Genetic polymorphism, mapping, and characterization of isocitrate dehydrogenase in Anopheles quadrimaculatus.

The isocitrate dehydrogenase-2 (Idh-2) locus of Anopheles quadrimaculatus was analyzed genetically and the enzyme was characterized physiochemically. Three-point testcrosses involving chromosome 3 markers showed that in female hybrids the gene sequence and the map distances are: nonstripe (st)--6.8--Idh-2--43.5--short antenna (Sa). Reduced recombination frequencies were observed in male hybrids (st--3.4--Idh-2--25.5--Sa). Idh-2 activity gradually increases during development and reaches a peak intensity in adults. Maximum enzyme activity of Idh-2 was obtained at pH 7.5. One-minute heat treatment at 50 degrees C caused about 50 percent reduction of IDH-2. Ethylene diamine tetraacetic acid (EDTA 5 mM) and p-chloromercuribenzoate (pCMB 10(-5)M) caused complete loss of activity of IDH-2, but pretreatment of the enzyme in situ with mercaptoethanol protected the activity of allozymes from inhibition by pCMB treatment.