Department of Zoology, Faculty of Science, Charles University, Prague, Czech Republic.
Institute of Molecular Genetics, Czech Academy of Sciences, Prague, Czech Republic.
Nat Commun. 2023 Jul 29;14(1):4579. doi: 10.1038/s41467-023-40308-8.
The germline-restricted chromosome (GRC) of songbirds represents a taxonomically widespread example of programmed DNA elimination. Despite its apparent indispensability, we still know very little about the GRC's genetic composition, function, and evolutionary significance. Here we assemble the GRC in two closely related species, the common and thrush nightingale. In total we identify 192 genes across the two GRCs, with many of them present in multiple copies. Interestingly, the GRC appears to be under little selective pressure, with the genetic content differing dramatically between the two species and many GRC genes appearing to be pseudogenized fragments. Only one gene, cpeb1, has a complete coding region in all examined individuals of the two species and shows no copy number variation. The acquisition of this gene by the GRC corresponds with the earliest estimates of the GRC origin, making it a good candidate for the functional indispensability of the GRC in songbirds.
鸣禽的种系限制染色体 (GRC) 是一个在分类上广泛存在的程序化 DNA 消除的例子。尽管它显然是不可或缺的，但我们对 GRC 的遗传组成、功能和进化意义仍然知之甚少。在这里，我们在两个密切相关的物种，即普通歌鸲和欧亚鸲莺中组装了 GRC。我们总共在两个 GRC 中鉴定出 192 个基因，其中许多基因存在多个拷贝。有趣的是，GRC 似乎受到的选择压力很小，两个物种之间的遗传内容差异很大，许多 GRC 基因似乎是假基因化的片段。只有一个基因 cpeb1 在两个物种的所有被检查个体中都具有完整的编码区，并且没有拷贝数变异。这个基因的获得与 GRC 起源的最早估计相对应，这使其成为 GRC 在鸣禽中功能不可或缺的一个很好的候选基因。
