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Medina-Jiménez BI, Budd GE, Janssen R. Single-cell RNA sequencing of mid-to-late stage spider embryos: new insights into spider development. BMC Genomics 2024; 25:150. [PMID: 38326752 PMCID: PMC10848406 DOI: 10.1186/s12864-023-09898-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Accepted: 12/12/2023] [Indexed: 02/09/2024] Open
Abstract
BACKGROUND The common house spider Parasteatoda tepidariorum represents an emerging new model organism of arthropod evolutionary and developmental (EvoDevo) studies. Recent technical advances have resulted in the first single-cell sequencing (SCS) data on this species allowing deeper insights to be gained into its early development, but mid-to-late stage embryos were not included in these pioneering studies. RESULTS Therefore, we performed SCS on mid-to-late stage embryos of Parasteatoda and characterized resulting cell clusters by means of in-silico analysis (comparison of key markers of each cluster with previously published information on these genes). In-silico prediction of the nature of each cluster was then tested/verified by means of additional in-situ hybridization experiments with additional markers of each cluster. CONCLUSIONS Our data show that SCS data reliably group cells with similar genetic fingerprints into more or less distinct clusters, and thus allows identification of developing cell types on a broader level, such as the distinction of ectodermal, mesodermal and endodermal cell lineages, as well as the identification of distinct developing tissues such as subtypes of nervous tissue cells, the developing heart, or the ventral sulcus (VS). In comparison with recent other SCS studies on the same species, our data represent later developmental stages, and thus provide insights into different stages of developing cell types and tissues such as differentiating neurons and the VS that are only present at these later stages.
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Affiliation(s)
- Brenda I Medina-Jiménez
- Department of Earth Sciences, Palaeobiology, Uppsala University, Villavägen 16, 75236, Uppsala, Sweden.
| | - Graham E Budd
- Department of Earth Sciences, Palaeobiology, Uppsala University, Villavägen 16, 75236, Uppsala, Sweden
| | - Ralf Janssen
- Department of Earth Sciences, Palaeobiology, Uppsala University, Villavägen 16, 75236, Uppsala, Sweden.
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Janeschik M, Schacht MI, Platten F, Turetzek N. It takes Two: Discovery of Spider Pax2 Duplicates Indicates Prominent Role in Chelicerate Central Nervous System, Eye, as Well as External Sense Organ Precursor Formation and Diversification After Neo- and Subfunctionalization. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.810077] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Paired box genes are conserved across animals and encode transcription factors playing key roles in development, especially neurogenesis. Pax6 is a chief example for functional conservation required for eye development in most bilaterian lineages except chelicerates. Pax6 is ancestrally linked and was shown to have interchangeable functions with Pax2. Drosophila melanogaster Pax2 plays an important role in the development of sensory hairs across the whole body. In addition, it is required for the differentiation of compound eyes, making it a prime candidate to study the genetic basis of arthropod sense organ development and diversification, as well as the role of Pax genes in eye development. Interestingly, in previous studies identification of chelicerate Pax2 was either neglected or failed. Here we report the expression of two Pax2 orthologs in the common house spider Parasteatoda tepidariorum, a model organism for chelicerate development. The two Pax2 orthologs most likely arose as a consequence of a whole genome duplication in the last common ancestor of spiders and scorpions. Pax2.1 is expressed in the peripheral nervous system, including developing lateral eyes and external sensilla, as well as the ventral neuroectoderm of P. tepidariorum embryos. This not only hints at a conserved dual role of Pax2/5/8 orthologs in arthropod sense organ development but suggests that in chelicerates, Pax2 could have acquired the role usually played by Pax6. For the other paralog, Pt-Pax2.2, expression was detected in the brain, but not in the lateral eyes and the expression pattern associated with sensory hairs differs in timing, pattern, and strength. To achieve a broader phylogenetic sampling, we also studied the expression of both Pax2 genes in the haplogyne cellar spider Pholcus phalangioides. We found that the expression difference between paralogs is even more extreme in this species, since Pp-Pax2.2 shows an interesting expression pattern in the ventral neuroectoderm while the expression in the prosomal appendages is strictly mesodermal. This expression divergence indicates both sub- and neofunctionalization after Pax2 duplication in spiders and thus presents an opportunity to study the evolution of functional divergence after gene duplication and its impact on sense organ diversification.
