Courtot C, Fankhauser C, Simanis V, Lehner C F
Friedrich-Miescher-Laboratorium, Max-Planck-Gesellschaft, Tübingen, FRG.
Development. 1992 Oct;116(2):405-16. doi: 10.1242/dev.116.2.405.
We have identified a second cdc25 homolog in Drosophila. In contrast to string (the first homolog identified in Drosophila) this second homolog, twine, does not function in the mitotic cell cycle, but is specialized for meiosis. Expression of twine was observed exclusively in male and female gonads. twine transcripts are present in germ cells during meiosis, and appear only late during gametogenesis, well after the end of the mitotic germ cell divisions. The sterile Drosophila mutant, mat(2)synHB5, which had previously been isolated and mapped to the same genomic region as twine (35F), was found to carry a missense mutation in the twine gene. This missense mutation in twine abolished its ability to complement a mutation in Schizosaccharomyces pombe cdc25. Phenotypic analysis of mat(2)synHB5 mutant flies revealed a complete block of meiosis in males and severe meiotic defects in females.
我们在果蝇中鉴定出了第二个cdc25同源物。与string（在果蝇中鉴定出的第一个同源物）不同，这个第二个同源物twine不在有丝分裂细胞周期中发挥作用，而是专门用于减数分裂。仅在雄性和雌性性腺中观察到twine的表达。twine转录本在减数分裂期间存在于生殖细胞中，并且仅在配子发生后期出现，即在有丝分裂生殖细胞分裂结束后很久。之前已分离出不育果蝇突变体mat(2)synHB5，并将其定位到与twine相同的基因组区域（35F），发现该突变体在twine基因中携带一个错义突变。twine中的这个错义突变消除了其互补粟酒裂殖酵母cdc25突变的能力。mat(2)synHB5突变果蝇的表型分析显示，雄性减数分裂完全受阻，雌性减数分裂存在严重缺陷。
