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Candidate gene screen for potential interaction partners and regulatory targets of the Hox gene labial in the spider Parasteatoda tepidariorum.

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.

SUBMITTER: Schomburg C

PROVIDER: S-EPMC7128011 | biostudies-literature | 2020 Mar

REPOSITORIES: biostudies-literature

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Candidate gene screen for potential interaction partners and regulatory targets of the Hox gene labial in the spider Parasteatoda tepidariorum.

Schomburg Christoph C Turetzek Natascha N Prpic Nikola-Michael NM

Development genes and evolution 20200208 2

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 me ...[more]

PMID: 32036446

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Project description:BackgroundTwo visual systems are present in most arthropod groups: median and lateral eyes. Most of our current knowledge about the developmental and molecular mechanisms involved in eye formation in arthropods comes from research in the model system Drosophila melanogaster. Here, a core set of retinal determination genes, namely, sine-oculis (so), eyes absent (eya), dachshund (dac), and the two pax6 orthologues eyeless (ey) and twin of eyeless (toy) govern early retinal development. By contrast, not much is known about the development of the up-to-eight eyes present in spiders. Therefore, we analyzed the embryonic expression of core retinal determination genes in the common house spider Parasteatoda tepidariorum.ResultsWe show that the anlagen of the median and lateral eyes in P. tepidariorum originate from different regions of the non-neurogenic ectoderm in the embryonic head. The median eyes are specified as two individual anlagen in an anterior median position in the developing head and subsequently move to their final position following extensive morphogenetic movements of the non-neurogenic ectoderm. The lateral eyes develop from a more lateral position. Intriguingly, they are specified as a unique field of cells that splits into the three individual lateral eyes during late embryonic development. Using gene expression analyses, we identified a unique combination of determination gene expression in the anlagen of the lateral and median eyes, respectively.ConclusionsThis study of retinal determination genes in the common house spider P. tepidariorum represents the first comprehensive analysis of the well-known retinal determination genes in arthropods outside insects. The development of the individual lateral eyes via the subdivision of one single eye primordium might be the vestige of a larger composite eye anlage, and thus supports the notion that the composite eye is the plesiomorphic state of the lateral eyes in arthropods. The molecular distinction of the two visual systems is similar to the one described for compound eyes and ocelli in Drosophila, suggesting that a unique core determination network for median and lateral eyes, respectively, might have been in place already in the last common ancestor of spiders and insects.

Dataset Information

Candidate gene screen for potential interaction partners and regulatory targets of the Hox gene labial in the spider Parasteatoda tepidariorum.

Publications

Candidate gene screen for potential interaction partners and regulatory targets of the Hox gene labial in the spider Parasteatoda tepidariorum.

Similar Datasets

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