| Li chenghua (marine biology) Directed by professor Song linsheng, Li taiwu and Su xiurong Tegillarca granosa (Linnaeus) belongs to Bivalvia class, Pteriomorphiasub-class, Arcoida order, Arcidae family, Tegillarca genius according to up-to-datataxonomy system. As an important cash shellfish of seawater, it distributes along thewest of Pacific Ocean, the Indian Ocean and the Atlantic Ocean. Concerning ourcountry, it plays an important role in the marine aquaculture industry in theprovinces of Shandong, Zhejiang, Fujian and Guangdong. Nowadays, although much has been done on the research of the species biology,farming technology, breeding methods, karyotype and histology, there are muchmore left and expected to be studied, especially at DNA level which can throw lightto the species recovery. Regarding of T. granosa, the reasons for studying its geneticdifferentiation lie in two aspects. One is the potential problems occur in its breedingand aquaculture; the other is the diversity of its surroundings, spanning from Bohaito the south of China sea (abbreviation for SCS). In the first part of this paper, wefirstly adopted RAPD method to analysis the differential degree of the differentpopulations in China and Korea, then the internal transcribed spacer 2 (abbreviationfor ITS2) was amplified, sequenced to show more proof among the most differentialpopulations. Seven populations were analyzed in our RAPD experiment, there are as follows:Rongcheng in Shandong province(R), Fenghua(F) and Wenling(W) in Zhejiangprovince, Fuding in Fujian province(D), Shantou(S) and Zhanjiang(Z) in Guangdongprovince and Fushan in Korea(K), all samples were collected from China except toK. We preferred to nominated K, R, F, W and D as the north stocks (abbreviation forNP), the others as the south ones (abbreviation for SP). The samples employed toITS2 analysis randomly selected two populations from the NP and SP withTegillarca nodifera (Martens) as an outgroup. Under predetermined optical reaction conditions, all primers showed usinformative message except S-80 without any results in seven populations. 154 IVRAPD sites were detected ranging from 300bp to 2300bp in size. The number ofamplified bands ranged from 1 to 11 in every individual. The experimental data wereanalyzed with the Popgen3.2 and PHILIP3.5 softwares. The results showed that: (1)the high level of mean heterozygosities and polymorphic loci suggested that theresource of T. granosa was in good condition with high genetic variation, whichgave us more confidence to develop its aquaculture; (2) the degree of the geneticdifferentiation was much lower in the NP or SP comparing to that existing betweenthe NP and SP. The genetic distances were ranging from 0.0250 to 0.0901 in the NPand SP, while the corresponding valves were ranging from 0.3261 to 0.4511.betweenthe NP and SP. Other genetic parameters like the inbreeding coefficient (abbreviationfor Fst) also verified the above judgment; (3) the heterozygosities and proportion ofpolymorphic loci of the hatchery populations were lower than that of the wildpopulation (K). What's more, the quantitative character variability between W and Kwas significant (p<0.01), the shell length and height of the former were24.45±1.84mm and 19.50±1.74mm in turn, the latter were 30.80±2.80mm and23.30±2.06mm respectively. All these deviations could be attributed to artificial orother factors. (4) the nearest phylogenetic relationship occurs between thepopulations with the nearest blood relationship. The NP or SP was firstly cluster nomatter what methods we adopted (NJ and UPGMA), indicating their close sibship. The ITS2 sequences showed the similar trends inferred from RAPD analysis.There are more or less variation existing between each other in our experiment at thedefault parameters with ClustalW software aid, ranging from one base deletion and asingle transversion (G →... |
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