Willard H F
Am J Hum Genet. 1985 May;37(3):524-32.
Restriction endonuclease analysis of human genomic DNA has previously revealed several prominent repeated DNA families defined by regularly spaced enzyme recognition sites. One of these families, termed alpha satellite DNA, was originally identified as tandemly repeated 340- or 680-base pair (bp) EcoRI fragments that hybridize to the centromeric regions of human chromosomes. We have investigated the molecular organization of alpha satellite DNA on individual human chromosomes by filter hybridization and in situ hybridization analysis of human DNA and DNA from rodent/human somatic cell hybrids, each containing only a single human chromosome. We used as probes a cloned 340-bp EcoRI alpha satellite fragment and a cloned alpha satellite-containing 2.0-kilobase pair (kbp) BamHI fragment from the pericentromeric region of the human X chromosome. In each somatic cell hybrid DNA, the two probes hybridized to a distinct subset of DNA fragments detected in total human genomic DNA. Thus, alpha satellite DNA on each of the human chromosomes examined--the X and Y chromosomes and autosomes 3, 4, and 21--is organized in a specific and limited number of molecular domains. The data indicate that subsets of alpha satellite DNA on individual chromosomes differ from one another, both with respect to restriction enzyme periodicities and with respect to their degree of sequence relatedness. The results suggest that some, and perhaps many, human chromosomes are characterized by a specific organization of alpha satellite DNA at their centromeres and that, under appropriate experimental conditions, cloned representatives of alpha satellite subfamilies may serve as a new class of chromosome-specific DNA markers.
对人类基因组DNA进行限制性内切酶分析，此前已揭示出几个由规则间隔的酶识别位点所定义的突出的重复DNA家族。其中一个家族，称为α卫星DNA，最初被鉴定为串联重复的340或680碱基对（bp）的EcoRI片段，它们可与人类染色体的着丝粒区域杂交。我们通过对人类DNA以及来自啮齿动物/人类体细胞杂种（每个杂种仅含一条人类染色体）的DNA进行滤膜杂交和原位杂交分析，研究了α卫星DNA在单个人类染色体上的分子组织。我们使用一个克隆的340 bp EcoRI α卫星片段和一个来自人类X染色体着丝粒周围区域的克隆的含α卫星的2.0千碱基对（kbp）BamHI片段作为探针。在每个体细胞杂种DNA中，这两个探针与在总人类基因组DNA中检测到的不同DNA片段子集杂交。因此，在所检测的每条人类染色体——X和Y染色体以及常染色体3、4和21上，α卫星DNA都以特定且数量有限的分子结构域形式存在。数据表明，单个染色体上的α卫星DNA子集在限制性酶切周期性以及序列相关性程度方面彼此不同。结果表明，一些，也许是许多人类染色体在其着丝粒处具有α卫星DNA的特定组织形式，并且在适当的实验条件下，α卫星亚家族的克隆代表可作为一类新的染色体特异性DNA标记。
