Davis A H, Kidd G H, Carter C E
Biochim Biophys Acta. 1979 Dec 17;565(2):315-25. doi: 10.1016/0005-2787(79)90208-9.
The swine intestinal nematode, Ascaris suum, eliminates chromatin material from its primordial somatic cells during early embryogenesis. A technique for isolation of nuclei from pre- and post-diminution stage embryos has been developed and these isolated nuclei were used in investigations of nuclear events during diminution. The amount of DNA per nucleus determined by diphenylamine assays and isotope dilutions was 0.66 pg and 0.29 pg in pre- and post-diminution nuclei, respectively. Thus, A. suum loses 56% of its nuclear DNA during diminution. The loss of nuclear DNA enabled in vivo examination of histone to DNA ratios as a function of changes in DNA quantities. Ascaris histones were identified by acid extractability and tryptic fingerprint comparison with rat liver histones. Measurement of histone quantities was accomplished using linearity of Coomassie blue binding to histones separated in dodecyl sulfate gels. Ascaris nucleosomal histones levels were relatively constant in pre- and post-diminution nuclei. However, nucleosomal histone to DNA ratios approximately doubled during diminution.
猪肠道线虫猪蛔虫在胚胎发育早期会从其原始体细胞中去除染色质物质。现已开发出一种从减缩前期和减缩后期胚胎中分离细胞核的技术，这些分离出的细胞核被用于研究减缩过程中的核事件。通过二苯胺测定法和同位素稀释法确定，减缩前期和减缩后期细胞核中每个细胞核的DNA量分别为0.66皮克和0.29皮克。因此，猪蛔虫在减缩过程中损失了56%的核DNA。核DNA的损失使得能够在体内检测组蛋白与DNA的比例随DNA数量变化的情况。通过酸提取能力以及与大鼠肝脏组蛋白的胰蛋白酶指纹图谱比较来鉴定猪蛔虫组蛋白。使用考马斯亮蓝与十二烷基硫酸盐凝胶中分离出的组蛋白结合的线性关系来完成组蛋白量的测量。在减缩前期和减缩后期细胞核中，猪蛔虫核小体组蛋白水平相对恒定。然而，在减缩过程中，核小体组蛋白与DNA的比例大约增加了一倍。
