Trends in lipid and protein contents during medfly aging: An harmonic path to death (original) (raw)
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Proceedings of the Royal Society B: Biological Sciences, 2004
Understanding the factors that determine the allocation and utilization of organism resources may provide an insight into the mechanisms of adaptation, ageing and reproduction. Resource allocation, which is regarded as a method of adaptation, increases fitness and is genetically controlled. Experiments with variable diet feeding of female Mediterranean fruitflies (Ceratitis capitata) demonstrated that the feeding regime dramatically influences lifespan, mortality and the reproduction of flies. An analysis of experimental data and numerical experiments reveals that resource allocation could explain lifespan increase when females are switched from a sugar-only to a protein-containing diet. The heterogeneity of the initial female cohort in terms of the total amount of resources and its allocation to the processes of maintenance and reproduction plays a significant role in this.
Macronutrient balance, reproductive function, and lifespan in aging mice
Proceedings of the National Academy of Sciences of the United States of America, 2015
In invertebrates, reproductive output and lifespan are profoundly impacted by dietary macronutrient balance, with these traits achieving their maxima on different diet compositions, giving the appearance of a resource-based tradeoff between reproduction and longevity. For the first time in a mammal, to our knowledge, we evaluate the effects of dietary protein (P), carbohydrate (C), fat (F), and energy (E) on lifespan and reproductive function in aging male and female mice. We show that, as in invertebrates, the balance of macronutrients has marked and largely opposing effects on reproductive and longevity outcomes. Mice were provided ad libitum access to one of 25 diets differing in P, C, F, and E content, with reproductive outcomes assessed at 15 months. An optimal balance of macronutrients exists for reproductive function, which, for most measures, differs from the diets that optimize lifespan, and this response differs with sex. Maximal longevity was achieved on diets containing a P:C ratio of 1:13 in males and 1:11 for females. Diets that optimized testes mass and epididymal sperm counts (indicators of gamete production) contained a higher P:C ratio (1:1) than those that maximized lifespan. In females, uterine mass (an indicator of estrogenic activity) was also greatest on high P:C diets (1:1) whereas ovarian follicle number was greatest on P:C 3:1 associated with high-F intakes. By contrast, estrous cycling was more likely in mice on lower P:C (1:8), and the number of corpora lutea, indicative of recent ovulations, was greatest on P:C similar to those supporting greatest longevity (1:11).
Diet has independent effects on the pace and shape of aging in Drosophila melanogaster
Biogerontology
Studies examining how diet affects mortality risk over age typically characterise mortality using parameters such as aging rates, which condense how much and how quickly the risk of dying changes over time into a single measure. Demographers have suggested that decoupling the tempo and the magnitude of changing mortality risk may facilitate comparative analyses of mortality trajectories, but it is unclear what biologically meaningful information this approach offers. Here, we determine how the amount and ratio of protein and carbohydrate ingested by female Drosophila melanogaster affects how much mortality risk increases over a timestandardised life-course (the shape of aging) and the tempo at which animals live and die (the pace of aging). We find that pace values increased as flies consumed more carbohydrate but declined with increasing protein consumption. Shape values were independent of protein intake but were lowest in flies consuming~90 μg of carbohydrate daily. As protein intake only affected the pace of aging, varying protein intake rescaled mortality trajectories (i.e. stretched or compressed survival curves), while Electronic supplementary material The online version of this article (
Rejuvenation research, 2005
Fecundity seems to stop declining and plateaus at low levels very late in Drosophila melanogaster populations. Here we test whether this apparent cessation of reproductive aging by a population, herein referred to as fecundity plateaus, is robust under various environmental influences: namely, male age and nutrition. The effect of male age on late age fecundity patterns was tested by supplying older females with young males before average population fecundity declined to plateau levels. The second possible ...
