Biosynthesis and metabolism of juvenile hormone III from methyl farnesoate by exposed corpora allata of Lutzomyia anthophora

Abstract

The in-vitro biosynthesis of [12-3H] juvenile hormone (JH) III by exposed corpora allata (CA) of teneral, sugar-fed, and blood-fed female Lutzomyia anthophora (Addis) was followed by incubating the CA for 4 h with [12-3H]methyl farnesoate. Synthesis of [12-3H]H III was determined by C18 reversed-phase high-pressure liquid chromatography (HPLC) and preparative gas chromatography. The rate of synthesis of JH III by teneral females was 5.6 fmol/h per CA. The CA of 1-d-old females synthesized 17 fmol/h per CA, whereas 3-d-old females synthesized 5.4 fmol/h per CA. The rate of synthesis of JH III 4 h after the blood meal increased to 17.3 fmol/h per CA and then declined to reach a minimum of 1.6 fmol/h per CA at 30 h before increasing again to reach 21.6 fmol/h per CA at 96 h. The concentration of methyl farnesoate in the tissue culture medium during incubation of CA from sugar- and blood-fed females was compared with the rate of synthesis of JH III and its metabolites diol-acid, diol, acid, and bisepoxide. The rate of synthesis of JH III and its metabolites from methyl farnesoate indicated a steady-state equilibrium of synthesis and metabolism of JH III by the exposed CA. The rapid increase in JH III synthesis immediately after the blood meal confirmed that in sand flies, like mosquitoes, there is an increase in the rate of synthesis of JH III immediately after the female takes blood. The role of the hormone in vitellogenin biosynthesis is also discussed.