Nasonia segmentation is regulated by an ancestral insect segmentation regulatory network also present in flies

Abstract

Insect segmentation is a well-studied and tractable system with which to investigate the genetic regulation of development. Though insects segment their germband using a variety of methods, modelling work implies that a single gene regulatory network can underpin the two main types of insect segmentation. This means limited genetic changes are required to explain significant differences in segmentation mode between different insects. Evidence for this idea is limited to Drosophila melanogaster, Tribolium castaneum, and the spider Parasteatoda tepidariorum, and the nature of the gene regulatory network (GRN) underlying this model has not been tested. Some insects, for example Nasonia vitripennis and Apis mellifera segment progressively, a pattern not examined in studies of this segmentation model, producing stripes at different times throughout the embryo, but not from a segment addition zone. Here we aim to understand the GRNs patterning Nasonia using a simulation-based approach. We found that an existing model of Drosophila segmentation (Clark, 2017) can be used to recapitulate Nasonias progressive segmentation, if provided with altered inputs in the form of expression of the timer genes N{nu}-caudal and N{nu}-odd paired. We also predict limited topological changes to the pair rule network. Together this implies that very limited changes to the Drosophila network are required to simulate Nasonia segmentation, despite the differences in segmentation modes, implying that Nasonia use a very similar version of an ancestral GRN also used by Drosophila.