Distribution by Scientific Domains
Distribution within Life Sciences

Kinds of Lifespan

  • adult lifespan
  • chronological lifespan
  • entire lifespan
  • expected lifespan
  • extend lifespan
  • human lifespan
  • leaf lifespan
  • long lifespan
  • maximum lifespan
  • median lifespan
  • replicative lifespan
  • reproductive lifespan
  • short lifespan
  • shorter lifespan

  • Selected Abstracts

    Lifespan is unrelated to investment in reproduction in populations of mammals and birds in captivity

    ECOLOGY LETTERS, Issue 10 2007
    Robert E. Ricklefs
    Abstract We examined the relationship between number of offspring produced to a certain age and subsequent longevity in captive zoo populations of 18 species of mammal and 12 species of bird. The age cut-offs in each analysis were set to include 50%, 75% and 90% of the offspring produced in each of the population samples. Only one of 68 regressions was significant, and its slope was positive. In addition, we examined the relationship between age at first reproduction up to a certain age and longevity after that age, generally 5 years (3,8), among 17 species of mammal and 12 species of bird. Only one of these regressions had a significantly positive slope, indicating that early reproduction rarely reduces lifespan. Overall, we found no evidence that producing offspring in a zoo environment influences the age at death. Thus, although trade-offs might apply in natural populations under resource limitation, neither pregnancy, growth of the foetus and lactation in mammals, nor egg production in birds, reduces lifespan in the absence of such stress. If genetically based or other intrinsic antagonistic pleiotropy underlies the evolution of senescence, it was not evident in our analyses. [source]

    Commentary on Ricklefs & Cadena (2007): Reproductive Investment and Lifespan

    ECOLOGY LETTERS, Issue 10 2007
    Georgina M. Mace
    No abstract is available for this article. [source]

    The senescence of Daphnia from risky and safe habitats

    ECOLOGY LETTERS, Issue 2 2001
    Evaluating life history in an ecological context is critical for understanding the diversity of life histories found in nature. Lifespan and senescence differ greatly among taxa, but their ecological context is not well known. Life history theory proposes that senescence is ultimately caused by a reduction of the effectiveness of natural selection as organisms age. A key prediction is that different levels of extrinsic mortality risk lead to the evolution of different senescence patterns. I quantified both mortality risk and investment in late-life fitness of Daphnia pulex-pulicaria, a common freshwater zooplankter. I found that Daphnia from high-risk pond habitats invest relatively little in late-life fitness, whereas those from low-risk lake habitats invest relatively more in late-life fitness. This suggests that ecological approaches can be useful for understanding senescence variation. [source]

    Cognitive Therapy Across the Lifespan.

    D. A. Clark., Edited by M. A. Reinecke
    No abstract is available for this article. [source]

    Lifetime reproductive success in relation to morphology in the house sparrow Passer domesticus

    Henrik Jensen
    Summary 1In this study we relate variation in lifetime reproductive success (LRS) of male and female house sparrows Passer domesticus to morphological characteristics. 2Our analyses demonstrated no sex-specific difference in the distribution of LRS. The variance in LRS was influenced mainly by variation in individual annual reproductive success, and to a lesser extent by variation in individual lifespan. 3Phenotypic traits explained a significant proportion of the variation in LRS in males, but not in females. The effect of male morphology on LRS operated mainly through an effect on the number of recruiting daughters. 4The size of the patch of black feathers on the chest of males (badge size) and male bill length were both positively associated with LRS. Lifespan and bill length were positively related and reproductive success increased with badge size. In females, number of recruiting daughters was positively related to bill length, body mass and body condition index due to the positive effect of these traits on annual production of daughters. 5These results indicate that identifying factors causing the large individual variation in LRS, which is likely to be closely related to fitness, will be important to understand microevolutionary processes in this metapopulation, and hence their demographic feedbacks. [source]

    The effect of caloric restriction interventions on growth hormone secretion in nonobese men and women

