Mayfield J E, McKenna J F
Chromosoma. 1978 Jun 28;67(2):157-63. doi: 10.1007/BF00293173.
Partially denatured DNAs from mouse, cow, and chicken were visualized in the electron microscope by the basic protein film technique and the size and distribution of the denatured regions characterized. A-T rich sequences visualized at 15% denaturation average about 1500 bases in length for all three species and are arranged quite non-randomly in the genome. This arrangement is such that 30--50% of the entire genome contains no A-T rich DNA, and another 20% is composed about one-half of A-T rich sequences and one-half of other sequences. Comparison with DNA denaturation profiles indicates that for each organism these sequences are from 25--30% G+C and that there is very little if any DNA more A-T rich than these. Estimates from published studies of fluorescence enhancement of quinacrine bound to A-T rich DNAs suggest that the observed non-random organization of A-T rich sequences is sufficient to account for Q banding of metaphase chromosomes.
利用碱性蛋白质膜技术在电子显微镜下观察了来自小鼠、牛和鸡的部分变性DNA，并对变性区域的大小和分布进行了表征。在15%变性条件下可见的富含A-T的序列，这三个物种的平均长度约为1500个碱基，并且在基因组中的排列相当不随机。这种排列使得整个基因组的30%-50%不包含富含A-T的DNA，另外20%大约由一半富含A-T的序列和一半其他序列组成。与DNA变性图谱的比较表明，对于每种生物体，这些序列的G+C含量为25%-30%，并且几乎没有比这些序列富含更多A-T的DNA。对已发表的关于与富含A-T的DNA结合的喹吖因荧光增强研究的估计表明，观察到的富含A-T的序列的非随机组织足以解释中期染色体的Q带。
