Exploring Patterns of Human Mortality and Aging: A Reliability Theory Viewpoint

The most important manifestation of aging is an increased risk of death with advancing age, a mortality pattern characterized by empirical regularities known as mortality laws. We highlight three significant ones: the Gompertz law, compensation effect of mortality (CEM), and late-life mortality deceleration and describe new developments in this area. It is predicted that CEM should result in declining relative variability of mortality at older ages. The quiescent phase hypothesis of negligible actuarial aging at younger adult ages is tested and refuted by analyzing mortality of the most recent birth cohorts. To comprehend the aging mechanisms, it is crucial to explain the observed empirical mortality patterns. As an illustrative example of data-directed modeling and the insights it provides, we briefly describe two different reliability models applied to human mortality patterns. The explanation of aging using a reliability theory approach aligns with evolutionary theories of aging, including idea of chronic phenoptosis. This alignment stems from their focus on elucidating the process of organismal deterioration itself, rather than addressing the reasons why organisms are not designed for perpetual existence. This article is a part of a special issue of the journal that commemorates the legacy of the eminent Russian scientist Vladimir Petrovich Skulachev (1935-2023) and his bold ideas about evolution of biological aging and phenoptosis.

Does Nrf2 Play a Role of a Master Regulator of Mammalian Aging?

For a long time Nrf2 transcription factor has been attracting attention of researchers investigating phenomenon of aging. Numerous studies have investigated effects of Nrf2 on aging and cell senescence. Nrf2 is often considered as a key player in aging processes, however this needs to be proven. It should be noted that most studies were carried out on invertebrate model organisms, such as nematodes and fruit flies, but not on mammals. This paper briefly presents main mechanisms of mammalian aging and role of inflammation and oxidative stress in this process. The mechanisms of Nrf2 activity regulation, its involvement in aging and development of the senescence-associated secretory phenotype (SASP) are also discussed. Main part of this review is devoted to critical analysis of available experimental data on the role of Nrf2 in mammalian aging.

SkQ1 as a Tool for Controlling Accelerated Senescence Program: Experiments with OXYS Rats

According to the concept suggested by V. P. Skulachev and co-authors, aging of living organisms can be considered as a special case of programmed death of an organism - phenoptosis, and mitochondrial antioxidant SkQ1 is capable of inhibiting both acute and chronic phenoptosis (aging). The authors of the concept associate effects of SkQ1 with suppression of the enhanced generation of ROS in mitochondria. Numerous studies have confirmed the ability of SkQ1 to inhibit manifestations of the "healthy", or physiological, aging. According to the results of our studies, SkQ1 is especially effective in suppressing the program of genetically determined accelerated senescence in OXYS rats, which appears as an early development of a complex of age-related diseases: cataracts, retinopathy (similar to the age-related macular degeneration in humans), osteoporosis, and signs of Alzheimer's disease. Accelerated senescence in OXYS rats is associated with mitochondrial dysfunction, but no direct associations with oxidative stress have been identified. Nevertheless, SkQ1 is able to prevent and/or suppress development of all manifestations of accelerated senescence in OXYS rats. Its effects are due to impact on the activity of many signaling pathways and processes, but first of all they are associated with restoration of the structural and functional parameters of mitochondria. It could be suggested that the use of SkQ1 could represent a promising strategy in prevention of accelerated phenoptosis - early development of a complex of age-related diseases (multimorbidity) in people predisposed to it.

Discovery and Study of Transmembrane Rotary Ion-Translocating Nano-Motors: F-ATPase/Synthase of Mitochondria/Bacteria and V-ATPase of Eukaryotic Cells

This review discusses the history of discovery and study of the operation of the two rotary ion-translocating ATPase nano-motors: (i) F-ATPase/synthase (holocomplex F₁F_O) of mitochondria/bacteria and (ii) eukaryotic V-ATPase (holocomplex V₁V_O). Vacuolar adenosine triphosphatase (V-ATPase) is a transmembrane multisubunit complex found in all eukaryotes from yeast to humans. It is structurally and functionally similar to the F-ATPase/synthase of mitochondria/bacteria and the A-ATPase/synthase of archaebacteria, which indicates a common evolutionary origin of the rotary ion-translocating nano-motors built into cell membranes and invented by Nature billions of years ago. Previously we have published several reviews on this topic with appropriate citations of our original research. This review is focused on the historical analysis of the discovery and study of transmembrane rotary ion-translocating ATPase nano-motors functioning in bacteria, eukaryotic cells and mitochondria of animals.

