Zagradisnik B, Kokalj-Vokac N
Laboratory for Medical Genetics, Maribor Teaching Hospital, Slovenia.
Pflugers Arch. 2000;440(5 Suppl):R190-2.
The pattern of DNA methylation can be analyzed on methaphase chromosomes with fluorescein labeled antibodies against 5-methylcytosine. In human extraembryonic tissue lower overall intensity of immunofluorescence in centromeric chromosomal regions correspond to hypomethylation of the DNA when compared with normal human lymphocytes. Pericentromeric regions on chromosomes 1,9,16 and heterochromatin on chromosome Y, which reveal lower levels of immunofluorescence, are rich in classical satellite DNA type II and III. In our experiment methylation-sensitive restriction enzymes, alphoid and classical satellite DNA probes specific for chromosomes 1,9,16 and Y were used. Southern blot analysis on cells from extraembryonic tissue revealed different extent of hypomethylation in different chromosomal regions. Our results confirm overall and sequence-specific hypomethylation of DNA in cells from extraembryonic tissue in comparison with somatic cells.
DNA甲基化模式可以通过用针对5-甲基胞嘧啶的荧光素标记抗体在中期染色体上进行分析。与正常人淋巴细胞相比，人类胚胎外组织着丝粒染色体区域免疫荧光的总体强度较低，这对应于DNA的低甲基化。1号、9号、16号染色体的着丝粒周围区域以及Y染色体上的异染色质显示出较低水平的免疫荧光，富含经典的II型和III型卫星DNA。在我们的实验中，使用了甲基化敏感的限制性内切酶、对1号、9号、16号和Y染色体特异的α卫星和经典卫星DNA探针。对胚胎外组织细胞的Southern印迹分析显示不同染色体区域低甲基化程度不同。我们的结果证实，与体细胞相比，胚胎外组织细胞中的DNA存在整体和序列特异性低甲基化。