    AGING CELL, Issue 1 2010
    Leanne M. Redman
    Summary Lifespan in rodents is prolonged by caloric restriction (CR) and by mutations affecting the somatotropic axis. It is not known if CR can alter the age-associated decline in growth hormone (GH), insulin-like growth factor (IGF)-1 and GH secretion. To evaluate the effect of CR on GH secretory dynamics; forty-three young (36.8 ± 1.0 years), overweight (BMI 27.8 ± 0.7) men (n = 20) and women (n = 23) were randomized into four groups; control = 100% of energy requirements; CR = 25% caloric restriction; CR + EX = 12.5% CR + 12.5% increase in energy expenditure by structured exercise; LCD = low calorie diet until 15% weight reduction followed by weight maintenance. At baseline and after 6 months, body composition (DXA), abdominal visceral fat (CT) 11 h GH secretion (blood sampling every 10 min for 11 h; 21:00,08:00 hours) and deconvolution analysis were measured. After 6 months, weight (control: ,1 ± 1%, CR: ,10 ± 1%, CR + EX: ,10 ± 1%, LCD: ,14 ± 1%), fat mass (control: ,2 ± 3%, CR: ,24 ± 3%, CR + EX: ,25 ± 3%, LCD: ,31 ± 2%) and visceral fat (control: ,2 ± 4%, CR: ,28 ± 4%, CR + EX: ,27 ± 3%, LCD: ,36 ± 2%) were significantly (P < 0.001) reduced in the three intervention groups compared to control. Mean 11 h GH concentrations were not changed in CR or control but increased in CR + EX (P < 0.0001) and LCD (P < 0.0001) because of increased secretory burst mass (CR + EX: 34 ± 13%, LCD: 27 ± 22%, P < 0.05) and amplitude (CR + EX: 34 ± 14%, LCD: 30 ± 20%, P < 0.05) but not to changes in secretory burst frequency or GH half-life. Fasting ghrelin was significantly increased from baseline in all three intervention groups; however, total IGF-1 concentrations were increased only in CR + EX (10 ± 7%, P < 0.05) and LCD (19 ± 4%, P < 0.001). A 25% CR diet for 6 months does not change GH, GH secretion or IGF-1 in nonobese men and women. [source]

    Annotated Bibliography of NINR Findings on Women's Health Across the Lifespan, 2008 Update

    Raymond J. Bingham
    No abstract is available for this article. [source]

    Narrative Identity and Meaning Making Across the Adult Lifespan: An Introduction

    Jefferson A. Singer
    First page of article [source]

    Ageism Across the Lifespan: Towards a Self-Categorization Model of Ageing

    Howard Giles
    This article uses this collection of articles on ageism as a springboard to discuss empirical lacunae in the literature as well as propose a self-categorization model of ageing phenomena. In particular, we argue that research would benefit from a more lifespan communication perspective. This includes the social origins of ageism that can be laid down early in development and perpetuated through collusiveprocesses as individuals themselves age. Further, problems of interactively managing ageism, its intragenerational parameters, and the variable consequences of making death salient, are identified. Finally, we elaborate and illustrate a self-categorization model of ageing processes before critically examining panaceas proposed by others to ameliorate ageism. [source]

    Lifespan and patterns of accumulation and mobilization of nutrients in the sugar-fed phorid fly, Pseudacteon tricuspis

    Henry Y. Fadamiro
    Abstract., The effect of sugar feeding on the survival of adult phorid fly Pseudacteon tricuspis is investigated. Flies fed 25% sucrose in aqueous solution continuously throughout their lifespan have greater longevity (mean ± SE longevity: female = 7.9 ± 0.8 days, male = 8.9 ± 0.9 days) than completely starved (provided no water and no sugar solution) flies, sugar-starved (provided water only) flies, or flies fed sugar solution only on their first day of adult life. Completely starved flies rarely lived beyond one day. Provision of water increases longevity by 2 days, and one full day of sugar feeding further increases longevity by an additional 1,2 days. Flies fed 50% sucrose have similar survivorship as those fed 25% sucrose. The temporal patterns of nutrient accumulation and utilization are also compared in P. tricuspis fed different diets: sugar-starved, sucrose-fed on the first day of adult life only, and sucrose-fed continuously. Adult P. tricuspis emerge with no gut sugars, and only minimal amounts of body sugars and glycogen. Although the levels of body sugars and glycogen decline gradually in sugar-starved flies, a single day of sugar feeding results in the accumulation of maximum amounts of gut sugars, body sugars and glycogen. High levels of these nutrients are maintained in female and male phorid flies fed on sucrose continuously over the observation period, whereas nutrient levels decline in flies fed only on the first day of life, beginning 1 day postfeeding. Female and male P. tricuspis emerge with an estimated 12.3 ± 2.3 and 7.2 ± 1 g of lipid reserves per fly, respectively. These teneral amounts represent the highest lipid levels detected in adult flies, irrespective of their diet, and are maintained over the life times of sucrose-fed female and male flies, but declined steadily in sugar-starved females. These data suggest that adult P. tricuspis are capable of converting dietary sucrose to body sugars and glycogen, but not lipids. [source]

