1
|
Hassan A, Blakeley G, McGregor AP, Zancolli G. Venom gland organogenesis in the common house spider. Sci Rep 2024; 14:15379. [PMID: 38965282 PMCID: PMC11224297 DOI: 10.1038/s41598-024-65336-2] [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: 03/14/2024] [Accepted: 06/19/2024] [Indexed: 07/06/2024] Open
Abstract
Venom is a remarkable innovation found across the animal kingdom, yet the evolutionary origins of venom systems in various groups, including spiders, remain enigmatic. Here, we investigated the organogenesis of the venom apparatus in the common house spider, Parasteatoda tepidariorum. The venom apparatus consists of a pair of secretory glands, each connected to an opening at the fang tip by a duct that runs through the chelicerae. We performed bulk RNA-seq to identify venom gland-specific markers and assayed their expression using RNA in situ hybridisation experiments on whole-mount time-series. These revealed that the gland primordium emerges during embryonic stage 13 at the chelicera tip, progresses proximally by the end of embryonic development and extends into the prosoma post-eclosion. The initiation of expression of an important toxin component in late postembryos marks the activation of venom-secreting cells. Our selected markers also exhibited distinct expression patterns in adult venom glands: sage and the toxin marker were expressed in the secretory epithelium, forkhead and sum-1 in the surrounding muscle layer, while Distal-less was predominantly expressed at the gland extremities. Our study provides the first comprehensive analysis of venom gland morphogenesis in spiders, offering key insights into their evolution and development.
Collapse
Affiliation(s)
- Afrah Hassan
- Department of Ecology and Evolution, University of Lausanne, Lausanne, 1015, Switzerland
| | - Grace Blakeley
- Department of Biological and Medical Sciences, Oxford Brookes University, Oxford, OX3 0BP, UK
| | | | - Giulia Zancolli
- Department of Ecology and Evolution, University of Lausanne, Lausanne, 1015, Switzerland.
- Swiss Institute of Bioinformatics, Lausanne, 1015, Switzerland.
| |
Collapse
|
2
|
Janssen R, Pechmann M. Expression of posterior Hox genes and opisthosomal appendage development in a mygalomorph spider. Dev Genes Evol 2023; 233:107-121. [PMID: 37495828 PMCID: PMC10746769 DOI: 10.1007/s00427-023-00707-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2023] [Accepted: 07/11/2023] [Indexed: 07/28/2023]
Abstract
Spiders represent an evolutionary successful group of chelicerate arthropods. The body of spiders is subdivided into two regions (tagmata). The anterior tagma, the prosoma, bears the head appendages and four pairs of walking legs. The segments of the posterior tagma, the opisthosoma, either lost their appendages during the course of evolution or their appendages were substantially modified to fulfill new tasks such as reproduction, gas exchange, and silk production. Previous work has shown that the homeotic Hox genes are involved in shaping the posterior appendages of spiders. In this paper, we investigate the expression of the posterior Hox genes in a tarantula that possesses some key differences of posterior appendages compared to true spiders, such as the lack of the anterior pair of spinnerets and a second set of book lungs instead of trachea. Based on the observed differences in posterior Hox gene expression in true spiders and tarantulas, we argue that subtle changes in the Hox gene expression of the Hox genes abdA and AbdB are possibly responsible for at least some of the morphological differences seen in true spiders versus tarantulas.
Collapse
Affiliation(s)
- Ralf Janssen
- Department of Earth Sciences, Palaeobiology, Uppsala University, Villavägen 16, 75236, Uppsala, Sweden.
| | - Matthias Pechmann
- Institute for Zoology, Biocenter, University of Cologne, Zuelpicher Str. 47b, 50674, Cologne, Germany
| |
Collapse
|
3
|
Napiórkowska T, Templin J, Napiórkowski P, Townley MA. Appendage abnormalities in spiders induced by an alternating temperature protocol in the context of recent advances in molecular spider embryology. PeerJ 2023; 11:e16011. [PMID: 37701827 PMCID: PMC10493090 DOI: 10.7717/peerj.16011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Accepted: 08/10/2023] [Indexed: 09/14/2023] Open
Abstract
In the literature there are numerous reports of developmental deformities in arthropods collected in their natural habitat. Since such teratogenically affected individuals are found purely by chance, the causes of their defects are unknown. Numerous potential physical, mechanical, chemical, and biological teratogens have been considered and tested in the laboratory. Thermal shocks, frequently used in teratological research on the spider Eratigena atrica, have led to deformities on both the prosoma and the opisthosoma. In the 2020/2021 breeding season, by applying alternating temperatures (14 °C and 32 °C, changed every 12 h) for the first 10 days of embryonic development, we obtained 212 postembryos (out of 3,007) with the following anomalies: oligomely, heterosymely, bicephaly, schistomely, symely, polymely, complex anomalies, and others. From these we selected six spiders with defects on the prosoma and two with short appendages on the pedicel for further consideration. The latter cases seem particularly interesting because appendages do not normally develop on this body part, viewed as the first segment of the opisthosoma, and appear to represent examples of atavism. In view of the ongoing development of molecular techniques and recent research on developmental mechanisms in spiders, we believe the observed phenotypes may result, at least in part, from the erroneous suppression or expression of segmentation or appendage patterning genes. We consider "knockdown" experiments described in the literature as a means for generating hypotheses about the sources of temperature-induced body abnormalities in E. atrica.
Collapse
Affiliation(s)
- Teresa Napiórkowska
- Department of Invertebrate Zoology and Parasitology, Faculty of Biological and Veterinary Sciences, Nicolaus Copernicus University in Toruń, Toruń, Poland
| | - Julita Templin
- Faculty of Biological and Veterinary Sciences, Department of Invertebrate Zoology and Parasitology, Nicolaus Copernicus University in Torun, Toruń, Poland
| | - Paweł Napiórkowski
- Department of Hydrobiology, Faculty of Biological Sciences, Kazimierz Wielki University in Bydgoszcz, Bydgoszcz, Poland
| | - Mark A. Townley
- University Instrumentation Center, University of New Hampshire, Durham, New Hampshire, United States
| |
Collapse
|
4
|
Joel AC, Rawal A, Yao Y, Jenner A, Ariotti N, Weissbach M, Adler L, Stafstrom J, Blamires SJ. Physico-chemical properties of functionally adhesive spider silk nanofibres. Biomater Sci 2023; 11:2139-2150. [PMID: 36727424 DOI: 10.1039/d2bm01599d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Currently, synthetic fibre production focuses primarily on high performance materials. For high performance fibrous materials, such as silks, this involves interpreting the structure-function relationship and downsizing to a smaller scale to then harness those properties within synthetic products. Spiders create an array of fibres that range in size from the micrometre to nanometre scale. At about 20 nm diameter spider cribellate silk, the smallest of these silks, is too small to contain any of the typical secondary protein structures of other spider silks, let alone a hierarchical skin-core-type structure. Here, we performed a multitude of investigations to elucidate the structure of cribellate spider silk. These confirmed our hypothesis that, unlike all other types of spider silk, it has a disordered molecular structure. Alanine and glycine, the two amino acids predominantly found in other spider silks, were much less abundant and did not form the usual α-helices and β-sheet secondary structural arrangements. Correspondingly, we characterized the cribellate silk nanofibre to be very compliant. This characterization matches its function as a dry adhesive within the capture threads of cribellate spiders. Our results imply that at extremely small scales there may be a limit reached below which a silk will lose its structural, but not functional, integrity. Nano-sized fibres, such as cribellate silk, thus offer a new opportunity for inspiring the creation of novel scaled-down functional adhesives and nano meta-materials.
