Rosu Simona, Cohen-Fix Orna
The Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
Dev Biol. 2017 Mar 15;423(2):93-100. doi: 10.1016/j.ydbio.2017.02.008. Epub 2017 Feb 17.
The C. elegans adult hermaphrodite contains a renewable pool of mitotically dividing germ cells that are contained within the progenitor zone (PZ), at the distal region of the germline. From the PZ, cells enter meiosis and differentiate, ensuring the continued production of oocytes. In this study, we investigated the proliferation strategy used to maintain the PZ pool by using a photoconvertible marker to follow the fate of selected germ cells and their descendants in live worms. We found that the most distal pool of 6-8 rows of cells in the PZ (the distal third) behave similarly, with a fold expansion corresponding to one cell division every 6h on average. Proximal to this region, proliferation decreases, and by the proximal third of the PZ, most cells have stopped dividing. In addition, we show that all the descendants of cells in rows 3 and above move proximally and leave the PZ over time. Combining our data with previous studies, we propose a stochastic model for the C. elegans PZ proliferation, where a pool of proliferating stem cells divide symmetrically within the distal most 6-8 rows of the germline and exit from this stem cell niche occurs by displacement due to competition for limited space.
秀丽隐杆线虫成年雌雄同体在生殖系远端的祖细胞区（PZ）中含有一群可再生的有丝分裂生殖细胞。细胞从PZ进入减数分裂并分化，确保卵母细胞持续产生。在本研究中，我们通过使用光转化标记追踪活虫中选定生殖细胞及其后代的命运，研究了用于维持PZ库的增殖策略。我们发现，PZ中最远端的6 - 8排细胞（远端三分之一）表现相似，平均每6小时进行一次细胞分裂，细胞数量呈倍数增长。在该区域近端，增殖减少，到PZ近端三分之一时，大多数细胞已停止分裂。此外，我们表明第3排及以上细胞的所有后代会随着时间向近端移动并离开PZ。将我们的数据与之前的研究相结合，我们提出了一个秀丽隐杆线虫PZ增殖的随机模型，即一群增殖干细胞在生殖系最远端的6 - 8排内进行对称分裂，由于对有限空间的竞争，干细胞龛中的细胞通过位移而离开。
