Hunt P, LeMaire R, Embury P, Sheean L, Mroz K
Department of Genetics, Case Western Reserve University School of Medicine, Cleveland, OH 44106-4955, USA.
Hum Mol Genet. 1995 Nov;4(11):2007-12. doi: 10.1093/hmg/4.11.2007.
To monitor the behavior of specific chromosomes at various stages of mammalian female meiosis, we have combined immunofluorescence staining and fluorescence in situ hybridization (FISH) on intact oocytes. We have utilized this technique to evaluate the behavior of the single X chromosome in oocytes from XO female mice, providing the first observations on segregation of an achiasmate chromosome during mammalian female meiosis and its effect on the meiotic process. As has been described in other species, we found that the univalent chromosome could either segregate as an intact chromosome to one pole or divide equationally at the first meiotic division. Our results also indicate that the presence of a univalent chromosome causes severe meiotic disruption during mammalian meiosis, affecting the alignment and segregation of other chromosomes in the complement. Despite these meiotic abnormalities, the vast majority of oocytes from XO females were able to resume and successfully complete the first meiotic division. This is in contrast to previous studies of male mice with sex chromosome abnormalities where the presence of a univalent acts to arrest meiosis at metaphase of the first meiotic division. This sex-specific difference in the ability of a cell with a univalent chromosome to initiate anaphase suggests that cell cycle control differs between male and female meiosis and that monitoring of meiotic chromosome behavior is less efficient in the female. The combined use of immunofluorescence staining and FISH on intact oocytes has obvious application to the study of meiotic chromosome non-disjunction in the human female. Simultaneous study of the meiotic cell cycle, protein components of the meiotic apparatus, and chromosome-specific behaviors during mammalian female meiosis provides a new approach to defining age-related changes in the meiotic process that result in increased chromosome malsegregation.
为了监测特定染色体在哺乳动物雌性减数分裂各个阶段的行为，我们将免疫荧光染色与荧光原位杂交（FISH）技术结合应用于完整的卵母细胞。我们利用这项技术评估了XO雌性小鼠卵母细胞中单个X染色体的行为，首次观察到了无交叉染色体在哺乳动物雌性减数分裂过程中的分离情况及其对减数分裂过程的影响。正如在其他物种中所描述的那样，我们发现单价染色体在第一次减数分裂时既可以作为完整染色体分离到一极，也可以进行均等分裂。我们的结果还表明，单价染色体的存在会在哺乳动物减数分裂过程中导致严重的减数分裂紊乱，影响其他染色体在互补组中的排列和分离。尽管存在这些减数分裂异常情况，但XO雌性小鼠的绝大多数卵母细胞仍能够恢复并成功完成第一次减数分裂。这与之前对具有性染色体异常的雄性小鼠的研究形成了对比，在那些研究中，单价染色体的存在会使减数分裂在第一次减数分裂中期停滞。具有单价染色体的细胞启动后期的能力存在这种性别特异性差异，这表明雄性和雌性减数分裂过程中的细胞周期控制有所不同，并且雌性减数分裂染色体行为的监测效率较低。将免疫荧光染色和FISH技术结合应用于完整的卵母细胞，在研究人类女性减数分裂染色体不分离方面具有明显的应用价值。同时研究哺乳动物雌性减数分裂过程中的减数分裂细胞周期、减数分裂装置的蛋白质成分以及染色体特异性行为，为确定导致染色体错分增加的减数分裂过程中与年龄相关的变化提供了一种新方法。
