartite diversification of bilaterians using multiple genomic characteristics and identify ancient conserved long- and short-range genetic linkages across metazoans. Superimposed on this broadly conserved pan-bilaterian background we find examples of lineage-specific genome evolution, including varying rates of rearrangement, intron gain and loss, expansions and contractions of gene families, and the evolution of clade-specific genes that produce the unique content of each genome.
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Affiliation(s)
- Oleg Simakov
- European Molecular Biology Laboratory, Meyerhofstraße 1, 69117 Heidelberg, Germany
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Santagata S, Resh C, Hejnol A, Martindale MQ, Passamaneck YJ. Development of the larval anterior neurogenic domains of Terebratalia transversa (Brachiopoda) provides insights into the diversification of larval apical organs and the spiralian nervous system. EvoDevo 2012; 3:3. [PMID: 22273002 PMCID: PMC3314550 DOI: 10.1186/2041-9139-3-3] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2011] [Accepted: 01/24/2012] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND Larval features such as the apical organ, apical ciliary tuft, and ciliated bands often complicate the evaluation of hypotheses regarding the origin of the adult bilaterian nervous system. Understanding how neurogenic domains form within the bilaterian head and larval apical organ requires expression data from animals that exhibit aspects of both centralized and diffuse nervous systems at different life history stages. Here, we describe the expression of eight neural-related genes during the larval development of the brachiopod, Terebratalia transversa. RESULTS Radially symmetric gastrulae broadly express Tt-Six3/6 and Tt-hbn in the animal cap ectoderm. Tt-NK2.1 and Tt-otp are restricted to a central subset of these cells, and Tt-fez and Tt-FoxQ2 expression domains are already asymmetric at this stage. As gastrulation proceeds, the spatial expression of these genes is split between two anterior ectodermal domains, a more dorsal region comprised of Tt-Six3/6, Tt-fez, Tt-FoxQ2, and Tt-otp expression domains, and an anterior ventral domain demarcated by Tt-hbn and Tt-NK2.1 expression. More posteriorly, the latter domains are bordered by Tt-FoxG expression in the region of the transverse ciliated band. Tt-synaptotagmin 1 is expressed throughout the anterior neural ectoderm. All genes are expressed late into larval development. The basiepithelial larval nervous system includes three neurogenic domains comprised of the more dorsal apical organ and a ventral cell cluster in the apical lobe as well as a mid-ventral band of neurons in the mantle lobe. Tt-otp is the only gene expressed in numerous flask-shaped cells of the apical organ and in a subset of neurons in the mantle lobe. CONCLUSIONS Our expression data for Tt-Six3/6, Tt-FoxQ2, and Tt-otp confirm some aspects of bilaterian-wide conservation of spatial partitioning within anterior neurogenic domains and also suggest a common origin for central otp-positive cell types within the larval apical organs of spiralians. However, the field of sensory neurons within the larval apical organ of Terebratalia is broader and composed of more cells relative to those of other spiralian larvae. These cellular differences are mirrored in the broader spatial and temporal expression patterns of Tt-FoxQ2 and Tt-otp. Corresponding differences in the expression of Tt-hbn, Tt-NK2.1, and Tt-FoxG are also observed relative to their respective domains within the cerebral ganglia of spiralians. Based on these data we argue that the anterior region of the bilaterian stem species included Six3/6, NK2.1, otp, hbn, fez, and FoxQ2 expression domains that were subsequently modified within larval and adult neural tissues of protostome and deuterostome animals.
