Expression of allatostatin in the oviducts of the cockroach Diploptera punctata.

The cockroach allatostatins (Y/FXFGL/Ia ASTs) are a ubiquitous family of peptides in the invertebrates. They affect numerous physiological processes including the inhibition of juvenile hormone III (JH) biosynthesis, inhibition of muscle contraction, inhibition of ovarian ecdysteroid biosynthesis and inhibition of vitellogenin (Vg) release from the fat body. We have developed and optimized a sensitive and specific quantitative competitive reverse transcriptase polymerase chain reaction (QC-RT-PCR) method to quantify Diploptera punctata AST (Dippu-AST) expression. Using this technique we show that tissues of both lateral and common oviducts and the ovary express message for Dippu-AST. Moreover, the pattern of expression observed in the oviducts and ovary is strikingly similar with significant changes occurring during the reproductive cycle. Specifically, expression of AST is drastically reduced during the time of maximal vitellogenin (Vg) uptake, with higher levels measured prior to and following vitellogenesis. Furthermore, using immunocytochemistry, we have shown Dippu-AST-like-immunoreactivity in the terminal abdominal ganglion, as well as in ventral nerve 7, some branches of which innervate the common and lateral oviducts with other branches innervating the bursa copulatrix and brood sac of mated female D. punctata. The pattern of Dippu-AST expression and immunocytochemical staining suggests that ASTs function, in part, to regulate the cycle of vitellogenesis in mated female D. punctata.