Meeting Abstract

S2.5  Monday, Jan. 4  Nutrient allocation in long-lived ovariectomized grasshoppers: tests of the disposable soma hypothesis JUDD, Evan T; DREWRY, Michelle; WRIGHT, Katharine; WESSELS, Frank; HAHN, Daniel A; HATLE, John D*; University of North Florida; University of North Florida; University of North Florida; University of Florida; University of Florida; University of North Florida jhatle@unf.edu

The conserved trade-off between reduced reproduction and extended longevity is often posited to occur through nutrient allocation (aka. disposable soma hypothesis). There is circumstantial evidence to support this hypothesis, but little direct evidence. Stable isotopes have been used to track ingested nutrients in reproduction, but only two studies have applied this to aging, both using dietary restriction. In grasshoppers, directly curtailing reproduction via ovariectomy increases lifespan by ~30%. Here, diets with distinct stable isotope signatures were used to track the allocation of ingested nutrients in individuals that were either ovariectomized or sham operated. Data on hemolymph proteins hinted that, in ovariectomized females, nutrients are shifted from reproduction to storage after parallel controls lay their 1st clutch. To test this, after the 1st clutch we switched the stable isotope composition of the diet of some individuals. Fat body mass (P<0.0001) wase larger in ovariectomized individuals, so morphological results indicate that ovariectomy increases storage. Opposite of the prediction of the disposable soma hypothesis, aqueous extracts of the fat body of ovariectomized females accumulated less 15N ingested during the 2nd clutch (P = 0.002) than did the fat body of sham females. Accumulation of 13C was also in the opposite direction of that predicted (P = 0.053). Hence, the stable isotope results suggest that allocation of nutrients is not increased in somatic tissues upon ovariectomy, which is inconsistent with the disposable soma hypothesis. Future work will examine allocation between hemolymph storage proteins and vitellogenin.