Guo Ya-ping

Activity of the enzymes of the antioxidative system in cadmium-treated Oxya chinensis (Orthoptera Acridoidae)

One purpose in this research was to determine the toxic effects of Cd on antioxidant enzymes of Oxya chinensis (Orthoptera: Acridoidae). Changes in the activities of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), and guaiacol peroxidase (GPx) were measured in O. chinensis insects injected with Cd(2+). Fifth-nymphs of O. chinensis insects were injected with Cd(2+) at different concentrations (0, 0.55×10(-4), 1.10×10(-4), 1.65×10(-4), 2.20×10(-4), and 2.75×10(-4)gg(-1)). An increase in SOD activity in O. chinensis was observed at 1.10×10(-4) to 2.75×10(-4)gg(-1) Cd(2+). The SOD activity was lower at 2.20×10(-4)and 2.75×10(-4)gg(-1) than that at 1.10×10(-4) and 1.65×10(-4)gg(-1). It appears that SOD had a positive protective effect at low Cd(2+) concentrations, and that this effect disappeared at high Cd(2+) concentrations. CAT activity was accelerated to varying degrees at 1.10×10(-4) to 2.75×10(-4)gg(-1) for males and at 1.10×10(-4), 2.20×10(-4), and 2.75×10(-4)gg(-1) for females. CAT showed a strong detoxification effect with all treatments. GPx activity decreased with increasing Cd(2+) concentration with all treatments for males and at 2.20×10(-4) and 2.65×10(-4)gg(-1) for females. We showed that GPx activity had a weak detoxification function with all treatments for males and at high Cd(2+) for females. Thus, CAT had a strong detoxification effect, whereas SOD had a medium and GPx had a weak detoxification effect. Among the three enzymes, CAT played an important role in the damaging mechanisms of reactive oxygen species in O. chinensis insects. Alterations of the antioxidant enzyme level under environmental stresses are suggested as indicators of biotic and abiotic stress.

Expression and Characterization of a Sigma-Class Glutathione S-transferase of the Oriental Migratory Locust, Locusta migratoria manilensis (Meyen)

Abstract A cDNA encoding a sigma-class glutathione S-transferase of the locust, Locusta migratoria manilensis (LmGSTsl), was cloned by reverse transcriptase-polymerase chain reaction. The 830 bp-long cDNA encoded a 615 bp open reading frame (204 amino acid polypeptide), which exhibited the structural motif and domain organization characteristic of GST sigma-class. It revealed 59, 57, 57, and 56% identities to sigma-class GSTs from Blattella germanica, Gryllotalpa orientalis, Nasonia vitripennis, and Pediculus humanus corporis, respectively. A recombinant protein (LmGSTsl) was functionally expressed in Escherichia coli cells in a soluble form and purified to homogeneity. LmGSTsl was able to catalyze the biotranslation of glutathione with l-chloro-2,4-dinitrobenzene, a model substrate for GSTs, as well as with/?-nitro-benzyl chloride. Its optimal activity was observed at pH 8.0 and at 30°C. Incubation for 30 min at temperatures below 50°C scarcely affected the activity. The I 50 of reactive blue (RB) was 18.5 umol L- 1 . In the presence of 0.05 mmol L- 1 ethacrynic acid (ECA), LmGSTsl showed (81±3)% of the original activities.

Genetic diversity of six populations of Atractomorpha sinensis and Atractomorpha peregrina in Shanxi Province, China

Ten enzymes (AAT, CK, G3PDH, HEX, IDH, LDH, MDH, ME, PGI, PGM) were examined using horizontal starch gel electrophoresis to estimate the levels of genetic variation within and among six natural populations of two grasshopper species Atractomorpha sinensis and A. peregrina from Shanxi, China. The collecting sites were geographically distant from each other from south to north: Quwo district, Linfen city; Xiangyuan county, Changzhi; Jinyuan district, Taiyuan city; Yuanping county, Xinzhou city and Fanshi county of Xinzhou.A. sinensis showed 43 alleles at 16 loci but A. peregrine showed 39 alleles at 15 loci (Idh-1 was deficient). The zymograms showed that some common alleles were shared at several loci in these two species (Aat-1-b, Aat-2-b, G3pdh-a, Ck-1-b and Ldh-b). However, Hex-1-a, Hex-2-a, Hex-3-a, Idh-2-b, Mdh-2-b, Mdh-1-f, Pgi-b, Pgm-b had common alles in A. sinensis and Hex-1-b, Hex-2-b, Hex-3-b, Idh-2-a, Mdh-2-a, Mdh-1-d, Pgi-a, Pgm-c were of high frequency in A. peregrine instead. Most of the observed genotype frequencies were found to significantly deviate from the Hardy-Weinberg expectations in both species. A tendency of clinal distribution of allele frequency was observed at three loci. The frequency of the moderately migrating allele Me-c (0.318–0.740) in A. peregrina, Hex-1-a (0.800–1.000) and Ldh-b (0.487–0.750) in A. sinensis demonstrated increased frequency from north to south. Such tendency suggests that the allele frequency in these three loci may be correlated with the species’ geographic distributions. A. sinensis showed higher genetic diversity than A. peregrina as indicated by higher mean number of alleles per locus (A = 1.9–2.3 in A. sinensis and 1.7–2.2 in A. peregrina), percentage of polymorphic loci (56.3%–68.8% in A. sinensis and 43.8%–56.3% in A. peregrina), and the observed heterozygosities (Ho = 0.072–0.096 in A. sinensis and 0.70–0.107 in A. peregrina). The observed heterozygosities of the six populations were all noticeably lower than the Hardy-Weinberg expectations, mostly due to heterozygote deficiency in the populations of both species. The overall mean FST were small (FST = 0.045, P > 0.05 in A. sinensis populations and 0.087, P > 0.05 in A. peregrina populations). Nei’s genetic identity (I) estimates indicate low intraspecific (>0.95) but higher interspecific (0.377–0.447) genetic diversity. The cluster analysis based on modified Roger’s genetic distance (D) showed that the two species were divided into two branches.Both species are of limited dispersal capacity and a moderate geographical barrier might significantly restrict the gene exchange among populations, resulting in accumulation of local genetic differentiations. The A. sinensis populations used in this study were separated from each other by 155.2 to 271.4 km and the A. peregrina populations were separated from each other by 78.8 to 174.9 km with observable physical barriers. The allozyme data showed only minimal genetic differentiation at population level, most likely as a result of gene exchange. It is reasoned that natural factors and human agricultural activities might have facilitated migration and dispersal for the two species.