Oocyte development has been studied as a model system for developmental cell biology. Researchers demonstrated that the body plan of fruit flies is established by localization of key polarity determinants within developing oocyte cells. These elements of development are messenger RNAs that localize very specific areas of the oocyte at particular developmental time points. These localization patterns enable spatial restriction of polarity determinant translation and induction of patterning responses. The most critical of these rely upon gurken (grk), a protein that specifies both the anterior-posterior and dorsal-ventral axes. Gurken is secreted from specific areas of the oocyte to activate an EGF receptor on the adjacent somatic follicle cells. This activates a RAS-MEK-MAP kinase relay that ultimately specifies patterning of the oocyte. Notably, nutrient-induced signaling cues have also been shown to activate RAS-MEK-MAP kinase responses. Because of the predicted overlap between Grk and nutritional signaling, it is hypothesized that axis determination in oogenesis is nutrient-sensitive. Therefore, nutrient supplementation was used to test for the ability to overcome Grk signaling defects induced by MAP kinase inhibition. The dietary treatments involved feeding D. melanogaster minimal nutrient food versus foods supplemented with sucrose, yeast, and a yeast/sucrose combination. Both yeast and sucrose conferred rescue of signaling inhibition, as measured by severity of dorsal appendage defects, and the effects appear additive. The data presented suggest that specific nutritional enhancements rescue Grk-associated developmental defects, and underscore the importance of nutrition in supporting embryogenesis.
