Duplication and expression of Sox genes in spiders

Christian L Bonatto Paese,Steven Russell,Alistair P Mcgregor,Anna Schönauer,Daniel J Leite

doi:10.1186/s12862-018-1337-4

Christian L Bonatto Paese, Steven Russell + Show 3 more

Open Access

https://doi.org/10.1186/s12862-018-1337-4

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Abstract

BackgroundThe Sox family of transcription factors is an important part of the genetic ‘toolbox’ of all metazoans examined to date and is known to play important developmental roles in vertebrates and insects. However, outside the commonly studied Drosophila model little is known about the repertoire of Sox family transcription factors in other arthropod species. Here we characterise the Sox family in two chelicerate species, the spiders Parasteatoda tepidariorum and Stegodyphus mimosarum, which have experienced a whole genome duplication (WGD) in their evolutionary history.ResultsWe find that virtually all of the duplicate Sox genes have been retained in these spiders after the WGD. Analysis of the expression of Sox genes in P. tepidariorum embryos suggests that it is likely that some of these genes have neofunctionalised after duplication. Our expression analysis also strengthens the view that an orthologue of vertebrate Group B1 genes, SoxNeuro, is implicated in the earliest events of CNS specification in both vertebrates and invertebrates. In addition, a gene in the Dichaete/Sox21b class is dynamically expressed in the spider segment addition zone, suggestive of an ancient regulatory mechanism controlling arthropod segmentation as recently suggested for flies and beetles. Together with the recent analysis of Sox gene expression in the embryos of other arthropods, our findings support the idea of conserved functions for some of these genes, including a potential role for SoxC and SoxD genes in CNS development and SoxF in limb development.ConclusionsOur study provides a new chelicerate perspective to understanding the evolution and function of Sox genes and how the retention of duplicates of such important tool-box genes after WGD has contributed to different aspects of spider embryogenesis. Future characterisation of the function of these genes in spiders will help us to better understand the evolution of the regulation of important developmental processes in arthropods and other metazoans including neurogenesis and segmentation.

Highlights

The evolution of metazoan life forms was in part driven by the acquisition of novel families of transcription factors and signalling molecules that were subsequently expanded by gene duplications and evolved new functions [1, 2]
In the case of S. mimosarum we identified 14 genomic regions, 11 of which correspond to annotated Sox genes
The only tentative example of retained synteny within a species was in the SoxF group, where we found that the two SoxF genes of P. tepidariorum have an upstream flanking sequence with homology to a transposable element (TE) with matching transcriptional orientation

Summary

Introduction

The evolution of metazoan life forms was in part driven by the acquisition of novel families of transcription factors and signalling molecules that were subsequently expanded by gene duplications and evolved new functions [1, 2]. One such family, encoded by Sox genes, encompasses a set of conserved metazoan specific transcriptional regulators that play critical roles in a range of important developmental processes, in particular, aspects of stem cell biology and nervous system development [3,4,5]. We characterise the Sox family in two chelicerate species, the spiders Parasteatoda tepidariorum and Stegodyphus mimosarum, which have experienced a whole genome duplication (WGD) in their evolutionary history

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