Meeting Abstract

129.1  Tuesday, Jan. 7 13:30  Elucidating the Synthesis of Methyl Farnesoate in the Tissues of the Tadpole Shrimp, Triops longicaudatus TERUSAKI, A.T.*; TSUKIMURA, B.; California State University, Fresno; California State University, Fresno Aterusaki@gmail.com

In crustaceans, methyl farnesoate (MF) acts as a juvenilizing factor, maintaining juvenile characteristics and delaying reproductive development. The synthesis of MF is catalyzed by the enzyme farnesoic acid O-methyltransferase (FAMeT) in the mandibular organ (MO) of crustaceans through the methylation of farnesoic acid (FA). The tadpole shrimp (TPS) have a simplified body structure lacking such endocrine organs like the MO. Previous research in our lab showed that TPS fed on nutrient pellets containing the hormone MF have decreased oocyte production during larval and juvenile stages. This decrease in oocyte production is due to a delay in the reproductive development mirroring the effects seen in other crustaceans. However, the site for MF synthesis has yet to be determined. In this study we look to identify tissues responsible for the synthesis of MF. A radiochemical assay was used to measure the synthesis activity of select TPS tissues. Our results show that TPS synthesize MF ubiquitously across their entire body. This notable difference correlates with the absence of a MO in the TPS and suggests that there may be no central site of synthesis of MF. FAMeT activity decreased in 6 day old TPS. This decrease at 6 days old may be associated with the end of the TPS juvenile stage and reproductive development. We also measured the activity of TPS fed daily on a diet containing MF. Isolated tissues and whole body homogenates of animals fed on the MF diet showed no observable difference in activity compared to controls. FAMeT activity increased on day 9 and then decreased by day 12, which corresponds to low MF levels in adults.