LAUFER, H; JOHNSON, M; DEMIR, N; TWIDY, K; CHANG, E; BAGSHAW, J; SOYEZ, D (CNRS Paris), VAN HERP, F (Nijmegen Netherlands); The University of Connecticut, Storrs; The University of Connecticut, Storrs &MBL, Woods Hole; The University of Connecticut, Storrs& MBL, Woods Hole; The University of Connecticut, Storrs&MBL, Woods Hole; Bodega Marine Lab, CA; Worcester Polytech Institute, MA: Identification of Lobster Hyperglycemic Hormones (CHHs) with Mandibular Organ Inhibiting Activity

CHHs are a family of neuropeptides synthesized mostly in the crustacean X-organ and sinus gland (SG). They are multifunctional, 72 to 83 amino acids long. Molt inhibiting hormone (MIH), crustacean hyperglycemic hormone A and B (CHHA, CHHB), and gonad-inhibiting hormone (GIH), also termed vitellogenin inhibiting hormone (VIH), have been sequenced and some have been cloned from the lobster. To date no mandibular organ inhibiting hormones (MOIHs) have been identified in the lobster, Homarus americanus. We had shown earlier that MOIHs from Libinia emarginata are members of the CHH family. MOIHs inhibit synthesis of methyl farnesoate (MF) by the mandibular organ (MO). MF is a crustacean juvenile hormone and plays a role in reproduction, morphogenesis, and metamorphosis. We used absorption with MIH, CHHA and VIH lobster antibodies to reverse MOIH inhibition by SG extracts on MO cell cultures. While MIH and CHHA antibodies had no significant effect on the ability of SG extracts to inhibit MF synthesis by MO cells, antibody to VIH reversed the effects of SG extracts on the ability of MO cells to synthesize MF by about 50%. We used media from Pichia cultures expressing CHHB peptide to assay MOIH activity on cultured MO cells. Fifty ml of media was equivalent to 0.4 SG of MOIH activity. We conclude that both CHHB and VIH or GIH from the lobster exhibit significant MOIH activity in vitro bioassays, and appear to be lobster MOIHs. (Research supported by Sea Grant College Program and Connecticut DEP)