Vaginal candidiasis affects approximately 75% of all women. Hormone levels have been associated with an increased incidence of vaginal candidiasis, especially during pregnancy, and for individuals who use oral contraceptives or hormone replacement therapy. C. albicans is the etiological agent in over 80% of vaginal candidiasis cases, thus making the relationship between estrogen and C. albicans an important one to study. Research into the effect of estrogen on C. albicans has been limited and the signaling mechanisms involved are unknown. Because great variability exists in various estrogen response elements in mammalian genes and because of the differences between mammalian systems and yeast, it is unlikely that a genome database search will identify all of the estrogen response mechanisms at work in C. albicans. This proposal seeks to determine the cellular growth characteristics of C. albicans in the presence of estrogen, identify C. albicans genes responsive to estrogen and define estrogen-responsive promoter elements using molecular biology techniques. Upon completion of these studies, we will have significant new knowledge about the interaction between C. albicans and estrogen.