RT Journal Article
SR Electronic
T1 Free-living human cells reconfigure their chromosomes in the evolution back to uni-cellularity
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 152223
DO 10.1101/152223
A1 Jin Xu
A1 Xinxin Peng
A1 Yuxin Chen
A1 Yuezheng Zhang
A1 Qin Ma
A1 Liang Liang
A1 Ava C. Carter
A1 Xuemei Lu
A1 Chung-I Wu
YR 2017
UL http://biorxiv.org/content/early/2017/06/19/152223.abstract
AB Cells of multi-cellular organisms evolve toward uni-cellularity in the form of cancer and, if humans intervene, continue to evolve in cell culture. During this process, gene dosage relationships may evolve in novel ways to cope with the new environment and may regress back to the ancestral unicellular state. In this context, the evolution of sex chromosomes vis-a-vis autosomes is of particular interest. Here, we report the chromosomal evolution in ~600 cancer cell lines. Many of them jettisoned either Y or the inactive X; thus, free-living male and female cells converge by becoming “de-sexualized”. Surprisingly, the active X often doubled, accompanied by the addition of one haploid complement of autosomes, leading to an X:A ratio of 2:3 from the extant ratio of 1:2. Theoretical modeling of the frequency distribution of X:A karyotypes suggests that the 2:3 ratio confers a higher fitness and may reflect aspects of sex chromosome evolution.