Energy Metabolism Focused Analysis of Sexual Dimorphism in Biological Aging and Hypothesized Sex-specificity in Sirtuin Dependency.

The process of biological aging or senescence refers to the gradual loss of homeostasis and subsequent loss of function - leading to higher chances of mortality. Many mechanisms and driving forces have been suggested to facilitate the evolution of a molecular circuit acting as a trade-off between survival and proliferation, resulting in senescence. A major observation on biological aging and longevity in humans and model organisms is the prevalence of significant sexual divergence in the onset, mechanisms and effects of aging associated processes. In the current account, we describe possible mechanisms by which aging, sex and reproduction are evolutionarily intertwined in order to maintain systemic energy homeostasis. We also interrogate existing literature on the sexual dimorphism of genetic, cellular, metabolic, endocrine and epigenetic processes driving cellular and systemic aging. Subsequently, based on available evidence, we propose a hypothetic model of sex-limited decoupling of female longevity from sirtuins, a major family of regulator proteins of the survival-proliferation trade-off. We also provide necessary considerations to be made in order to test the hypothesis and explore the physiological and therapeutic implications of this decoupling event in male and female longevity after reaching reproductive maturity. HYPOTHESIS STATEMENT: Sirtuins provide survival benefits in a sex-nonspecific manner but the dependency on sirtuins in driving metabolic networks after reaching reproductive maturity is evolutionarily decoupled from female longevity.

Fast Screening of Tissue Samples for Glycogen.

Screening of tissue samples for glycogen is very important in assessing the ageing, but also the state of health of the tissue. Therefore, two needle stochastic sensors based on maltodextrins presenting different dextrose equivalence (DE) MD-m (DE 13.0-17.0), and MD-M (DE 16.5-19.5) immobilized in diamond paste (obtained from synthetic diamond and paraffin oil) were designed and characterized. These stochastic sensors were used reliable for both qualitative and quantitative analysis for the assay of glycogen in tissue samples with limits of determination as low as 1fmol L-1.

A new hypothesis of aging.

INTRODUCTION AND AIMS: There are over 300 hypotheses of aging, but none of them has enough predictive power to explain most experiments and observations on this process. On the basis of a critical analysis of the most relevant data on aging, especially on the factors that influences its rhythm, we present a new hypothesis, as well as the way the hypothesis' predictions explain some of the phylogenetic implications of the aging process. METHODS: The hypothesis starts from a new, biochemical view on evolution and the behavior of living matter. According to this view, life is a fabric of chemical reactions that sustain each other. Reactants and energy support are needed for these reactions to take place in a cell. Given this, aging stems from a leftward shift of the global equilibrium of some biochemical reactions involved in cell differentiation and repair, which take place at a high level during the organism's growth period. In time, for species with evident aging, some reactions lose their specificity, which affects cell division and differentiation. This, in turn, influences cell energy metabolism. RESULTS: Cell and tissue degeneration appears when, while some specific reactions are absent, non-specific reactions such as those of cell proliferation receive additional energy support. CONCLUSIONS: This hypothesis explains phylogenetic differences related to lifespan and longevity, and body-size differences between species and within the same species.