RESUMO
Little is known about the distribution of Rhodococcus equi in the soil environment of native horses in China. One hundred and eight soil samples were collected from native-horse farms in the Hulun Beier grasslands of eastern Mongolia, the Xilin Goler grasslands of southern Mongolia, and Tongliao city in Inner Mongolia of China for investigating the distribution of R. equi in these regions. The isolation rates of R. equi from soil samples from the Hulun Beier and Xilin Goler grasslands ranged from 25.9% to 30.0%. In contrast, isolation rates from soil samples from Tongliao city was as high as 82.3% and the mean number of R. equi in soil samples from Tongliao city was 10 times more than those of samples from the grasslands. The 488 isolates were examined using PCR for the presence of genes that encode virulence-associated 15 000-17 000 antigen protein (VapA) and the 20 000 antigen protein (VapB). All isolates were negative for virulence-associated proteins. Plasmid profiles of these avirulent isolates showed that cryptic plasmids of various sizes were present with an incidence of 13.3% to 21.5%. The results of the present study contrast with those of our recent study, in which we reported that R. equi was absent from Mongolian horses in Ulaanbaatar, Mongolia. It is suggested that the difference between the results of these two studies is due to the mobile pasturing system in Mongolia and nonmobile pasturing system in Inner Mongolia.
RESUMO
The study was carried out to investigate the genetic polymorphism of the serum proteins of horses in Cheju. They were assigned to three groups; 45 Cheju native horses(CNH), 60 Cheju racing horses(CRH) and 60 Thoroughbreds(TB). We analyzed the phenotypes and gene frequencies of serum proteins which were albumin (Alb), vitamin-D binding protein(GC), esterase (ES), A1B glycoprotein(A1B) and transferrin(TF) loci using horizontal polyacrylamide gel electrophoresis (HPAGE).All of the loci, except A1B in TB, showed polymorphisms and different allelic and phenotypic frequencies in all three groups. ESS and TFF1 were not observed in CNH. Allelic frequencies of AlbB, ESI, TFD and TFF1 were high in TB. All of the loci, except ES locus in CRH, appeared to be in a state of Hardy-Weinberg equilibrium from goodness-of-fit test in all three groups Heterozygosity estimates at Alb, ES and TF loci were high, but GC and A1B loci were low in all three groups. Average heterozygosities in CNH, CRH and TB were 0.3535, 0.3555 and 0.2726, respectively. Results showed differences in the frequencies of alleles and phenotypes of several serum protein loci between CNH and CRH, suggested that CRH might be crossed with other breeds of horses in some degree.