Sex peptide and the sperm effect in Drosophila melanogaster
- Department of Genome Sciences, University of Washington, Box 357730, Seattle, WA 98195-7730
On mating, Drosophila females undergo dramatic alterations in their reproductive physiology and behavior (Fig. 1) (1). Egg production and egg laying are significantly increased, and the female's propensity to remate is drastically reduced. These changes in the female have been shown to be initially induced by seminal fluids transferred from the male to the female during mating and to persist because of the presence of stored sperm in the female (referred to as the “sperm effect”). The male seminal fluid proteins are synthesized in paired secretory organs of the male reproductive tract called accessory glands, the products of which are referred to as accessory gland proteins (Acps). Acps have been studied because of their importance for reproduction as well as their interesting evolutionary dynamics. Two articles in this issue of PNAS provide additional insights into Acp function and the sperm effect by characterizing a null mutant (2) and RNA interference knockdowns (3) for one of the most interesting Acps, the Sex Peptide (SP) [Acp70A (4)].
Image of Drosophila mating. The female decreases her remating rate and increases her egg-laying rate after mating due, in part, to the transfer of SP from the male to the female. (Photograph courtesy of Avis C. James and Gary Wolsieffer.)
Mating-induced changes in female Drosophila have been described as occurring in two phases, short- and long-term stages. The short-term effect is attributed largely to the rapid action of several Acps, some acting before and during the storage of sperm. Through the use of males lacking Acps, sperm, or both, it was determined that the actions of Acps on their own last no longer than 1 day after mating (5, 6). The functions of the Acps have been studied by several methods, the two most robust using genetics to either ectopically express the Acp …
