Institute of Cytology and Genetics, Russian Academy of Sciences, Siberian Department, 630090 Novosibirsk, Russia.
Department of Cytology and Genetics, Novosibirsk State University, 630090 Novosibirsk, Russia.
Proc Natl Acad Sci U S A. 2019 Jun 11;116(24):11845-11850. doi: 10.1073/pnas.1817373116. Epub 2019 Apr 29.
An unusual supernumerary chromosome has been reported for two related avian species, the zebra and Bengalese finches. This large, germline-restricted chromosome (GRC) is eliminated from somatic cells and spermatids and transmitted via oocytes only. Its origin, distribution among avian lineages, and function were mostly unknown so far. Using immunolocalization of key meiotic proteins, we found that GRCs of varying size and genetic content are present in all 16 songbird species investigated and absent from germline genomes of all eight examined bird species from other avian orders. Results of fluorescent in situ hybridization of microdissected GRC probes and their sequencing indicate that GRCs show little homology between songbird species and contain a variety of repetitive elements and unique sequences with paralogs in the somatic genome. Our data suggest that the GRC evolved in the common ancestor of all songbirds and underwent significant changes in the extant descendant lineages.
已经报道了两种相关的鸟类，斑马雀和贝氏金丝雀，存在一条异常的额外染色体。这条大型的、限于生殖细胞的染色体（GRC）从体细胞和精细胞中被消除，并且仅通过卵母细胞传递。其起源、在鸟类谱系中的分布以及功能至今还大多未知。通过对关键减数分裂蛋白的免疫定位，我们发现，在所研究的 16 种鸣禽中存在大小和遗传内容不同的 GRC，而在来自其他鸟类目 8 种被检查的鸟类种的生殖系基因组中则不存在。微切割 GRC 探针的荧光原位杂交及其测序的结果表明，GRC 之间在鸣禽物种中显示出很少的同源性，并且含有各种重复元件和独特序列，这些序列在体细胞基因组中有同源基因。我们的数据表明，GRC 是在所有鸣禽的共同祖先中进化的，并在现存的后裔谱系中经历了重大变化。
