【摘要】 本文研究了BrdU取代胸苷、紫外线照射染色体标本、5-氮咆苷去甲基化和染色体DNA盐酸变性对限制酶显带效应的影响。结果表明:1.BrdU取代胸苷不影响限制酶HaeⅢ和HinfⅠ的显带效应;2.限制酶HaeⅢ和PstⅠ不再使紫外线照射后的染色体标本显带;3.DNA去甲基化对限制酶HaeⅢ.HinfⅠ的显带效应无明显影响,但可使原先不能使染色体显带的HpaⅡ显示G或弱C带;4.染色体DNA盐酸变性不影响限制酶HaeⅢ和HinfⅠ的作用。更多还原

【Abstract】 Previous investigations have demonstrated that the restriction endonucleases HaeⅢ, HinfⅠ and PstⅠ can induce banding patterns of human metaphasic chromosomes. Therefore, banding by restriction endonucleases may be useful in searching for new chromosomal markers and in studying the chromatin organization. This paper presents the results of studies on the effects of some DNA alterating factors on human chromosome banding by restriction endonucleases.1.The banding patterns induced by Hae Ⅲ and Hinf Ⅰ remained the same after BrdU substitution of thymidine in cultured cells. This means that the substitution does not eliminate the subsequent action of these two restriction endonucleases.2.Irradiation of chromosomal preparations with ultraviolet light prevented the induction of chromosome bands by HaeⅢ and PstⅠ. This may be explained by the formation of pyrimidine dimers which prevented the restriction endonucleases from recognition and cleavage of their specific DNA sequences, or by the formation of DNA-protein cross-linkage which prevents chromosomal DNA from extraction.3.Hpa Ⅱ digestion induced C or G bands after demethylation of chromosomal cytidines by 5-azaeytidine treatment in vivo. No banding effects of Hpa Ⅱ could be observed without demethylation. This means that most cytidines in Hpa Ⅱ recognition sequences are methylated in human chromosomes. Demethylation does not influence the banding effects of Hae Ⅲ and Hinf Ⅰ.4.The denature of chromosomal DNA by HCl did not eliminate the action of Hae Ⅲ and Hinf Ⅰ on human chromosomes.更多还原