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Klann M, Schacht MI, Benton MA, Stollewerk A. Functional analysis of sense organ specification in the Tribolium castaneum larva reveals divergent mechanisms in insects. BMC Biol 2021; 19:22. [PMID: 33546687 PMCID: PMC7866635 DOI: 10.1186/s12915-021-00948-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Accepted: 01/04/2021] [Indexed: 12/27/2022] Open
Abstract
Abstract Insects and other arthropods utilise external sensory structures for mechanosensory, olfactory, and gustatory reception. These sense organs have characteristic shapes related to their function, and in many cases are distributed in a fixed pattern so that they are identifiable individually. In Drosophila melanogaster, the identity of sense organs is regulated by specific combinations of transcription factors. In other arthropods, however, sense organ subtypes cannot be linked to the same code of gene expression. This raises the questions of how sense organ diversity has evolved and whether the principles underlying subtype identity in D. melanogaster are representative of other insects. Here, we provide evidence that such principles cannot be generalised, and suggest that sensory organ diversification followed the recruitment of sensory genes to distinct sensory organ specification mechanism. Results We analysed sense organ development in a nondipteran insect, the flour beetle Tribolium castaneum, by gene expression and RNA interference studies. We show that in contrast to D. melanogaster, T. castaneum sense organs cannot be categorised based on the expression or their requirement for individual or combinations of conserved sense organ transcription factors such as cut and pox neuro, or members of the Achaete-Scute (Tc ASH, Tc asense), Atonal (Tc atonal, Tc cato, Tc amos), and neurogenin families (Tc tap). Rather, our observations support an evolutionary scenario whereby these sensory genes are required for the specification of sense organ precursors and the development and differentiation of sensory cell types in diverse external sensilla which do not fall into specific morphological and functional classes. Conclusions Based on our findings and past research, we present an evolutionary scenario suggesting that sense organ subtype identity has evolved by recruitment of a flexible sensory gene network to the different sense organ specification processes. A dominant role of these genes in subtype identity has evolved as a secondary effect of the function of these genes in individual or subsets of sense organs, probably modulated by positional cues. Supplementary Information The online version contains supplementary material available at 10.1186/s12915-021-00948-y.
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Affiliation(s)
- Marleen Klann
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS, UK.,Marine Eco-Evo-Devo Unit, Okinawa Institute for Science and Technology (OIST), 1919-1 Tancha, Onna-son, Okinawa, 904-0495, Japan
| | - Magdalena Ines Schacht
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS, UK
| | - Matthew Alan Benton
- Department of Zoology, University of Cambridge, Downing St, Cambridge, CB2 3EJ, UK
| | - Angelika Stollewerk
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS, UK.
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Distribution and development of the external sense organ pattern on the appendages of postembryonic and adult stages of the spider Parasteatoda tepidariorum. Dev Genes Evol 2020; 230:121-136. [PMID: 32036445 PMCID: PMC7128012 DOI: 10.1007/s00427-020-00655-8] [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: 01/20/2020] [Accepted: 01/30/2020] [Indexed: 11/17/2022]
Abstract
Spiders are equipped with a large number of innervated cuticular specializations, which respond to various sensory stimuli. The physiological function of mechanosensory organs has been analysed in great detail in some model spider species (e.g. Cupiennius salei); however, much less is known about the distribution and function of chemosensory organs. Furthermore, our knowledge on how the sense organ pattern develops on the spider appendages is limited. Here we analyse the development of the pattern and distribution of six different external mechano- and chemosensory organs in all postembryonic stages and in adult male and female spiders of the species Parasteatoda tepidariorum. We show that except for small mechanosensory setae, external sense organs appear in fixed positions on the pedipalps and first walking legs, arranged in longitudinal rows along the proximal-distal axis or in invariable positions relative to morphological landmarks (joints, distal tarsal tip). A comparison to other Entelegynae spiders shows that these features are conserved. We hope that this study lays the foundation for future molecular analysis to address the question how this conserved pattern is generated.
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Zobel M, Disanza A, Senic-Matuglia F, Franco M, Colaluca IN, Confalonieri S, Bisi S, Barbieri E, Caldieri G, Sigismund S, Pece S, Chavrier P, Di Fiore PP, Scita G. A NUMB-EFA6B-ARF6 recycling route controls apically restricted cell protrusions and mesenchymal motility. J Cell Biol 2018; 217:3161-3182. [PMID: 30061108 PMCID: PMC6123001 DOI: 10.1083/jcb.201802023] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Revised: 05/17/2018] [Accepted: 06/05/2018] [Indexed: 12/13/2022] Open
Abstract
The endocytic protein NUMB has been implicated in the control of various polarized cellular processes, including the acquisition of mesenchymal migratory traits through molecular mechanisms that have only been partially defined. Here, we report that NUMB is a negative regulator of a specialized set of understudied, apically restricted, actin-based protrusions, the circular dorsal ruffles (CDRs), induced by either PDGF or HGF stimulation. Through its PTB domain, NUMB binds directly to an N-terminal NPLF motif of the ARF6 guanine nucleotide exchange factor, EFA6B, and promotes its exchange activity in vitro. In cells, a NUMB-EFA6B-ARF6 axis regulates the recycling of the actin regulatory cargo RAC1 and is critical for the formation of CDRs that mark the acquisition of a mesenchymal mode of motility. Consistently, loss of NUMB promotes HGF-induced cell migration and invasion. Thus, NUMB negatively controls membrane protrusions and the acquisition of mesenchymal migratory traits by modulating EFA6B-ARF6 activity.