A Mechanistic Theory of Development-Aging Continuity in Humans and Other Mammals

There is consensus among biogerontologists that aging occurs either as the result of a purposeful genome-based, evolved program or due to spontaneous, randomly occurring, maladaptive events. Neither concept has yet identified a specific mechanism to explain aging’s emergence and acceleration during mid-life and beyond. Presented herein is a novel, unifying mechanism with empirical evidence that describes how aging becomes continuous with development. It assumes that aging emerges from deterioration of a regulatory process that directs morphogenesis and morphostasis. The regulatory system consists of a genome-wide “backbone” within which its specific genes are differentially expressed by the local epigenetic landscapes of cells and tissues within which they reside, thereby explaining its holistic nature. Morphostasis evolved in humans to ensure the nurturing of dependent offspring during the first decade of young adulthood when peak parental vitality prevails in the absence of aging. The strict redundancy of each morphostasis regulatory cycle requires sensitive dependence upon initial conditions to avoid initiating deterministic chaos behavior. However, when natural selection declines as midlife approaches, persistent, progressive, and specific DNA damage and misrepair changes the initial conditions of the regulatory process, thereby compromising morphostasis regulatory redundancy, instigating chaos, initiating senescence, and accelerating aging thereafter.

Disentangling Mitochondria in Alzheimer's Disease

Alzheimer's disease (AD) is a major cause of dementia in older adults and is fast becoming a major societal and economic burden due to an increase in life expectancy. Age seems to be the major factor driving AD, and currently, only symptomatic treatments are available. AD has a complex etiology, although mitochondrial dysfunction, oxidative stress, inflammation, and metabolic abnormalities have been widely and deeply investigated as plausible mechanisms for its neuropathology. Aβ plaques and hyperphosphorylated tau aggregates, along with cognitive deficits and behavioral problems, are the hallmarks of the disease. Restoration of mitochondrial bioenergetics, prevention of oxidative stress, and diet and exercise seem to be effective in reducing Aβ and in ameliorating learning and memory problems. Many mitochondria-targeted antioxidants have been tested in AD and are currently in development. However, larger streamlined clinical studies are needed to provide hard evidence of benefits in AD. This review discusses the causative factors, as well as potential therapeutics employed in the treatment of AD.

Treating Neurodegenerative Disease with Antioxidants: Efficacy of the Bioactive Phenol Resveratrol and Mitochondrial-Targeted MitoQ and SkQ

Growing evidence from neurodegenerative disease research supports an early pathogenic role for mitochondrial dysfunction in affected neurons that precedes morphological and functional deficits. The resulting oxidative stress and respiratory malfunction contribute to neuronal toxicity and may enhance the vulnerability of neurons to continued assault by aggregation-prone proteins. Consequently, targeting mitochondria with antioxidant therapy may be a non-invasive, inexpensive, and viable means of strengthening neuronal health and slowing disease progression, thereby extending quality of life. We review the preclinical and clinical findings available to date of the natural bioactive phenol resveratrol and two synthetic mitochondrial-targeted antioxidants, MitoQ and SkQ.

The ocular surface immune system through the eyes of aging

Since the last century, advances in healthcare, housing, and education have led to an increase in life expectancy. Longevity is accompanied by a higher prevalence of age-related diseases, such as cancer, autoimmunity, diabetes, and infection, and part of this increase in disease incidence relates to the significant changes that aging brings about in the immune system. The eye is not spared by aging either, presenting with age-related disorders of its own, and interestingly, many of these diseases have immune pathophysiology. Being delicate organs that must be exposed to the environment in order to capture light, the eyes are endowed with a mucosal environment that protects them, the so-called ocular surface. As in other mucosal sites, immune responses at the ocular surface need to be swift and potent to eliminate threats but are at the same time tightly controlled to prevent excessive inflammation and bystander damage. This review will detail how aging affects the mucosal immune response of the ocular surface as a whole and how this process relates to the higher incidence of ocular surface disease in the elderly.

