The establishment of the embryonic body plan during the development of many animals results from the asymmetric distribution of molecules or organelles in the egg. One particularly clear example is the specification of anterior development in Drosophila embryos. The messenger RNA of the bicoid gene is localized at the anterior margin of the egg during oogenesis; following fertilization the bicoid protein activates the expression of anterior-specific zygotic genes. Experiments in this proposal are directed toward learning how bicoid RNA is localized during oogenesis, including molecular associations of the RNA and the cellular mechanisms of localization. Proposed experiments include an investigation of molecular interactions that cause bicoid RNA to be associated with the cytoskeleton or other large organelles, particularly the involvement of microtubules in this process. The function of the swallow gene in bicoid RNA localization during oogenesis will be investigated in experiments to learn whether swallow protein is associated with bicoid RNA, and to identify functionally important parts of the swallow protein. A search of the group of maternal effect genes with early arrest phenotypes will be made for other genes whose products are involved in bicoid RNA localization. The time course of bicoid RNA localization will be monitored through the construction and expression of an inducible RNA that is localized via the bicoid pathway, allowing tests of the idea that bicoid RNA is transported to the oocyte by an active mechanism.
