Predation and control efficacies of Misgurnus mizolepis (Cypriniformes: Cobitidae) toward Culex pipiens molestus (Diptera: Culicidae) and fish toxicity of temephos in laboratory and septic tank conditions.

Culex pipiens molestus Forskal (Diptera: Culicidae) is the dominant mosquito species in septic tanks in South Korea. An assessment was made of the biological control potential of mud loaches, Misgurnus mizolepis Günther (Cypriniformes: Cobitidae), toward Cx. p. molestus larvae in laboratory and septic tanks. Results were compared with those of temephos 20% emulsifiable concentrate. In laboratory tests, all mud loaches survived on sedimentation chamber- and effluent chamber-collected water of aerobic septic tanks (ASTs), whereas all mud loaches died within 3-12 h after introduction into sedimentation chamber- and effluent chamber-collected water of anaerobic septic tanks, Gill hyperplasia and hemorrhages at the bases of pectoral fins were detected in all dead mud loaches. These appeared to have been caused by bacterial disease, rather than the physical and chemical characteristics of the septic tank water. A mud loach consumed an average range of 1,072-1,058 larvae of Cx. p. molestus in the AST water at 24 h. At the manufacturer's recommended rate (10 ml/ton) in the AST water, the temephos formulation did not cause fish mortality. In the AST experiment, predation of mosquito larvae by mud loaches at a release rate of one fish per 900 mosquito larvae resulted in complete mosquito control from the third day after treatment throughout the 18-wk survey period, compared with temephos 20% emulsifiable concentrate-treated AST water (reduction rate, 40% at 28 days after treatment). Reasonable mosquito control in aerobic septic tanks can be achieved by mosquito breeding season stocking of a rate of one mud loach per 900 mosquito larvae.

Gender-specific molecular heterosis of dopamine D2 receptor gene (DRD2) for smoking in schizophrenia.

We examined the genetic effect of DRD2 A1 allele in 167 Korean schizophrenics in relation to their smoking habit. Although there was no apparent difference in the genotype distributions of DRD2 gene among the female schizophrenics (n = 66), the male counterpart (n = 101) showed significant differences in their genotype distributions. The comparison between male smoking and non-smoking patients showed the difference in genotype distribution (P = 0.010) with a higher prevalence of A1 allele (P = 0.020) and frequency of heterozygotes (P = 0.005), but not frequency of the A1 allele. The A1A2 heterozygotes male showed significantly higher smoking rate compared to the A1A1 or A2A2 homozygotes male, and non-smokers were deficient in heterozygotes. By contrast, among female schizophrenics, the heterozygotes showed a lower smoking rate than homozygotes and there were more heterozygotes in non-smokers. The deviation from Hardy-Weinberg expectations was observed in male and female non-smokers showing quite opposite profiles. Highly significant differences were seen between male and female non-smokers in A1 prevalence (P = 0.001), genotype distribution (P = 0.00011), and frequency of heterozygotes (P = 0.00003), but not in A1 frequency. The analyses from both male and female as one group showing no significant difference in the genotype distributions between smokers and non-smokers could be explained by the gender difference in the genetic effect of DRD2 A1 allele. Our findings present the gender-specific molecular heterosis of DRD2 gene in relation specifically to the smoking status of schizophrenic patients. They indicate the importance of heterosis and gender effects that should be taken into consideration for the association studies.