Biosynthesis of (10R)‐Juvenile hormone III from farnesoic acid by Aedes aegypti ovary

Abstract

AbstractSynthesis of (10R)‐juvenile hormone III (JH III) outside the corpora allata (CA) was investigated in female Aedes aegypti. Intact females or ligated abdomens of blood‐fed and sugar‐fed females synthesized in vivo [12‐3H]JH III‐like molecules from [12‐3H]‐methyl farnesoate, indicating that an organ(s) in the female abdomen, other than the CA, converted methyl farnesoate into JH III. To find out the organ(s) that synthesized JH III‐like molecules, ovaries, fat bodies, and midguts were incubated in vitro with [12‐3H]methyl farnesoate and the synthesis of JH III‐like molecules was compared with JH III synthesized by CA. To identify tissue(s) having both farnesoic acid methyl transferase and farnesoate epoxidase, enzymes that convert farnesoic acid into JH III, ovaries, and fat bodies were removed from sugar and blood‐fed females and incubated with [12‐3H]farnesoic acid. Chemical derivatization by methoxyhydrin formation followed by esterification with (+)‐α‐methoxy‐ α‐trifluoromethyl phenylacetic (MTPA) acid chloride and reversed phase liquid chromatography identified (10R)‐JH III methoxyhydrin (+)‐MTPA ester as the sole JH III‐like molecule produced in tissue culture incubation of ovaries. Since only (10R)‐JH III is produced and not racemic JH III, the oxidation of farnesoic acid must be enzymatically mediated. Ovaries and corpora allata of female A. aegypti also synthesized [3H,14C]JH III from L‐[methyl‐3H]methionine and [14C]acetate which was characterized by HPLC and gas chromatography. These results suggest that mosquito ovary can synthesize (10R)‐JH III from farnesoic acid, and that this tissue synthesizes JH III‐like molecules from L‐methionine and acetate. © 1994 Wiley‐Liss, Inc.