中华稻蝗镉急性死亡率差异与等位酶基因型研究

Effect of Cadmium on Mortality of Oxya chinensis Among Allozyme Genotypes

为研究镉毒性与中华稻蝗种群等位酶基因型之间的关系,将采自山西省原平市的中华稻蝗(Oxyachinensis)为研究对象进行镉的LD50急性毒性实验,并对所研究个体进行等位酶水平淀粉凝胶电泳。结果表明,中华稻蝗种群LDH、GPI、PGM和ME均为多态基因座位。在LDH、PGM、ME多态基因座位上,各基因个体的死亡率差异显著(P<0.05),其中PGM及ME的基因型频率显著偏离哈-温平衡预期值,且LDH、PGM、ME为杂合体缺乏(F>0);在GPI多态基因座位上,各基因型个体的死亡率差异不显著(P>0.05),GPI基因型频率符合哈-温(H-W)平衡预期值,而GPI为杂合体过剩(F<0)。中华稻蝗在这4个基因座位具有较高的平均每个基因座位的等位基因数(A=2.5),平均观察杂合度(Ho=0.314～0.325)和平均期望杂合度(He=0.471～0.496)。结论:由于中华稻蝗种群不同基因型对Cd2+的敏感性不同,因而导致其不同基因型死亡率的差异。

The mortality differences of cadmium （Cd^2＋）-exposed Oxya chine nsis among allozyme genotypes were compared to better understand the relationship between the genetic variations and environmental disturbance. This study analyzed the occurrence of genotypes in O. chinen- sis population exposed to Cd^2＋ stress. Specimens of O. chinensis were collected at Yuanping, Shanxi province, China and were used in acute toxicity tests. Specimens were assigned to Cd^2＋ exposure （LD50 110.21 μg·g^1） for 24 h. The genotypic structure of beth dead and survived specimens was analyzed with allozyme electrophoresis at four loci （GPI, PGM, LDH, and ME）. The results showed there were polymorphic loci at LDH, GPI, PGM and Me. There were significant mortality differences for PGM, LDH, and ME loci （P〈0.05）. X2 test showed that the significant mortality differences were found among the following genotype pairs： LDH-AB vs. LDH-AA, LDH-AB vs. LDH-BB; PGM-CC vs. PGM-AA, PGM-CC vs. PGM-BB, PGM-CC vs. PGM-AB; Me-AA vs. Me-BB, Me-AA vs. Me-AC, Me-AA vs. Me-BC, Me-BB vs. Me- CC, Me-BB vs. Me-AB, Me-BB vs. Me-AC, Me-CC vs. Me-AC, Me-AB vs. Me-BC, Me-AC vs. Me-BC. Genotype frequencies deviated from the Hardy-Weinberg＇s expectations at PGM and Me, and the heterozygosis were absent for LDH, PGM, ME （F〉0）. There was no signif- icant mortality difference for GPI loci （P〉0.05）, and no significant mortality differences was found among different genotypes by X2 test. Genotype frequency fitted with Hardy-Weinberg＇ s expectations at GPI, and the heterozygosis was overmuch （F〈0） for it. The mean number of al- leles per locus （A =2.5）, the observed mean heterozygosities （Ho=0.314-0.325） and the expected mean heterozygosities （He=0.471 -0.496） of the species suggested that O. chinensis possessed sufficient genetic diversity.