    Populations at Risk Across the Lifespan: Case Studies: Psychological and Physical Abuse Among Pregnant Women in a Medicaid-Sponsored Prenatal Program

    Jennifer E. Raffo
    ABSTRACT Objectives: To document psychological and physical abuse during pregnancy among women enrolled in enhanced prenatal services (EPS); explore the associations between maternal risk factors and type of abuse; and examine the relationship between abuse and EPS participation. Design and Sample: Cross-sectional study utilizing screening data collected between 2005 and 2008. Convenience sample of Medicaid-insured pregnant women enrolled in EPS selected from urban and rural providers. Measures: A prenatal screening tool that included measures such as Cohen's Perceived Stress Scale-4, Patient Health Questionnaire-2, and Abuse Assessment Screen was used. Results: Logistic regressions showed that high perceived stress and lack of father support were associated with all types of abuse and abuse history. Women with risk factors, such as a positive depression screen (odds ratio [OR]=2.36), were associated with psychological abuse but not with physical abuse during pregnancy. Less than a 12th-grade education was associated with physical abuse (OR=1.64) but not psychological abuse during pregnancy. The amount or the timing of EPS participation was not significantly associated with abuse history or abuse during pregnancy. Conclusions: Risk factors, such as high perceived stress and lack of father support, may alert nurses to further explore abuse during pregnancy. Additional research is needed for understanding the relationship between abuse and EPS participation. [source]

    Biological and environmental factors controlling root dynamics and function: effects of root ageing and soil moisture

    L.H. COMAS
    Abstract Understanding factors controlling root dynamics and functioning can lead to more efficient and profitable vineyard management. However, our current understanding of root dynamics and their regulation by plant and environmental factors is limited, particularly under field conditions. This paper presents current understanding of grape root dynamics, highlighting studies using minirhizotron cameras, which directly assess root dynamics, and experiments on roots of known age, which link root phenology and function. Data summarised here show timing of grape root production varies widely among different regions, as well as among rootstocks and canopy management systems in the same region. Timing of production can be responsive to differences in soil moisture. Lifespan of grape roots, however, appears less affected by soil moisture because of nocturnal hydraulic redistribution. Root function, such as capacity for P and N uptake, declines rapidly with root age. Differences in timing and spatial distribution of root production can effect above-ground growth and vineyard water-use efficiency. Improving our understanding of when roots grow and are functionally active in agricultural systems can lead to improved water and fertiliser applications, and more precise vineyard management. Because both environmental and biological factors affect root dynamics, simple predictions of timing of root production or standing populations with shoot development are unlikely to be achieved. However, with multi-year data on root dynamics, and environmental and biological factors, regionally specific models of root populations and their functioning may be possible to develop. [source]

    Etiology of Bipolar Disorder Across the Lifespan: Essential Interplay With Diagnosis, Classification, and Assessment

    Benjamin L. HankinArticle first published online: 10 JUN 200
    Bipolar disorder has garnered increasing attention as many argue that rates of bipolar disorder are skyrocketing and the definition of the classic bipolar disorder phenotype should be expanded, especially among children and adolescents. Understanding the psychosocial etiologies of bipolar disorder across the lifespan is critically important, and Alloy and colleagues' (2009) scholarly review makes an important contribution. Given the debate and controversy surrounding the description, diagnosis, and phenotype of bipolar disorder, having an accurate, reliable, and valid classification for definition, diagnosis, and assessment is critical for explicating potential etiology. Likewise, advanced understanding of etiology, especially when grounded in basic psychological science as Alloy and colleagues' review is, can importantly inform clinical phenomenology, course, assessment, and intervention. In summary, there is an essential interplay among description, classification, assessment, etiology, and intervention, such that a deeper understanding of all these areas is necessary for advancing an empirically based practice of assessment and intervention. [source]

