科學家揭示基因組滲入的起源
作者:
小柯機器人發布時間:2020/11/14 23:31:33
法國蔚藍海岸大學Gianni Liti研究小組近日取得一項新成果。他們利用酵母揭示了基因組滲入現象的起源。相關論文在線發表在2020年11月11日出版的《自然》雜誌上。
在本研究中,研究人員確定了雜合酵母祖先的無性後代,後者形成了現存的釀酒酵母Alpechin亞群,該亞群攜帶豐富的奇異酵母滲入。研究表明,該克隆後代(以下定義為「活祖先」)保留了第一代雜合祖先的基因組結構,其包含釀酒酵母和奇異酵母的亞基因組。該雜合祖先通過一百多次有絲分裂重組產生了嚴重的基因組不穩定性,主要表現為由於雜合性喪失而產生的純合基因組。
這些純合序列通過恢復減數分裂重組而阻止了雜合物種的繁殖,並且是Alpechin譜系中基因滲入的直接起源。研究人員提出了物質在滅絕階段通過重建進行基因組滲入進化的可行途徑,並提出基因組不穩定性允許雜合物種克服生殖隔離並利於基因組滲入出現。
據悉,基因組滲入促進了動物、植物和真菌的進化。基因組滲入最先發生在古老的雜合物種中,然後反覆回交到一種親本物種。但是,目前尚不清楚在生殖隔離的物種(如酵母)中如何發生基因組滲入。
附:英文原文
Title: A yeast living ancestor reveals the origin of genomic introgressions
Author: Melania DAngiolo, Matteo De Chiara, Jia-Xing Yue, Agurtzane Irizar, Simon Stenberg, Karl Persson, Agns Llored, Benjamin Barr, Joseph Schacherer, Roberto Marangoni, Eric Gilson, Jonas Warringer, Gianni Liti
Issue&Volume: 2020-11-11
Abstract: Genome introgressions drive evolution across the animal1, plant2 and fungal3 kingdoms. Introgressions initiate from archaic admixtures followed by repeated backcrossing to one parental species. However, how introgressions arise in reproductively isolated species, such as yeast4, has remained unclear. Here we identify a clonal descendant of the ancestral yeast hybrid that founded the extant Saccharomyces cerevisiae Alpechin lineage5, which carries abundant Saccharomyces paradoxus introgressions. We show that this clonal descendant, hereafter defined as a 『living ancestor』, retained the ancestral genome structure of the first-generation hybrid with contiguous S. cerevisiae and S. paradoxus subgenomes. The ancestral first-generation hybrid underwent catastrophic genomic instability through more than a hundred mitotic recombination events, mainly manifesting as homozygous genome blocks generated by loss of heterozygosity. These homozygous sequence blocks rescue hybrid fertility by restoring meiotic recombination and are the direct origins of the introgressions present in the Alpechin lineage. We suggest a plausible route for introgression evolution through the reconstruction of extinct stages and propose that genome instability allows hybrids to overcome reproductive isolation and enables introgressions to emerge.
DOI: 10.1038/s41586-020-2889-1
Source: https://www.nature.com/articles/s41586-020-2889-1