Courret Cécile, Hemmer Lucas W, Wei Xiaolu, Patel Prachi D, Chabot Bryce J, Fuda Nicholas J, Geng Xuewen, Chang Ching-Ho, Mellone Barbara G, Larracuente Amanda M
Department of Biology, University of Rochester, Rochester, New York, United States of America.
Department of Molecular and Cell Biology, University of Connecticut, Storrs, Connecticut, United States of America.
PLoS Biol. 2024 Nov 21;22(11):e3002911. doi: 10.1371/journal.pbio.3002911. eCollection 2024 Nov.
Centromeres reside in rapidly evolving, repeat-rich genomic regions, despite their essential function in chromosome segregation. Across organisms, centromeres are rich in selfish genetic elements such as transposable elements and satellite DNAs that can bias their transmission through meiosis. However, these elements still need to cooperate at some level and contribute to, or avoid interfering with, centromere function. To gain insight into the balance between conflict and cooperation at centromeric DNA, we take advantage of the close evolutionary relationships within the Drosophila simulans clade-D. simulans, D. sechellia, and D. mauritiana-and their relative, D. melanogaster. Using chromatin profiling combined with high-resolution fluorescence in situ hybridization on stretched chromatin fibers, we characterize all centromeres across these species. We discovered dramatic centromere reorganization involving recurrent shifts between retroelements and satellite DNAs over short evolutionary timescales. We also reveal the recent origin (<240 Kya) of telocentric chromosomes in D. sechellia, where the X and fourth centromeres now sit on telomere-specific retroelements. Finally, the Y chromosome centromeres, which are the only chromosomes that do not experience female meiosis, do not show dynamic cycling between satDNA and TEs. The patterns of rapid centromere turnover in these species are consistent with genetic conflicts in the female germline and have implications for centromeric DNA function and karyotype evolution. Regardless of the evolutionary forces driving this turnover, the rapid reorganization of centromeric sequences over short evolutionary timescales highlights their potential as hotspots for evolutionary innovation.
尽管着丝粒在染色体分离中具有重要功能,但它们位于快速进化、富含重复序列的基因组区域。在所有生物中,着丝粒富含自私遗传元件,如转座元件和卫星DNA,这些元件会影响它们在减数分裂中的传递。然而,这些元件仍需要在某种程度上进行协作,以促进或避免干扰着丝粒功能。为了深入了解着丝粒DNA中冲突与合作之间的平衡,我们利用了拟暗果蝇分支(包括拟暗果蝇、塞舌尔果蝇和毛里求斯果蝇)及其近缘种黑腹果蝇之间密切的进化关系。通过结合染色质分析和在拉伸染色质纤维上进行的高分辨率荧光原位杂交,我们对这些物种的所有着丝粒进行了表征。我们发现了显著的着丝粒重组,涉及在短时间进化尺度上逆转录元件和卫星DNA之间的反复转换。我们还揭示了塞舌尔果蝇中近着丝粒染色体的起源(<24万年),其X染色体和第四条染色体的着丝粒现在位于端粒特异性逆转录元件上。最后,Y染色体着丝粒是唯一不经历雌性减数分裂的染色体,在卫星DNA和转座元件之间没有显示出动态循环。这些物种中着丝粒的快速更替模式与雌性生殖系中的遗传冲突一致,对着丝粒DNA功能和核型进化具有重要意义。无论驱动这种更替的进化力量是什么,着丝粒序列在短时间进化尺度上的快速重组突出了它们作为进化创新热点的潜力。