Ohsako Takashi, Yamamoto Masa-Toshi
Drosophila Genetic Resource Center, Kyoto Institute of Technology, Kyoto 616-8354, Japan.
Genes Genet Syst. 2011;86(2):97-108. doi: 10.1266/ggs.86.97.
Females of many animal species store sperm after copulation for use in fertilization, but the mechanisms controlling sperm storage and utilization are largely unknown. Here we describe a novel male sterile mutation of Drosophila melanogaster, wasted (wst), which shows defects in various processes of sperm utilization. The sperm of wst mutant males are stored like those of wild-type males in the female sperm storage organs, the spermathecae and seminal receptacles, after copulation and are released at each ovulation. However, an average of thirteen times more wst sperm than wild type sperm are released at each ovulation, resulting in rapid loss of sperm stored in seminal receptacles within a few days after copulation. wst sperm can enter eggs efficiently at 5 hr after copulation, but the efficiency of sperm entry decreases significantly by 24 hr after copulation, suggesting that wst sperm lose their ability to enter eggs during storage. Furthermore, wst sperm fail to undergo nuclear decondensation, which prevents the process of fertilization even when sperm enter eggs. Our results indicate that the wst gene is essential for independent processes in the utilization of stored sperm; namely, regulation of sperm release from female storage organs, maintenance of sperm efficiency for entry into eggs, and formation of the male pronucleus in the egg at fertilization.
许多动物物种的雌性在交配后会储存精子以供受精使用，但控制精子储存和利用的机制在很大程度上尚不清楚。在这里，我们描述了一种新的黑腹果蝇雄性不育突变体，名为“浪费”（wst），它在精子利用的各个过程中都表现出缺陷。交配后，wst突变体雄性的精子与野生型雄性的精子一样，被储存在雌性的精子储存器官——受精囊和受精囊中，并在每次排卵时释放。然而，每次排卵时释放的wst精子平均比野生型精子多13倍，导致交配后几天内受精囊中储存的精子迅速流失。交配后5小时，wst精子能够有效地进入卵子，但交配后24小时，精子进入卵子的效率显著降低，这表明wst精子在储存过程中失去了进入卵子的能力。此外，wst精子无法进行核解聚，即使精子进入卵子，这也会阻止受精过程。我们的结果表明，wst基因对于储存精子利用的独立过程至关重要；即，调节精子从雌性储存器官的释放、维持精子进入卵子的效率以及受精时卵子中雄性原核的形成。
