Molecular basis of development control mediated by Ilp8 in Hermetia illucens and Drosophila melanogaster

Abstract

Tissue development must be extremely refined and controlled, to ensure the characteristic proportions of the species in the adult stage. In the order Diptera, one of the mechanisms that regulate the larval development is the metamorphosis delay when lavae face tissue damage. Studies using Drosophila melanogaster demonstrated that the protein Ilp8 is involved in this control since, in high concentrations, it slows the pupation and provides additional time for the recovery of the damaged tissue or uncoordinated growth. Despite its importance, little is known about the evolution of the Ilp8 gene among dipterans and its involvement in the metamorphosis delay, a mechanism observed since basal dipterans. Preliminary analysis using sequences of different species indicate the Ilp8 as an innovation of the Brachycera group, but its role in the delay of metamorphosis was only characterized in D. melanogaster. To understand how this regulatory mechanism evolved, it is necessary to investigate when the increased expression of Ilp8 gene became associated with metamorphosis. Hence, functional studies using the Ilp8 orthologs are essential to understand this mechanism. Using sequences from different species, it will be possible to express the heterologous gene in D. melanogaster larvae and test if the metamorphosis is delayed in the modified organisms. We expect that this approach will shed light into to the evolution of the control of tissue development by elucidating which Ilp8 orthologs are involved in this mechanism.