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Affiliation(s)
- Scott Santagata
- Long Island University-Post, 720 Northern Blvd., Brookville, NY 11709, USA
| | - Carlee Resh
- Long Island University-Post, 720 Northern Blvd., Brookville, NY 11709, USA
| | - Andreas Hejnol
- Sars International Center for Marine Molecular Biology, University of Bergen, Thormøhlensgate 55, 5008 Bergen, Norway
| | - Mark Q Martindale
- Kewalo Marine Laboratory, Pacific Biosciences Research Center, University of Hawaii, 41 Ahui Street, Honolulu, HI 96813, USA
| | - Yale J Passamaneck
- Kewalo Marine Laboratory, Pacific Biosciences Research Center, University of Hawaii, 41 Ahui Street, Honolulu, HI 96813, USA
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Mazza ME, Pang K, Reitzel AM, Martindale MQ, Finnerty JR. A conserved cluster of three PRD-class homeobox genes (homeobrain, rx and orthopedia) in the Cnidaria and Protostomia. EvoDevo 2010; 1:3. [PMID: 20849646 PMCID: PMC2938728 DOI: 10.1186/2041-9139-1-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2009] [Accepted: 07/05/2010] [Indexed: 01/25/2023] Open
Abstract
Background Homeobox genes are a superclass of transcription factors with diverse developmental regulatory functions, which are found in plants, fungi and animals. In animals, several Antennapedia (ANTP)-class homeobox genes reside in extremely ancient gene clusters (for example, the Hox, ParaHox, and NKL clusters) and the evolution of these clusters has been implicated in the morphological diversification of animal bodyplans. By contrast, similarly ancient gene clusters have not been reported among the other classes of homeobox genes (that is, the LIM, POU, PRD and SIX classes). Results Using a combination of in silico queries and phylogenetic analyses, we found that a cluster of three PRD-class homeobox genes (Homeobrain (hbn), Rax (rx) and Orthopedia (otp)) is present in cnidarians, insects and mollusks (a partial cluster comprising hbn and rx is present in the placozoan Trichoplax adhaerens). We failed to identify this 'HRO' cluster in deuterostomes; in fact, the Homeobrain gene appears to be missing from the chordate genomes we examined, although it is present in hemichordates and echinoderms. To illuminate the ancestral organization and function of this ancient cluster, we mapped the constituent genes against the assembled genome of a model cnidarian, the sea anemone Nematostella vectensis, and characterized their spatiotemporal expression using in situ hybridization. In N. vectensis, these genes reside in a span of 33 kb with the same gene order as previously reported in insects. Comparisons of genomic sequences and expressed sequence tags revealed the presence of alternative transcripts of Nv-otp and two highly unusual protein-coding polymorphisms in the terminal helix of the Nv-rx homeodomain. A population genetic survey revealed the Rx polymorphisms to be widespread in natural populations. During larval development, all three genes are expressed in the ectoderm, in non-overlapping territories along the oral-aboral axis, with distinct temporal expression. Conclusion We report the first evidence for a PRD-class homeobox cluster that appears to have been conserved since the time of the cnidarian-bilaterian ancestor, and possibly even earlier, given the presence of a partial cluster in the placozoan Trichoplax. Very similar clusters comprising these three genes exist in Nematostella and diverse protostomes. Interestingly, in chordates, one member of the ancestral cluster (homeobrain) has apparently been lost, and there is no linkage between rx and orthopedia in any of the vertebrates. In Nematostella, the spatial expression of these three genes along the body column is not colinear with their physical order in the cluster but the temporal expression is, therefore, using the terminology that has been applied to the Hox cluster genes, the HRO cluster would appear to exhibit temporal but not spatial colinearity. It remains to be seen whether the mechanisms responsible for the evolutionary conservation of the HRO cluster are the same mechanisms responsible for cohesion of the Hox cluster and other ANTP-class homeobox clusters that have been widely conserved throughout animal evolution.
