Cellular analyses of the mitotic region in the Caenorhabditis elegans adult germ line
Cellular analyses of the mitotic region in the Caenorhabditis elegans adult germ line
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DOI：
10.1091/mbc.e06-03-0170
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发表时间：
2006-07-01
影响因子：
3.3
通讯作者：
Kimble, Judith
中科院分区：
文献类型：
--
作者：
Crittenden, Sarah L.;Leonhard, Kimberly A.;Kimble, Judith
秀丽隐杆线虫生殖系提供了一个模型，用于理解来自干细胞小生境的信号传导如何以分化为代价促进持续的有丝分裂。在这里，我们报告的细胞分析，旨在确定生殖干细胞内的生殖细胞有丝分裂区的成年雌雄同体。我们的研究结果支持几个结论。首先，有丝分裂区域内的所有生殖细胞都在活跃地循环，如溴脱氧尿苷（BrdU）标记所示。第二，在有丝分裂区域的生殖细胞失去BrdU标记均匀，无论是移动标记的细胞进入减数分裂区域或稀释，可能是由于复制。在有丝分裂区未发现标记保留细胞。第三，末端细胞龛延伸的突起几乎包围了相邻的生殖细胞，这种现象很可能将最远端的生殖细胞锚在龛内。第四，生殖细胞有丝分裂的方向是不可复制的，即使是在生态位的直接范围内。我们认为，生殖细胞在有丝分裂区的最远行作为干细胞和更近端的生殖细胞走上分化的道路。我们还提出C.线虫成体生殖系干细胞通过接近小生境而不是通过程序化的不对称分裂来维持。
The Caenorhabditis elegans germ line provides a model for understanding how signaling from a stem cell niche promotes continued mitotic divisions at the expense of differentiation. Here we report cellular analyses designed to identify germline stem cells within the germline mitotic region of adult hermaphrodites. Our results support several conclusions. First, all germ cells within the mitotic region are actively cycling, as visualized by bromodeoxyuridine (BrdU) labeling. No quiescent cells were found. Second, germ cells in the mitotic region lose BrdU label uniformly, either by movement of labeled cells into the meiotic region or by dilution, probably due to replication. No label-retaining cells were found in the mitotic region. Third, the distal tip cell niche extends processes that nearly encircle adjacent germ cells, a phenomenon that is likely to anchor the distal-most germ cells within the niche. Fourth, germline mitoses are not oriented reproducibly, even within the immediate confines of the niche. We propose that germ cells in the distal-most rows of the mitotic region serve as stem cells and more proximal germ cells embark on the path to differentiation. We also propose that C. elegans adult germline stem cells are maintained by proximity to the niche rather than by programmed asymmetric divisions.