镉暴露对钩虾磷酸葡萄糖异构酶基因型的致死性差异研究

Differential Mortality Among the Gammarrus Spetulus Genotypes at Glucose-6-phosphate Isomerase by Cadmium Exposure

采用水平淀粉凝胶电泳技术和等位酶分析方法,比较了氯化镉处理后钩虾种群多态基因座Gpi各基因型个体的死亡率差异。将268头钩虾暴露于50g·L-1氯化镉中96h后平均死亡率为56.5%,将存活个体和死亡个体分别进行等位酶分析以确定每个个体的基因型。结果表明,氯化镉对钩虾Gpi6种不同的基因型表现出不同的选择性致死效应,各种基因型个体的死亡率分别为:67%(Gpi-aa)、50%(Gpi-ab)、57%(Gpi-ac)、69%(Gpi-bb)、56%(Gpi-bc)和73%(Gpi-cc)。列联表!2检验表明:Gpi-ab个体与Gpi-cc个体之间的基因型与死亡率存在显著关联(P<0.05)。以上结果说明该钩虾种群Gpi-cc基因型很可能与钩虾对镉毒性的敏感性存在相关关系。

The horizontal starch gel electrophoretic and staining techniques were used to identify allozyme banding patterns of phosphoglucose isomerase （Gpi）, an enzyme involved in glycolysis, in each shrimp of Gammarrus spetulus exposed to cadmium. The shrimp samples were collected from Xinzhou District, Yunzhonghe of Yuanping City, China. The population had polymorphic loci at Gpi as shown by horizontal starch gel electrophoresis. When exposed to 50 g· L^-1 CdCl2 solution for 96 hours, a mortality of 56.5% for 268 Gammarrus spetulus individuals was obtained. The allozyme analysis was then employed to determine the number of each genotype for both surviving and dead individuals. The differential mortality among the allozyme genotypes of Gpi was compared between surviving and dead groups of the shrimp. Mortalities of the individuals with different genotypes were 67% （Gpi-aa）, 50%（Gpi-ab）, 57%（Gpi-ac）, 69%（Gpi-bb）, 56%（Gpi-bc）, 73% （Gpi-cc）, respectively. Contingency table X^2 tests demonstrated that significant genotypic effect was observed between Gpi-ab and Gpi-cc in dead and surviving groups （P〈0.05）. These results suggested that cadmium toxicity displayed nonrandom lethal effects on individuals with different genotype of Gpi, and perhaps Gpi-cc genotype frequency in a population of Gammarrus spetulus could be considered as the potential sensitive biomarker to cadmium exposure. More scrutinizing on the integration of other molecular markers and detailed toxicology should be done in order to clearly determine the relationship of Gpi genotypes and toxicity of cadmium exposure.