Are lampbrush chromosomes unique to meiotic cells?
Are lampbrush chromosomes unique to meiotic cells?
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DOI：
10.1007/s10577-012-9329-5
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发表时间：
2012-12-01
影响因子：
2.6
通讯作者：
Gall, Joseph G.
中科院分区：
文献类型：
--
作者：
Gall, Joseph G.
灯刷染色体(LBC)是在许多脊椎动物和无脊椎动物的大卵母细胞的生发泡(GV)中发现的转录活性染色体，也存在于巨大的单细胞藻类Acetumularia中。这些细胞都处于第一次减数分裂的前期。然而，许多减数分裂细胞不发育LBC，认为LBC不是减数分裂的基本特征。LBC可能代表了必须产生二倍体后代的细胞所能达到的最活跃的转录状态。多倍体允许细胞达到更高的每个核的转录速率，但排除了回到二倍体的可能性。在这个意义上，LBC代表了大型减数分裂细胞使用的一种相对低效的转录妥协。这些考虑有助于解释为什么转录活性的GV发展LBC，但它们不能解释为什么LBC从未在体细胞中出现，无论是二倍体还是其他。如果LBC真的仅限于生殖细胞，那么它们的一些不寻常的特征可能反映了基因组的重新编程。如果是这样的话，LBC提供了在单个转录单位水平上研究重新编程的独特机会。
Lampbrush chromosomes (LBCs) are transcriptionally active chromosomes found in the germinal vesicle (GV) of large oocytes of many vertebrate and invertebrate animals and also in the giant single-celled alga Acetabularia. These cells are all in prophase of the first meiotic division. Nevertheless, many meiotic cells do not develop LBCs, arguing that LBCs are not an essential feature of meiosis. LBCs probably represent the most active transcriptional state that can be attained by cells that must give rise to diploid progeny. Polyploidy permits cells to reach higher rates of transcription per nucleus but precludes a return to diploidy. In this sense, LBCs represent a relatively inefficient transcriptional compromise employed by large meiotic cells. These considerations help to explain why transcriptionally active GVs develop LBCs, but they do not explain why LBCs have never been seen in somatic cells, diploid or otherwise. If LBCs are truly limited to germ cells, then some of their unusual features may reflect reprogramming of the genome. If this is the case, LBCs provide unique opportunities to study reprogramming at the level of the individual transcription unit.