Genetic and molecular evidence for a trans-acting regulatory locus controlling glutathione S-transferase-2 expression in Aedes aegypti.
The amount of glutathione S-transferase-2 (GST-2) protein and enzyme activity in a mutant strain (strain GG) of the yellow fever mosquito (Aedes aegypti) is approximately 25-fold higher than in the wild-type (++) strain. The mode of inheritance of the GG phenotype was studied in F1 and backcross progeny using GST enzyme assays, isozyme-specific antisera, and Northern blot analysis. Enzyme assay of parental and F1 progeny showed that the ++ phenotype was dominant to the GG phenotype. This was true for larvae as well as for all tissues examined in adults in both sexes. Immunoblotting experiments showed that, like the ++ strain, F1 larvae and adults express very low levels of GST-2 protein compared with the GG strain. Northern blotting experiments showed that the steady-state levels of GST-2 mRNA in parental and F1 hybrid larvae closely matched the enzyme activity and immunological data. These results suggest the existence of a trans-acting regulatory locus that acts to repress GST-2 mRNA transcription and/or decrease GST-2 mRNA stability in ++ and F1 hybrids. GST enzyme activity in backcross progeny, however, did not segregate into the two distinct phenotypes (low and high) predicted for a single locus, dominant allele model. Backcross progeny expressed a wide range of GST activity and GST-2 protein amount with no apparent fit to simple Mendelian ratios. These backcross data suggest that additional loci are also involved in regulating GST-2 isozyme expression.(ABSTRACT TRUNCATED AT 250 WORDS)
Grant
D F
DF
Department of Environmental Toxicology, University of California, Davis 95616.
Hammock
B D
BD
D000330:Aedes / Q000201:enzymology* / Q000235:genetics; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D003001:Cloning, Molecular; D015971:Gene Expression Regulation, Enzymologic / Q000235:genetics*; D005809:Genes, Regulator / Q000235:genetics*; D005982:Glutathione Transferase / Q000235:genetics*; D015151:Immunoblotting; D007305:Insecticide Resistance / Q000235:genetics*; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics
D005982:Glutathione Transferase