Maternal age affects offspring nutrient dynamics
Journal of insect physiology, 2017
The internal physiological state of a mother can have major effects on her fitness and that of her offspring. We show that maternal effects in the parasitic wasp Eupelmus vuilleti become apparent when old mothers provision their eggs with less protein, sugar and lipid. Feeding from a host after hatching allows the offspring of old mothers to overcome initial shortages in sugars and lipids, but adult offspring of old mothers still emerged with lower protein and glycogen quantities. Reduced egg provisioning by old mothers had adverse consequences for the nutrient composition of adult female offspring, despite larval feeding from a high-quality host. Lower resource availability in adult offspring of old mothers can affect behavioural decisions, life histories and performance. Maternal effects on egg nutrient provisioning may thus affect nutrient availability and fitness of future generations in oviparous animals.
Experimental Gerontology, 2011
We examined experimentally the relationship between the period of unhealthy life and longevity in the medfly by using the first sign of supine behavior (upside down; immobile) in medflies as an indication of their poor health and by altering cohort longevity through dietary manipulations. Our main findings included the following: i) for longer lived medflies it was more likely to observe the supine behavior while shorter lived flies would more likely die before exhibiting the supine behavior. ii) males have similar total life expectancy as females but a longer healthy life expectancy; iii) the total number of healthy days, spent in the pre-supine period, and the amount of healthy life span as a fraction of the total lifespan varied with both sex and diet; iv) despite the large difference in longevity between both male and female medflies when reared on sugar-only diets versus on full diets, the differences in the fraction of their lifespans in the disabled state were relatively modest (64 vs 61% in females and 77 vs 72% in males. This finding that there is no significant change in the proportion of the life course in the unhealthy state is consistent with the 'dynamic equilibrium' model of healthy aging.
Empirical analysis of survival data obtained from large samples of Mediterranean fruit flies shows that the trajectory of the mortality rate for virgin females departs from that for females maintained in mixed sex cages. It increases, decelerates, reaches its maximum, declines and then increases again within the reproductive interval. Non-virgin females, however, display an early-age plateau instead of this dip. We assume that these deviations are produced by the interplay between changes in oxygen consumption associated with reproductive behavior and the antioxidant defense that acts against anticipated oxidative damage caused by reproduction. Since there are no data on antioxidant mechanisms in medflies available that explain the observed patterns of mortality, we develop a model of physiological aging based on oxidative stress theory, which describes age-related changes in oxygen consumption and in antioxidative capacity during the reproductive period. Using this model, we simulate virtual populations of 25,000 virgin and non-virgin flies, calculate the respective mortality rates and show that they practically coincide with those of experimental populations. We show that the hypothesis about the biological support of reproduction used in our model does not contradict experimental data. The model explains how the early-age dip and plateau might arise in the mortality rates of female medflies and why the male mortality pattern does not exhibit such deviations. ᭧
Mechanisms of Ageing and Development, 2003
Reproduction is usually characterised by an average fecundity pattern having a maximum at earlier ages and a subsequent gradual decline later on. An individual fecundity trajectory does not follow such a pattern and has no maximum. A three-stage pattern, which includes maturation, maturity and reproductive senescence, is a more appropriate description. An analysis of the power balance of an adult female fly during its life course allows us to predict two critical periods in an individual life history. The first crisis occurs at early ages when the increasing power demand becomes greater than the power supply. It often results in premature death. The surviving flies enjoy maturity and lay eggs at a presumably constant rate. The second critical period at advanced ages ends up in a senescence-caused death. Our approach predicts that there will be a bimodal death time distribution for a population of flies.
Proceedings of the National Academy of Sciences, 1997
Experiments based on over 400,000 medf lies revealed that females maintained on a normal diet (sucrose plus protein) have a higher life expectancy than males maintained on a normal diet, with a difference of 1.30 ؎ 0.27 days in favor of females. However, this sex differential reverses under protein deprivation, with a difference of 2.24 ؎ 0.18 days in favor of males. The reversal of the male-female life expectancy differential is caused by a sustained surge in early female mortality under protein deprivation that is tied to egg-laying and physiological processes. In contrast, male mortality and life expectancy are only mildly affected by protein deprivation. The surge in early mortality for female medf ly cohorts is an instance of a vulnerable period. These vulnerable periods are linked with patterns in hazard rates.