Chelicerata

Schwager, Evelyn E.; Schönauer, Anna; Leite, Daniel J.; Sharma, Prashant P.; McGregor, Alistair P.

doi:10.1007/978-3-7091-1865-8_5

Cited by 32 publications

(64 citation statements)

References 204 publications

(384 reference statements)

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“…The spider Parasteatoda tepidariorum (formerly Achaearanea tepidariorum) has proved to be an excellent chelicerate model for studying segmentation in short-germ arthropods (Schwager et al, 2015). This success has been facilitated by detailed descriptions of its early embryogenesis (Akiyama- Oda and Oda, 2003;Mittmann and Wolff, 2012), the establishment of tools to study gene expression and gene function (Akiyama- Oda and Oda, 2006;McGregor et al, 2008a;Kanayama et al, 2010;Kanayama et al, 2011;Hilbrant et al, 2012), as well as the availability of embryonic transcriptomic resources (Posnien et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

The Wnt and Delta-Notch signalling pathways interact to direct pair-rule gene expression via caudal during segment addition in the spider Parasteatoda tepidariorum

et al. 2016

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In short-germ arthropods, posterior segments are added sequentially from a segment addition zone (SAZ) during embryogenesis. Studies in spiders such as Parasteatoda tepidariorum have provided insights into the gene regulatory network (GRN) underlying segment addition, and revealed that Wnt8 is required for dynamic Delta (Dl) expression associated with the formation of new segments. However, it remains unclear how these pathways interact during SAZ formation and segment addition. Here, we show that Delta-Notch signalling is required for Wnt8 expression in posterior SAZ cells, but represses the expression of this Wnt gene in anterior SAZ cells. We also found that these two signalling pathways are required for the expression of the spider orthologues of even-skipped (eve) and runt-1 (run-1), at least in part via caudal (cad). Moreover, it appears that dynamic expression of eve in this spider does not require a feedback loop with run-1, as is found in the pair-rule circuit of the beetle Tribolium. Taken together, our results suggest that the development of posterior segments in Parasteatoda is directed by dynamic interactions between Wnt8 and Delta-Notch signalling that are read out by cad, which is necessary but probably not sufficient to regulate the expression of eve and run-1. Our study therefore provides new insights towards better understanding the evolution and developmental regulation of segmentation in other arthropods, including insects.

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Section: Introductionmentioning

confidence: 99%

The Wnt and Delta-Notch signalling pathways interact to direct pair-rule gene expression via caudal during segment addition in the spider Parasteatoda tepidariorum

et al. 2016

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“…Rounded eggs rich in yolk are characteristic of most chelicerates. Only mites, pseudoscorpions and viviparous scorpions produce small eggs showing evidence of a secondary reduction in yolk (Anderson, ; Schwager et al, ). The sister group of euchelicerates, pycnogonids, display total and equal cleavages that are irregular (Ungerer & Scholtz, ).…”

Section: Discussionmentioning

confidence: 99%

“…Classical studies in Xiphosura (horseshoe crabs) (reviewed in Anderson, ) and recent fluorescent injection studies in P. tepidariorum (Kanayama, Akiyama‐Oda, & Oda, ) show that early cleavages in these groups are superficial (i.e., without membrane formation between energids and in the centre of the egg). This superficial cleavage mode has been considered the ancestral type among chelicerates (reviewed in Anderson, ; Schwager et al, ). After the 16‐cell stage, at least in P. tepidariorum , cell proliferation takes place, leading to the formation of a contiguous blastoderm at stage 2.…”

Section: Discussionmentioning

confidence: 99%

“…Among the 14 recognized orders, Araneae (spiders) are the most studied chelicerates regarding evolutionary developmental biology (Evo‐Devo). The common house spider Parasteatoda tepidariorum (formerly Achaearanea tepidariorum ) is considered an excellent chelicerate model system for Evo‐Devo studies since several important techniques required for the analysis of gene expression and function (e.g., in situ hybridization, RNA interference) have been established in this species (Hilbrant, Damen, & McGregor, ; Schwager, Schönauer, Leite, Sharma, & McGregor, ).…”

