DYNAMIC CHANGES IN RAD51 DISTRIBUTION ON CHROMATIN DURING MEIOSIS IN MALE AND FEMALE VERTEBRATES
DYNAMIC CHANGES IN RAD51 DISTRIBUTION ON CHROMATIN DURING MEIOSIS IN MALE AND FEMALE VERTEBRATES
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DOI：
10.1007/bf00352222
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发表时间：
1995-10-01
期刊：
影响因子：
1.6
通讯作者：
WARD, DC
中科院分区：
文献类型：
--
作者：
ASHLEY, T;PLUG, AW;WARD, DC
用抗人RAD51蛋白的抗体检测了小鼠精母细胞、卵母细胞和鸡卵母细胞减数分裂过程中染色质上RadS1的分布。我们观察到RAD51在减数分裂过程中分布的动态变化：(1)在早期的细线虫核中，有多个明显随机分布的焦点，到纤毛虫晚期，这些焦点被组织成焦点的轨迹。(2)这些病灶持续存在于合子体内，但大多数病灶定位于RAD51阳性轴线上，与联会复合体的侧向成分相对应。当同源突触焦点来自同源轴时融合。RAD51作为同源基因接触点的分布和参与提示它们可能是早期重组结节的组成部分。(3)随着肥厚病的进展，病灶数量急剧减少；时间上的出现(小鼠)和轴上病灶(鸡)的物理和数字分布表明它们可能是晚期重组结节的一个组成部分。(4)在早期肥厚线虫中，X(小鼠精母细胞)或Z(鸡卵母细胞)染色体的单轴上存在大量既不配对也不重组的RadS1灶。(5)在小鼠精母细胞的晚期粗面，而不是卵母细胞中，RADS1信号在所有二价体的两端优先增强。作为精母细胞中的二价体，而不是卵母细胞中的二价体，在复丝分裂时开始去突触，它们通常在这些RAD51阳性的末端结合在一起。这些观察与染色体末端附近的重组率异常高的观察结果相平行，雄性真兽类动物的重组率非常高，而雌性真兽类哺乳动物则不是。(6)从终变期到中期I，RAD51蛋白被检测到是与波峰特异抗原(动点)定位的低强度荧光二重体，这表明RAD51至少作为相关物质的一个结构成分参与了姐妹着丝粒的凝聚力。最后，RAD51在减数分裂过程中的分布变化似乎不是物种特有的，而是减数分裂过程中固有的。
Antibodies against human Rad51 protein were used to examine the distribution of RadS1 on meiotic chromatin in mouse spermatocytes and oocytes as well as chicken oocytes during sequential stages of meiosis. We observed the following dynamic changes in distribution of Rad51 during meiosis: (1) in early leptotene nuclei there are multiple, apparently randomly distributed, foci that by late leptonema become organized into tracks of foci. (2) These foci persist into zygonema, but most foci are now localized on Rad51-positive axes that correspond to lateral elements of the synaptonemal complex. As homologs synapse foci from homologous axes fuse. The distribution and involvement of Rad51 foci as contact points between homologs suggest that they may be components to early recombination nodules. (3) As pachynema progresses the number of foci drops dramatically; the temporal occurrence (mice) and physical and numerical distribution of foci on axes (chickens) suggest that they may be a component of late recombination nodules. (4) In early pachynema there are numerous RadS1 foci on the single axis of the X (mouse spermatocytes) or the Z (chicken oocytes) chromosomes that neither pair, nor recombine. (5) In late pachynema in mouse spermatocytes, but not oocytes, the RadS1 signal is preferentially enhanced at both ends of all the bivalents. As bivalents in spermatocytes, but not oocytes, begin to desynapse at diplonema they are often held together at these Rad51-positive termini. These observations parallel observations that recombination rates are exceptionally high near chromosome ends in male but not female eutherian mammals. (6) From diakinesis through metaphase I, Rad51 protein is detected as low-intensity fluorescent doublets that localize with CREST-specific antigens (kinetochores), suggesting that Rad51 participates, at least as a structural component of the materials involved, in sister kinetochore cohesiveness. Finally, the changes in Rad51 distribution during meiosis do not appear to be species specific, but intrinsic to the meiotic process.