From gerontology to geroscience: a synopsis on ageing

Biological ageing can be tentatively defined as an intrinsic and inevitable degradation of biological function that accumulates over time at every level of biological organisation from molecules to populations. Senescence is characterised by a progressive loss of physiological integrity, leading to impaired function and increased vulnerability to death. With advancing age, all components of the human body undergo these cumulative, universal, progressive, intrinsic and deleterious (CUPID) changes. Although ageing is not a disease per se, age is the main risk factor for the development of a panoply of age-related diseases. From a mechanistic perspective, a myriad of molecular processes and components of ageing can be studied. Some of them seem especially important and they are referred to as the hallmarks of ageing. There is compelling evidence that senescence has evolved as an emergent metaphenomenon that originates in the difficulty in maintaining homeodynamics in biological systems. From an evolutionary perspective, senescence is the inevitable outcome of an evolutionarily derived equilibrium between the amount of resources devoted to somatic maintenance and the amount of resources devoted to sexual reproduction. Single-target, single-molecule and disease-oriented approaches to ageing are severely limited because they neglect the dynamic, interactive and networking nature of life. These limitations notwithstanding, many authors promote single-target and disease-oriented approaches to senescence, e.g. repurposed drugs, claiming that these methods can enhance human health and longevity. Senescence is neither a disease nor a monolithic process. In this review, the limitations of these methods are discussed. The current state of biogerontology is also summarised.

Manipulating Cellular Energetics to Slow Aging of Tissues and Organs

Up to now numerous studies in the field of gerontology have been published. Nevertheless, a well-known food restriction remains the most reliable and efficient way of lifespan extension. Physical activity is also a well-documented anti-aging intervention being especially efficient in slowing down the age-associated decline of skeletal muscle mass. In this review we focus on the molecular mechanisms of the effect of physical exercise on muscle tissues. We also discuss the possibilities of pharmacological extension of this effect to the rest of the tissues. During the exercise, the level of ATP decreases triggering activation of AMP-dependent protein kinase (AMPK). This kinase stimulates antioxidant potential of the cells and their mitochondrial respiratory capacity. The exercise also induces mild oxidative stress, which, in turn, mediates the stimulation via hormetic response. Furthermore, during the exercise cells generate activators of mammalian target of rapamycin (mTOR). The intracellular ATP level increases during the rest periods between exercises thus promoting mTOR activation. Therefore, regular exercise intermittently activates anti-oxidant defenses and mitochondrial biogenesis (via AMPK and the hormetic response) of the muscle tissue, as well as its proliferative potential (via mTOR), which, in turn, impedes the age-dependent muscle atrophy. Thus, the intermittent treatment with activators of (i) AMPK combined with the inducers of hormetic response and of (ii) mTOR might partly mimic the effects of physical exercise. Importantly, pharmacological activation of AMPK takes place in the absence of ATP level decrease. The use of uncouplers of respiration and oxidative phosphorylation at the phase of AMPK activation could also prevent negative consequences of the cellular hyper-energization. It is believed that the decline of both antioxidant and proliferative potentials of the cells causes the age-dependent decline of multiple tissues, rather than only the muscular one. We argue that the approach above is applicable for the majority of tissues in an organism.

Perspectives of Homo sapiens lifespan extension: focus on external or internal resources?

Homo sapiens and naked mole rats (Heterocephalus glaber) are vivid examples of social mammals that differ from their relatives in particular by an increased lifespan and a large number of neotenic features. An important fact for biogerontology is that the mortality rate of H. glaber (a maximal lifespan of more than 32 years, which is very large for such a small rodent) negligibly grows with age. The same is true for modern people in developed countries below the age of 60. It is important that the juvenilization of traits that separate humans from chimpanzees evolved over thousands of generations and millions of years. Rapid advances in technology resulted in a sharp increase in the life expectancy of human beings during the past 100 years. Currently, the human life expectancy has exceeded 80 years in developed countries. It cannot be excluded that the potential for increasing life expectancy by an improvement in living conditions will be exhausted after a certain period of time. New types of geroprotectors should be developed that protect not only from chronic phenoptosis gradual poisoning of the body with reactive oxygen species (ROS) but also from acute phenoptosis, where strong increase in the level of ROS immediately kills an already aged individual. Geroprotectors might be another anti-aging strategy along with neoteny (a natural physiological phenomenon) and technical progress.

Mild depolarization of the inner mitochondrial membrane is a crucial component of an anti-aging program

The mitochondria, organelles that produce the largest amounts of ATP and reactive oxygen species (mROS) in living cells, are equipped with a universal mechanism that can completely prevent mROS production. This mechanism consists of mild depolarization of the inner mitochondrial membrane to decrease the membrane potential to a level sufficient to form ATP but insufficient to generate mROS. In short-lived mice, aging is accompanied by inactivation of the mild depolarization mechanism, resulting in chronic poisoning of the organism with mROS. However, mild depolarization still functions for many years in long-lived naked mole rats and bats.

