Meeting Abstract

46.5  Saturday, Jan. 5  Developmental evolution of insect metamorphosis: mimicking the temporal dynamics of visual system development in endopterygote insects by transient knock down of eye selector gene activity in the directly developing grasshopper Schistocerca americana FRIEDRICH, Markus*; DONG, Ying; Wayne State University, Detroit; UT Southwestern Medical Center, Dallas friedrichm@wayne.edu

The adult compound eye of directly developing insects like grasshopper is produced through continuous differentiation initiated in the embryo persisting through juvenile development. The compound eye of endopterygote insects like Drosophila, on the other hand, forms exclusively during postembryogenesis, while the embryonic phase generates specialized larval eyes. We have begun to investigate the evolutionary transformation of insect visual system development by studying eye development in the grasshopper species Schistocerca americana. Taking advantage of systemic RNAi mediated gene knockdown in grasshopper nymphs, we imitated the temporal dynamics of Drosophila eye selector gene expression in the grasshopper by transiently silencing the orthologs of eyes absent (eya) and sine oculis (so) during juvenile development. Both regimens induced long-term but transient arrest of postembryonic eye development thereby mirroring the long intermission between the development of larval and adult eyes in holometabolous insects. These data unravel an inherent capacity of the eye developmental gene network in primitive insects to partition visual system development into life cycle stage restricted phases. We further propose that this developmental potential is tied to the existence of a retinal stem cell population in the anterior margin of the postembryonic eye in directly developing insects. The lesser studied grasshopper is uniquely suited to study the significance of stem cells and selector genes during the evolution of endoperygote development.