Collapse
Affiliation(s)
- Anna-Christin Joel
- Department of Biological Sciences, Macquarie University, Sydney, Australia. .,School of Biological, Earth and Environmental Sciences, The University of New South Wales, Sydney, Australia.,Institute of Zoology, RWTH Aachen University, Aachen, Germany
| | - Aditya Rawal
- Mark Wainwright Analytical Centre, University of New South Wales, Sydney, Australia
| | - Yin Yao
- Mark Wainwright Analytical Centre, University of New South Wales, Sydney, Australia
| | - Andrew Jenner
- Mark Wainwright Analytical Centre, University of New South Wales, Sydney, Australia
| | - Nicholas Ariotti
- Mark Wainwright Analytical Centre, University of New South Wales, Sydney, Australia.,Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia
| | | | - Lewis Adler
- Mark Wainwright Analytical Centre, University of New South Wales, Sydney, Australia
| | - Jay Stafstrom
- School of Biological, Earth and Environmental Sciences, The University of New South Wales, Sydney, Australia.,Department of Neurobiology and Behavior, Cornell University, Ithaca, New York, USA
| | - Sean J Blamires
- School of Biological, Earth and Environmental Sciences, The University of New South Wales, Sydney, Australia.,Mark Wainwright Analytical Centre, University of New South Wales, Sydney, Australia.,School of Mechanical and Mechatronic Engineering, University of Technology Sydney, Sydney, Australia
| |
Collapse
|
5
|
Hox genes in spiders: Their significance for development and evolution. Semin Cell Dev Biol 2022:S1084-9521(22)00355-X. [PMID: 36522242 DOI: 10.1016/j.semcdb.2022.11.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Revised: 11/13/2022] [Accepted: 11/30/2022] [Indexed: 12/15/2022]
Abstract
Hox genes are known for their role in the specification of typical body plan features in animals. Evolutionary changes in Hox gene function are believed to be involved in the emergence of the diverse body plans we observe in animals today. Spiders share many body plan features with other arthropods, but also have numerous unique traits of their own. Studies of spider Hox genes have already provided insights into evolutionarily conserved and derived features of the spider body plan and their genetic basis. However, many aspects of Hox gene biology have been insufficiently studied in spiders so far. In this review, we highlight previous comparative studies of Hox genes in spiders and their significance for our understanding of the evolution of the spider body plan. We also identify aspects of Hox gene biology that need to be studied in greater detail. Many spider Hox genes have not been investigated beyond their mRNA expression patterns, and the role of Hox genes with apparently plesiomorphic or dual functions, like ftz and Hox3 is still unclear. Spiders have a duplicated Hox gene cluster, but possible sub- or neofunctionalisation of duplicates have not yet been studied systematically. Future research should therefore focus on these issues, in addition to the role of Polycomb and trithorax-mediated regulation, the identification of regulatory regions, cofactors or spider-specific target genes, and the significance of non-coding RNAs transcribed from within the Hox cluster and even from the antisense strand of particular Hox genes.
Collapse
|
6
|
Mariano-Martins P, Monfardini RD, Lo-Man-Hung N, Torres TT. Evidence of positive selection on six spider developmental genes. JOURNAL OF EXPERIMENTAL ZOOLOGY. PART B, MOLECULAR AND DEVELOPMENTAL EVOLUTION 2022; 338:314-322. [PMID: 34985811 DOI: 10.1002/jez.b.23119] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 11/16/2021] [Accepted: 12/04/2021] [Indexed: 06/14/2023]
Abstract
Spiders constitute more than 49,000 described species distributed all over the world, and all ecological environments. Their order, Araneae, is defined by a set of characteristics with no parallel among their arachnid counterparts (e.g., spinnerets, silk glands, chelicerae that inoculate venom, among others). Changes in developmental pathways often underlie the evolution of morphological synapomorphies, and as such spiders are a promising model to study the role of developmental genes in the origin of evolutionary novelties. With that in mind, we investigated changes in the evolutionary regime of a set of six developmental genes, using spiders as our model. The genes were mainly chosen for their roles in spinneret ontogeny, yet they are pleiotropic, and it is likely that the origins of other unique morphological phenotypes are also linked to changes in their sequences. Our results indicate no great differences in the selective pressures on those genes when comparing spiders to other arachnids, but a few site-specific positive selection evidence were found in the Araneae lineage. These findings lead us to new insights on spider evolution that are to be further tested.
Collapse
Affiliation(s)
- Pedro Mariano-Martins
- Department of Genetics and Evolutionary Biology, Institute of Biosciences, University of São Paulo, São Paulo - SP, Brazil
| | - Raquel Dietsche Monfardini
- Department of Genetics and Evolutionary Biology, Institute of Biosciences, University of São Paulo, São Paulo - SP, Brazil
| | - Nancy Lo-Man-Hung
- Department of Genetics and Evolutionary Biology, Institute of Biosciences, University of São Paulo, São Paulo - SP, Brazil
| | - Tatiana Teixeira Torres
- Department of Genetics and Evolutionary Biology, Institute of Biosciences, University of São Paulo, São Paulo - SP, Brazil
| |
Collapse
|
7
|
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.
Collapse
|
8
|
Medina-Jiménez BI, Budd GE, Janssen R. Panarthropod tiptop/teashirt and spalt orthologs and their potential role as "trunk"-selector genes. EvoDevo 2021; 12:7. [PMID: 34078450 PMCID: PMC8173736 DOI: 10.1186/s13227-021-00177-y] [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: 02/02/2021] [Accepted: 05/17/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND In the vinegar fly Drosophila melanogaster, the homeodomain containing transcription factor Teashirt (Tsh) appears to specify trunk identity in concert with the function of the Hox genes. While in Drosophila there is a second gene closely related to tsh, called tiptop (tio), in other arthropods species only one copy exists (called tio/tsh). The expression of tsh and tio/tsh, respectively, is surprisingly similar among arthropods suggesting that its function as trunk selector gene may be conserved. Other research, for example on the beetle Tribolium castaneum, questions even conservation of Tsh function among insects. The zinc-finger transcription factor Spalt (Sal) is involved in the regulation of Drosophila tsh, but this regulatory interaction does not appear to be conserved in Tribolium either. Whether the function and interaction of tsh and sal as potential trunk-specifiers, however, is conserved is still unclear because comparative studies on sal expression (except for Tribolium) are lacking, and functional data are (if at all existing) restricted to Insecta. RESULTS Here, we provide additional data on arthropod tsh expression, show the first data on onychophoran tio/tsh expression, and provide a comprehensive investigation on sal expression patterns in arthropods and an onychophoran. CONCLUSIONS Our data support the idea that tio/tsh genes are involved in the development of "trunk" segments by regulating limb development. Our data suggest further that the function of Sal is indeed unlikely to be conserved in trunk vs head development like in Drosophila, but early expression of sal is in line with a potential homeotic function, at least in Arthropoda.
Collapse
Affiliation(s)
- Brenda I Medina-Jiménez
- Department of Earth Sciences, Palaeobiology, Uppsala University, Villavägen 16, Uppsala, Sweden
| | - Graham E Budd
- Department of Earth Sciences, Palaeobiology, Uppsala University, Villavägen 16, Uppsala, Sweden
| | - Ralf Janssen
- Department of Earth Sciences, Palaeobiology, Uppsala University, Villavägen 16, Uppsala, Sweden.
| |
Collapse
|
9
|
Cribellate thread production as model for spider's spinneret kinematics. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2021; 207:127-139. [PMID: 33483834 PMCID: PMC8046689 DOI: 10.1007/s00359-020-01460-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 12/15/2020] [Accepted: 12/17/2020] [Indexed: 11/24/2022]
Abstract
Spider silk attracts researchers from the most diverse fields, such as material science or medicine. However, still little is known about silk aside from its molecular structure and material strength. Spiders produce many different silks and even join several silk types to one functional unit. In cribellate spiders, a complex multi-fibre system with up to six different silks affects the adherence to the prey. The assembly of these cribellate capture threads influences the mechanical properties as each fibre type absorbs forces specifically. For the interplay of fibres, spinnerets have to move spatially and come into contact with each other at specific points in time. However, spinneret kinematics are not well described though highly sophisticated movements are performed which are in no way inferior to the movements of other flexible appendages. We describe here the kinematics for the spinnerets involved in the cribellate spinning process of the grey house spider, Badumna longinqua, as an example of spinneret kinematics in general. With this information, we set a basis for understanding spinneret kinematics in other spinning processes of spiders and additionally provide inspiration for biomimetic multiple fibre spinning.