    Consequences of insect herbivory on grape fine root systems with different growth rates

    PLANT CELL & ENVIRONMENT, Issue 7 2007
    ABSTRACT Herbivory tolerance has been linked to plant growth rate where plants with fast growth rates are hypothesized to be more tolerant of herbivory than slower-growing plants. Evidence supporting this theory has been taken primarily from observations of aboveground organs but rarely from roots. Grapevines differing in overall rates of new root production, were studied in Napa Valley, California over two growing seasons in an established vineyard infested with the sucking insect, grape phylloxera (Daktulosphaira vitifoliae Fitch). The experimental vineyard allowed for the comparison of two root systems that differed in rates of new root tip production (a ,fast grower', Vitis berlandieri × Vitis rupestris cv. 1103P, and a slower-growing stock, Vitis riparia × Vitis rupestris cv. 101,14 Mgt). Each root system was grafted with a genetically identical shoot system (Vitis vinifera cv. Merlot). Using minirhizotrons, we did not observe any evidence of spatial or temporal avoidance of insect populations by root growth. Insect infestations were abundant throughout the soil profile, and seasonal peaks in phylloxera populations generally closely followed peaks in new root production. Our data supported the hypothesis that insect infestation was proportional to the number of growing tips, as indicated by similar per cent infestation in spite of a threefold difference in root tip production. In addition, infested roots of the fast-growing rootstock exhibited somewhat shorter median lifespans (60 d) than the slower-growing rootstock (85 d). Lifespans of uninfested roots were similar for the two rootstocks (200 d). As a consequence of greater root mortality of younger roots, infested root populations in the fast-growing rootstock had an older age structure. While there does not seem to be a trade-off between potential growth rate and relative rate of root infestation in these cultivars, our study indicates that a fast-growing root system may more readily shed infested roots that are presumably less effective in water and nutrient uptake. Thus, differences in root tip production may be linked to differences in the way plants cope with roots that are infested by sucking insects. [source]

    Regulation of skeletal muscle mitochondrial function: genes to proteins

    ACTA PHYSIOLOGICA, Issue 4 2010
    I. R. Lanza
    Abstract The impact of ageing on mitochondrial function and the deterministic role of mitochondria on senescence continue to be topics of vigorous debate. Many studies report that skeletal muscle mitochondrial content and function are reduced with ageing and metabolic diseases associated with insulin resistance. However, an accumulating body of literature suggests that physical inactivity typical of ageing may be a more important determinant of mitochondrial function than chronological age, per se. Reports of age-related declines in mitochondrial function have spawned a vast body of literature devoted to understanding the underlying mechanisms. These mechanisms include decreased abundance of mtDNA, reduced mRNA levels, as well as decreased synthesis and expression of mitochondrial proteins, ultimately resulting in decreased function of the whole organelle. Effective therapies to prevent, reverse or delay the onset of the aforementioned mitochondrial changes, regardless of their inevitability or precise underlying causes, require an intimate understanding of the processes that regulate mitochondrial biogenesis, which necessitates the coordinated regulation of nuclear and mitochondrial genomes. Herein we review the current thinking on regulation of mitochondrial biogenesis by transcription factors and transcriptional co-activators and the role of hormones and exercise in initiating this process. We review how exercise may help preserve mitochondrial content and functionality across the lifespan, and how physical inactivity is emerging as a major determinant of many age-associated changes at the level of the mitochondrion. We also review evidence that some mitochondrial changes with ageing are independent of exercise or physical activity and appear to be inevitable consequences of old age. [source]

    Incorporating Uncertainty into Demographic Modeling: Application to Shark Populations and Their Conservation

