1. Transcriptional Regulation

The Drosophila transcription factor Defective proventriculus (Dve) is expressed in various types of cells including epidermis, midgut, imaginal discs (wing, leg, eye-antenna), and neuronal cells. The homeodomain (HD) of Dve is a K50-type and binds to the consensus sequence TAATCC.

2. Reproductive and Behavioral Biology

The Drosophila male accessory gland has functions similar to those of the mammalian prostate gland and the seminal vesicle, and secretes accessory gland proteins (Acps) into the seminal fluid. Each of the two lobes of the accessory gland is composed of two types of binucleated cells: about 1,000 main cells and 60 secondary cells. A well-known Acp, sex peptide, is secreted from main cells and induces female postmating response to increase progeny production.

The homeodomain transcriptional repressor Defective proventriculus (Dve) is strongly expressed in adult secondary cells, and its mutation resulted in loss of secondary cells, mononucleation of main cells, and reduced size of the accessory gland. dve mutant males had low fecundity despite the presence of sex peptide, and failed to induce the female postmating responses of increased egg laying and reduced sexual receptivity. RNAi-mediated dve knockdown males also had low fecundity with normally binucleated main cells. We showed that secondary cells are crucial for male fecundity, and also that Dve activity is required for survival of the secondary cells.

Dve-expressing cells in the brain are involved in male courtship behavior.

3. Nutritional and Metabolic Genetics

Nutrient conditions affect the reproductive potential and life span of many organisms through the insulin signaling pathway. Although this is well characterized in female oogenesis, nutrient-dependent regulation of fertility/fecundity in males is not known. Seminal fluid components synthesized in the accessory gland are required for high fecundity in Drosophila males. The accessory gland is composed of two types of binucleated cells: a main cell and a secondary cell (SC). The transcription factors Defective proventriculus (Dve) and Abdominal-B (Abd-B) are strongly expressed in adult SCs, whose functions are essential for male fecundity. We found that gene expression of both Dve and Abd-B was downregulated under nutrient-poor conditions. In addition, nutrient conditions during the pupal stage affected the size and number of SCs. These morphological changes clearly correlated with fecundity, suggesting that SCs act as nutrient sensors. Dve associates nutrient conditions with optimal reproductive potential in a target of rapamycin (TOR) signaling-dependent manner.

Contact

Hideki Nakagoshi

Graduate School of Natural Science and Technology

Okayama University

E-mail: goshi(at)cc.okayama-u.ac.jp (at) = @