Ayres K N
J Cell Physiol. 1977 Oct;93(1):137-46. doi: 10.1002/jcp.1040930117.
Embryonic chick DNA from different tissues was examined for differences in relative content of highly repetitive DNA which might indicate specific DNA amplification in somatic cells. The content of repetitive sequences in DNA isolated from cerebrum, muscle, and neural retina tissues, at the same and at different embryonic stages, was determined by hydroxyapatite fractionation of partially reassociated DNA samples. An unrenatured marker DNA (C14-labeled E. coli DNA) was added to each chick DNA sample in order to monitor the nonspecific single-stranded DNA retention by each hydroxyapatite column. When chick DNA samples were sheared to a double-stranded length of 1,300 nucleotide pairs, an average of 20.2% +/- 2.2% of the DNA was found to reassociate at a Cot value of 10. The quantity of the fast reassociating sequences was found to constitute the same fraction of the DNA in all the tissues studied. In addition, all the reassociated DNA samples exhibited the same CsCl density classes. The studies also indicated that most chick DNA repetitive sequences are interspersed with nonrepetitive sequences.
对来自不同组织的鸡胚DNA进行检测，以寻找高度重复DNA相对含量的差异，这种差异可能表明体细胞中存在特定的DNA扩增。通过对部分复性的DNA样品进行羟基磷灰石分级分离，测定了在相同和不同胚胎阶段从大脑、肌肉和神经视网膜组织中分离出的DNA中重复序列的含量。向每个鸡胚DNA样品中添加未复性的标记DNA（C14标记的大肠杆菌DNA），以监测每个羟基磷灰石柱对非特异性单链DNA的保留情况。当鸡胚DNA样品被剪切成1300个核苷酸对的双链长度时，发现平均20.2%±2.2%的DNA在Cot值为10时复性。在所研究的所有组织中，快速复性序列的数量占DNA的比例相同。此外，所有复性的DNA样品都表现出相同的氯化铯密度类别。研究还表明，大多数鸡胚DNA重复序列与非重复序列相间分布。
