Meeting Abstract
Dietary restriction (DR) is known to increase lifespan. Recent work has concluded that protein restriction is more effective at extending lifespan than DR. Amino acids in proteins, especially branched chain amino acids (BCAAs), stimulate a major cellular growth pathway, the Target of Rapamycin (TOR) pathway, resulting in growth but also accumulated damage. This has been observed in a wide range of organisms, from S. cerevisiae to D. melanogaster and M. musculus. In mammals, increased BCAA consumption activates proteins of the TOR pathway, while reduced BCAA consumption has beneficial effects such as improved glucose tolerance and decreased fat levels. To further investigate the role of BCAAs in life-extension, Eastern lubber grasshoppers (Romalea microptera) were fed different quantities of lettuce and supplemental BCAAs in a 2 x 2 design. Treatment groups were: DR lettuce & BCAAs, DR lettuce & buffer, ad libitum lettuce & BCAAs, or ad libitum lettuce & buffer. BCAA supplementation was equivalent to the BCAAs in the additional lettuce consumed by ad libitum grasshoppers in comparison to DR grasshoppers. In two similar studies BCAAs were administered for ~50 days (1/3 of the normal lubber lifespan). DR lettuce & BCAA grasshoppers, in comparison to DR lettuce & buffer grasshoppers, had significantly increased isoleucine in the hemolymph (P=0.042). There was a similar trend for leucine and valine (P=0.105). These data suggest our dietary regimens successfully altered the BCAA availability in the grasshoppers. Molecular analyses such as Western blot will determine the degree to which proteins in the TOR pathway have altered phosphorylation. Transcript levels for proteins will also be quantified to further characterize the TOR pathway when the diet of an insect is altered.
