Meeting Abstract

P2.143  Thursday, Jan. 5  Physiological effects of RNAi for vitellogenin on somatic storage and reproduction in grasshoppers TOKAR, DR*; VELETA, K; CANZANO, J; HAHN, DA; HATLE, JD; Univ. of North Florida; Univ. of North Florida; Univ. of North Florida; Univ. of Florida; Univ. of North Florida jhatle@unf.edu

Trade-offs between reproduction and storage are widespread in animals, but the physiological basis of these trade-offs is known in only a few cases. To understand how organismal storage responds to the investment of protein resources in reproduction, we investigated the physiological responses to direct reduction of vitellogenin. In the grasshopper Romalea microptera, vitellogenin is a precursor protein to vitellin. Eggs are ~50% lipid and ~50% protein, of which ~90% is vitellin. We used RNAinterference (RNAi) to reduce vitellogenin transcript abundance. We compared vitellogenin RNAi treatments to two control groups, buffer-injected individuals, and individuals treated with RNAi against a 90 kDa hexameric storage protein from the hemolymph. Individuals were injected with dsRNA 5 days after adult ecdysis. Dissections were performed at ages 12, 19, 26, and 33 days. Ovarian mass and oocyte length were significantly decreased in the vitellogenin knockdown group (P=0.0152 and P<0.0001, respectively); in contrast, they were not changed in the buffer or 90 kDa hexamerin RNAi groups. Early results suggest that mRNA levels of vitellogenin and 90 kDa hexamerin were reduced substantially by their respective RNAi treatments. Fat body mass was significantly increased (P<0.0001) in the vitellogenin knockdown group. This suggests that knockdown of reproductive protein may result in greater storage of somatic lipids. This preliminary conclusion will be further tested by measures of fat body composition and hemolymph protein levels in response to RNAi treatment. Funding provided by NIH 2R15AG028512-02A1 to JDH.