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Affiliation(s)
- Maureen E Mazza
- Department of Biology, Boston University, 5 Cummington Street, Boston, MA 02215, USA
| | - Kevin Pang
- Kewalo Marine Lab, Pacific Biosciences Research Center, University of Hawaii, 41 Ahui St., Honolulu, HI 96813, USA
| | - Adam M Reitzel
- Department of Biology, Boston University, 5 Cummington Street, Boston, MA 02215, USA.,Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
| | - Mark Q Martindale
- Kewalo Marine Lab, Pacific Biosciences Research Center, University of Hawaii, 41 Ahui St., Honolulu, HI 96813, USA
| | - John R Finnerty
- Department of Biology, Boston University, 5 Cummington Street, Boston, MA 02215, USA
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11
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Macagno ER, Gaasterland T, Edsall L, Bafna V, Soares MB, Scheetz T, Casavant T, Da Silva C, Wincker P, Tasiemski A, Salzet M. Construction of a medicinal leech transcriptome database and its application to the identification of leech homologs of neural and innate immune genes. BMC Genomics 2010; 11:407. [PMID: 20579359 PMCID: PMC2996935 DOI: 10.1186/1471-2164-11-407] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2009] [Accepted: 06/25/2010] [Indexed: 11/17/2022] Open
Abstract
Background The medicinal leech, Hirudo medicinalis, is an important model system for the study of nervous system structure, function, development, regeneration and repair. It is also a unique species in being presently approved for use in medical procedures, such as clearing of pooled blood following certain surgical procedures. It is a current, and potentially also future, source of medically useful molecular factors, such as anticoagulants and antibacterial peptides, which may have evolved as a result of its parasitizing large mammals, including humans. Despite the broad focus of research on this system, little has been done at the genomic or transcriptomic levels and there is a paucity of openly available sequence data. To begin to address this problem, we constructed whole embryo and adult central nervous system (CNS) EST libraries and created a clustered sequence database of the Hirudo transcriptome that is available to the scientific community. Results A total of ~133,000 EST clones from two directionally-cloned cDNA libraries, one constructed from mRNA derived from whole embryos at several developmental stages and the other from adult CNS cords, were sequenced in one or both directions by three different groups: Genoscope (French National Sequencing Center), the University of Iowa Sequencing Facility and the DOE Joint Genome Institute. These were assembled using the phrap software package into 31,232 unique contigs and singletons, with an average length of 827 nt. The assembled transcripts were then translated in all six frames and compared to proteins in NCBI's non-redundant (NR) and to the Gene Ontology (GO) protein sequence databases, resulting in 15,565 matches to 11,236 proteins in NR and 13,935 matches to 8,073 proteins in GO. Searching the database for transcripts of genes homologous to those thought to be involved in the innate immune responses of vertebrates and other invertebrates yielded a set of nearly one hundred evolutionarily conserved sequences, representing all known pathways involved in these important functions. Conclusions The sequences obtained for Hirudo transcripts represent the first major database of genes expressed in this important model system. Comparison of translated open reading frames (ORFs) with the other openly available leech datasets, the genome and transcriptome of Helobdella robusta, shows an average identity at the amino acid level of 58% in matched sequences. Interestingly, comparison with other available Lophotrochozoans shows similar high levels of amino acid identity, where sequences match, for example, 64% with Capitella capitata (a polychaete) and 56% with Aplysia californica (a mollusk), as well as 58% with Schistosoma mansoni (a platyhelminth). Phylogenetic comparisons of putative Hirudo innate immune response genes present within the Hirudo transcriptome database herein described show a strong resemblance to the corresponding mammalian genes, indicating that this important physiological response may have older origins than what has been previously proposed.
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Affiliation(s)
- Eduardo R Macagno
- Division of Biological Sciences, University of California, San Diego, CA, USA.
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12
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Meyer NP, Seaver EC. Neurogenesis in an annelid: characterization of brain neural precursors in the polychaete Capitella sp. I. Dev Biol 2009; 335:237-52. [PMID: 19540831 DOI: 10.1016/j.ydbio.2009.06.017] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2009] [Revised: 06/11/2009] [Accepted: 06/12/2009] [Indexed: 12/01/2022]
Abstract
Intertaxonomic comparisons are important for understanding neurogenesis and evolution of nervous systems, but high-resolution, cellular studies of early central nervous system development and the molecular mechanisms controlling this process in lophotrochozoans are still lacking. We provide a detailed cellular and molecular description of early brain neurogenesis in a lophotrochozoan annelid, Capitella sp. I. We utilized different approaches including DiI lineage tracing, immunohistochemistry, BrdU labeling, and gene expression analyses to characterize neural precursor cells in Capitella sp. I. Brain neurogenesis proceeds by the ingression of single cells from the anterior ectoderm to generate a stratified epithelial layer. Most cell divisions are restricted to apically localized cells with mitotic spindles oriented parallel to the epithelial layer. Prior to and during this process, an achaete-scute complex homolog, CapI-ash1, is expressed in clusters of surface cells in the anterior ectoderm, consistent with a proneural function for CapI-ash1. In contrast, a homolog of the neural differentiation marker elav, CapI-elav1, is restricted to basally localized cells within the forming brain. Unlike insects, Capitella sp. I does not have morphologically obvious enlarged neuroblasts, although Capitella sp. I brain neurogenesis displays several similarities with non-insect arthropod and vertebrate neurogenesis, providing a useful lophotrochozoan model for comparison.
