Suka N, Shinohara Y, Saitoh Y, Saitoh H, Ohtomo K, Harata M, Shpigelman E, Mizuno S
Department of Applied Biological Science, Faculty of Agriculture, Tohoku University, Sendai, Japan.
Genetica. 1993;88(2-3):93-105. doi: 10.1007/BF02424466.
About 65% of DNA in the chicken W chromosome has been shown to consist of XhoI and EcoRI family repetitive sequences. These sequences showed remarkable delay in the electrophoretic mobility at low temperature on a polyacrylamide gel. Three dimensional structures of the 0.7-kb XhoI and the 1.2-kb EcoRI family repeating units were estimated to be irregular solenoids using a computer program based on wedge angles of all the 16 dinucleotide steps. Fluorescence in situ hybridization demonstrated that these two family sequences were localized in a major heterochromatic body in an interphase nucleus. Incorporation of bromodeoxyuridine into the W chromosome in the synchronous culture of MSB-1 cells occurred about 1 h later than the peak of S phase. The chromatin structure formed along XhoI and EcoRI family sequences was suggested to be different from the total chromatin or chromatin containing the beta-actin gene sequence in that the linker DNA lengths of the former were significantly longer. Fractionation of the HaeIII-digested MSB-1 nuclei yielded a chromatin fraction in which XhoI family sequences were partially enriched. Several DNA-binding proteins showing higher affinity for the XhoI family sequence were present in this fraction.
鸡W染色体中约65%的DNA已被证明由XhoI和EcoRI家族重复序列组成。这些序列在低温下于聚丙烯酰胺凝胶上的电泳迁移率显示出显著延迟。使用基于所有16个二核苷酸步的楔形角的计算机程序，估计0.7 kb的XhoI和1.2 kb的EcoRI家族重复单元的三维结构为不规则螺线管。荧光原位杂交表明，这两个家族序列定位于间期核中的一个主要异染色质体。在MSB - 1细胞的同步培养中，溴脱氧尿苷掺入W染色体的时间比S期峰值晚约1小时。沿着XhoI和EcoRI家族序列形成的染色质结构被认为与总染色质或含有β - 肌动蛋白基因序列的染色质不同，因为前者的连接DNA长度明显更长。对经HaeIII消化的MSB - 1细胞核进行分级分离，得到了一个染色质级分，其中XhoI家族序列部分富集。该级分中存在几种对XhoI家族序列具有更高亲和力的DNA结合蛋白。
