DISTRIBUTION AND REGULATION OF ESTERASES THAT HYDROLYZE METHYL FARNESOATE IN HOMARUS-AMERICANUS AND OTHER CRUSTACEANS

Ester hydrolysis of methyl farnesoate (MF) by crustacean tissue homoge nates was measured using the substrate [H-3]MF in a radiochemical part ition assay. Tissues were obtained from the lobster Homarus americanus , penaeid shrimp Sicyonia ingentis, thalanassid shrimp Callianassa cal iforniensis, sand crab Emerita analoga, and spider crab Pugettia produ cta. The greatest specific activities were recovered from the hepatopa ncreas (239 to 11,500 pmol MF/min-mg total protein). Hepatopancreatic homogenates of C. californiensis were significantly more active than h omogenates from the other species. In the lobster, esterases that hydr olyze MF were associated with lipid storage (R) cells of the hepatopan creas. Enzyme activity of lobster larval homogenates increased 1.5-fol d during the second stage of development. The rate of MF hydrolysis by esterases extracted from the juvenile lobster hepatopancreas could no t be correlated with molt stage or sex and was not significantly influ enced by eyestalk ablation, mandibular organ ablation, or MF injection . (C) 1997 Academic Press.