| 摘要: |
| 采用聚丙烯酰胺凝胶电泳技术，研究了锯缘青蟹(Scylla serrate)6个自然种群杂合体缺乏及过量情况；进行了11种等位酶的电泳检测和谱带遗传分析，在所研究的锯缘青蟹22个等位酶位点和30个等位基因中，有7个位点是多态的，分别为Est-1、Est-2(在此位点厦门锯缘青蟹为单态)、Est-3、Sod-1、Me-2、Mdh-2(在此位点厦门锯缘青蟹为多态)、Mdh-3，在这些位点有2—3个等位基因。结果表明，宁海和三亚种群的Est-1和Est-2位点、厦门种群的Est-1和
Mdh-2位点、深圳和北海种群的Est-1位点符合H-W 平衡标准(P>0.05)；连江种群的Est-1位点显著偏离H-w 平衡(P<0.05)；而宁海、三亚和厦门种群的Est-3、Sod-1、Me-2和Mdh-3位点、连江种群的Est-2、Est-3、Sod-1、Me-2和Mdh-3位点及深圳和北海种群的Est-2、Est-3、Sod-1、Me-2和Mdh-3位点均非常显著偏离H-W 平衡(P<0.01)。男外，除连江种群的Est-1位点表现出杂合子缺失(F>0)外，各种群中每个多态位点均表现为杂合子过量(F<0)。总结了各种群中每个多态位点的观察杂合度和期望杂合度，认为导致杂合子缺乏的主要原因可能是自然选择、近交、哑等位基因、Wahland效应等。杂合子缺乏会导致某些基因从基因库中消失，造成种群遗传多样性的降低，从而降低物种适应环境的能力。 |
| 关键词: 锯缘青蟹,等位酶,种群,杂合子缺乏,杂合子过量 |
| DOI： |
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| 基金项目:国家自然科学基金资助项目，40376044号；国家海洋863资助项目，2002AA603013号；福建省重中之重项目“福建海岸优良种质生物学和生物活性物质的基础应用研究”资助，1998-2002；集美大学校基金资助项目，2000-2003 |
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| HETEROZYGOSITY IN SIX POPULATIONS OF CRAB SCYLLA SERRATA |
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LI Zhong-Bao1,2, LI Shao-Jing2, WANG Gui-Zhong2
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1.Fisheries College，Jimei University;2.School of Marine and Environmental Studies，Xiamen University
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| Abstract: |
| Heterozygosity was investigated using an assay of vertical slab polyacrylamide gel electrophoresis in six crab Scylla serrata populations from six sites：Ninghai(Zhejiang Province), Lianj"iang and Xiamen (Fujian Province), Shenzhen(Guangdong Province), Beihai(Guangxi Province)and Sanya(Hainan Province). The large size, fast growth and high economic value of S. serrata all make it very amendable to aquaculture. In recent years, culture of S. serrata has seen in rapid expansion. Main constraint in aquaculture expansion is broodstock supply in China, captive breeding technology for S. serrata has yet to be fully developed with broodstocks currently collected from the wild. Although the culture and ecology of S. serrata have been previously studied in China, study on their heterozygosity is limited. To help protect this valuable marine resource and help progress the culture of this species, heterozygosity of S. serrata populations across China was studied by the authors.
Allozyme is co-dominant and can be analyzed under standard Hardy-Weinberg model. Allozyme electrophoresis is considered to be an critical useful technique in population genetics. This technique was used in the present study to examine the heterozygosity of S. serrata populations. Results presented here provide basic genetic information valuable for developing captive breeding programs and protecting and improving genetic resources of this species.
Eleven enzymes presumably encoded by 22 allozyme loci and 30 alleles are scored in S. serrata. 7 loci with 2—3 alleles are polymorphic. They are Est-1, Est-2(monomorphic locus in Xiamen population), Est-3, Sod-1, Me-2, Mdh-2(polymorphic locus in Xiamen population)and Mdh-3. Results also showed that the genetypic distribution observed at Est-1 and Est-2 in Ninghai and Sanya, Est-1 and Mdh-2 in Xiamen and Est-1 in Shezhen and Beihai were found to be in agreement with those expected from the Hardy-Weinberg equilibrium (P>0.05). But other polymorphic locus in the six populations were found to depart clearly from those expected from the Hardy-Weinberg equilibrium (Est-1 in Lianjiang, P<0.05；other loci, P<0.01). There was heterozygote deficiency in Est-1 in Lianjiang(F>0, F=0.123), and heterozygote excess in other polymorphic locus in the six populations(F<0). The paper also summarized the observed heterozygosity and expected heterozygosity per polymorphic locus per population. Main causes of heterozygote deficiency, resulting in disappearance of allele, lower genetic diversity and lower environmental adaptation ability, were natural selection, inbreeding effects, presence of null allele and the Wahland effect. |
| Key words: Scylla serrata, Allozyme, Population, Heterozygote deficiency, Heterozygote excess |
