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PubMed1993

Temperature- and humidity-dependent longevity of unfed adult Hyalomma truncatum (Acari: Ixodidae).

The survival of unfed adult Hyalomma truncatum Koch held under different regimes of constant temperature (5, 17, 24, and 30 degrees C) and relative humidity (10, 50, and 80%) was monitored during > 1 yr. Longevity of this medically important African tick was shortest at the highest temperature and lowest relative humidity (100% dead at week 25). Conversely, H. truncatum lived longest at lower temperatures and higher relative humidity (< 100% dead at week 64). The combined effects of temperature and humidity, measured as vapor pressure deficit, were strongly related to survival of these ticks. The survival of males and females was similar and was independent of the weight of ticks. These findings have implications for the maintenance and study of laboratory colonies of H. truncatum and for the development of tick control strategies to reduce vectorial capacity.

Animals↗

PubMed1995

Estimates of population size, dispersal, and longevity of domestic Aedes aegypti aegypti (Diptera: Culicidae) by mark-release-recapture in the village of Shauri Moyo in eastern Kenya.

Estimates of the absolute size of a domestic population of Aedes aegypti aegypti (L.) were made in the Rabai area of Kenya, based on a single release, followed by either single or repeated recaptures. From single recapture within 24 h of release, the size of the female Ae. a. aegypti population in the Shauri Moyo village was estimated by the Lincoln index to be 365. Using a single release and repeated recaptures, population size was estimated by Jackson's positive method to be 337. Depletion of the unmarked females by daily removal sampling provided us with two additional, direct estimates of the size of the village population (451 by Kano's method and [464 +/- 18.9 SEM] by the Moran-Zippin method). The longevity of marked females was at least 9 d. The day-to-day movement of marked mosquitoes revealed the dispersal pattern of Ae. a. aegypti among houses clustered within different distance zones. Marked mosquitoes reached all houses of the village within 24 h of release. After 5 d, the dispersion of both marked and unmarked mosquitoes among houses was similar.

Animal Identification Systems↗

PubMed1995

Reduced longevity of Dermacentor variabilis and Ixodes scapularis (Acari: Ixodidae) molting from immatures fed on Rattus norvegicus.

Nymphal and adult Dermacentor variabilis (Say) molting from larvae and nymphs, respectively, that fed on a Holtzman strain of Rattus norvegicus demonstrated reduced longevity compared with those from immature stages that fed on albino laboratory mice, Mus musculus. The decrease in survivorship did not appear to be caused by host-acquired resistance; lower feeding weights, longer feeding times, and reduced molting were not observed. In addition, reduced survivorship was not limited to ticks fed on Holtzman rats. It was also demonstrated in adult D. variabilis molting from nymphs that fed on Wistar strain rats, but the effect was not as severe as with Holtzman rats. Moreover, reduced survivorship occurred in Ixodes scapularis Say that fed on rats, but, again, the effect as less severe than on D. variabilis. Nymphal feeding on mice appeared to counteract the negative effect of larval feeding on rats in both adult D. variabilis and I. scapularis.

Animals↗

PubMed1988

Food restriction, circadian disorder and longevity of rats and mice.

Evidence that food restriction alters circadian rhythms as it prolongs the healthful life of rats and mice is reviewed. Because rhythms in different variables are changed in different ways, the circadian organization that is characteristic of freely feeding animals is disrupted. In the case of daily food restriction (meal feeding), the extent of disruption depends on the timing of the meal in relation to the daily light-dark schedule. Recent studies indicate that the extension of life span by a given level of food restriction is similar regardless of mealtime, whether fixed or shifted at weekly intervals throughout life. Such results suggest that the effects of food restriction on circadian organization are not involved in the effect on survival. On the other hand, changes in any given rhythm (such as an increased amplitude and a decreased overall average of body temperature) could point to the mechanism by which longevity is increased.

Animals↗

PubMed2000

Associations of light, moderate, and vigorous intensity physical activity with longevity. The Harvard Alumni Health Study.