Collapse
|
10
|
Townley MA, Harms D. Temperature fluctuations during embryonic development implicated in a naturally occurring instance of abnormal spinnerets in the spider Australomimetus maculosus (Araneae, Mimetidae). ARTHROPOD STRUCTURE & DEVELOPMENT 2020; 57:100945. [PMID: 32361425 DOI: 10.1016/j.asd.2020.100945] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2020] [Revised: 03/26/2020] [Accepted: 04/04/2020] [Indexed: 06/11/2023]
Abstract
We record developmental abnormalities of the spinnerets in a field-collected adult male specimen of Australomimetus maculosus. These include (1) a supernumerary right posterior lateral spinneret (PLS), (2) ectopic piriform silk gland spigots and tartipores on the left PLS that are normally restricted to anterior lateral spinnerets (ALSs), and (3) what appear to be ectopic ALS sensilla on the left posterior median spinneret (PMS). Published results of teratological experiments and climate data for the collection site indicate that fluctuating sub- and supra-optimal temperatures during embryogenesis may have been responsible for these anomalies. This specimen thus supports the view that spinneret abnormalities, among other aberrations, may be induced when embryos of entelegyne spiders are exposed to fluctuations between high and low temperatures, whether in the laboratory or, as here, in nature. To our knowledge, the ectopic structures seen on the left PLS and left PMS have not been observed previously. Their locations are consistent with a hypothesis by which only the lateral portion of the araneomorph ALS is serially homologous to the PLS, while the remainder of the ALS, along with the colulus/cribellum, is homologous to the PMS.
Collapse
Affiliation(s)
- Mark A Townley
- University Instrumentation Center, University of New Hampshire, 23 Academic Way, Durham, NH, 03824, USA.
| | - Danilo Harms
- Zoological Museum, Center of Natural History, Universität Hamburg, Martin-Luther-King-Platz 3, D-20146, Hamburg, Germany.
| |
Collapse
|
11
|
Kiseleva AP, Krivoshapkin PV, Krivoshapkina EF. Recent Advances in Development of Functional Spider Silk-Based Hybrid Materials. Front Chem 2020; 8:554. [PMID: 32695749 PMCID: PMC7338834 DOI: 10.3389/fchem.2020.00554] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Accepted: 05/29/2020] [Indexed: 01/10/2023] Open
Abstract
Silkworm silk is mainly known as a luxurious textile. Spider silk is an alternative to silkworm silk fibers and has much more outstanding properties. Silk diversity ensures variation in its application in nature and industry. This review aims to provide a critical summary of up-to-date fabrication methods of spider silk-based organic-inorganic hybrid materials. This paper focuses on the relationship between the molecular structure of spider silk and its mechanical properties. Such knowledge is essential for understanding the innate properties of spider silk as it provides insight into the sophisticated assembly processes of silk proteins into the distinct polymers as a basis for novel products. In this context, we describe the development of spider silk-based hybrids using both natural and bioengineered spider silk proteins blended with inorganic nanoparticles. The following topics are also covered: the diversity of spider silk, its composition and architecture, the differences between silkworm silk and spider silk, and the biosynthesis of natural silk. Referencing biochemical data and processes, this paper outlines the existing challenges and future outcomes.
Collapse
Affiliation(s)
| | | | - Elena F. Krivoshapkina
- Laboratory of Solution Chemistry of Advanced Materials and Technologies, ITMO University, St. Petersburg, Russia
| |
Collapse
|
12
|
Mariano-Martins P, Lo-Man-Hung N, Torres TT. Evolution of Spiders and Silk Spinning: Mini Review of the Morphology, Evolution, and Development of Spiders’ Spinnerets. Front Ecol Evol 2020. [DOI: 10.3389/fevo.2020.00109] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
|
13
|
Janssen R, Budd GE. Expression of the zinc finger transcription factor Sp6-9 in the velvet worm Euperipatoides kanangrensis suggests a conserved role in appendage development in Panarthropoda. Dev Genes Evol 2020; 230:239-245. [PMID: 32430690 PMCID: PMC7260272 DOI: 10.1007/s00427-020-00661-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2020] [Accepted: 05/11/2020] [Indexed: 11/01/2022]
Abstract
The Sp-family genes encode important transcription factors in animal development. Here we investigate the embryonic expression patterns of the complete set of Sp-genes in the velvet worm Euperipatoides kanangrensis (Onychophora), with a special focus on the Sp6-9 ortholog. In arthropods, Sp6-9, the ortholog of the Drosophila melanogaster D-Sp1 gene plays a conserved role in appendage development. Our data show that the expression of Sp6-9 during the development of the velvet worm is conserved, suggesting that the key function of the Sp6-9 gene dates back to at least the last common ancestor of arthropods and onychophorans and thus likely the last common ancestor of Panarthropoda.
Collapse
Affiliation(s)
- Ralf Janssen
- Department of Earth Sciences, Uppsala University, Palaeobiology, Villavägen 16, Uppsala, Sweden.
| | - Graham E Budd
- Department of Earth Sciences, Uppsala University, Palaeobiology, Villavägen 16, Uppsala, Sweden
| |
Collapse
|
14
|
Rodrigues BVB, Rheims CA. Phylogenetic analysis of the subfamily Prodidominae (Arachnida: Araneae: Gnaphosidae). Zool J Linn Soc 2020. [DOI: 10.1093/zoolinnean/zlaa013] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Abstract
Prodidominae was recently re-established as a subfamily of Gnaphosidae, comprising 316 species placed in 33 genera. In this study, we conduct a cladistic analysis including 59 species of Prodidominae and 32 outgroup species. The matrix is composed of 291 morphological characters and the data are analysed under the parsimony criterion, using differing weighting regimes. Prodidominae is not recovered as monophyletic, because Anagrina did not arise within the subfamily. Cryptotoerithus, Molycria, Myandra, Nomindra, Wesmaldra and Wydundra arise to form a clade. Thus, we re-establish Molycriinae as a distinct subfamily in Gnaphosidae, sister to Prodidominae. We redefine the limits of Prodidominae to include the genera Austrodomus, Brasilomma, Caudalia, Chileomma, Chileuma, Chilongius, Eleleis, Indiani, Katumbea, Lygromma, Lygrommatoides, Moreno, Namundra, Neozimiris, Nopyllus, Paracymbiomma, Plutonodomus, Prodidomus, Purcelliana, Theuma, Theumella, Tivodrassus, Tricongius, Zimirina and Zimiris. Species of these genera share the presence of anterior lateral spinnerets with pyriform gland spigots associated with patches of long setae and the presence of a large protrusion between coxae IV with erect setae and unsclerotized margins. In addition, we propose three new synonymies: Oltacloea as a junior synonym of Tricongius, and Prodida as junior synonym of Prodidomus. Lygromma ybyguara is transferred to Tricongius.
Collapse
Affiliation(s)
- Bruno V B Rodrigues
- Laboratório Especial de Coleções Zoológicas, Instituto Butantan. Av. Vital Brasil, CEP, São Paulo, SP, Brazil
- Departamento de Zoologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP, Brazil
| | - Cristina A Rheims
- Laboratório Especial de Coleções Zoológicas, Instituto Butantan. Av. Vital Brasil, CEP, São Paulo, SP, Brazil
| |
Collapse
|
15
|
Oda H, Akiyama-Oda Y. The common house spider Parasteatoda tepidariorum. EvoDevo 2020; 11:6. [PMID: 32206294 PMCID: PMC7082966 DOI: 10.1186/s13227-020-00152-z] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Accepted: 03/12/2020] [Indexed: 11/20/2022] Open
Abstract
The common house spider Parasteatoda tepidariorum, belonging to the Chelicerata in the phylum Arthropoda, has emerged as an experimental system for studying mechanisms of development from an evolutionary standpoint. In this article, we review the distinct characteristics of P. tepidariorum, the major research questions relevant to this organism, and the available key methods and resources. P. tepidariorum has a relatively short lifecycle and, once mated, periodically lays eggs. The morphogenetic field of the P. tepidariorum embryo is cellular from an early stage and exhibits stepwise symmetry-breaking events and stripe-forming processes that are associated with body axes formation and segmentation, respectively, before reaching the arthropod phylotypic stage. Self-regulatory capabilities of the embryonic field are a prominent feature in P. tepidariorum. The mechanisms and logic underlying the evolvability of heritable patterning systems at the phylum level could be one of the major avenues of research investigated using this animal. The sequenced genome reveals whole genome duplication (WGD) within chelicerates, which offers an invertebrate platform for investigating the potential roles of WGD in animal diversification and evolution. The development and evolution of lineage-specific organs, including the book lungs and the union of spinnerets and silk glands, are attractive subjects of study. Studies using P. tepidariorum can benefit from the use of parental RNA interference, microinjection applications (including cell labeling and embryonic RNA interference), multicolor fluorescence in situ hybridization, and laser ablation as well as rich genomic and transcriptomic resources. These techniques enable functional gene discoveries and the uncovering of cellular and molecular insights.![]()
Collapse
Affiliation(s)
- Hiroki Oda
- 1Laboratory of Evolutionary Cell and Developmental Biology, JT Biohistory Research Hall, 1-1 Murasaki-cho, Takatsuki, Osaka 569-1125 Japan.,2Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka Japan
| | - Yasuko Akiyama-Oda
- 1Laboratory of Evolutionary Cell and Developmental Biology, JT Biohistory Research Hall, 1-1 Murasaki-cho, Takatsuki, Osaka 569-1125 Japan.,3Microbiology and Infection Control, Osaka Medical College, Takatsuki, Osaka Japan
| |
Collapse
|
16
|
Pechmann M. Embryonic development and secondary axis induction in the Brazilian white knee tarantula Acanthoscurria geniculata, C. L. Koch, 1841 (Araneae; Mygalomorphae; Theraphosidae). Dev Genes Evol 2020; 230:75-94. [PMID: 32076811 PMCID: PMC7128004 DOI: 10.1007/s00427-020-00653-w] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Accepted: 01/29/2020] [Indexed: 02/07/2023]
Abstract
Tarantulas represent some of the heaviest and most famous spiders. However, there is little information about the embryonic development of these spiders or their relatives (infraorder Mygalomorphae) and time-lapse recording of the embryonic development is entirely missing. I here describe the complete development of the Brazilian white knee tarantula, Acanthoscurria geniculata, in fixed and live embryos. The establishment of the blastoderm, the formation, migration and signalling of the cumulus and the shape changes that occur in the segment addition zone are analysed in detail. In addition, I show that there might be differences in the contraction process of early embryos of different theraphosid spider species. A new embryonic reference transcriptome was generated for this study and was used to clone and analyse the expression of several important developmental genes. Finally, I show that embryos of A. geniculata are amenable to tissue transplantation and bead insertion experiments. Using these functional approaches, I induced axis duplication in embryos via cumulus transplantation and ectopic activation of BMP signalling. Overall, the mygalomorph spider A. geniculata is a useful laboratory system to analyse evolutionary developmental questions, and the availability of such a system will help understanding conserved and divergent aspects of spider/chelicerate development.
