Yu X C, Wu G L, Zhang Y J, Wu Y Q, Zhu C L, Zhang Z H, Chen B Y
Dept. of Molecular Genetics, Institute of Genetics, CAS, Beijing, China.
Yi Chuan Xue Bao. 2000;27(6):498-505.
In order to analyze the interspecies diversity and the extent of diversity among Schistosoma japonicum Chinese mainland strains, the genetic variation on gene level among 6 isolates collected from Jiangxi, Hunan, Hubei, Anhui, Sichuan, Yunnan and a cultured isolate from a laboratory were studied using molecular biological technique. There were only two different bases at position 112 and 143 in 536 bp sequence of 28S rDNA-D2 domain between Anhui and Yunnan isolates, the homology was 99.6%. The result could be explained the reason of why the migration rates of single chain 28S rDNA-D2 domain among the above 7 isolates were the same completely in PCR-SSCP. However, comparing with the sequences of the Philippine isolate of S. japonicum, S. mansoni and S. aematobium, there were 6, 94 and 93 different bases and the homologies were 98.9, 82.5 and 82.7 per cent separately. With 8 restriction endonucleases to analyze the ITS of rDNA obtained by PCR from the 7 isolates, the results showed that only 3 minor bands were different, e.g. 5.3% of total 58 fragments. It was suggested that the ITS of rDNA among 7 isolates were highly conserved. Using randomly amplified polymorphic DNA (RAPD) to analyze the genetic diversity of the genomes of the 7 isolates, the average genetic distance (D) calculated from total 284 amplified fragments was 0.22. The maximum D was 0.30 and existed between Anhui and Yunnan isolates. The minimum D was 0.13 and existed between Sichuan and Yunnan isolates. The clustering analysis of genetic distances showed that the 7 isolates could be gathered in one group. From above three results, it could be considered that the genetic diversity on gene level among S. japonicum Chinese mainland strains was very low.
为分析日本血吸虫中国大陆株的种间多样性及多样性程度，采用分子生物学技术研究了从江西、湖南、湖北、安徽、四川、云南收集的6个分离株以及1个实验室培养分离株在基因水平上的遗传变异。安徽分离株和云南分离株28S rDNA - D2区536bp序列中，仅在第112和143位有两个不同碱基，同源性为99.6%。该结果可以解释为什么在PCR - SSCP中上述7个分离株的单链28S rDNA - D2区迁移率完全相同。然而，与日本血吸虫菲律宾分离株、曼氏血吸虫和埃及血吸虫的序列相比，分别有6、94和93个不同碱基，同源性分别为98.9%、82.5%和82.7%。用8种限制性内切酶分析7个分离株PCR扩增得到的rDNA的ITS，结果显示仅3条小带不同，占总58条片段的5.3%。提示7个分离株rDNA的ITS高度保守。用随机扩增多态性DNA（RAPD）分析7个分离株基因组的遗传多样性，从总共284个扩增片段计算出的平均遗传距离（D）为0.22。最大D为0.30，存在于安徽和云南分离株之间。最小D为0.13，存在于四川和云南分离株之间。遗传距离聚类分析表明，7个分离株可聚为一组。从上述三个结果可以认为，日本血吸虫中国大陆株在基因水平上的遗传多样性非常低。