Physical activity is associated with better health; however, the optimal intensity of activity remains unclear. A total of 13,485 men (mean age, 57.5 years) from the Harvard Alumni Health Study reported their walking, stair climbing, and sports/recreation in 1977. Between 1977 and 1992, 2,539 died. After adjusting for the different activity components, distance walked and storeys climbed independently predicted longevity (p, trend = 0.004 and <0.001, respectively). Light activities (<4 multiples of resting metabolic rate (METs)) were not associated with reduced mortality rates, moderate activities (4-<6 METs) appeared somewhat beneficial, and vigorous activities (> or =6 METs) clearly predicted lower mortality rates (p, trend = 0.72, 0.07, and <0.001, respectively). These data provide some support for current recommendations that emphasize moderate intensity activity; they also clearly indicate a benefit of vigorous activity.

Aged↗

PubMed2001

Effects of group selection for productivity and longevity on blood concentrations of serotonin, catecholamines, and corticosterone of laying hens.

Selection of a line of White Leghorn chickens for high group productivity and longevity resulted in reducing cannibalism and flightiness in multiple-hen cages. Improvements in survival might have been due to changes of physiological homeostasis. The objective of the present study was to test the hypothesis that genetic selection for high (HGPS) and low (LGPS) group productivity and survivability also altered regulation of neuroendocrine homeostasis. Hens were randomly assigned to individual cages at 17 wk of age. At 21 wk of age, blood concentrations of dopamine, epinephrine, norepinephrine, and serotonin were measured using HPLC assay. Blood concentrations of corticosterone were measured using radioimmunoassay. The LGPS hens had greater blood concentrations of dopamine and epinephrine than the HGPS hens (P < 0.01). The blood concentration of norepinephrine was not significantly different between the lines, but the ratio of epinephrine to norepinephrine was greater in the LGPS hens (P < 0.01). The blood concentrations of serotonin were also higher in the LGPS hens compared to those in the HGPS hens (P < 0.01). Although the HGPS hens tended to have a higher level of blood corticosterone, the difference was not significant (1.87 +/- 0.19 vs. 1.49 +/- 0.21 ng/mL; P = 0.08). The results suggest that selection for group productivity and survivability alters the chickens' neuroendocrine homeostasis, and these changes may correlate with its line-unique coping ability to domestic environments and survivability.

Animals↗

PubMed2003

Caenorhabditis elegans mutants resistant to phosphine toxicity show increased longevity and cross-resistance to the synergistic action of oxygen.

Phosphine (hydrogen phosphide, PH3) is the fumigant most widely used to protect stored products from pest infestation. Despite the importance of this chemical, little is known about its mode of action. We have created three phosphine-resistant lines (pre-1, pre-7, pre-33) in the model organism C. elegans, with LC50 values 2, 5, and 9 times greater than the fully susceptible parental strain. Molecular oxygen was shown to be an extremely effective synergist with phosphine as, under hyperoxic conditions, 100% mortality was observed in wild-type nematodes exposed to 0.1 mg/l phosphine, a nonlethal concentration in air. All three mutants were resistant to the synergistic effects of oxygen in proportion to their resistance to phosphine with one mutant, pre-33, showing complete resistance to this synergism. We take the proportionality of cross-resistance between phosphine and the synergistic effect of oxygen to imply that all three mutants circumvent a mechanism of phosphine toxicity that is directly coupled to oxygen metabolism. Compared with the wild-type strain, all three mutants have an extended average life expectancy of from 12.5 to 25.3%. This is consistent with the proposed involvement of oxidative stress in both phosphine toxicity and ageing. Because the wild-type and mutant nematodes develop at the same rate, the longevity is unlikely to be caused by a clk-type reduction in oxidative metabolism, a potential alternative mechanism of phosphine resistance.

Aging↗

PubMed1994

Methionine restriction increases blood glutathione and longevity in F344 rats.