Section: Introductionmentioning

confidence: 99%

“…Second, D. melanogaster is a long‐germ insect, where all segments are established almost simultaneously and the posterior ectodermal primordium invaginates early in development. In contrast, in short‐germ arthropods such as the spider P. tepidariorum , the posterior segments are generated by a secondary process from a segment addition zone (SAZ) (reviewed in Hilbrant et al, ; Schwager et al, ).…”

Section: Introductionmentioning

confidence: 99%

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Molecular control of gut formation in the spider Parasteatoda tepidariorum

Feitosa

Pechmann

Schwager

et al. 2017

Genesis

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The development of a digestive system is an essential feature of bilaterians. Studies of the molecular control of gut formation in arthropods have been studied in detail in the fruit fly Drosophila melanogaster. However, little is known in other arthropods, especially in noninsect arthropods. To better understand the evolution of arthropod alimentary system, we investigate the molecular control of gut development in the spider Parasteatoda tepidariorum (Pt), the primary chelicerate model species for developmental studies. Orthologs of the ectodermal genes Pt-wingless (Pt-wg) and Pt-hedgehog (Pt-hh), of the endodermal genes, Pt-serpent (Pt-srp) and Pt-hepatocyte-nuclear factor-4 (Pt-hnf4) and of the mesodermal gene Pt-twist (Pt-twi) are expressed in the same germ layers during spider gut development as in D. melanogaster. Thus, our expression data suggest that the downstream molecular components involved in gut development in arthropods are conserved. However, Pt-forkhead (Pt-fkh) expression and function in spiders is considerably different from its D. melanogaster ortholog. Pt-fkh is expressed before gastrulation in a cell population that gives rise to endodermal and mesodermal precursors, suggesting a possible role for this factor in specification of both germ layers. To test this hypothesis, we knocked down Pt-fkh via RNA interference. Pt-fkh RNAi embryos not only fail to develop a proper gut, but also lack the mesodermal Pt-twi expressing cells. Thus, in spiders Pt-fkh specifies endodermal and mesodermal germ layers. We discuss the implications of these findings for the evolution and development of gut formation in Ecdysozoans.

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Screwed up: Spirality of segments and other iterated structures suggest an underlying principle of seriality in bilaterians

Scholtz

2021

Journal of Morphology

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This review deals with helicomery, that is, the specific malformation of a spiral arrangement of segments and other serial structures. Helicomery was first described in annelid and arthropod body segments. However, corresponding patterns occur in arthropod appendages and other bilaterians with serially arranged body parts, such as tapeworms, nematodes, vertebrates, and probably chitons. The specifics of the spirals such as length, orientation, and handedness are described. Most spirals are dorsal and comprise only a few loops. Helicomery is formed by a shift of cells during development or in adults caused by changes in cell adhesion or mechanical impacts such as lesions. A model for the formation of helicomery is proposed, which is based on medieval church labyrinths. These complex spiral structures are derived from concentric lines by the shift of relatively few tiles. This principle of “small causes, great effect” also applies to “spiral segments,” because helicomery dissolves segmental patterns and questions the concept of segments as distinct structures. The widespread occurrence of helicomery in nonhomologous serial structures might indirectly indicate an underlying principle of seriality among Bilateria.

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Chelicerata

Cited by 32 publications

References 204 publications

The Wnt and Delta-Notch signalling pathways interact to direct pair-rule gene expression via caudal during segment addition in the spider Parasteatoda tepidariorum

The Wnt and Delta-Notch signalling pathways interact to direct pair-rule gene expression via caudal during segment addition in the spider Parasteatoda tepidariorum

Molecular control of gut formation in the spider Parasteatoda tepidariorum

Screwed up: Spirality of segments and other iterated structures suggest an underlying principle of seriality in bilaterians

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