The mitochondria of various tissues from mice, naked mole rats (NMRs), and bats possess two mechanistically similar systems to prevent the generation of mitochondrial reactive oxygen species (mROS): hexokinases I and II and creatine kinase bound to mitochondrial membranes. Both systems operate in a manner such that one of the kinase substrates (mitochondrial ATP) is electrophoretically transported by the ATP/ADP antiporter to the catalytic site of bound hexokinase or bound creatine kinase without ATP dilution in the cytosol. One of the kinase reaction products, ADP, is transported back to the mitochondrial matrix via the antiporter, again through an electrophoretic process without cytosol dilution. The system in question continuously supports H⁺-ATP synthase with ADP until glucose or creatine is available. Under these conditions, the membrane potential, ∆ψ, is maintained at a lower than maximal level (i.e., mild depolarization of mitochondria). This ∆ψ decrease is sufficient to completely inhibit mROS generation. In 2.5-y-old mice, mild depolarization disappears in the skeletal muscles, diaphragm, heart, spleen, and brain and partially in the lung and kidney. This age-dependent decrease in the levels of bound kinases is not observed in NMRs and bats for many years. As a result, ROS-mediated protein damage, which is substantial during the aging of short-lived mice, is stabilized at low levels during the aging of long-lived NMRs and bats. It is suggested that this mitochondrial mild depolarization is a crucial component of the mitochondrial anti-aging system.

Probing Pedomorphy and Prolonged Lifespan in Naked Mole-Rats and Dwarf Mice

Pedomorphy, maintenance of juvenile traits throughout life, is most pronounced in extraordinarily long-lived naked mole-rats. Many of these traits (e.g., slow growth rates, low hormone levels, and delayed sexual maturity) are shared with spontaneously mutated, long-lived dwarf mice. Although some youthful traits likely evolved as adaptations to subterranean habitats (e.g., thermolability), the nature of these intrinsic pedomorphic features may also contribute to their prolonged youthfulness, longevity, and healthspan.

Human ageing, longevity and evolution: can ageing be programmed?

Understanding the proximate and ultimate causes of ageing is one of the key challenges in current biology and medicine. These problems are so important that they are sometimes referred to as the Holy Grail of biology and the Great Conundrum in biogerontology. From an evolutionary perspective, ageing is due to a failure of selection that is caused either by declining strength of selection after the onset of sexual reproduction (Medawar’s theory and Charlesworth’s model) or pleiotropic constraints (Williams’ theory). According to the disposable soma theory, which was proposed by Kirkwood and Holliday, ageing is driven by the accumulation of damage during life and failures of defensive and repair mechanisms as the more an animal expends on sexual reproduction, the less it can expend on bodily maintenance, and vice versa. Although these standard models rule out the possibility that ageing is programmed, there is no consensus about the nature of ageing within the life history in current biogerontology. Interestingly, empirical studies show that there are molecular instructions for ageing and evolutionarily conserved mechanisms for ageing, which seems inconsistent with the idea that ageing is a matter of neglect or a consequence of a failure of selection due to pleiotropic constraints. Here, selected arguments for programmed (i.e. either determined and adaptive or prearranged but non-adaptive) and non-programmed ageing are discussed. Recent advances in biogerontology that cast new light on these problems are outlined here in the context of the idea that the pace of ageing can act as an adaptation in nature, even though ageing is non-programmed and non-adaptive.

Screening for mouse genes lost in mammals with long lifespans

Background

Gerontogenes include those that modulate life expectancy in various species and may be the actual longevity genes. We believe that a long (relative to body weight) lifespan in individual rodent and primate species can be due, among other things, to the loss of particular genes that are present in short-lived species of the same orders. These genes can also explain the widely different rates of aging among diverse species as well as why similarly sized rodents or primates sometimes have anomalous life expectancies (e.g., naked mole-rats and humans). Here, we consider the gene loss in the context of the prediction of Williams’ theory that concerns the reallocation of physiological resources of an organism between active reproduction (r-strategy) and self-maintenance (K-strategy). We have identified such lost genes using an original computer-aided approach; the software considers the loss of a gene as disruptions in gene orthology, local gene synteny or both.