Little is known about the biochemical mechanisms responsible for the biological aging process. Our previous results and those of others suggest that one possible mechanism is based on the loss of glutathione (GSH), a multifunctional tripeptide present in high concentrations in nearly all living cells. The recent finding that life-long dietary restriction of the GSH precursor methionine (Met) resulted in increased longevity in rats led us to hypothesize that adaptive changes in Met and GSH metabolism had occurred, leading to enhanced GSH status. To test this, blood and tissue GSH levels were measured at different ages throughout the life span in F344 rats on control or Met-restricted diets. Met restriction resulted in a 42% increase in mean and 44% increase in maximum life span, and in 43% lower body weight compared to controls (P < 0.001). Increases in blood GSH levels of 81% and 164% were observed in mature and old Met-restricted animals, respectively (P < 0.001). Liver was apparently the source for this increase as hepatic GSH levels decreased to 40% of controls. Except for a 25% decrease in kidney, GSH was unchanged in other tissues. All changes in GSH occurred as early as 2 months after the start of the diet. Altogether, these results suggest that dramatic adaptations in sulfur amino acid metabolism occur as a result of chronic Met restriction, leading to increases in blood GSH levels and conservation of tissue GSH during aging.

Animals↗

PubMed2001

Longevity and heavy metal resistance in daf-2 and age-1 long-lived mutants of Caenorhabditis elegans.

In the nematode Caenorhabditis elegans, dauer formation, stress resistance, and longevity are determined in part by DAF-2 (insulin receptor-like protein), AGE-1 (phosphatidylinositol-3-OH kinase catalytic subunit), and DAF-16 (forkhead transcription factor). Mutations in daf-2 and age-1 result in increased resistance to heat, oxidants, and UV. We have discovered that daf-2 and age-1 mutations result in increased Cd and Cu ion resistance in a 24 h toxicity assay. Lethal concentration (LC50) values for Cd and Cu ions in daf-2 and age-1 mutants were significantly (P<0.001) higher than in wild-type nematodes. However, LC50 values in daf-16;age-1 mutants were not significantly different, implying that metal resistance is influenced by a DAF-16-related function. As metallothionein (MT) proteins play a major role in metal detoxification, we examined the expression of MT genes both under noninducing conditions and after exposure to sublethal and acute heavy metal stress. MT1 mRNA levels were significantly (P<0.05) higher in daf-2 mutants compared to age-1 mutants and wild-type C. elegans under basal conditions. After 10 mM Cd treatment, induction of MT1 and MT2 mRNA was three- and twofold higher, respectively, in daf-2 mutant worms than in wild-type. However, a sublethal concentration of Cd (0.1 mM) resulted in even higher (three- to sevenfold) levels of both MT mRNAs in all strains. Cu did not induce MT1 or MT2 mRNAs. These results are consistent with a model in which the insulin-signaling pathway determines life span through regulation of stress protein genes

Animals↗

PubMed1994

Apolipoprotein E epsilon 2 allele promotes longevity and protects patients with Down's syndrome from dementia.

Although individuals with Down's syndrome nearly always develop the clinical and pathological features of Alzheimer's disease, some clearly do not become demented despite living into their sixth and seventh decades. Genetic variation at the apolipoprotein E locus has recently been shown to be an important determinant of Alzheimer's disease, with the epsilon 4 allele having been shown to be associated with the disease and, at least in some cases, the epsilon 2 allele being negatively associated with the disease. Here we show, in a series of clinically assessed individuals with Down's syndrome, that the epsilon 2 allele of ApoE is associated with both longevity and the absence of clinical evidence of dementia. These data show that the clinical phenotype of Down's syndrome can be modulated by genes on chromosomes other than chromosome 21. The importance of this observation to the pathogenesis of Alzheimer's disease, both in Down's syndrome and in general, is discussed.

Age of Onset↗

PubMed1999

Thinness and weight loss: beneficial or detrimental to longevity?