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Affiliation(s)
- Néva P Meyer
- Kewalo Marine Laboratory, Pacific Biosciences Research Center, University of Hawaii, Honolulu, HI 96813, USA
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13
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Wei Z, Yaguchi J, Yaguchi S, Angerer RC, Angerer LM. The sea urchin animal pole domain is a Six3-dependent neurogenic patterning center. Development 2009; 136:1179-89. [PMID: 19270175 PMCID: PMC2685935 DOI: 10.1242/dev.032300] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/29/2009] [Indexed: 11/20/2022]
Abstract
Two major signaling centers have been shown to control patterning of sea urchin embryos. Canonical Wnt signaling in vegetal blastomeres and Nodal signaling in presumptive oral ectoderm are necessary and sufficient to initiate patterning along the primary and secondary axes, respectively. Here we define and characterize a third patterning center, the animal pole domain (APD), which contains neurogenic ectoderm, and can oppose Wnt and Nodal signaling. The regulatory influence of the APD is normally restricted to the animal pole region, but can operate in most cells of the embryo because, in the absence of Wnt and Nodal, the APD expands throughout the embryo. We have identified many constituent APD regulatory genes expressed in the early blastula and have shown that expression of most of them requires Six3 function. Furthermore, Six3 is necessary for the differentiation of diverse cell types in the APD, including the neurogenic animal plate and immediately flanking ectoderm, indicating that it functions at or near the top of several APD gene regulatory networks. Remarkably, it is also sufficient to respecify the fates of cells in the rest of the embryo, generating an embryo consisting of a greatly expanded, but correctly patterned, APD. A fraction of the large group of Six3-dependent regulatory proteins are orthologous to those expressed in the vertebrate forebrain, suggesting that they controlled formation of the early neurogenic domain in the common deuterostome ancestor of echinoderms and vertebrates.
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Affiliation(s)
- Zheng Wei
- National Institute for Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892, USA
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15
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Cho SJ, Park SC. Paired-like subclass homeobox genes from the clitellate annelid Perionyx excavatus. Biochem Genet 2008; 46:737-43. [PMID: 18784999 DOI: 10.1007/s10528-008-9189-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2007] [Accepted: 05/30/2008] [Indexed: 11/29/2022]
Affiliation(s)
- Sung-Jin Cho
- Department of Life Science, Chung-Ang University, 221 Hukseok-Dong, Dongjak-Ku, Seoul, 156-756, Republic of Korea
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Dill KK, Thamm K, Seaver EC. Characterization of twist and snail gene expression during mesoderm and nervous system development in the polychaete annelid Capitella sp. I. Dev Genes Evol 2007; 217:435-47. [PMID: 17473935 DOI: 10.1007/s00427-007-0153-4] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2007] [Accepted: 03/28/2007] [Indexed: 10/23/2022]
Abstract
To investigate the evolutionary history of mesoderm in the bilaterian lineage, we are studying mesoderm development in the polychaete annelid, Capitella sp. I, a representative lophotrochozoan. In this study, we focus on the Twist and Snail families as candidate mesodermal patterning genes and report the isolation and in situ expression patterns of two twist homologs (CapI-twt1 and CapI-twt2) and two snail homologs (CapI-sna1 and CapI-sna2) in Capitella sp. I. CapI-twt1 is expressed in a subset of mesoderm derivatives during larval development, while CapI-twt2 shows more general mesoderm expression at the same stages. Neither twist gene is detected before the completion of gastrulation. The two snail genes have very distinct expression patterns. At cleavage and early gastrula stages, CapI-sna1 is broadly expressed in precursors of all three germ layers and becomes restricted to cells around the closing blastopore during late gastrulation; CapI-sna2 expression is not detected at these stages. After gastrulation, both snail genes are expressed in the developing central nervous system (CNS) at stages when neural precursor cells are internalized, and CapI-sna1 is also expressed laterally within the segmental mesoderm. Based on the expression patterns in this study, we suggest a putative function for Capitella sp. I twist genes in mesoderm differentiation and for snail genes in regulating CNS development and general cell migration during gastrulation.
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Affiliation(s)
- Kariena K Dill
- Kewalo Marine Laboratory, Pacific Biosciences Research Center, University of Hawaii, 41 Ahui Street, Honolulu, HI 96813, USA
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