Origin and chromatin remodeling of young X/Y sex chromosomes in catfish with sexual plasticity

作者：Gaorui Gong, Yang Xiong, Shijun Xiao, Xi‐Yin Li, Peipei Huang, Qian Liao, Qingqing Han, Qiaohong Lin, Cheng Dan, Li Zhou, Fan Ren, Qi Zhou, Jian‐Fang Gui, Jie Mei · 发表于：National Science Review · 年份：2022 · DOI：10.1093/nsr/nwac239 · 被引用次数：55 · 研究领域：Genetic and Clinical Aspects of Sex Determination and Chromosomal Abnormalities、Chromosomal and Genetic Variations、Animal Genetics and Reproduction

ABSTRACT Assembly of a complete Y chromosome is a significant challenge in animals with an XX/XY sex-determination system. Recently, we created YY-supermale yellow catfish by crossing XY males with sex-reversed XY females, providing a valuable model for Y-chromosome assembly and evolution. Here, we assembled highly homomorphic Y and X chromosomes by sequencing genomes of the YY supermale and XX female in yellow catfish, revealing their nucleotide divergences with only less than 1% and with the same gene compositions. The sex-determining region (SDR) was identified to locate within a physical distance of 0.3 Mb by FST scanning. Strikingly, the incipient sex chromosomes were revealed to originate via autosome–autosome fusion and were characterized by a highly rearranged region with an SDR downstream of the fusion site. We found that the Y chromosome was at a very early stage of differentiation, as no clear evidence of evolutionary strata and classical structure features of recombination suppression for a rather late stage of Y-chromosome evolution were observed. Significantly, a number of sex-antagonistic mutations and the accumulation of repetitive elements were discovered in the SDR, which might be the main driver of the initial establishment of recombination suppression between young X and Y chromosomes. Moreover, distinct three-dimensional chromatin organizations of the Y and X chromosomes were identified in the YY supermales and XX females, as the X chromosome exhibited de...