中文摘要：

目的应用微卫星DNA分子标志分析中国长江中下游地区湖北钉螺群体的遗传结构。方法利用6对微卫星DNA引物，对采集自湖沼型血吸虫病流行区的湖南汉寿县、湖北阳新县、江西星子县、安徽当涂县和江苏扬州邗江区的湖北钉螺的P84、T5-13、T5-11、T4-22、T6-27和P82等6个位点进行荧光标记通用引物PCR扩增。每个采集点采集20--50个钉螺标本，共165个。统计分析各群体的等位基因数（N_a）、近交系数（F_IS）、期望杂合度（H_e）、观察杂合度（H_o）、多态信息含量（PIC）、群体间的遗传分化系数（F_ST）和遗传距离，根据遗传距离进行聚类分析，并进行分子变异方差分析（AMOVA）。结果5个湖北钉螺群体在6个微卫星位点等位基因数范围为3～33，平均为15．833。群体的平均以和见范围分别为0．600～0．883和0．308～0．759，两者在湖北群体最高，在江苏群体最低。群体的民范围为0．143～0．539。成对群体间的岛范围为0．0006-0．0531，由于％值较小，提示群体间未出现明显遗传分化。各群体的平均PIC为0．511-0．850，除江苏群体外，均为高度多态。分级AMOVA结算结果显示，变异主要存在于个体间，占总变异的95-2％。聚类分析结果显示，安徽群体与江苏群体首先聚为一支，然后依次同湖南、江西、湖北群体聚在一起。结论湖北钉螺多样性较为丰富；聚类分析结果符合湖北钉螺的地理分布格局；5个群体之间遗传差异较小，微卫星DNA的变异主要存在个体间。

英文摘要：

Objective To identify the genetic structure of Oncomelania hupensis in the middle and lower reaches of Yangtze River by using microsatellite DNA molecular markers. Methods O. hupensis snails were collected from the provinces of Anhui, Hunan, Hubei, Jiangxi, and Jiangsu, of which 6 polymorphic microsatellite DNA loci （P84, T5-13, T5-11, T4-22, T6-27 and P82） were amplified with fluorescence labeled universal primer. 20-50 snail samples were collected at each spot, adding up to 165 samples. The number of alleles （N_a）, inbreeding coefficient （F_IS）, heterozygosity （H）, fixation index （F_ST） of each group snails, genetic distance between groups, and the polymorphic information content （PIC） were calculated. Cluster analysis was then carried out based on genetie distance, and hierarchical AMOVA calculation was done. Results The number of alleles in each population range from 3 to 33, and the inbreeding coefficient ranged from 0.143 to 0.539. The average expected heterozygosity and observed heterozygosity ranged from 0.600 to 0.883 and 0.308 to 0.759, respectively, being the highest in Hubei population and the lowest in Jiangsu population. The range of Fsr value between paired populations was from 0.0006 to 0.053 I. The small Fsr valuesuggested that genetic differentiation did not occur among the populations. The average polymorphic information content in the populations ranged from 0.511 to 0.850, showing a high polymorphism except the .liangsu population. Hierarchical AMOVA calculations showed that inter-individual variation of the snails occupied 95.2% of the total variations. Cluster analysis revealed that Anhui group clustered first to Jiangsu, followed with Hunan, Jiangxi and Hubei. Conclusion There is a rich diversity in O. hupensis. Cluster analysis shows a consistency with the geographical distribution pattern. The genetic differences among the 5 snail populations are trivial with microsatellite DNA variation mostly present in individuals.