    Enric Cortés
    I used age-structured life tables and Leslie matrices based on a prebreeding survey and a yearly time step applied only to females to model the demography of 41 populations from 38 species of sharks representing four orders and nine families. I used Monte Carlo simulation to reflect uncertainty in the estimates of demographic traits and to calculate population statistics and elasticities for these populations; I used correlation analysis to identify the demographic traits that explained most of the variation in population growth rates ( , ). The populations I examined fell along a continuum of life-history characteristics that can be linked to elasticity patterns. Sharks characterized by early age at maturity, short lifespan, and large litter size had high , values and short generation times, whereas sharks that mature late and have long lifespans and small litters have low , values and long generation times. Sharks at the "fast" end of the spectrum tended to have comparable adult and juvenile survival elasticities, whereas sharks at the "slow" end of the continuum had high juvenile survival elasticity and low age,zero survival ( or fertility ) elasticity. Ratios of adult survival to fertility elasticities and juvenile survival to fertility elasticities suggest that many of the populations studied do not possess the biological attributes necessary to restore , to its original level after moderate levels of exploitation. Elasticity analysis suggests that changes in juvenile survival would have the greatest effect on ,, and correlation analysis indicates that variation in juvenile survival, age at maturity, and reproduction account for most of the variation in ,. In general, combined results from elasticity and correlation analyses suggest that research, conservation, and management efforts should focus on these demographic traits. Resumen: Exploré los efectos de la incertidumbre en los caracteres demográficos en análisis demográficos de tiburones, un método no empleado con anterioridad para este taxón. Utilicé tablas de vida estructuradas por edades y matrices de Leslie basadas en evaluaciones pre-gestación y pasos de tiempo de un año aplicados solo a las hembras para modelar la demografía de 41 poblaciones de 38 especies de tiburones que representan cuatro órdenes y nueve familias. Utilicé la simulación de Monte Carlo para reflejar la incertidumbre en las estimaciones de caracteres demográficos y calcular las estadísticas y elasticidades poblacionales para estas poblaciones y el análisis de correlación para identificar los caracteres demográficos que explican la mayoría de la variación en las tasas de crecimiento poblacional ( , ). Las poblaciones examinadas caen dentro de un continuo de características de historias de vida que pueden estar vinculadas con los patrones de elasticidad. Los tiburones que maduran a temprana edad y tienen corta duración de vida y grupos grandes de crías tuvieron valores altos de , y tiempos generacionales cortos, mientras que los tiburones que maduran tarde y tienen una duración de vida larga y grupos pequeños de crías tienen valores bajos de , y tiempos generacionales largos. Los tiburones que se encuentran en el punto final "rápido" del espectro tendieron a tener elasticidades de supervivencia de adultos y juveniles comparables, mientras que los tiburones en el punto final "lento" del continuo tuvieron una alta elasticidad de supervivencia de juveniles y una baja elasticidad en supervivencia a la edad cero (o fertilidad ). Las proporciones de elasticidades de supervivencia de adultos y fertilidad y de elasticidades de supervivencia de juveniles y fertilidad sugieren que muchas de las poblaciones estudiadas no poseen los atributos biológicos necesarios para restaurar , a su nivel original después de niveles moderados de explotación. El análisis de elasticidad sugiere que en la supervivencia de juveniles se podría tener el efecto mayor de , y el análisis de correlación indica que la variación en la supervivencia de juveniles, la edad de maduración y reproducción explican la mayor parte de la variación en ,. En general, los resultados combinados de los análisis de elasticidad y correlación sugieren que los esfuerzos de investigación, conservación y manejo deberían enfocarse a estas características demográficas. [source]

    Mathematical development in spina bifida

    Lianne H. English
    Abstract Spina bifida (SB) is a neural tube defect diagnosed before or at birth that is associated with a high incidence of math disability often without co-occurring difficulties in reading. SB provides an interesting population within which to examine the development of mathematical abilities and disability across the lifespan and in relation to the deficits in visual-spatial processing that are also associated with the disorder. An overview of math and its cognitive correlates in preschoolers, school-age children and adults with SB is presented including the findings from a longitudinal study linking early executive functions in infancy to the development of later preschool and school age math skills. These findings are discussed in relation to socio-historical perspectives on math education and implications for intervention and directions for further research are presented. © 2009 Wiley-Liss, Inc. Dev Disabil Res Rev 2009;15:28,34. [source]