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Affiliation(s)
- Martina Zobel
- IFOM, the FIRC Institute of Molecular Oncology, Milan, Italy
| | - Andrea Disanza
- IFOM, the FIRC Institute of Molecular Oncology, Milan, Italy
| | | | - Michel Franco
- Université Côte d'Azur, Centre National de la Recherche Scientifique, Institut de Pharmacologie Moléculaire et Cellulaire, Valbonne, France
| | | | | | - Sara Bisi
- IFOM, the FIRC Institute of Molecular Oncology, Milan, Italy
| | - Elisa Barbieri
- Department of Experimental Oncology, European Institute of Oncology, Milan, Italy
| | - Giusi Caldieri
- Department of Experimental Oncology, European Institute of Oncology, Milan, Italy
- Department of Oncology and Hemato-Oncology, University of Milan, Milan, Italy
| | - Sara Sigismund
- Department of Experimental Oncology, European Institute of Oncology, Milan, Italy
- Department of Oncology and Hemato-Oncology, University of Milan, Milan, Italy
| | - Salvatore Pece
- Department of Experimental Oncology, European Institute of Oncology, Milan, Italy
- Department of Oncology and Hemato-Oncology, University of Milan, Milan, Italy
| | - Philippe Chavrier
- Institut Curie, PSL Research University, Paris, France
- Centre National de la Recherche Scientifique UMR 144, Membrane and Cytoskeleton Dynamics Team, Paris, France
| | - Pier Paolo Di Fiore
- IFOM, the FIRC Institute of Molecular Oncology, Milan, Italy
- Department of Experimental Oncology, European Institute of Oncology, Milan, Italy
- Department of Oncology and Hemato-Oncology, University of Milan, Milan, Italy
| | - Giorgio Scita
- IFOM, the FIRC Institute of Molecular Oncology, Milan, Italy
- Department of Oncology and Hemato-Oncology, University of Milan, Milan, Italy
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Evolutionary variation in neural gene expression in the developing sense organs of the crustacean Daphnia magna. Dev Biol 2017; 424:50-61. [PMID: 28238736 DOI: 10.1016/j.ydbio.2017.02.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Revised: 12/21/2016] [Accepted: 02/17/2017] [Indexed: 11/23/2022]
Abstract
Arthropods have numerous sense organs, which are adapted to their habitat. While some sense organs are similar in structure and function in all arthropod groups, structural differences in functionally related sense organs have been described, as well as the absence of particular sense organ subtypes in individual arthropod groups. Here we address the question of how the diverse structures of arthropod sense organs have evolved by analysing the underlying molecular developmental processes in a crustacean, an arthropod group that has been neglected so far. We have investigated the development of four types of chemo- and mechanosensory sense organs in the branchiopod Daphnia magna (Cladocera) that either cannot be found in arthropods other than crustaceans or represent adaptations to an aquatic environment. The formation of the sensory organ precursors shows greater similarity to the arthropod taxa Chelicerata and Myriapoda than to the more closely related insects. All analysed sense organ types co-express the proneural genes ASH and atonal regardless of their structure and function. In contrast, in Drosophila melanogaster, ASH and atonal expression does not overlap and the genes confer different sense organ subtype identities. We performed experimental co-expression studies in D. melanogaster and found that the combinatorial expression of ato and ASH can change the external structure of sense organs. Our results indicate a central role for ASH and Atonal family members in the emergence of structural variations in arthropod sense organs.
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Stollewerk A. A flexible genetic toolkit for arthropod neurogenesis. Philos Trans R Soc Lond B Biol Sci 2016; 371:20150044. [PMID: 26598727 DOI: 10.1098/rstb.2015.0044] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Arthropods show considerable variations in early neurogenesis. This includes the pattern of specification, division and movement of neural precursors and progenitors. In all metazoans with nervous systems, including arthropods, conserved genes regulate neurogenesis, which raises the question of how the various morphological mechanisms have emerged and how the same genetic toolkit might generate different morphological outcomes. Here I address this question by comparing neurogenesis across arthropods and show how variations in the regulation and function of the neural genes might explain this phenomenon and how they might have facilitated the evolution of the diverse morphological mechanisms of neurogenesis.
