This study will determine the direct effects of the adult ovary on mortality rate in an insect model organism. Reproduction may shorten lifespan in at least two ways: limited nutrients may be allocated to reproductive processes instead of the soma, or reproduction may create direct negative effects on longevity that are independent of nutritional allocation (e.g., release of aging hormones). The effects of calorie restriction on longevity are well studied. The contributions of reproduction that are independent of nutrition are not well understood. In this project, I examine the model of direct effects of reproduction on longevity. This model posits that when germ-line tissue is intact it directly reduces the individual's ability to resist cellular stress or minimize oxidation, thereby increasing age-specific mortality rate independently of nutrition. Grasshoppers are excellent models for this approach to aging because they are large enough for tracking individuals and analyzing multiple tissues, but are shorter-lived (approximately 80 days) and cheaper than mice. Plasticity of reproduction in grasshoppers is well characterized; this proposal extends these studies to plasticity of stress tolerance and age-specific mortality.
Aim #1 will test whether ovariectomized females have higher constitutive levels of heat shock protein 70 and superoxide dismutase activity. The model of direct effects on reproduction predicts higher Hsp70 levels and superoxide dismutase activities.
Aim #2 will test whether the ovary decreases age-specific mortality rate independently of nutritional allocation to vitellogenesis. The model of direct effects of reproduction on longevity predicts the ovary will decrease mortality rate with decreasing vitellogenesis.
Aim #3 will test whether ovarian effects on mortality rate are linked to nutrient allocation. The model of direct effects of reproduction on longevity predicts that ovarian effects do not act through nutritional allocation. Understanding the basic biology of aging is critical to the health care of the nation. Reproduction is known to reduce longevity, but how this can occur independently of nutrition is not clear. Using an insect model, this proposal will examine whether the ovary decreases life-span, without the confounding affects of nutritional distribution. Ovarian control of stress proteins and anti-oxidants will also be tested. Last but not least, this grant will have a profound effect on the research environment in biology at the University of North Florida. ? ? ? ?

National Institute of Health (NIH)
National Institute on Aging (NIA)
Academic Research Enhancement Awards (AREA) (R15)
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Cellular Mechanisms in Aging and Development Study Section (CMAD)
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Murthy, Mahadev
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University of North Florida
Schools of Arts and Sciences
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Hatle, John D; Awan, Ayesha; Nicholas, Justin et al. (2017) Life-extending dietary restriction and ovariectomy each increase leucine oxidation and alter leucine allocation in grasshoppers. Exp Gerontol 96:155-161
Tetlak, Alicia G; Burnett, Jacob B; Hahn, Daniel A et al. (2015) Vitellogenin-RNAi and ovariectomy each increase lifespan, increase protein storage, and decrease feeding, but are not additive in grasshoppers. Biogerontology 16:761-74
Tokar, Derek R; Veleta, Katherine A; Canzano, Joseph et al. (2014) Vitellogenin RNAi halts ovarian growth and diverts reproductive proteins and lipids in young grasshoppers. Integr Comp Biol 54:931-41
Hatle, John D; Kellenberger, James W; Viray, Ephraim et al. (2013) Life-extending ovariectomy in grasshoppers increases somatic storage, but dietary restriction with an equivalent feeding rate does not. Exp Gerontol 48:966-72
Wessels, Frank J; Kristal, Ross; Netter, Fleta et al. (2011) Does it pay to delay? Flesh flies show adaptive plasticity in reproductive timing. Oecologia 165:311-20
Urian, Alyson G; Hatle, John D; Gilg, Matthew R (2011) Thermal constraints for range expansion of the invasive green mussel, Perna viridis, in the southeastern United States. J Exp Zool A Ecol Genet Physiol 315:12-21
Judd, Evan T; Wessels, Frank J; Drewry, Michelle D et al. (2011) Ovariectomy in grasshoppers increases somatic storage, but proportional allocation of ingested nutrients to somatic tissues is unchanged. Aging Cell 10:972-9
Stauffer, Timothy W; Hatle, John D; Whitman, Douglas W (2011) Divergent egg physiologies in two closely related grasshopper species: Taeniopoda eques versus Romalea microptera (Orthoptera: Romaleidae). Environ Entomol 40:157-66
Drewry, M D; Williams, J M; Hatle, J D (2011) Life-extending dietary restriction and ovariectomy result in similar feeding rates but different physiologic responses in grasshoppers. Exp Gerontol 46:781-6
Judd, Evan T; Hatle, John D; Drewry, Michelle D et al. (2010) Allocation of nutrients to somatic tissues in young ovariectomized grasshoppers. Integr Comp Biol 50:818-28

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