在用一種具有單染色體分辨率的CO-FISH方法所進(jìn)行的實(shí)驗(yàn)中,，Yukiko Yamashita 和 Swathi Yadlapalli發(fā)現(xiàn)，性染色體（而不是常染色體）的姐妹染色單體在果蠅雄性生殖細(xì)胞 (GSCs) 的非對(duì)稱細(xì)胞分裂過(guò)程中是被非隨機(jī)分離的。姐妹染色單體分離在GSC過(guò)度增殖過(guò)程中和在“去分化的”GSCs中被隨機(jī)化,。鑒于這些發(fā)現(xiàn)，作者提出：非隨機(jī)姐妹染色單體分離不大可能像以前人們所提出的那樣保護(hù)所謂的“不朽鏈”（immortal strand）,，以避免發(fā)生由復(fù)制誘導(dǎo)的突變,。(生物谷Bioon.com)

生物谷推薦英文摘要：

Nature          doi:10.1038/nature12106

Chromosome-specific nonrandom sister chromatid segregation during stem-cell division

Swathi Yadlapalli & Yukiko M.Yamashita

Adult stem cells undergo asymmetric cell division to self-renew and give rise to differentiated cells that comprise mature tissue. Sister chromatids may be distinguished and segregated nonrandomly in asymmetrically dividing stem cells, although the underlying mechanism and the purpose it may serve remain elusive. Here we develop the CO-FISH (chromosome orientation fluorescence in situ hybridization) technique with single-chromosome resolution and show that sister chromatids of X and Y chromosomes, but not autosomes, are segregated nonrandomly during asymmetric divisions of Drosophila male germline stem cells. This provides the first direct evidence, to our knowledge, that two sister chromatids containing identical genetic information can be distinguished and segregated nonrandomly during asymmetric stem-cell divisions. We further show that the centrosome, SUN–KASH nuclear envelope proteins and Dnmt2 (also known as Mt2) are required for nonrandom sister chromatid segregation. Our data indicate that the information on X and Y chromosomes that enables nonrandom segregation is primed during gametogenesis in the parents. Moreover, we show that sister chromatid segregation is randomized in germline stem cell overproliferation and dedifferentiated germline stem cells. We propose that nonrandom sister chromatid segregation may serve to transmit distinct information carried on two sister chromatids to the daughters of asymmetrically dividing stem cells.