INVESTIGATIONS ON THE KINETOPLAST DNA MINICIRLES OF TRYPANOSOMA EVANSI

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