Studies of Methyl Farnesoate in Crustaceans: Physiological Significance and Peptide Regulation

Board Of Trustees Of Illinois State University, Normal IL

Investigators

Abstract

Crustaceans have a rich diversity of hormones that regulate their physiology, development, reproduction, and behavior. One of these compounds appears to be methyl farnesoate (MF), a sesquiterpene produced by the mandibular organ (MO). Recent research suggests that MF may affect crustacean growth and reproduction, but these studies do not definitively prove these roles. Other research has shown that the eyestalk produces a peptide (MO-inhibiting hormone, MO-IH) that can inhibit the production of MF by MO in vitro, but it has not been shown that MO-IH regulates MF in vivo. The research described in this proposal will explore these issues in the green crab, Carcinus maenas. The physiological role(s) of MF will be investigated by infusing crabs with MF (to increase MF levels) and/or with purified MO-IH (to decrease MF levels). Some animals will be transferred to dilute seawater, which causes a chronic rise in MF levels, before infusion with MF and/or MO-IH. These procedures will be used to test hypotheses that MF regulates osmoregulation and stimulates ovarian and testicular development. Purified MO-IH will also be used to develop antisera to MO-IH, and these antisera will be used to develop immunological test for this peptide. MO-IH and MF will be measured in hemolymph from crabs in different physiological states to test the hypothesis that MO-IH regulates hemolymph levels of MF. These studies will answer fundamental questions about the roles of MF in the physiology and development of this important group of animals. The results may be useful in designing strategies to increase the growth rate and reproductive fecundity of valuable crustaceans (e.g. shrimp), which could benefit consumer and the aquaculture industry. Finally, many of these studies will be performed by undergraduate students, providing them with a hands-on opportunity to learn science during the academic year and for extended periods during the summer.