Functional Analysis of Eye Development in the Grasshopper

Wayne State University, Detroit MI

Investigators

Abstract

0091926 Friedrich Studies of insect compound eye development have focussed in great detail on the model Drosophila melanogaster but very little is known about this process in other insect species. This is particularly notable as the eyes are formed during postembryogenesis from imaginal disc tissue in the holometabolous fruitfly Drosophila, whereas eye development initiates during early embryogenesis in most other animal species. Drosophila eye development thus represents an evolutionarily highly derived process associated with an advanced form of insect metamorphosis. The PI has begun to study eye development in the more primitive grasshopper Schistocerca americana, which represents a hemimetabolous species with embryonic eye development. Comparing Drosophila with Schistocerca makes it possible to reconstruct the ancestral patterning mechanisms of insect eye development and to identify molecular-developmental changes associated with the evolution of insect metamorphosis. This proposal specifically addresses the roles of the wingless, decapentaplegic and hedgehog genes in the grasshopper eye. In Drosophila, these signaling factors orchestrate the global patterning of the eye field in a multitasking manner. Gene expression pattern comparisons indicate that only some of the respective patterning functions are conserved while others are specific to either Drosophila or Schistocerca. The functional relevance of patterning gene expression in the grasshopper eye is being investigated by pharmacological and Sindbis virus mediated perturbation of gene activity in cultured embryos.