Collapse
Affiliation(s)
- Matthias Pechmann
- Institute for Zoology, Department for Developmental Biology, Biocenter, University of Cologne, Zuelpicher Str. 47b, 50674, Cologne, Germany.
| |
Collapse
|
17
|
Schomburg C, Turetzek N, Prpic NM. Candidate gene screen for potential interaction partners and regulatory targets of the Hox gene labial in the spider Parasteatoda tepidariorum. Dev Genes Evol 2020; 230:105-120. [PMID: 32036446 PMCID: PMC7128011 DOI: 10.1007/s00427-020-00656-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2019] [Accepted: 01/31/2020] [Indexed: 12/21/2022]
Abstract
The Hox gene labial (lab) governs the formation of the tritocerebral head segment in insects and spiders. However, the morphology that results from lab action is very different in the two groups. In insects, the tritocerebral segment (intercalary segment) is reduced and lacks appendages, whereas in spiders the corresponding segment (pedipalpal segment) is a proper segment including a pair of appendages (pedipalps). It is likely that this difference between lab action in insects and spiders is mediated by regulatory targets or interacting partners of lab. However, only a few such genes are known in insects and none in spiders. We have conducted a candidate gene screen in the spider Parasteatoda tepidariorum using as candidates Drosophila melanogaster genes known to (potentially) interact with lab or to be expressed in the intercalary segment. We have studied 75 P. tepidariorum genes (including previously published and duplicated genes). Only 3 of these (proboscipedia-A (pb-A) and two paralogs of extradenticle (exd)) showed differential expression between leg and pedipalp. The low success rate points to a weakness of the candidate gene approach when it is applied to lineage specific organs. The spider pedipalp has no counterpart in insects, and therefore relying on insect data apparently cannot identify larger numbers of factors implicated in its specification and formation. We argue that in these cases a de novo approach to gene discovery might be superior to the candidate gene approach.
Collapse
Affiliation(s)
- Christoph Schomburg
- Institut für Allgemeine Zoologie und Entwicklungsbiologie, AG Zoologie mit dem Schwerpunkt Molekulare Entwicklungsbiologie, Justus-Liebig-Universität Gießen, Heinrich-Buff-Ring 38, 35392, Gießen, Germany
| | - Natascha Turetzek
- Ludwig-Maximilians-Universität München, Lehrstuhl für Evolutionäre Ökologie, Biozentrum II, Großhadernerstraße 2, 82152, Planegg-Martinsried, Germany
| | - Nikola-Michael Prpic
- Institut für Allgemeine Zoologie und Entwicklungsbiologie, AG Zoologie mit dem Schwerpunkt Molekulare Entwicklungsbiologie, Justus-Liebig-Universität Gießen, Heinrich-Buff-Ring 38, 35392, Gießen, Germany.
| |
Collapse
|
18
|
Formation and development of the male copulatory organ in the spider Parasteatoda tepidariorum involves a metamorphosis-like process. Sci Rep 2019; 9:6945. [PMID: 31061504 PMCID: PMC6502807 DOI: 10.1038/s41598-019-43192-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Accepted: 04/16/2019] [Indexed: 11/26/2022] Open
Abstract
Spiders have evolved a unique male copulatory organ, the pedipalp bulb. The morphology of the bulb is species specific and plays an important role in species recognition and prezygotic reproductive isolation. Despite its importance for spider biodiversity, the mechanisms that control bulb development are virtually unknown. We have used confocal laser scanning microscopy (CLSM) and diffusible iodine-based contrast-enhanced micro computed tomography (dice-µCT) to study bulb development in the spider Parasteatoda tepidariorum. These imaging technologies enabled us to study bulb development in situ, without the use of destructive procedures for the first time. We show here that the inflated pedipalp tip in the subadult stage is filled with haemolymph that rapidly coagulates. Coagulation indicates histolytic processes that disintegrate tibia and tarsus, similar to histolytic processes during metamorphosis in holometabolous insects. The coagulated material contains cell inclusions that likely represent the cell source for the re-establishment of tarsus and tibia after histolysis, comparable to the histoblasts in insect metamorphosis. The shape of the coagulated mass prefigures the shape of the adult tarsus (cymbium) like a blueprint for the histoblasts. This suggests a unique role for controlled coagulation after histolysis in the metamorphosis-like morphogenesis of the male pedipalp.
Collapse
|
19
|
Expression of meis and hoxa11 in dipnoan and teleost fins provides new insights into the evolution of vertebrate appendages. EvoDevo 2018; 9:11. [PMID: 29719716 PMCID: PMC5924435 DOI: 10.1186/s13227-018-0099-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Accepted: 04/20/2018] [Indexed: 11/22/2022] Open
Abstract
Background The concerted activity of Meis and Hoxa11 transcription factors is essential for the subdivision of tetrapod limbs into proximo-distal (PD) domains; however, little is know about the evolution of this patterning mechanism. Here, we aim to study the expression of meis and hoxa11 orthologues in the median and paired rayed fins of zebrafish and in the lobed fins of the Australian lungfish. Results First, a late phase of expression of meis1.1 and hoxa11b in zebrafish dorsal and anal fins relates with segmentation of endochondral elements in proximal and distal radials. Second, our zebrafish in situ hybridization results reveal spatial and temporal changes between pectoral and pelvic fins. Third, in situ analysis of meis1, meis3 and hoxa11 genes in Neoceratodus pectoral fins identifies decoupled domains of expression along the PD axis. Conclusions Our data raise the possibility that the origin of stylopod and zeugopod lies much deeper in gnathostome evolution and that variation in meis and hoxa11 expression has played a substantial role in the transformation of appendage anatomy. Moreover, these observations provide evidence that the Meis/Hoxa11 profile considered a hallmark of stylopod/zeugopod patterning is present in Neoceratodus. Electronic supplementary material The online version of this article (10.1186/s13227-018-0099-9) contains supplementary material, which is available to authorized users.