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Affiliation(s)
- Angelika Stollewerk
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, UK
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8
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Abstract
The foundation of the diverse metazoan nervous systems is laid by embryonic patterning mechanisms, involving the generation and movement of neural progenitors and their progeny. Here we divide early neurogenesis into discrete elements, including origin, pattern, proliferation, and movement of neuronal progenitors, which are controlled by conserved gene cassettes. We review these neurogenetic mechanisms in representatives of the different metazoan clades, with the goal to build a conceptual framework in which one can ask specific questions, such as which of these mechanisms potentially formed part of the developmental "toolkit" of the bilaterian ancestor and which evolved later.
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Affiliation(s)
- Volker Hartenstein
- Department of Molecular Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, CA 90095, USA.
| | - Angelika Stollewerk
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, UK.
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9
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Smith FW, Angelini DR, Gaudio MS, Jockusch EL. Metamorphic labral axis patterning in the beetle Tribolium castaneum requires multiple upstream, but few downstream, genes in the appendage patterning network. Evol Dev 2014; 16:78-91. [PMID: 24617987 DOI: 10.1111/ede.12066] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The arthropod labrum is an anterior appendage-like structure that forms the dorsal side of the preoral cavity. Conflicting interpretations of fossil, nervous system, and developmental data have led to a proliferation of scenarios for labral evolution. The best supported hypothesis is that the labrum is a novel structure that shares development with appendages as a result of co-option. Here, we use RNA interference in the red flour beetle Tribolium castaneum to compare metamorphic patterning of the labrum to previously published data on ventral appendage patterning. As expected under the co-option hypothesis, depletion of several genes resulted in similar defects in the labrum and ventral appendages. These include proximal deletions and proximal-to-distal transformations resulting from depletion of the leg gap genes homothorax and extradenticle, large-scale deletions resulting from depletion of the leg gap gene Distal-less, and smaller distal deletions resulting from knockdown of the EGF ligand Keren. However, depletion of dachshund and many of the genes that function downstream of the leg gap genes in the ventral appendages had either subtle or no effects on labral axis patterning. This pattern of partial similarity suggests that upstream genes act through different downstream targets in the labrum. We also discovered that many appendage axis patterning genes have roles in patterning the epipharyngeal sensillum array, suggesting that they have become integrated into a novel regulatory network. These genes include Notch, Delta, and decapentaplegic, and the transcription factors abrupt, bric à brac, homothorax, extradenticle and the paralogs apterous a and apterous b.
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Affiliation(s)
- Frank W Smith
- Department of Ecology & Evolutionary Biology, University of Connecticut, 75 N. Eagleville Rd., U-3043, Storrs, CT, 06269-3043, USA
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10
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de Sena Oliveira I, Tait NN, Strübing I, Mayer G. The role of ventral and preventral organs as attachment sites for segmental limb muscles in Onychophora. Front Zool 2013; 10:73. [PMID: 24308783 PMCID: PMC3866996 DOI: 10.1186/1742-9994-10-73] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Accepted: 11/27/2013] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND The so-called ventral organs are amongst the most enigmatic structures in Onychophora (velvet worms). They were described as segmental, ectodermal thickenings in the onychophoran embryo, but the same term has also been applied to mid-ventral, cuticular structures in adults, although the relationship between the embryonic and adult ventral organs is controversial. In the embryo, these structures have been regarded as anlagen of segmental ganglia, but recent studies suggest that they are not associated with neural development. Hence, their function remains obscure. Moreover, their relationship to the anteriorly located preventral organs, described from several onychophoran species, is also unclear. To clarify these issues, we studied the anatomy and development of the ventral and preventral organs in several species of Onychophora. RESULTS Our anatomical data, based on histology, and light, confocal and scanning electron microscopy in five species of Peripatidae and three species of Peripatopsidae, revealed that the ventral and preventral organs are present in all species studied. These structures are covered externally with cuticle that forms an internal, longitudinal, apodeme-like ridge. Moreover, phalloidin-rhodamine labelling for f-actin revealed that the anterior and posterior limb depressor muscles in each trunk and the slime papilla segment attach to the preventral and ventral organs, respectively. During embryonic development, the ventral and preventral organs arise as large segmental, paired ectodermal thickenings that decrease in size and are subdivided into the smaller, anterior anlagen of the preventral organs and the larger, posterior anlagen of the ventral organs, both of which persist as paired, medially-fused structures in adults. Our expression data of the genes Delta and Notch from embryos of Euperipatoides rowelli revealed that these genes are expressed in two, paired domains in each body segment, corresponding in number, position and size with the anlagen of the ventral and preventral organs. CONCLUSIONS Our findings suggest that the ventral and preventral organs are a common feature of onychophorans that serve as attachment sites for segmental limb depressor muscles. The origin of these structures can be traced back in the embryo as latero-ventral segmental, ectodermal thickenings, previously suggested to be associated with the development of the nervous system.
