POWRE: Genetic Regulatory Shifts in Insect Evolution

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+Studies of insect embryogenesis have defined two major development types. Most insects display a short germ type of development in which a germ rudiment forms and additional segments are added sequentially. In contrast, long germ type insects form segments along the entire anterior-posterior axis virtually simultaneously. This behavior, thought to be derived, is due in part to an increased maternal contribution of materials and patterning information, and presumably offers the selective advantage of rapid early development. It has been suggested that regulatory changes occurred via a shift of some embryonic patterning mechanisms from zygotic to maternal regulation. In Drosophila, a long germ insect, several gene products are provided maternally and stored until required for specific functions. However, the extent to which these genes may be zygotically controlled in other insects is not known. The Drosophila gene ftz transcription factor 1 (ftz-f1) is maternally transcribed. The encoded protein is translated in the embryo and required for normal segmentation . In the short germ beetle, Tribolium castaneum, the ftz-f1 ortholog is expressed in embryonic pair-rule stripes. This apparent shift of ftz-f1 control from zygotic to maternal may provide a general paradigm for the regulatory changes which accompanied the evolution of long germ development. Alternatively, the regulatory change observed for ftz-f1 may be unique to this gene. Analysis of the Tribolium homologs of several other Drosophila zygotic lethal genes with maternal effects will provide the information necessary to distinguish between these possibilities. The research described in this POWRE proposal represents a new line of inquiry for Dr. Brown and will provide the opportunity to achieve a level of recognizable independence required for advancement to full Research Professor.