de la Torre J, Sumner A T, Gosalvez J, Stuppia L
MRC Human Genetics Unit, Western General Hospital, Edinburgh, U.K.
Genome. 1992 Oct;35(5):890-4. doi: 10.1139/g92-135.
We have studied the distribution of potentially active genes on human chromosomes, using two methods: DNAse I hypersensitivity and restriction enzyme--nick translation with enzymes sensitive to methylation of CpG doublets. DNAse hypersensitivity is known to be associated with potentially active genes, and, when the reaction is detected by "in situ" nick translation, produces an R-banding pattern. Digestion of chromosomes with HpaII or CfoI, both of which should preferentially cut unmethylated sequences in the CpG islands associated with the majority of genes, also produces R-banding patterns. Deviations are attributable to overdigestion of the chromosomes, leading to extraction of DNA and loss of the specific sites that were to be detected. Contrary to the results of a number of previous workers, we have failed to demonstrate any differences between the DNAse I hypersensitivity or the degree of methylation of the active and inactive X chromosomes in metaphases from females.
DNA酶I超敏感性和用对CpG双联体甲基化敏感的酶进行限制性内切酶切口平移。已知DNA酶超敏感性与潜在活性基因相关，并且当通过“原位”切口平移检测到反应时，会产生R带型。用HpaII或CfoI消化染色体，这两种酶都应优先切割与大多数基因相关的CpG岛中的未甲基化序列，也会产生R带型。偏差归因于染色体的过度消化，导致DNA提取以及要检测的特定位点的丢失。与许多先前研究人员的结果相反，我们未能证明女性中期活性和非活性X染色体在DNA酶I超敏感性或甲基化程度上存在任何差异。
