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The Genetic Diversity Of Farmed Mandarin Fish (Siniperca Chuatsi Baslesky) Stocks In Guangdong & Hunan, China

Posted on:2006-03-21Degree:MasterType:Thesis
Country:ChinaCandidate:G Q LiFull Text:PDF
GTID:2133360152990728Subject:Zoology
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In China , the mandarin fish , Siniperca chuatsi Basilewsky (Perciformes: Serranidae) has a relatively high market value, and is widely cultured throughout the country, with importance also in stocking fisheries in lakes and reservoirs, especially in Guangdong and Hunan provinces. Study on the genetic diversity of farmed mandarin fish stocks in Guangdong & Hunan using karyotype, allozyme and RAPD analyses, has important content, at the same time, protects fish genetic diversity and germ plasm resources, promotes sustainable utility of bioresources.Karyotypes of farmed mandarin fish stocks in Guangdong & Hunan were obtained from kidney cells after in vivo treatment with PHA and colchicine injection-air drying method. The results showed that there were same karyotype formula as 2n=48=24sm,st+24t, NF=70, consisting of 22 submetacentric , 2 subtelocentric and 24 telocentric pairs.In both male and female of the stocks studies, the special big , small-chromosomes or heteromorphic sex-chromosomes were not found. The possible evolutionary relations in chromosome are discussed.Comparative studies of genetic diversity of farmed mandarin fish ftocks in Guangdong & Hunan were investigated by polyacrylamid gel electrophoresis(PAGE). Among 22 loci for the 7 enzymes examined. Three loci, which were ADH,MDH-2 and MDH-3 were found ploymorphic in Guangdong stock, the mean proportions of ploymorphic loci was 13.64%. Two loci, which were MDH-2 and MDH-3 were found ploymorphic in Hunan stock, the mean proportions of ploymorphic loci was 9.09%. The results showed that the genetic similarity and genetic distance between two stocks are 0.9994 and 0.0006 respectively. Theaverage heterozygosity and mean number of alleles per locus of Guangdong stock were 0.1818 and 1.1364 respectively, and Hunan stock were 0.1959 and 1.0909 respectively. The genetic diversity level of Guangdong stock was higher than that of Hunan stock. Various genetic indexes show that Mandarin Fish resource quality is still good, but should protect resources.RAPD method was used in analyzing the genetic diversity of two stocks of farmed mandarin fish. The blood was used to extract the genetic DNA. The best reaction system concluded DNA 25ng genetic DNA, 10mmol/L Tris-HCl(pH8.0), 50mmol/L KC1, 2.0mmol/L MgCl2 , 0.2mmol/L dNTP, 10pmol primers, l.0UTaq DNA ploymerase per 25μ1. Amplifications were performed for 30 cycles with an initial 3-minute denaturing step at 95℃ and a final extension at 72℃ for 6 minutes. The temperature profiles for each PCR cycle were 30 seconds of denaturation at 94℃,1 minute of low stringency annealing at 36℃, and 2 minute of primer extension at 72 ℃ . Forty random primers were used for the analysis of nuclear DNA polymorphism of two stocks. The results showed that twenty-two primers were effective. 289 bands were obtained by the experiment.Among them, 155 bands were acquired from Guangdong stock, while 134bands from Hunan stock. Two stocks shared 122 bands.According to the pattern, The average inter-stock genetic distance of Guangdong stock is 0.0633,while Hunan stock 0.0629. The intra-stock genetic distance between two stocks is 0.1299. Values of Shannon diversity of Guangdong stock and Hunan stock were 0.0690 and 0.0723 respectively.The percentage of polymorphic loci of Guangdong stock is 25.16%, a little higher than the average percentage of vertebrate(24.7%). The percentage of polymorphic loci of Hunan stock is 10.15%, 14.55% lower than Guangdong stock and vertebrate. These results suggest thatdiversity of two stocks is not good. As a result, it implied that effective husbandry and management measures must be taken to avoid reduction of genetic diversity so as to enable the sustainable development of the mariculture.
Keywords/Search Tags:Mandarin fish (Siniperca chuatsi Basilewsky), Karyotype, Allozyme, RAPD, Genetic diversity
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