Collapse
|
20
|
Cooption of an appendage-patterning gene cassette in the head segmentation of arachnids. Proc Natl Acad Sci U S A 2018; 115:E3491-E3500. [PMID: 29581309 DOI: 10.1073/pnas.1720193115] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The jointed appendages of arthropods have facilitated the spectacular diversity and success of this phylum. Key to the regulation of appendage outgrowth is the Krüppel-like factor (KLF)/specificity protein (Sp) family of zinc finger transcription factors. In the fruit fly, Drosophila melanogaster, the Sp6-9 homolog is activated by Wnt-1/wingless (wg) and establishes ventral appendage (leg) fate. Subsequently, Sp6-9 maintains expression of the axial patterning gene Distal-less (Dll), which promotes limb outgrowth. Intriguingly, in spiders, Dll has been reported to have a derived role as a segmentation gap gene, but the evolutionary origin and regulation of this function are not understood because functional investigations of the appendage-patterning regulatory network are restricted to insects. We tested the evolutionary conservation of the ancestral appendage-patterning network of arthropods with a functional approach in the spider. RNAi-mediated knockdown of the spider Sp6-9 ortholog resulted in diminution or loss of Dll expression and truncation of appendages, as well as loss of the two body segments specified by the early Dll function. In reciprocal experiments, Dll is shown not to be required for Sp6-9 expression. Knockdown of arrow (Wnt-1 coreceptor) disrupted segmentation and appendage development but did not affect the early Sp6-9 expression domain. Ectopic appendages generated in the spider "abdomen" by knockdown of the Hox gene Antennapedia-1 (Antp-1) expressed Sp6-9 comparably to wild-type walking legs. Our results support (i) the evolutionary conservation of an appendage-patterning regulatory network that includes canonical Wnt signaling, Sp6-9, and Dll and (ii) the cooption of the Sp6-9/Dll regulatory cassette in arachnid head segmentation.
Collapse
|
21
|
Sharma PP. Chelicerates and the Conquest of Land: A View of Arachnid Origins Through an Evo-Devo Spyglass. Integr Comp Biol 2018; 57:510-522. [PMID: 28957520 DOI: 10.1093/icb/icx078] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The internal phylogeny of Chelicerata and the attendant evolutionary scenario of arachnid terrestrialization have a long and contentious history. Previous studies of developmental gene expression data have suggested that respiratory systems of spiders, crustaceans, and insects are all serially homologous structures derived from the epipods (outer appendage rami) of the arthropod ancestor, corresponding to an ancestral gill. A separate body of evidence has suggested that the respiratory systems of arachnids are modified, inverted telopods (inner rami, or legs). Here I review these dissonant homology statements and compare the developmental genetic basis for respiratory system development in insects and arachnids. I show that the respiratory primordia of arachnids are not positionally homologous to those of insects. I further demonstrate that candidate genes critical to tracheal fate specification in Drosophila melanogaster are expressed very differently in arachnid exemplars. Taken together, these data suggest that mechanisms of respiratory system development are not derived from homologous structures or mechanisms in insects and arachnids, and that different terrestrial arthropod lineages have solved the challenge of aerial respiration using different developmental mechanisms.
Collapse
Affiliation(s)
- Prashant P Sharma
- Department of Zoology, University of Wisconsin-Madison, 352 Birge Hall, 430 Lincoln Drive, Madison, WI 53706, USA
| |
Collapse
|
22
|
Farley RD. Book lung development in juveniles and adults of the cobweb spider, Parasteatoda tepidariorum C. L. Koch, 1841 (Araneomorphae, Theridiidae). ARTHROPOD STRUCTURE & DEVELOPMENT 2018; 47:180-198. [PMID: 29341927 DOI: 10.1016/j.asd.2018.01.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Revised: 01/02/2018] [Accepted: 01/02/2018] [Indexed: 06/07/2023]
Abstract
Light and transmission electron microscopy were used to study the development of new book lung lamellae in juvenile and adult spiders (Parasteatoda tepidariorum). As hypothesized earlier in a study of embryos, mesenchyme cells dispersed throughout the opisthosoma (EMT) are a likely source of precursor epithelial cells (MET) for the new lamellae. The precursor cells in juveniles and adults continue many of the complex activities observed in embryos, e.g., migration, alignment, lumen formation, thinning, elongation, and secretion of the cuticle of air channel walls and trabeculae. The apicobasal polarity of precursor cells for new channels is apparently induced by the polarity pattern of precursor cells of channels produced earlier. Thus, new air and hemolymph channels extend and continue the alternating pattern of older channels. At sites more distant from the spiracle and atrium, new channels are usually produced by the mode II process (intracellular alignment and merging of vesicles). These air channels have bridging trabeculae and are quite stable in size throughout their length. At sites closer to the spiracle and atrium, new channels may be produced by mode I (coalescence of merocrine vesicle secretion). This raises the hypothesis that structural and functional differences in mode I and II channels and differing oxygen and fluid conditions with distance from the spiracle and atrium determine the mode of formation of new channels. Observations herein support an earlier hypothesis that there is some intercellular apical/apical and basal/basal affinity among the opposed surfaces of aligned precursor cells. This results in the alternating pattern of air channels at the apical and hemolymph channels at the basal cell surfaces.
Collapse
Affiliation(s)
- Roger D Farley
- Department of Biology, University of California, Riverside, CA 92521, USA.
| |
Collapse
|
23
|
Alfaro RE, Griswold CE, Miller KB. -Comparative spigot ontogeny across the spider tree of life. PeerJ 2018; 6:e4233. [PMID: 29362692 PMCID: PMC5772386 DOI: 10.7717/peerj.4233] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Accepted: 12/14/2017] [Indexed: 11/20/2022] Open
Abstract
Spiders are well known for their silk and its varying use across taxa. Very few studies have examined the silk spigot ontogeny of the entire spinning field of a spider. Historically the spider phylogeny was based on morphological data and behavioral data associated with silk. Recent phylogenomics studies have shifted major paradigms in our understanding of silk use evolution, reordering phylogenetic relationships that were once thought to be monophyletic. Considering this, we explored spigot ontogeny in 22 species, including Dolomedes tenebrosus and Hogna carolinensis, reported here for the first time. This is the first study of its kind and the first to incorporate the Araneae Tree of Life. After rigorous testing for phylogenetic signal and model fit, we performed 60 phylogenetic generalized least squares analyses on adult female and second instar spigot morphology. Six analyses had significant correlation coefficients, suggesting that instar, strategy, and spigot variety are good predictors of spigot number in spiders, after correcting for bias of shared evolutionary history. We performed ancestral character estimation of singular, fiber producing spigots on the posterior lateral spinneret whose potential homology has long been debated. We found that the ancestral root of our phylogram of 22 species, with the addition of five additional cribellate and ecribellate lineages, was more likely to have either none or a modified spigot rather than a pseudoflagelliform gland spigot or a flagelliform spigot. This spigot ontogeny approach is novel and we can build on our efforts from this study by growing the dataset to include deeper taxon sampling and working towards the capability to incorporate full ontogeny in the analysis.
Collapse
Affiliation(s)
- Rachael E. Alfaro
- Museum of Southwestern Biology, Division of Arthropods, University of New Mexico, Albuquerque, NM, United States of America
| | - Charles E. Griswold
- Entomology, California Academy of Sciences, San Francisco, CA, United States of America
| | - Kelly B. Miller
- Museum of Southwestern Biology, Division of Arthropods, University of New Mexico, Albuquerque, NM, United States of America
| |
Collapse
|
24
|
Jockusch EL. Developmental and Evolutionary Perspectives on the Origin and Diversification of Arthropod Appendages. Integr Comp Biol 2017; 57:533-545. [DOI: 10.1093/icb/icx063] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
|
25
|
Wang ZL, Yang XQ, Wang TZ, Yu X. Assessing the effectiveness of mitochondrial COI and 16S rRNA genes for DNA barcoding of farmland spiders in China. Mitochondrial DNA A DNA Mapp Seq Anal 2017; 29:695-702. [PMID: 28712321 DOI: 10.1080/24701394.2017.1350949] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
DNA barcoding has been widely used to identify and discover new species in a wide range of taxa. In order to assess the effectiveness of COI (cytochrome C oxidase subunit I) and 16S (16S ribosomal RNA) in the discrimination of spiders, we have generated 289 barcodes for a total of 56 farmland spider species from 14 different families for the first time in China. Our results reveal that the standard barcoding marker COI can be used to distinguish the farmland spiders both in species and family level by NJ tree-based method, despite the absence of a barcode gap between the intra- and inter-specific genetic divergences. 16S has a lower species identification success as compared with COI. However, almost 98% of the species can be correctly distinguished for both COI and 16S when a threshold of 3% nucleotide divergence was used for species discrimination. Our study significantly improves the barcode reference sequence library for Chinese farmland spiders, and will be very useful in pest management and eco-environmental monitoring and protection.
