Study On Population Genetic Structure Of Small Scale Landscape Group Of Snails In The Middle And Lower Reaches Of The Yangtze River

Schistosoma japonicum Katsurada is a major public health and social problem, and is a serious hazard parasite to human health. Oncomelania hupensis Gredler is the only intermediate host of Schistosoma japonicum. Its distribution is highly correlated to Schistosoma japonicum. So it plays a key role in the process of the spread of Schistosoma japonicum. Oncomelania hupensis is distributed mainly over Yangtze river basin and the south of Jiangsu, Zhejiang, Anhui, Jiangxi, Hunan, Hubei, Fujian, Shanghai, Guangdong, Guangxi, Yunnan, Sichuan and other provinces, municipalities and autonomous regions. Due to the distance between different species of Oncomelania hupensis, it has geographical isolation, which results in a significant genetic variation between different populations in different areas, and then divided into a number of different subspecies. Because of the influence of external environment such as temperature, humidity, altitude, Schistosoma japonicum in different environments have completely different susceptibility. The polymorphism analysis of Oncomelania hupensis genetic provides theoretical guiding significance and medical practical value for studying the interaction of Schistosoma japonicum and Oncomelania, groups of Oncomelania diffusion mechanism and active monitoring of the low infection rate of Schistosomiasis.This study is based on an existing mitochondrial genome sequences of Oncomelania hupensis in our laboratory and microsatellite DNA library of Oncomelania. First of all, we selected rDNA-ITS sequence to analyze population genetic structure of Oncomelania hupensis under different geographical environments of the Yangtze river, exploring the value of molecular markers of rDNA-ITS in Oncomelania hupensis diffusion path monitoring. Secondly, comparing to two kinds of DNA kit and price, we chose the appropriate extraction kit to extract DNA from1548Oncomelania hupensis samples. Finally, by using microsatellite marker, we analyzed the population genetic structure on small scale landscape of Oncomelania hupensis on Songzi city, Hubei province. The results are shown as follows:(1) Compared to the Tiangen (Tiangen Biotech (Beijing) Co., LTD.) DNA extraction kit and OMEGA eZNA Mollusc DNA extraction kit. The extraction effect of OMEGA kit extraction effect is better but the cost is higher, which is16yuan per sample; the extraction effect of Tiangen DNA kit is normal but the cost is low, which is8yuan per sample. The reason of the limitation of samples and money, we decided to use Tiangen DNA extraction kit for500samples which were obtained before2012and use OMEGA kit for1048samples which were obtained before2012,(2) By using rDNA-ITS genetic sequence we analyzed Oncomelania hupensis population genetic diversity which belong to the downstream of Yangtze River from three provinces. The results show that nine species from three provinces have abundant genetic diversity; AMOVA analysis showed that the genetic differences between nine populations Oncomelania hupensis mainly exists between individuals; all haploid type was divided into three main pedigrees by family network of Haploid, and Oncomelania hupensis population in Gaochun Jiangsu existed primitive types (Shared haploid type), between family and family in transitional type, terminal types, which showed that the population genetic heterogeneity. Research also suggests that rDNA-ITS molecular markers worth further discussion in Oncomelania hupensis diffusion path monitoring utility.(3) Microsatellite marker results show that although the shell morphology of Oncomelania hupensis in Songzi district has smooth shell, shallow ribbed shell, deep-ribbed shell three forms, the microsatellite DNA scan on Oncomelania hupensis accessions showed the genetic variation among individuals mainly came from individuals in a group, the landscape environment of the genetic differentiation between groups of Oncomelania hupensis was not obvious although the genetic diversity within population was higher; thus, although genetic and geographic distances showed some correlation, it is not obvious; currently presumably it might be due to the influence of different ecological environment, resulting shell form is different. Two kinds of shell found that light shell or ribbed shell should belong to the same subspecies by using UPGMA cluster analysis.