Heterochromatic Threads Connect Oscillating Chromosomes during Prometaphase I in Drosophila Oocytes
Heterochromatic Threads Connect Oscillating Chromosomes during Prometaphase I in Drosophila Oocytes
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DOI：
10.1371/journal.pgen.1000348
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发表时间：
2009-01-01
期刊：
影响因子：
4.5
通讯作者：
Hawley, R. Scott
中科院分区：
文献类型：
--
作者：
Hughes, Stacie E.;Gilliland, William D.;Hawley, R. Scott
在果蝇的卵母细胞中，在减数分裂I中，通过一个称为非同系体同源分离的过程，非同系体同源物忠实地分离到相反的两极。我们观察到，在减数分裂中期，非交配同源物在纺锤体上表现出动态运动。对活的早中期卵母细胞的分析表明，最初位于相反半纺锤体上的不重合X染色体的重新结合和最初位于同一半纺锤体上的两条X染色体的相反极分离。当两条不对称X染色体位于纺锤体的对半部分时，它们的着丝点表现出适当的共取向。然而，当两个x位于相同的半纺锤体上时，它们的着丝点似乎指向相同的方向。因此，非合染色体的前中期运动是一个类似大会的过程，在这个过程中，两个同源物经历分离和重新连接事件，导致着丝点共取向的丧失或建立。在这一动态染色体运动期间，非同染色体同源物通过异色线连接起来，这些异色线相对于发育纺锤体的长度可以跨越很远的距离。此外，乘客复合体蛋白Incenp和Aurora B似乎定位于这些异色线。我们认为，这些丝线有助于同源物的重新连接，以及在中期停止之前，迁移的非同染色体同源物聚集回主染色体团块。
In Drosophila oocytes achiasmate homologs are faithfully segregated to opposite poles at meiosis I via a process referred to as achiasmate homologous segregation. We observed that achiasmate homologs display dynamic movements on the meiotic spindle during mid-prometaphase. An analysis of living prometaphase oocytes revealed both the rejoining of achiasmate X chromosomes initially located on opposite half-spindles and the separation toward opposite poles of two X chromosomes that were initially located on the same half spindle. When the two achiasmate X chromosomes were positioned on opposite halves of the spindle their kinetochores appeared to display proper co-orientation. However, when both Xs were located on the same half spindle their kinetochores appeared to be oriented in the same direction. Thus, the prometaphase movement of achiasmate chromosomes is a congression-like process in which the two homologs undergo both separation and rejoining events that result in the either loss or establishment of proper kinetochore co-orientation. During this period of dynamic chromosome movement, the achiasmate homologs were connected by heterochromatic threads that can span large distances relative to the length of the developing spindle. Additionally, the passenger complex proteins Incenp and Aurora B appeared to localize to these heterochromatic threads. We propose that these threads assist in the rejoining of homologs and the congression of the migrating achiasmate homologs back to the main chromosomal mass prior to metaphase arrest.