Armakolas Athanasios, Klar Amar J S
Gene Regulation and Chromosome Biology Laboratory, Center for Cancer Research, National Cancer Institute at Frederick, Frederick, MD 21702-1201, USA.
Science. 2006 Feb 24;311(5764):1146-9. doi: 10.1126/science.1120519.
After chromosome replication, sister chromatid copies are generally thought to segregate randomly to daughter cells. However, sister chromatids differ in their DNA strands, with each chromatid inheriting one older strand that is paired to a newly synthesized strand. Genetic analysis with a homologous chromosome pair indicated nonrandom chromatid distribution in embryonic stem cells. Biased segregation pattern was also found in all 100 endoderm cells examined, but not in any of the 165 neuroectoderm cells. In contrast, the mesoderm, cardiomyocyte, and pancreatic cells exhibited a random mode of segregation. Strand distribution mechanisms regulated by cell type may have consequences for cellular differentiation and for evolving strategies for developmental mechanisms.
染色体复制后，一般认为姐妹染色单体拷贝会随机分离到子细胞中。然而，姐妹染色单体的DNA链存在差异，每个染色单体继承一条较旧的链，该链与新合成的链配对。对一对同源染色体进行的遗传分析表明，胚胎干细胞中染色单体的分布是非随机的。在所检测的所有100个内胚层细胞中也发现了偏向性分离模式，但在165个神经外胚层细胞中均未发现。相比之下，中胚层、心肌细胞和胰腺细胞表现出随机的分离模式。由细胞类型调控的链分布机制可能会对细胞分化以及发育机制的进化策略产生影响。
