JH regulation of gene expression in the ovaries: implication of the apterous gene of Drosophila melanogaster. E.B. Dubrovsky , V.A Dubrovskaya , E.M. Berger. Department of Biology, Dartmouth College, Hanover, NH 03755.
Juvenile hormone (JH) is an important regulator of reproductive maturation in insects. In Drosophila females JH is known to be involved in the yolk protein production and trafficking within a growing oocyte. By utilizing Differential Display technique, we previously identified a group of five JH-inducible (JhI) genes, whose expression is highly up-regulated in S2 cultured cells upon methoprene treatment and whose developmental profiles are consistent with JH regulation in vivo. Importantly, all JhI genes show the sex-specific distribution of RNA appearing in adults, e.g. for the three genes - JhI-1, JhI-21 and minidiscs (mnd) - high levels of expression were found only in females. Corresponding transcripts begin to accumulate at the time of eclosion and localize primarily in the ovary and later in the mature egg. During embryonic development, transcripts from JhI-1, JhI-21 and mnd persist for the first 3-4 hours and then decline. Mutations at the apterous gene show several distinct phenotypes, among which some are caused by a JH deficiency - arrested vitellogenesis and aberrant sexual behavior. We found that expression of female-specific JhI genes is altered in a loss-of-function ap4 mutant. Thus, the current thinking, that the JH signal during oogenesis is exclusively involved in the production and localization of nutrients in the egg must now be expended.