Embryonic development and staging of the cobweb spider Parasteatoda tepidariorum C. L. Koch, 1841 (syn.: Achaearanea tepidariorum; Araneomorphae; Theridiidae)

Mittmann, Beate; Wolff, Carsten

doi:10.1007/s00427-012-0401-0

Cited by 111 publications

(143 citation statements)

References 53 publications

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“…One of these genes, that we denote as lab-1, is expressed in the early embryo (starting at stage 4; staging after [14]) in a circumferential ring along the rim of the germ disc (figure 1a), which becomes broader during stage 5 (figure 1b).…”

Section: Resultsmentioning

confidence: 99%

Regressive evolution of the arthropod tritocerebral segment linked to functional divergence of the Hox genelabial

et al. 2015

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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 a way to avoid adverse pleiotropic effects normally associated with mutations in developmental genes, and may thus be a common mechanism to accelerate regressive evolution.

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Section: Resultsmentioning

confidence: 99%

Regressive evolution of the arthropod tritocerebral segment linked to functional divergence of the Hox genelabial

et al. 2015

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“…Thus, using the example of a specimen presented extensively in this paper, a 4 th instar that undergoes apolysis, considered as a whole, remains a 4 th instar throughout proecdysis, and the pharate 5 th instar constitutes only a part (albeit the predominant part) of this proecdysial 4 th instar. As proposed by Downes (1987), and adopted by others (e.g., Townley and Tillinghast 2009, Wolff and Hilbrant 2011, Hilbrant et al 2012, Mittmann and Wolff 2012, when an embryo hatches, the postembryo is released, and ecdysis in the postembryo, including the discarding of its exuvium (shed exoskeleton), produces the 1 st instar and marks the start of the 1 st stadium. The molt between the postembryonic stage and 1 st stadium is taken to be the 1 st molt (Downes 1987).…”

Section: Terminologymentioning

confidence: 99%

Comparative study of spinning field development in two species of araneophagic spiders (Araneae, Mimetidae, Australomimetus)

Townley¹,

Harms²

2017

EvolSyst

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External studies of spider spinning fields allow us to make inferences about internal silk gland biology, including what happens to silk glands when the spider molts. Such studies often focus on adults, but juveniles can provide additional insight on spinning apparatus development and character polarity. Here we document and describe spinning fields at all stadia in two species of pirate spider (Mimetidae: Australomimetus spinosus, A. djuka). Pirate spiders nest within the ecribellate orb-building spiders (Araneoidea), but are vagrant, araneophagic members that do not build prey-capture webs. Correspondingly, they lack aggregate and flagelliform silk glands (AG, FL), specialized for forming prey-capture lines in araneoid orb webs. However, occasional possible vestiges of an AG or FL spigot, as observed in one juvenile A. spinosus specimen, are consistent with secondary loss of AG and FL. By comparing spigots from one stadium to tartipores from the next stadium, silk glands can be divided into those that are tartipore-accommodated (T-A), and thus functional during proecdysis, and those that are not (non-T-A). Though evidence was more extensive in A. spinosus, it was likely true for both species that the number of non-T-A piriform silk glands (PI) was constant (two pairs) through all stadia, while numbers of T-A PI rose incrementally. The two species differed in that A. spinosus had T-A minor ampullate and aciniform silk glands (MiA, AC) that were absent in A. djuka. First instars of A. djuka, however, appeared to retain vestiges of T-A MiA spigots, consistent with a plesiomorphic state in which T-A MiA (called secondary MiA) are present. T-A AC have not previously been observed in Australomimetus and the arrangement of their spigots on posterior lateral spinnerets was unlike that seen thus far in other mimetid genera. Though new AC and T-A PI apparently form throughout much of a spider's ontogeny, recurring spigot/tartipore arrangements indicated that AC and PI, after functioning during one stadium, were used again in each subsequent stadium (if non-T-A) or in alternate subsequent stadia (if T-A). In A. spinosus, sexual and geographic dimorphisms involving AC were noted. Cylindrical silk gland (CY) spigots were observed in mid-to-late juvenile, as well as adult, females of both species. Their use in juveniles, however, should not be assumed and only adult CY spigots had wide openings typical of mimetids. Neither species exhibited two pairs of modified PI spigots present in some adult male mimetids.

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“…The spider culture was kept at 25°C and embryos of stages 5 to 9 fixed as described in Akiyama- Oda and Oda (2003). Embryos were staged according to Mittmann and Wolff (2012). Note that these stages were chosen for this study because the SAZ develops from the caudal lobe, which is formed during stages 5 and 6.…”

Section: Embryo Collection Fixation and Stagingmentioning

confidence: 99%

“…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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Embryonic development and staging of the cobweb spider Parasteatoda tepidariorum C. L. Koch, 1841 (syn.: Achaearanea tepidariorum; Araneomorphae; Theridiidae)

Cited by 111 publications

References 53 publications

Regressive evolution of the arthropod tritocerebral segment linked to functional divergence of the Hox genelabial

Regressive evolution of the arthropod tritocerebral segment linked to functional divergence of the Hox genelabial

Comparative study of spinning field development in two species of araneophagic spiders (Araneae, Mimetidae, Australomimetus)

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

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