This review examined the hypotheses that 1) low body mass index (BMI) is optimal for longevity and 2) weight loss reduces mortality rates. The preponderance of epidemiological evidence fails to support either of these hypotheses. Indeed, a number of studies show that thinness and weight loss (regardless of initial BMI) are associated with increased mortality rates. These findings cannot be attributed to smoking status or to weight loss resulting from subclinical disease. The effect of intentional weight loss on mortality rates depends upon health status. For overweight individuals in good health, there is no compelling evidence to show that mortality rates are reduced with weight loss. Even among overweight persons with one or more obesity-related health conditions, specific weight loss recommendations may be unnecessary: 1) the reduction in mortality rate associated with intentional weight loss is independent of the amount of weight loss, 2) the reductions in all-cause mortality rate associated with increased physical activity and fitness (23-44%), independent of changes in body weight, are greater than that reported for intentional weight loss (approximately 20%), and 3) many obesity-related health conditions (e.g., hypertension, dyslipidemias, insulin resistance, glucose intolerance) can be ameliorated independently of weight loss. In view of the potential risks associated with weight loss and weight cycling, it is suggested that public health may be better served by placing greater emphasis on lifestyle changes and less attention to weight loss per se.

Body Mass Index↗

PubMedDate not supplied

Social environment and longevity in schizophrenia.

OBJECTIVE: The role of social support as a predictor of long-term survival among patients with schizophrenia was examined. METHODS: Social histories were abstracted from the medical records of a cohort of 133 deceased schizophrenic patients admitted for inpatient treatment between 1934 and 1944. Two independent raters assessed the quantity and quality of support available in each patient's social environment. RESULTS: Cox regression analysis revealed that higher quantity of social support was significantly related to survival time (p<.05) after controlling for marital status and quality of support. The Cox model indicated that a 1-point increase in the support quantity rating was associated with a proportional 25% decrease in the hazard rate. CONCLUSIONS: The present findings suggest that social environment, specifically the quantity of social support available to the patient, may impact longevity in psychiatric populations.

Cohort Studies↗

PubMed2003

Effects of sperm on female longevity in the bumble-bee Bombus terrestris L.

The male ejaculate, particularly the accessory gland products, has been shown to affect female survival (as is best understood in Drosophila melanogaster). So far, these findings have primarily been discussed in the context of a sexual conflict and multiple mating. Here, we show that in the bumble-bee Bombus terrestris, male genotype influences female longevity even though B. terrestris generally is a singly mated species and male and female interests may thus be more convergent. In addition, the effect could not be owing to accessory gland products, as we artificially inseminated the queens with the content of the accessory testes only.

Analysis of Variance↗

PubMed2026

The interplay of epigenetic remodelling and transposon-mediated genomic instability in ageing and longevity.

Ageing and age-related diseases are the result of complex biological processes that progressively cause deterioration of cellular and tissue function. Among the key hallmarks of ageing are epigenetic alterations and genomic instability, both of which are closely interconnected and significantly contribute to the ageing process. The epigenome, encompassing both DNA and histone modifications, regulates gene expression and maintains genomic integrity throughout life. With age, these regulatory systems become dysregulated, leading to genome-wide changes in chromatin structure, histone modifications and the reactivation of transposable elements (TEs). TEs, typically silenced in heterochromatic regions, become active in aged cells, contributing to genomic instability, mutagenesis, inflammation and metabolic disruption. Despite their significant implications, the role of TEs in the ageing process remains underexplored, and the interplay between epigenomic remodelling and TE activity remains poorly understood. In this review, we explore the molecular mechanisms underlying epigenetic alterations and TE reactivation during ageing, the impact of these changes on genomic stability and the potential therapeutic interventions targeting this interplay. By deciphering the role of epigenetic modifications and TE derepression in the ageing process, we aim to highlight novel avenues for anti-ageing and pro-longevity strategies.

Aging↗

PubMed2002

A novel song parameter correlates with extra-pair paternity and reflects male longevity.

Although elaborate bird song provides one of the prime examples of a trait that evolved under sexual selection, it is still unclear whether females judge the quality of males by attributes of their song and whether these song features honestly signal a male's genetic quality. We measured the ability of male dusky warblers Phylloscopus fuscatus to maintain a high sound amplitude during singing, which probably reflects an individual's physiological limitations. This new measure of singing performance was correlated with male longevity and with extra-pair paternity, indicating that females who copulated with better singers obtained 'good genes' for their offspring. Our findings are consistent with the idea that females assess male quality by subtle differences in their performance during the production of notes, rather than by the quantity or versatility of song. In addition, observations on territorial conflicts indicate that attractive males invest less in competition over territories because they can reproduce via extra-pair paternity.

