Male meiotic spindle features that efficiently segregate paired and lagging chromosomes
Male meiotic spindle features that efficiently segregate paired and lagging chromosomes
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DOI：
10.7554/elife.50988
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发表时间：
2020-03-10
期刊：
影响因子：
7.7
通讯作者：
Mueller-Reichert, Thomas
中科院分区：
文献类型：
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作者：
Fabig, Gunar;Kiewisz, Robert;Mueller-Reichert, Thomas
雄性减数分裂过程中的染色体分离是为了快速产生大量精子而设计的。人们对有效分配染色体产生精子的机制知之甚少。通过对秀丽隐杆线虫精母细胞减数分裂纺锤体的实时成像和断层扫描重建，我们发现滞后X染色体是由于缺乏染色体配对而导致的，这是秀丽隐杆线虫雄性后期I的一个显着特征。未配对的染色体通过延长处于张力下的动粒微管而仍然与中心体相连，这表明“拉锯战”可靠地解决了滞后问题。我们发现精母细胞同时表现出极到染色体缩短（后期 A）和极到极伸长（后期 B）。电子断层扫描意外地揭示了精母细胞后期 A 不仅仅源于着丝粒微管缩短。相反，常染色体的运动很大程度上是由后期张力释放时染色体、微管和中心体之间的距离变化驱动的。总的来说，我们定义了分离滞后染色体和配对染色体的新颖特征，以实现最佳精子产生。
Chromosome segregation during male meiosis is tailored to rapidly generate multitudes of sperm. Little is known about mechanisms that efficiently partition chromosomes to produce sperm. Using live imaging and tomographic reconstructions of spermatocyte meiotic spindles in Caenorhabditis elegans, we find the lagging X chromosome, a distinctive feature of anaphase I in C. elegans males, is due to lack of chromosome pairing. The unpaired chromosome remains tethered to centrosomes by lengthening kinetochore microtubules, which are under tension, suggesting that a 'tug of war' reliably resolves lagging. We find spermatocytes exhibit simultaneous pole-to-chromosome shortening (anaphase A) and pole-to-pole elongation (anaphase B). Electron tomography unexpectedly revealed spermatocyte anaphase A does not stem solely from kinetochore microtubule shortening. Instead, movement of autosomes is largely driven by distance change between chromosomes, microtubules, and centrosomes upon tension release during anaphase. Overall, we define novel features that segregate both lagging and paired chromosomes for optimal sperm production.