Results

A method and software identifying the genes that are absent from a predefined set of species but present in another predefined set of species are suggested. Examples of such pairs of sets include long-lived vs short-lived, homeothermic vs poikilothermic, amniotic vs anamniotic, aquatic vs terrestrial, and neotenic vs nonneotenic species, among others. Species are included in one of two sets according to the property of interest, such as longevity or homeothermy. The program is universal towards these pairs, i.e., towards the underlying property, although the sets should include species with quality genome assemblies. Here, the proposed method was applied to study the longevity of Euarchontoglires species. It largely predicted genes that are highly expressed in the testis, epididymis, uterus, mammary glands, and the vomeronasal and other reproduction-related organs. This agrees with Williams’ theory that hypothesizes a species transition from r-strategy to K-strategy. For instance, the method predicts the mouse gene Smpd5, which has an expression level 20 times greater in the testis than in organs unrelated to reproduction as experimentally demonstrated elsewhere. At the same time, its paralog Smpd3 is not predicted by the program and is widely expressed in many organs not specifically related to reproduction.

Conclusions

The method and program, which were applied here to screen for gene losses that can accompany increased lifespan, were also applied to study reduced regenerative capacity and development of the telencephalon, neoteny, etc. Some of these results have been carefully tested experimentally. Therefore, we assume that the method is widely applicable.

MitoCLox: A Novel Mitochondria-Targeted Fluorescent Probe for Tracing Lipid Peroxidation

Peroxidation of cardiolipin (CL) in the inner mitochondrial membrane plays a key role in the development of various pathologies and, probably, aging. The four fatty acid tails of CL are usually polyunsaturated, which makes CL particularly sensitive to peroxidation. Peroxidation of CL is involved in the initiation of apoptosis, as well as in some other important cellular signaling chains. However, the studies of CL peroxidation are strongly limited by the lack of methods for its tracing in living cells. We have synthesized a new mitochondria-targeted fluorescent probe sensitive to lipid peroxidation (dubbed MitoCLox), where the BODIPY fluorophore, carrying a diene-containing moiety (as in the C11-BODIPY (581/591) probe), is conjugated with a triphenylphosphonium cation (TPP⁺) via a long flexible linker that contains two amide bonds. The oxidation of MitoCLox could be measured either as a decrease of absorbance at 588 nm or as an increase of fluorescence in the ratiometric mode at 520/590 nm (emission). In CL-containing liposomes, MitoCLox oxidation was induced by cytochrome c and developed in parallel with cardiolipin oxidation. TPP⁺-based mitochondria-targeted antioxidant SkQ1, in its reduced form, inhibited oxidation of MitoCLox concurrently with the peroxidation of cardiolipin. Molecular dynamic simulations of MitoCLox in a cardiolipin-containing membrane showed affinity of positively charged MitoCLox to negatively charged CL molecules; the oxidizable diene moiety of MitoCLox resided on the same depth as the cardiolipin lipid peroxides. We suggest that MitoCLox could be used for monitoring CL oxidation in vivo and, owing to its flexible linker, also serve as a platform for producing peroxidation sensors with affinity to particular lipids.

Human ageing as a dynamic, emergent and malleable process: from disease-oriented to health-oriented approaches

Over the decades, biogerontology has matured as a scientific discipline. Currently, a number of theoretical frameworks are available to researchers when interpreting empirical data. Despite the great progress that has been made, a comprehensive understanding of biological processes that shape ageing is lacking. Senescence is a dynamic, plastic and highly complex metaphenomenon whose aetiology remains unclear. The paucity of information notwithstanding, some researchers promote ‘anti-ageing’ drugs and formulae every now and again. The rationale behind this concept is that ageing can be reduced to a mixture of biochemical reactions. Furthermore, the distinction between ageing and disease has been questioned on the grounds that ageing is the root of age-related diseases. It has been claimed that disease-oriented approaches can help delay ageing and prevent age-related diseases. Although these methods seem incongruous from an evolutionary standpoint, they become popular amongst the public. Moreover, if ageing is classified as a disease, this situation is likely to be exacerbated. Therefore, it is important to recognise the limitations of these reductionist and disease-oriented approaches. Only holistic and evidence-based strategies might be useful in slowing down ageing and preventing age-related diseases in the future.

