10.1  Thursday, Jan. 3  A New Control Function for Recombinant CHHs: Control of Ovarian Ecdysteriods
LAUFER, H.*; SHIN, H.; BAGSHAW, J.; University of Connecticut, Storrs, CT AND Marine Biological Lab, Woods Hole, MA; University of Connecticut, Storrs, CT; Worcester Polytechnic Institute, Worcester, MA laufer@uconn.edu

The eyestalk Sinus Gland-x organ (SG- X organ) produces a family of neuropeptides, Crustacean Hyperglycemic Hormones (CHH), that are usually 72-85 amino acids in length, which increase blood glucose, inhibit the production of ecdysones, the molting hormone (MIH), inhibiting methyl farnesoate (MF) production by the mandibular organs (MIOH). MF is a crustacean juvenile hormone that inhibits vitellogenin synthesis by the hepatopancreas. A hormone that inhibits vitellogenin synthesis also affects reproduction and thus is a vitellogensis inhibiting hormone (VIH) also known as a gonad inhibiting hormone (GIH). We showed that a recombinant CHHb from the American lobster Homarus americanus, expressed in Pichia pastoris yeast cells, performed all of these activities, revealing CHHs to be a family of multi-functional regulatory iso-hormones. In the present study we investigated the control of ecdysteriod production by crayfish ovaries by recombinant CHHa and CHHb. Radioimmunoassays were preformed using cultured Y-organ cells (positive controls), hepatopancreas (HP) cells (negative controls), and dissociated ovarian cells (experimentals). While ovarian cells from vitellin containing ovaries produced ecdysteriods, the synthesis of ecdysone was inhibited by as much as 60% by 0.4 SG equivalents or 0.5 µg of rCHHa and b, while HP cells produced no ecdysteriods. The Y-organ cells produced ecdysteriods that were inhibited with 0.4 SG or 0.5 µg of rCHHa and b.
These results show that recombinant CHHa and b inhibit ecdysteriod synthesis by ovarian cells and indicated how CHHs can control crustacean ovarian reproduction in two distinct ways. First, by MOIH activity inhibiting MF synthesis, which is needed for vitellogenin synthesis by HP cells and by a new CHH function, inhibition of ecdysone synthesis, acting directly on ovarian cells, which also appear to play a role in reproduction. (Supported in part by the Sea Grant College Program, NOAA, and the CT Department of Environmental Protection’s Long Island Sound Research Fund)