White-Cooper H, Alphey L, Glover D M
Department of Anatomy and Physiology, Medical Sciences Institute, University of Dundee, Scotland, UK.
J Cell Sci. 1993 Dec;106 ( Pt 4):1035-44. doi: 10.1242/jcs.106.4.1035.
The twineHB5 mutation prevents spindle formation during the entry into meiosis in Drosophila males, but chromosome condensation and nuclear envelope breakdown both still occur. This suggests the possibility that this particular cdc25 homologue is required to activate a p34cdc2 kinase required for only some of the events of this G2-M transition. In contrast, meiotic spindles do form in twineHB5 females, although these appear abnormal. However, the female meiotic divisions do not arrest at metaphase I as in wild type, but continue repeatedly, leading to gross non-disjunction. Small chromatin masses, corresponding in size to the fourth chromosomes, often segregate properly to the spindle poles. These can persist into the embryos derived from twineHB5 females, where they appear to participate in mitotic divisions on thin spindles. In addition, these embryos contain a small number of large chromatin masses that are not associated with spindles.
twineHB5突变会阻止果蝇雄性个体进入减数分裂时纺锤体的形成，但染色体浓缩和核膜破裂仍会发生。这表明这种特定的cdc25同源物可能是激活仅参与该G2-M转换某些事件所需的p34cdc2激酶所必需的。相比之下，twineHB5雌性个体中会形成减数分裂纺锤体，尽管这些纺锤体看起来不正常。然而，雌性减数分裂并不像野生型那样在中期I停滞，而是持续反复进行，导致严重的不分离。大小与第四条染色体相当的小染色质团块通常会正常分离到纺锤体两极。这些染色质团块可以持续存在于来自twineHB5雌性个体的胚胎中，在那里它们似乎参与了细纺锤体上的有丝分裂。此外，这些胚胎还含有少量与纺锤体无关的大染色质团块。