Collapse
Affiliation(s)
- Zheng Liang Wang
- a Zhejiang Provincial Key Laboratory of Biometrology and Inspection and Quarantine, College of Life Sciences , China Jiliang University , Hangzhou , Zhejiang , People's Republic of China
| | - Xiao Qing Yang
- a Zhejiang Provincial Key Laboratory of Biometrology and Inspection and Quarantine, College of Life Sciences , China Jiliang University , Hangzhou , Zhejiang , People's Republic of China
| | - Tian Zhao Wang
- a Zhejiang Provincial Key Laboratory of Biometrology and Inspection and Quarantine, College of Life Sciences , China Jiliang University , Hangzhou , Zhejiang , People's Republic of China
| | - Xiaoping Yu
- a Zhejiang Provincial Key Laboratory of Biometrology and Inspection and Quarantine, College of Life Sciences , China Jiliang University , Hangzhou , Zhejiang , People's Republic of China
| |
Collapse
|
26
|
Turetzek N, Khadjeh S, Schomburg C, Prpic NM. Rapid diversification of homothorax expression patterns after gene duplication in spiders. BMC Evol Biol 2017; 17:168. [PMID: 28709396 PMCID: PMC5513375 DOI: 10.1186/s12862-017-1013-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Accepted: 07/04/2017] [Indexed: 01/09/2023] Open
Abstract
Background Gene duplications provide genetic material for the evolution of new morphological and physiological features. One copy can preserve the original gene functions while the second copy may evolve new functions (neofunctionalisation). Gene duplications may thus provide new genes involved in evolutionary novelties. Results We have studied the duplicated homeobox gene homothorax (hth) in the spider species Parasteatoda tepidariorum and Pholcus phalangioides and have compared these data with previously published data from additional spider species. We show that the expression pattern of hth1 is highly conserved among spiders, consistent with the notion that this gene copy preserves the original hth functions. By contrast, hth2 has a markedly different expression profile especially in the prosomal appendages. The pattern in the pedipalps and legs consists of several segmental rings, suggesting a possible role of hth2 in limb joint development. Intriguingly, however, the hth2 pattern is much less conserved between the species than hth1 and shows a species specific pattern in each species investigated so far. Conclusions We hypothesise that the hth2 gene has gained a new patterning function after gene duplication, but has then undergone a second phase of diversification of its new role in the spider clade. The evolution of hth2 may thus provide an interesting example for a duplicated gene that has not only contributed to genetic diversity through neofunctionalisation, but beyond that has been able to escape evolutionary conservation after neofunctionalisation thus forming the basis for further genetic diversification. Electronic supplementary material The online version of this article (doi:10.1186/s12862-017-1013-0) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Natascha Turetzek
- Abteilung für Entwicklungsbiologie, Johann-Friedrich-Blumenbach-Institut für Zoologie und Anthropologie, Georg-August-Universität, Göttingen, Germany.,Göttingen Center for Molecular Biosciences (GZMB), Ernst-Caspari-Haus, Göttingen, Germany.,Current address: Georg-August-Universität Göttingen, Johann-Friedrich-Blumenbach-Institut für Zoologie und Anthropologie, Abteilung Zelluläre Neurobiologie, 37077, Göttingen, Germany
| | - Sara Khadjeh
- Abteilung für Entwicklungsbiologie, Johann-Friedrich-Blumenbach-Institut für Zoologie und Anthropologie, Georg-August-Universität, Göttingen, Germany.,Göttingen Center for Molecular Biosciences (GZMB), Ernst-Caspari-Haus, Göttingen, Germany.,Present address: Clinic for Cardiology and Pneumology, University Medical Center Göttingen (UMG), Georg-August-University, Göttingen, Germany
| | - Christoph Schomburg
- Abteilung für Entwicklungsbiologie, Johann-Friedrich-Blumenbach-Institut für Zoologie und Anthropologie, Georg-August-Universität, Göttingen, Germany.,Göttingen Center for Molecular Biosciences (GZMB), Ernst-Caspari-Haus, Göttingen, Germany
| | - Nikola-Michael Prpic
- Abteilung für Entwicklungsbiologie, Johann-Friedrich-Blumenbach-Institut für Zoologie und Anthropologie, Georg-August-Universität, Göttingen, Germany. .,Göttingen Center for Molecular Biosciences (GZMB), Ernst-Caspari-Haus, Göttingen, Germany.
| |
Collapse
|
27
|
Dunlop JA, Lamsdell JC. Segmentation and tagmosis in Chelicerata. ARTHROPOD STRUCTURE & DEVELOPMENT 2017; 46:395-418. [PMID: 27240897 DOI: 10.1016/j.asd.2016.05.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Revised: 05/17/2016] [Accepted: 05/18/2016] [Indexed: 05/16/2023]
Abstract
Patterns of segmentation and tagmosis are reviewed for Chelicerata. Depending on the outgroup, chelicerate origins are either among taxa with an anterior tagma of six somites, or taxa in which the appendages of somite I became increasingly raptorial. All Chelicerata have appendage I as a chelate or clasp-knife chelicera. The basic trend has obviously been to consolidate food-gathering and walking limbs as a prosoma and respiratory appendages on the opisthosoma. However, the boundary of the prosoma is debatable in that some taxa have functionally incorporated somite VII and/or its appendages into the prosoma. Euchelicerata can be defined on having plate-like opisthosomal appendages, further modified within Arachnida. Total somite counts for Chelicerata range from a maximum of nineteen in groups like Scorpiones and the extinct Eurypterida down to seven in modern Pycnogonida. Mites may also show reduced somite counts, but reconstructing segmentation in these animals remains challenging. Several innovations relating to tagmosis or the appendages borne on particular somites are summarised here as putative apomorphies of individual higher taxa. We also present our observations within the concept of pseudotagma, whereby the true tagmata - the prosoma and opisthosoma - can be defined on a fundamental change in the limb series while pseudotagmata, such as the cephalosoma/proterosoma, are expressed as divisions in sclerites covering the body without an accompanying change in the appendages.
Collapse
Affiliation(s)
- Jason A Dunlop
- Museum für Naturkunde, Leibniz Institute for Evolution and Biodiversity Science, Invalidenstrasse 43, D-10115 Berlin, Germany.
| | - James C Lamsdell
- American Museum of Natural History, Division of Paleontology, Central Park West at 79th St, New York, NY 10024, USA.
| |
Collapse
|
28
|
Farley RD. Book lung development in embryos of the cobweb spider, Parasteatoda tepidariorum C. L. Koch, 1841 (Araneomorphae, Theridiidae). ARTHROPOD STRUCTURE & DEVELOPMENT 2016; 45:562-584. [PMID: 27693811 DOI: 10.1016/j.asd.2016.09.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2016] [Revised: 09/19/2016] [Accepted: 09/22/2016] [Indexed: 06/06/2023]
Abstract
Light and transmission electron microscopy were used to study the development of book lungs in embryos of the spider Parasteatoda tepidariorum. There is a bilateral cluster of temporary lamellae that form just posterior to the second opisthosomal (O2) limb buds. These lamellae are replaced by advanced embryo (AE) book lungs that continue into postembryonic stages. Results herein agree with earlier suggestions that the O2 limb buds become the AE book lungs. Each O2 limb bud merges with the ventral surface of the O2 segment, where the limb bud/book lung is internalized by covering with epidermis. A strand of tissue (entapophysis) from the epidermis at the posterior opisthosoma provides precursor cells for the book lung lamellae, and possibly entapophysis cells induce limb bud cells to align and produce lamellae. Electron micrographs show the different modes (I-III) of lumen formation. The result is a spiracle, atrium and alternating air and hemolymph channels. A hypothesis is presented for the role of precursor cell polarity in producing the planar tissue polarity of the channels. Some type of apical/apical affinity results in air channels, while basal/basal affinity results in hemolymph channels. Strong basal/basal affinity is likely as opposed cells in hemolymph channels extend basal processes that span the channel and start pillar trabeculae that continue in postembryonic stages.
