Lin T Y, Viswanathan S, Wood C, Wilson P G, Wolf N, Fuller M T
Department of Developmental Biology, Stanford University School of Medicine, CA 94305, USA.
Development. 1996 Apr;122(4):1331-41. doi: 10.1242/dev.122.4.1331.
Wild-type function of four Drosophila genes, spermatocyte arrest, cannonball, always early and meiosis I arrest, is required both for cell-cycle progression through the G2/M transition of meiosis I in males and for onset of spermatid differentiation. In males mutant for any one of these meiotic arrest genes, mature primary spermatocytes with partially condensed chromosomes accumulate and postmeiotic cells are lacking. The arrest in cell-cycle progression occurs prior to degradation of cyclin A protein. The block in spermatogenesis in these mutants is not simply a secondary consequence of meiotic cell-cycle arrest, as spermatid differentiation proceeds in males mutant for the cell cycle activating phosphatase twine. Instead, the arrest of both meiosis and spermiogenesis suggests a control point that may serve to coordinate the male meiotic cell cycle with the spermatid differentiation program. The phenotype of the Drosophila meiotic arrest mutants is strikingly similar to the histopathological features of meiosis I maturation arrest infertility in human males, suggesting that the control point may be conserved from flies to man.
果蝇的四个基因，即精母细胞停滞基因（spermatocyte arrest）、炮弹基因（cannonball）、总是早期基因（always early）和减数分裂I停滞基因（meiosis I arrest）的野生型功能，对于雄性减数分裂I通过G2/M转换的细胞周期进程以及精子细胞分化的起始都是必需的。在这些减数分裂停滞基因中任何一个发生突变的雄性果蝇中，会积累具有部分浓缩染色体的成熟初级精母细胞，而缺乏减数分裂后的细胞。细胞周期进程的停滞发生在细胞周期蛋白A蛋白降解之前。这些突变体中精子发生的阻滞并非仅仅是减数分裂细胞周期停滞的次要后果，因为在细胞周期激活磷酸酶twine发生突变的雄性果蝇中精子细胞分化仍在进行。相反，减数分裂和精子发生的停滞表明存在一个控制点，该控制点可能用于协调雄性减数分裂细胞周期与精子细胞分化程序。果蝇减数分裂停滞突变体的表型与人类男性减数分裂I成熟停滞性不育的组织病理学特征惊人地相似，这表明从果蝇到人类，该控制点可能是保守的。