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Affiliation(s)
- Ivo de Sena Oliveira
- Animal Evolution and Development, Institute of Biology, University of Leipzig, Talstraße 33, D-04103, Leipzig, Germany.
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Ungerer P, Eriksson BJ, Stollewerk A. Unravelling the evolution of neural stem cells in arthropods: notch signalling in neural stem cell development in the crustacean Daphnia magna. Dev Biol 2012; 371:302-11. [PMID: 22964415 DOI: 10.1016/j.ydbio.2012.08.025] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2012] [Revised: 08/14/2012] [Accepted: 08/23/2012] [Indexed: 01/13/2023]
Abstract
The genetic regulatory networks controlling major developmental processes seem to be conserved in bilaterians regardless of an independent or a common origin of the structures. This has been explained by the employment of a genetic toolkit that was repeatedly used during bilaterian evolution to build the various forms and body plans. However, it is not clear how genetic networks were incorporated into the formation of novel structures and how homologous genes can regulate the disparate morphological processes. Here we address this question by analysing the role of Notch signalling, which is part of the bilaterian toolkit, in neural stem cell evolution in arthropods. Within arthropods neural stem cells have evolved in the last common ancestor of insects and crustaceans (Tetraconata). We analyse here for the first time the role of Notch signalling in a crustacean, the branchiopod Daphnia magna, and show that it is required in neural stem cells for regulating the time of neural precursor production and for binary cell fate decisions in the ventral neuroectoderm. The function of Notch signalling has diverged in the ventral neuroectoderm of insects and crustaceans accompanied by changes in the morphogenetic processes. In the crustacean, Notch controlled mechanisms of neuroblast regulation have evolved that are surprisingly similar to vertebrates and thus present a remarkable case of parallel evolution. These new data on a representative of crustaceans complete the arthropod data set on Notch signalling in the nervous system and allow for reconstructing how the Notch signalling pathway has been co-opted from pre-existing structures to the development of the evolving neural stem cells in the Tetraconata ancestor.
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Affiliation(s)
- Petra Ungerer
- School of Biological and Chemical Sciences, Queen Mary, University of London, Mile End Road, London E1 4NS, UK.
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Pechmann M, Khadjeh S, Sprenger F, Prpic NM. Patterning mechanisms and morphological diversity of spider appendages and their importance for spider evolution. ARTHROPOD STRUCTURE & DEVELOPMENT 2010; 39:453-467. [PMID: 20696272 DOI: 10.1016/j.asd.2010.07.007] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2010] [Revised: 07/07/2010] [Accepted: 07/27/2010] [Indexed: 05/29/2023]
Abstract
The prosoma of spiders bears different gnathal (labrum, chelicerae, pedipalps) and locomotory appendages (legs). In most species these appendages are also used for additional functions, e.g. sensing, mating, and courtship. The opisthosoma is equipped with four pairs of highly specialized appendages. Two pairs of spinnerets are used for silk production and manipulation. The other two pairs of appendages are internalized during development and give rise to a complex respiratory system of book lungs and tracheae. Thus spiders have a number of different appendage types with radically different adult morphologies. Furthermore, all these appendage types display significant additional species specific diversity correlating with a large spectrum of functions of the appendages. Despite this importance of appendage diversity for the evolution of the spiders we know relatively little about the genetic patterning mechanisms producing this diversity of morphology. We review recent advances concerning the developmental genetics of spider appendage diversification, mainly concentrating on open questions and future directions of research. We conclude that the deeper understanding of appendage development and diversity in spiders can contribute significantly not only to evolutionary developmental biology, but also to behavioral biology, speciation research and population genetics, and the study of sexually dimorphic traits.
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Affiliation(s)
- Matthias Pechmann
- Georg-August-Universität Göttingen, Johann-Friedrich-Blumenbach-Institut für Zoologie und Anthropologie, Abteilung für Entwicklungsbiologie, GZMB Ernst-Caspari-Haus, Justus-von-Liebig-Weg 11, Göttingen, Germany
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