Collapse
Affiliation(s)
- Roger D Farley
- Department of Biology, University of California, Riverside, CA 92521, USA.
| |
Collapse
|
29
|
Pechmann M, Schwager EE, Turetzek N, Prpic NM. Regressive evolution of the arthropod tritocerebral segment linked to functional divergence of the Hox gene labial. Proc Biol Sci 2016; 282:rspb.2015.1162. [PMID: 26311666 DOI: 10.1098/rspb.2015.1162] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The intercalary segment is a limbless version of the tritocerebral segment and is present in the head of all insects, whereas other extant arthropods have retained limbs on their tritocerebral segment (e.g. the pedipalp limbs in spiders). The evolutionary origin of limb loss on the intercalary segment has puzzled zoologists for over a century. Here we show that an intercalary segment-like phenotype can be created in spiders by interfering with the function of the Hox gene labial. This links the origin of the intercalary segment to a functional change in labial. We show that in the spider Parasteatoda tepidariorum the labial gene has two functions: one function in head tissue maintenance that is conserved between spiders and insects, and a second function in pedipalp limb promotion and specification, which is only present in spiders. These results imply that labial was originally crucial for limb formation on the tritocerebral segment, but that it has lost this particular subfunction in the insect ancestor, resulting in limb loss on the intercalary segment. Such loss of a subfunction is away to avoid adverse pleiotropic effects normally associated with mutations in developmental genes, and may thus be a common mechanism to accelerate regressive evolution.
Collapse
|
30
|
Chen B, Piel WH, Monteiro A. Distal-less homeobox genes of insects and spiders: genomic organization, function, regulation and evolution. INSECT SCIENCE 2016; 23:335-352. [PMID: 26898323 DOI: 10.1111/1744-7917.12327] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Revised: 01/30/2016] [Accepted: 02/04/2016] [Indexed: 06/05/2023]
Abstract
The Distal-less (Dll) genes are homeodomain transcription factors that are present in most Metazoa and in representatives of all investigated arthropod groups. In Drosophila, the best studied insect, Dll plays an essential role in forming the proximodistal axis of the legs, antennae and analia, and in specifying antennal identity. The initiation of Dll expression in clusters of cells in mid-lateral regions of the Drosophila embryo represents the earliest genetic marker of limbs. Dll genes are involved in the development of the peripheral nervous system and sensitive organs, and they also function as master regulators of black pigmentation in some insect lineages. Here we analyze the complete genomes of six insects, the nematode Caenorhabditis elegans and Homo sapiens, as well as multiple Dll sequences available in databases in order to examine the structure and protein features of these genes. We also review the function, expression, regulation and evolution of arthropod Dll genes with emphasis on insects and spiders.
Collapse
Affiliation(s)
- Bin Chen
- Institute of Entomology and Molecular Biology, College of Life Sciences, Chongqing Normal University, Chongqing 401331, P.R. China
| | - William H Piel
- Yale-NUS College, Singapore
- Department of Biological Sciences, National University of Singapore, Singapore
| | - Antónia Monteiro
- Yale-NUS College, Singapore
- Department of Biological Sciences, National University of Singapore, Singapore
| |
Collapse
|
31
|
Farley RD. Book lung development in the embryo, postembryo and first instar of the cobweb spider, Parasteatoda tepidariorum C. L Koch, 1841 (Araneomorphae, Theridiidae). ARTHROPOD STRUCTURE & DEVELOPMENT 2015; 44:355-377. [PMID: 25936921 DOI: 10.1016/j.asd.2015.04.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Revised: 03/27/2015] [Accepted: 04/22/2015] [Indexed: 06/04/2023]
Abstract
Light and electron microscopy were used to compare spider book lung development with earlier studies of the development of horseshoe crab book gills and scorpion book lungs. Histological studies at the beginning of the 20th century provided evidence that spider and scorpion book lungs begin with outgrowth of a few primary lamellae (respiratory furrows, saccules) from the posterior surface of opisthosomal limb buds, reminiscent of the formation of book gills in the horseshoe crab. In spider embryos, light micrographs herein also show small primary lamellae formed at the posterior surface of opisthosomal limb buds. Later, more prominent primary lamellae extend into each book lung sinus from the inner wall of the book lung operculum formed from the limb bud. It appears most primary lamellae continue developing and become part of later book lungs, but there is variation in the rate and sequence of development. Electron micrographs show the process of air channel formation from parallel rows of precursor cells: mode I (cord hollowing), release of secretory vesicles into the extracellular space and mode II (cell hollowing), alignment and fusion of intracellular vesicles. Cell death (cavitation) is much less common but occurs in some places. Results herein support the early 20th century hypotheses that 1) book lungs are derived from book gills and 2) book lungs are an early step in the evolution of spider tracheae.
Collapse
Affiliation(s)
- Roger D Farley
- Department of Biology, University of California, Riverside, CA 92521, USA.
| |
Collapse
|
32
|
Hilbrant M, Damen WGM. The embryonic origin of the ampullate silk glands of the spider Cupiennius salei. ARTHROPOD STRUCTURE & DEVELOPMENT 2015; 44:280-288. [PMID: 25882741 DOI: 10.1016/j.asd.2015.04.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2015] [Revised: 03/31/2015] [Accepted: 04/01/2015] [Indexed: 06/04/2023]
Abstract
Silk production in spiders is considered a key innovation, and to have been vital for the diversification of the clade. The evolutionary origin of the organs involved in spider silk production, however, and in particular of the silk glands, is poorly understood. Homologies have been proposed between these and other glands found in arachnids, but lacking knowledge of the embryonic development of spider silk glands hampers an evaluation of hypotheses. This study focuses on the embryonic origin of the largest silk glands of the spider Cupiennius salei, the major and minor ampullate glands. We show how the ampullate glands originate from ectodermal invaginations on the embryonic spinneret limb buds, in relation to morphogenesis of these buds. Moreover, we visualize the subsequent growth of the ampullate glands in sections of the early postembryonic stages. The invaginations are shown to correlate with expression of the proneural gene CsASH2, which is remarkable since it has been proposed that spider silk glands and their nozzles originate from sensory bristles. Hence, by confirming the ectodermal origin of spider silk glands, and by describing the (post-)embryonic morphogenesis of the ampullate glands, this work provides a starting point for further investigating into the genetic program that underlies their development.
Collapse
Affiliation(s)
- Maarten Hilbrant
- Institute for Genetics, University of Cologne, Zülpicher Straße 47a, 50674 Cologne, Germany; Institute for Developmental Biology, University of Cologne, Zülpicher Straße 47b, 50674 Cologne, Germany.
| | - Wim G M Damen
- Institute for Genetics, University of Cologne, Zülpicher Straße 47a, 50674 Cologne, Germany; Department of Genetics, Friedrich Schiller University, Jena, Philosophenweg 12, 07743 Jena, Germany.
| |
Collapse
|
33
|
Janssen R, Jörgensen M, Prpic NM, Budd GE. Aspects of dorso-ventral and proximo-distal limb patterning in onychophorans. Evol Dev 2015; 17:21-33. [DOI: 10.1111/ede.12107] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- Ralf Janssen
- Department of Earth Sciences, Palaeobiology; Uppsala University; Villavägen 16 75236 Uppsala Sweden
| | - Mette Jörgensen
- Department of Earth Sciences, Palaeobiology; Uppsala University; Villavägen 16 75236 Uppsala Sweden
| | - Nikola-Michael Prpic
- Abteilung für Entwicklungsbiologie; Johann-Friedrich-Blumenbach-Institut für Zoologie und Anthropologie; Georg-August-Universität Göttingen; GZMB; Ernst-Caspari-Haus; Justus-von-Liebig-Weg 11 37077 Göttingen Germany
| | - Graham E. Budd
- Department of Earth Sciences, Palaeobiology; Uppsala University; Villavägen 16 75236 Uppsala Sweden
| |
Collapse
|
34
|
Identification and embryonic expression of Wnt2, Wnt4, Wnt5 and Wnt9 in the millipede Glomeris marginata (Myriapoda: Diplopoda). Gene Expr Patterns 2014; 14:55-61. [DOI: 10.1016/j.gep.2013.12.003] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2013] [Revised: 12/26/2013] [Accepted: 12/29/2013] [Indexed: 11/23/2022]
|
35
|
Barnett AA, Thomas RH. The expression of limb gap genes in the mite Archegozetes longisetosus reveals differential patterning mechanisms in chelicerates. Evol Dev 2013; 15:280-92. [PMID: 23809702 DOI: 10.1111/ede.12038] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The modular organization of arthropod limbs has lead to the evolution of a diversity of appendages within this phylum. A conserved trait within the arthropods is the utilization of a conserved set of regulatory genes that specify the appendage podomeres along the proximo-distal axis, termed the limb gap genes. These include extradenticle, homothorax, dachshund, and Distal-less. The deployment of these genes in the most basally branching arthropod group, the chelicerates, has only been studied in detail in two chelicerate groups, the harvestmen and spiders. Given the broad range of appendage diversity within the chelicerates, comparative studies of gap gene deployment in other chelicerates groups is needed. We therefore followed limb gap gene expression in a member of the largest chelicerate group, Acari, the oribatid mite Archegozetes longisetosus. We show that in contrast to many arthropod species, A. longisetosus expresses homothorax and extradenticle exclusively in the proximal portion of the appendages, which refutes the hypothesis of a sister-group relationship between chelicerates and myriapods. We also provide evidence that mites posses the ancestral chelicerate condition of possessing three-segmented chelicerae, which also express the gene dachshund. This adds support to the hypothesis that a cheliceral dachshund domain is ancestral to arachnids. Lastly, we provide evidence that the suppression of the fourth pair of walking legs, a putative synapomorphy for Acari, is accomplished by repressing the development of the medial and distal regions of the limb.
