伊氏锥虫动基体DNA微环的研究

INVESTIGATIONS ON THE KINETOPLAST DNA MINICIRLES OF TRYPANOSOMA EVANSI

采用限制性内切酶消化、琼脂糖凝胶电泳及分子杂交技术对８株中国伊氏锥虫动基体ＤＮＡ（ｋＤＮＡ）微环进行了比较研究。结果显示，我国伊氏锥虫株之间的ｋＤＮＡ微环序列具有较高的同源性，仅限制酶 ＡｌｕＩ，ＨｉｎｆＩ及 ＭｂｏＩ的酶解结果显示少数虫株的 ｋＤＮＡ微环存在异源序列。这种异源性可以作为伊氏锥虫种内分类的遗传学标志。

Restriction endonucleases digestion of kinetoplast DNA minicircle, combined with agarose gel electrophoresis and molecular hybridization to characterize 8 Trypanosoma evansi strains in China was performed. The results presented in restriction enzymes digestion showed that all minicircles of 8 T. evansi strains had identical electrophoretic patterns of restriction fragment with Dde I, Taq I and Sin I. However, the polymorphisms of minor restriction fragment length were observed with Alu I, Hinf I and Mbo I, the minicircles of 6 strains (YNB, ZJB, JSB2, HNB, HBM, GDH) were cleaved once by Hinf I, twice by Mbo I and none by Alu I, and had identical restriction fragment patterns; the minicircles of 2 other strains (XJCA, AHB) were cleaved once by Mbo I, Alu I and twice by Hinf I, When the probe PTK1 was used to hybridize to Hinf I digested fragments, 2 minicircle classes were found with AHB strain. The 8 T. evansi strains could be divided into 2 minicircle types (type A-YNB, ZJB, JSB2, HNB, HBM, GDH and type B-XJCA, AHB) and the type B could be further diveded into type B1 (XJCA)and type B2 (AHB)based on the results in this inves- tigation. The evidence provided by present investigation showed that Chinese T. evansi strains shared kDNA minicircle Sequence homology with each other, but also showed a minor minicircle sequence heterogeneity. It is suggested that low genetic variation occur in Chinese T. evansi, and all strains form a homogeneous species group. However, the above-mentioned minicrcle sequence heterogeneity might be used as a tool for intraspecies classification of T. evansi