Alteration of Hypoxia-Associated Gene Expression in Replicatively Senescent Mesenchymal Stromal Cells under Physiological Oxygen Level

Mesenchymal stromal cells (MSCs) are a population of adult stem cells that modulate functional state of neighboring tissues. During cell aging, the biological activity of MSC changes, which may affect tissue homeostasis. It is known that reducing the oxygen level in vitro to physiological values typical to a particular cell niche leads to attenuation of some morphological and functional changes associated with aging. This work aimed to study gene expression in MSCs involved in response to physiological hypoxia using a replicative aging model under physiological (5%) and atmospheric (20%) oxygen in cultures. Our results show that significant reduction of proliferative activity of MSCs is observed after 20 passages (~50 cell generations). Regardless of the oxygen, in senescent cells PKM2, SERPINE1, and VEGFA were upregulated while ANKRD37, DDIT4, HIF1A, and TXNIP were downregulated. Also, ADORA2B, BNIPL, CCNG2, EGLN1, MAP3K1, MXI1, and P4HA1 were downregulated under hypoxia. The effect of oxygen was more pronounced at earlier passages both on the cellular and transcription levels. Irrespective of the passage, genes ANGPTL4, GYS1, PKM2, SERPINE1, and TP53 were downregulated under hypoxia. Also, decreased expression was observed for ADM, F10, HMOX1, P4HB, PFKL, SLC16A3 in earlier passages, and for HK2 - in later passages. Upregulation was only observed for ANKRD37, both at early and late cultures.

Strategies to target bioactive molecules to subcellular compartments. Focus on natural compounds

Many potential pharmacological targets are present in multiple subcellular compartments and have different pathophysiological roles depending on location. In these cases, selective targeting of a drug to the relevant subcellular domain(s) may help to sharpen its impact by providing topological specificity, thus limiting side effects, and to concentrate the compound where needed, thus increasing its effectiveness. We review here the state of the art in precision subcellular delivery. The major approaches confer "homing" properties to the active principle via permanent or reversible (in pro-drug fashion) modifications, or through the use of special-design nanoparticles or liposomes to ferry a drug(s) cargo to its desired destination. An assortment of peptides, substituents with delocalized positive charges, custom-blended lipid mixtures, pH- or enzyme-sensitive groups provide the main tools of the trade. Mitochondria, lysosomes and the cell membrane may be mentioned as the fronts on which the most significant advances have been made. Most of the examples presented here have to do with targeting natural compounds - in particular polyphenols, known as pleiotropic agents - to one or the other subcellular compartment.

Amyloidosis and Longevity: A Lesson from Plants

The variety of lifespans of different organisms in nature is amazing. Although it is acknowledged that the longevity is determined by a complex interaction between hereditary and environmental factors, many questions about factors defining lifespan remain open. One of them concerns a wide range of lifespans of different organisms. The reason for the longevity of certain trees, which reaches a thousand years and exceeds the lifespan of most long living vertebrates by a huge margin is also not completely understood. Here we have discussed some distinguishing characteristics of plants, which may explain their remarkable longevity. Among them are the absence (or very low abundance) of intracellular inclusions composed of amyloidogenic proteins, the lack of certain groups of proteins prone to aggregate and form amyloids in animals, and the high level of compounds which inhibit protein aggregation and possess antiaging properties.

Mitochondria-targeted quinones suppress the generation of reactive oxygen species, programmed cell death and senescence in plants

This work focuses on the effect of mitochondria-targeted quinones (SkQs) on plants. SkQs with antioxidant properties are accumulated in the mitochondria of pea cells and suppress the generation of reactive oxygen species. At nanomolar concentrations, SkQs prevented the death of pea leaf epidermal or guard cells caused by chitosan, bacterial lipopolysaccharide or KCN. The protective effect of SkQs was removed by a protonophoric uncoupler. SkQs at micromolar concentrations inhibited the O2 evolution by illuminated chloroplasts and stimulated the respiration of mitochondria. SkQs slowed down the senescence and the death of Arabidopsis thaliana leaves and improved the wheat crop structure.

