The effects of thermal stress on embryonic development: from cellular defects to whole-organism survival. Brent L. Lockwood, Kristi L. Montooth. Department of Biology, Indiana University, Bloomington, IN.

   It is a widely held tenet in the field of developmental biology that embryos are canalized to develop normally despite environmental perturbation. However, in ectothermic organisms like Drosophila, changes in environmental temperature likely alter cellular processes, thus making development more challenging in thermally variable environments. Are ectothermic embryos actually vulnerable to thermal stress, and what cellular structures and developmental processes are most vulnerable? Here we investigate the effects of thermal stress on early stage embryos of Drosophila melanogaster by measuring whole-organism survival, the cellular structures that mediate this stress, and the mechanisms that may buffer this stress during development. We find that exposure of eggs to heat stress causes disruption of early mitotic events and a significant decrease in survival to adulthood. We also find that some genotypes are more tolerant to heat stress than others, suggesting that thermal tolerance in embryos has a genetic basis. We discuss our progress using confocal fluorescence microscopy to assess the effects of heat stress on cytoskeletal proteins that coordinate early development.