Animals↗

PubMed2001

Changes in gene expression associated with developmental arrest and longevity in Caenorhabditis elegans.

Gene expression in a developmentally arrested, long-lived dauer population of Caenorhabditis elegans was compared with a nondauer (mixed-stage) population by using serial analysis of gene expression (SAGE). Dauer (152,314) and nondauer (148,324) SAGE tags identified 11,130 of the predicted 19,100 C. elegans genes. Genes implicated previously in longevity were expressed abundantly in the dauer library, and new genes potentially important in dauer biology were discovered. Two thousand six hundred eighteen genes were detected only in the nondauer population, whereas 2016 genes were detected only in the dauer, showing that dauer larvae show a surprisingly complex gene expression profile. Evidence for differentially expressed gene transcript isoforms was obtained for 162 genes. H1 histones were differentially expressed, raising the possibility of alternative chromatin packaging. The most abundant tag from dauer larvae (20-fold more abundant than in the nondauer profile) corresponds to a new, unpredicted gene we have named tts-1 (transcribed telomere-like sequence), which may interact with telomeres or telomere-associated proteins. Abundant antisense mitochondrial transcripts (2% of all tags), suggest the existence of an antisense-mediated regulatory mechanism in C. elegans mitochondria. In addition to providing a robust tool for gene expression studies, the SAGE approach already has provided the advantage of new gene/transcript discovery in a metazoan.

Animals↗

PubMed2004

Costs of an induced immune response on sexual display and longevity in field crickets.

Immune system activation may benefit hosts by generating resistance to parasites. However, natural resources are usually limited, causing a trade-off between the investment in immunity and that in other life-history or sexually selected traits. Despite its importance for the evolution of host defense, state-dependent fitness costs of immunity received little attention under natural conditions. In a field experiment we manipulated the nutritional condition of male field crickets Gryllus campestris and subsequently investigated the effect of an induced immune response through inoculation of bacterial lipopolysaccharides. Immune system activation caused a condition-dependent reduction in body condition, which was proportional to the condition-gain during the preceding food-supplementation period. Independent of nutritional condition, the immune insult induced an enduring reduction in daily calling rate, whereas control-injected males fully regained their baseline level of sexual signaling following a temporary decline. Since daily calling rate affects female mate choice under natural conditions, this suggests a decline in male mating success as a cost of induced immunity. Food supplementation enhanced male life span, whereas the immune insult reduced longevity, independent of nutritional status. Thus, immune system activation ultimately curtails male fitness due to a combined decline in sexual display and life span. Our field study thus indicates a key role for fitness costs of induced immunity in the evolution of host defense. In particular, costs expressed in sexually selected traits might warrant the honest advertisement of male health status, thus representing an important mechanism in parasite-mediated sexual selection.

Animal Communication↗

PubMed1986

Physical activity, other life-style patterns, cardiovascular disease and longevity.

Longitudinal study of 16,936 Harvard alumni, followed for life-style experiences as related to cardiovascular disease (CVD) and longevity, identified 572 first coronary heart disease (CHD) attacks, 1962-1972, and 1,413 all-cause deaths, 1962-1978. Men expending 8.4+ MJ (2,000+ kcal) per week in walking, stair-climbing, and sports play were at 39% lower risk of developing CHD than less active classmates. Attributable risk estimates suggested: there might have been 16% fewer CVD deaths in the alumni population if every man had exercised 8.4+ MJ per week; 25% fewer from total cigarette abstinence; 9% fewer from abolition of hypertension; 6% fewer with less obesity; and 11% fewer CVD deaths in the absence of parental CHD. Discounting the influence of blood pressure status, cigarette habit, net weight gain since college, and parental history of early death, the more active alumni (39% of the population) are estimated to have lived on average one and one-quarter years longer than less active men.

Adult↗