Aerobic exercise-stimulated Klotho upregulation extends life span by attenuating the excess production of reactive oxygen species in the brain and kidney

Aerobic exercise induces many adaptive changes in the whole body and improves metabolic characteristics. Klotho, an anti-aging gene, is mainly expressed in the brain and kidney. The roles of Klotho in the brain and kidney during aerobic exercise remain largely unknown. The present study aimed to determine whether aerobic exercise could influence the expression of Klotho, decrease reactive oxygen species (ROS) and prolong life span. Sprague Dawley rats were exercised on a motor treadmill. Klotho mRNA and protein expression levels in rat brain and kidney tissues were examined using reverse transcription-quantitative polymerase chain reaction and western blotting, respectively. ROS production was detected following intermittent aerobic exercise (IAE) or continuous aerobic exercise (CAE). Kaplan-Meier curve analysis demonstrated that aerobic exercise significantly improved rat survival (P<0.001). The ROS levels in rat brain and kidney tissues were decreased in the aerobic exercise groups compared with the control group (P<0.05). In addition, Klotho mRNA and protein expression levels were increased significantly following aerobic exercise compared with controls (P<0.05). There was no significant difference between the IAE and CAE groups in any experiments (P>0.05). These results suggest that aerobic exercise-stimulated Klotho upregulation extends the life span by attenuating the excess production of ROS in the brain and kidney. As Klotho exhibits a potential anti-aging effect, promoting Klotho expression through aerobic exercise may be a novel approach for the prevention and treatment of aging and aging-related diseases.

Aging is an adaptation that selects in animals against disruption of homeostasis

During evolution, Muller's ratchet permanently generates deleterious germline mutations that eventually must be defused by selection. It seems widely held that cancer and aging-related diseases (ARDs) cannot contribute to this germline gene selection because they tail reproduction and thus occur too late, at the end of the life cycle. Here we posit however that by lessening the offspring's survival by proxy through diminishing parental care, they can still contribute to the selection. The hypothesis in detail: The widespread occurrence of aging in animals suggests that it is an adaptation. But to what benefit? Aging seems to have only drawbacks. In humans, ARDs cause today almost all mortality; they include heart disease, cerebrovascular disease, Alzheimer's disease, kidney disease and cancer. Compensation seems unthinkable. For cancer, the author proposed in a previous study a benefit to the species: purifying selection against deleterious germline genes that when expressed enhance intracellular energy dissipation. This multicausal energy dissipation, posited as the universal origin of cancer initiation, relates to cellular heat generation, disrupted metabolism, and inflammation. The organism reproduces during cancer's dormancy, and when approaching its end of life, the onset of cancer is accelerated in proportion to the cancer-initiating signal. Through cancer, the organism, now a parent, implements the self-actuated programmed death of Skulachev's phenoptosis. This "first death" enhances by proxy the offspring's chance of "second death" (or "double death") through diminished parental care. Repetition over generations realizes a purifying selection against genes causing energy dissipation. The removal of the deleterious germline gene mutations permanently generated by Muller's ratchet gives a benefit. We generalize, motivated by the parallels between cancer and aging, the purifying selection posited for cancer to aging. An ARD would be initiated in the organ by multicausal disruption of homeostasis, and be followed by dormancy and senescence until its onset near the end of the life cycle. Just as for cancer, the ARD eventually enhances double death, and the realized permanent selection gives a benefit to the species through the selection against germ line genes that disrupt homeostasis. Given their similarities, cancer and aging are combined in the posited Unified Cancer-Aging Adaptation (UCAA) model, which may be confirmed by next-generation sequencing data. Also because of the emerging important role of cellular senescence, the hypothesis may guide the development of therapies against both cancer and aging.

Spontaneous and Experimentally Induced Pathologies in the Naked Mole Rat (Heterocephalus glaber)

The naked mole rat (Heterocephalus glaber, Rüppell, 1842) is a unique eusocial rodent with unusually long lifespan. Therefore, the study of spontaneous and experimentally induced pathologies in these animals is one of the most important tasks of gerontology. Various infections, noninfectious pathologies (including age-dependent changes), and tumors have been described in the naked mole rat. The most frequent pathologies are traumas (bite wounds), purulent and septic complications of traumatic injuries, renal tubular calcinosis, chronic progressive nephropathy, hepatic hemosiderosis, testicular interstitial cell hyperplasia, calcinosis cutis, cardiomyopathy, and dysbiosis-related infectious lesions of the digestive system. However, the summarized data on pathology (including tumor incidence) and on the causes of mortality are insufficient. There are only few publications about the results of experiments where pathologies were induced in the naked mole rat. All these problems could be subjects for promising future studies without which adequate studies on mechanisms providing the long lifespan of the naked mole rat are impossible, as well as the elucidation of causes of tumor resistance of this species.