- http://scholar.harvard.edu/quattrochi
John Quattrochi
Simmons University, Public Health, Faculty Member
Summary Dietary restriction and reduced reproduction both e xtend lifespan in many animals. Because dietary restriction decreases reproductive output i n most species, the long-standing view has been that both extend lifespan via the same... more
Summary Dietary restriction and reduced reproduction both e xtend lifespan in many animals. Because dietary restriction decreases reproductive output i n most species, the long-standing view has been that both extend lifespan via the same fundame ntal mechanism: fewer nutrients are allocated to reproduction, allowing greater somatic maintenance and storage. We have used grasshoppers to address the linkages among nutritio n, reproduction, and longevity. Female grasshoppers offered 70% of an ad libitum diet live d nearly twice as long as females fed ad libitum. Females on the 70% diet did not delay ovip osition, reduce lifetime output of vitellin (i.e., egg protein), or reduce levels of hemolymph storage proteins in comparison to controls. In separate experiments, ovariectomy increased surv ivorship by 30% over sham controls. In contrast to dietary restriction, old ovariectomized females had lower levels of reproductive protein and higher levels of storage protein than c ontrols. Thes...
Research Interests:
Research Interests:
Calorie restriction (CR) and late-onset CR enhance longevity in many organisms. Resource allocation theory suggests that longevity is enhanced by increasing somatic storage, at the expense of current reproduction. Phytophagous insects... more
Calorie restriction (CR) and late-onset CR enhance longevity in many organisms. Resource allocation theory suggests that longevity is enhanced by increasing somatic storage, at the expense of current reproduction. Phytophagous insects accumulate amino acids as hemolymph storage proteins for major developmental events. We hypothesized that protein storage is involved in life extension from CR. In a longitudinal experiment, we tested whether CR altered protein storage in female grasshoppers. Individuals on CR (60 or 70% of ad libitum) or late-onset CR had at least 60% greater longevity than ad libitum individuals. Age at first oviposition, dry mass of the first clutch, or lifetime fecundity were not affected by CR, but CR did increase the number of clutches produced. Most important, females on life-extending CR and late-onset CR did not differ in the concentration of hemolymph storage of proteins in comparison to ad libitum females. Protein storage changed with time in all groups, demonstrating sufficient sensitivity in our methods. Previous experiments have shown that severe CR ( approximately 30% of ad libitum) can reduce hemolymph storage. Therefore, the reduction in intake needed to extend lifespan is not sufficient to reduce protein storage in the hemolymph. These results do not support the hypothesis that protein storage is involved in life extension from CR.
Research Interests:
Much research has focused on identifying species that are susceptible to extinction following ecosystem fragmentation, yet even those species that persist in fragmented habitats may have fundamentally different ecological roles than... more
Much research has focused on identifying species that are susceptible to extinction following ecosystem fragmentation, yet even those species that persist in fragmented habitats may have fundamentally different ecological roles than conspecifics in unimpacted areas. Shifts in trophic role induced by fragmentation, especially of abundant top predators, could have transcendent impacts on food web architecture and stability, as well as ecosystem function. Here we use a novel measure of trophic niche width, based on stable isotope ratios, to assess effects of aquatic ecosystem fragmentation on trophic ecology of a resilient, dominant, top predator. We demonstrate collapse in trophic niche width of the predator in fragmented systems, a phenomenon related to significant reductions in diversity of potential prey taxa. Collapsed niche width reflects a homogenization of energy flow pathways to top predators, likely serving to destabilize remnant food webs and render apparently resilient top predators more susceptible to extinction through time.