Collapse
Affiliation(s)
- Austen A Barnett
- Department of Zoology, Southern Illinois University, Carbondale, IL 62901, USA
| | | |
Collapse
|
36
|
Mulvany S, Motta PJ. The morphology of the cephalic lobes and anterior pectoral fins in six species of batoids. J Morphol 2013; 274:1070-83. [DOI: 10.1002/jmor.20163] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2012] [Revised: 03/04/2013] [Accepted: 03/28/2013] [Indexed: 11/09/2022]
Affiliation(s)
- Samantha Mulvany
- Department of Integrative Biology; University of South Florida; 4202 East Fowler Avenue; Tampa; Florida; 33620
| | - Philip J. Motta
- Department of Integrative Biology; University of South Florida; 4202 East Fowler Avenue; Tampa; Florida; 33620
| |
Collapse
|
37
|
Gainett G, Sharma PP, Pinto-da-Rocha R, Giribet G, Willemart RH. Walk it off: predictive power of appendicular characters toward inference of higher-level relationships in Laniatores (Arachnida: Opiliones). Cladistics 2013; 30:120-138. [DOI: 10.1111/cla.12029] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/27/2013] [Indexed: 11/29/2022] Open
Affiliation(s)
- Guilherme Gainett
- Departamento de Zoologia; Instituto de Biociências; Universidade de São Paulo; Caixa Postal 11461 05422-970 São Paulo SP Brazil
| | - Prashant P. Sharma
- Division of Invertebrate Zoology; American Museum of Natural History; 200 Central Park West New York NY 10024 USA
| | - Ricardo Pinto-da-Rocha
- Departamento de Zoologia; Instituto de Biociências; Universidade de São Paulo; Caixa Postal 11461 05422-970 São Paulo SP Brazil
| | - Gonzalo Giribet
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology; Harvard University; Cambridge MA 02138 USA
| | - Rodrigo H. Willemart
- Escola de Artes Ciências e Humanidades; Universidade de São Paulo; Rua Arlindo Béttio, 1000-Ermelino Matarazzo CEP: 03828-000 São Paulo SP Brazil
| |
Collapse
|
38
|
Sharma PP, Schwager EE, Giribet G, Jockusch EL, Extavour CG. Distal-lessanddachshundpattern both plesiomorphic and apomorphic structures in chelicerates: RNA interference in the harvestmanPhalangium opilio(Opiliones). Evol Dev 2013; 15:228-42. [DOI: 10.1111/ede.12029] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | - Evelyn E. Schwager
- Department of Organismic and Evolutionary Biology; Harvard University; 26 Oxford Street, Cambridge, MA 02138; USA
| | | | - Elizabeth L. Jockusch
- Department of Ecology and Evolutionary Biology; University of Connecticut; 75 N. Eagleville Road, Storrs, CT 06269; USA
| | - Cassandra G. Extavour
- Department of Organismic and Evolutionary Biology; Harvard University; 26 Oxford Street, Cambridge, MA 02138; USA
| |
Collapse
|
39
|
Sharma PP, Schwager EE, Extavour CG, Giribet G. Evolution of the chelicera: adachshunddomain is retained in the deutocerebral appendage of Opiliones (Arthropoda, Chelicerata). Evol Dev 2012; 14:522-33. [DOI: 10.1111/ede.12005] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
| | - Evelyn E. Schwager
- Department of Organismic and Evolutionary Biology; Harvard University; 26 Oxford Street; Cambridge; MA 02138; USA
| | - Cassandra G. Extavour
- Department of Organismic and Evolutionary Biology; Harvard University; 26 Oxford Street; Cambridge; MA 02138; USA
| | | |
Collapse
|
40
|
Abstract
Arthropods are the most diverse group of animals and have been so since the Cambrian radiation. They belong to the protostome clade Ecdysozoa, with Onychophora (velvet worms) as their most likely sister group and tardigrades (water bears) the next closest relative. The arthropod tree of life can be interpreted as a five-taxon network, containing Pycnogonida, Euchelicerata, Myriapoda, Crustacea, and Hexapoda, the last two forming the clade Tetraconata or Pancrustacea. The unrooted relationship of Tetraconata to the three other lineages is well established, but of three possible rooting positions the Mandibulata hypothesis receives the most support. Novel approaches to studying anatomy with noninvasive three-dimensional reconstruction techniques, the application of these techniques to new and old fossils, and the so-called next-generation sequencing techniques are at the forefront of understanding arthropod relationships. Cambrian fossils assigned to the arthropod stem group inform on the origin of arthropod characters from a lobopodian ancestry. Monophyly of Pycnogonida, Euchelicerata, Myriapoda, Tetraconata, and Hexapoda is well supported, but the interrelationships of arachnid orders and the details of crustacean paraphyly with respect to Hexapoda remain the major unsolved phylogenetic problems.
Collapse
Affiliation(s)
- Gonzalo Giribet
- Museum of Comparative Zoology, Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
| | | |
Collapse
|
41
|
Farley RD. The ultrastructure of book lung development in the bark scorpion Centruroides gracilis (Scorpiones: Buthidae). Front Zool 2011; 8:18. [PMID: 21791110 PMCID: PMC3199777 DOI: 10.1186/1742-9994-8-18] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2011] [Accepted: 07/27/2011] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Near the end of the nineteenth century the hypothesis was presented for the homology of book lungs in arachnids and book gills in the horseshoe crab. Early studies with the light microscope showed that book gill lamellae are formed by outgrowth and possibly some invagination (infolding) of hypodermis (epithelium) from the posterior surface of opisthosomal limb buds. Scorpion book lungs are formed near the bilateral sites of earlier limb buds. Hypodermal invaginations in the ventral opisthosoma result in spiracles and sac-like cavities (atria). In early histological sections of embryo book lungs, widening of the atrial entrance of some lamellae (air channels, air sacs, saccules) was interpreted as an indication of invagination as hypothesized for book gill lamellae. The hypodermal infolding was thought to produce the many rows of lamellar precursor cells anterior to the atrium. The ultrastructure of scorpion book lung development is compared herein with earlier investigations of book gill formation. RESULTS In scorpion embryos, there is ingression (inward migration) of atrial hypodermal cells rather than invagination or infolding of the atrial hypodermal layer. The ingressing cells proliferate and align in rows anterior to the atrium. Their apical-basal polarity results in primordial air channels among double rows of cells. The cuticular walls of the air channels are produced by secretion from the apical surfaces of the aligned cells. Since the precursor cells are in rows, their secreted product is also in rows (i.e., primordial air channels, saccules). For each double row of cells, their opposed basal surfaces are gradually separated by a hemolymph channel of increasing width. CONCLUSIONS The results from this and earlier studies show there are differences and similarities in the formation of book lung and book gill lamellae. The homology hypothesis for these respiratory organs is thus supported or not supported depending on which developmental features are emphasized. For both organs, when the epithelial cells are in position, their apical-basal polarity results in alternate page-like channels of hemolymph and air or water with outward directed hemolymph saccules for book gills and inward directed air saccules for book lungs.
Collapse
Affiliation(s)
- Roger D Farley
- Department of Biology, University of California, Riverside, California, 92521, USA.
| |
Collapse
|