    Differential expression of CaMK-II genes during early zebrafish embryogenesis

    Sarah C. Rothschild
    Abstract CaMK-II is a highly conserved Ca2+/calmodulin-dependent protein kinase expressed throughout the lifespan of all vertebrates. During early development, CaMK-II regulates cell cycle progression and "non-canonical" Wnt-dependent convergent extension. In the zebrafish, Danio rerio, CaMK-II activity rises within 2 hr after fertilization. At the time of somite formation, zygotic expression from six genes (camk2a1, camk2b1, camk2g1, camk2g2, camk2d1, camk2d2) results in a second phase of increased activity. Zebrafish CaMK-II genes are 92,95% identical to their human counterparts in the non-variable regions. During the first three days of development, alternative splicing yields at least 20 splice variants, many of which are unique. Whole-mount in situ hybridization reveals that camk2g1 comprises the majority of maternal expression. All six genes are expressed strongly in ventral regions at the 18-somite stage. Later, camk2a1 is expressed in anterior somites, heart, and then forebrain. Camk2b1 is expressed in somites, mid- and forebrain, gut, retina, and pectoral fins. Camk2g1 appears strongly along the midline and then in brain, gut, and pectoral fins. Camk2g2 is expressed early in the midbrain and trunk and exhibits the earliest retinal expression. Camk2d1 is elevated early at somite boundaries, then epidermal tissue, while camk2d2 is expressed in discrete anterior locations, steadily increasing along either side of the dorsal midline and then throughout the brain, including the retina. These findings reveal a complex pattern of CaMK-II gene expression consistent with pleiotropic roles during development. Developmental Dynamics 236:295,305, 2007. © 2006 Wiley-Liss, Inc. [source]

    Mechanical computation in neurons

    Jummi Laishram
    Abstract Growth cones are the main motile structures located at the tip of neurites and are composed of a lamellipodium from which thin filopodia emerge. In this article, we analyzed the kinetics and dynamics of growth cones with the aim to understand two major issues: first, the strategy used by filopodia and lamellipodia during their exploration and navigation; second, what kind of mechanical problems neurons need to solve during their operation. In the developing nervous system and in the adult brain, neurons constantly need to solve mechanical problems. Growth cones must decide how to explore the environment and in which direction to grow; they also need to establish the appropriate contacts, to avoid obstacles and to determine how much force to exert. Here, we show that in sparse cultures, filopodia grow and retract following statistical patterns, nearly optimal for an efficient exploration of the environment. In a dense culture, filopodia exploration is still present although significantly reduced. Analysis on 1271, 6432, and 185 pairs of filopodia of DRG, PC12 and Hippocampal neurons respectively showed that the correlation coefficient |,| of the growth of more than 50% of filopodia pairs was >0.15. From a computational point of view, filopodia and lamellipodia motion can be described by a random process in which errors are corrected by efficient feedback loops. This article argues that neurons not only process sensory signals, but also solve mechanical problems throughout their entire lifespan, from the early stages of embryogenesis to adulthood. © 2009 Wiley Periodicals, Inc. Develop Neurobiol, 2009 [source]

    Epigenetic influence of social experiences across the lifespan

    Frances A. Champagne
    Abstract The critical role of social interactions in driving phenotypic variation has long been inferred from the association between early social deprivation and adverse neurodevelopmental outcomes. Recent evidence has implicated molecular pathways involved in the regulation of gene expression as one possible route through which these long-term outcomes are achieved. These epigenetic effects, though not exclusive to social experiences, may be a mechanism through which the quality of the social environment becomes embedded at a biological level. Moreover, there is increasing evidence for the transgenerational impact of these early experiences mediated through changes in social and reproductive behavior exhibited in adulthood. In this review, recent studies which highlight the epigenetic effects of parent,offspring, peer and adult social interactions both with and across generations will be discussed and the implications of this research for understanding the developmental origins of individual differences in brain and behavior will be explored. © 2010 Wiley Periodicals, Inc. Dev Psychobiol 52: 299,311, 2010. [source]

    Development of learned flavor preferences

    Kevin P. Myers
    Abstract Rats, like humans, are born with only a few innate flavor preferences and aversions. Preferences retain great plasticity throughout the lifespan because they are sensitive to modification by experience. From an early age, rats can rapidly learn to prefer or avoid a flavor (conditioned stimulus, CS) that is associated with a positive or negative unconditioned stimulus (US). The US may be the mother's milk, social or thermotactile stimulation, or other food-related stimuli. Flavor-flavor learning occurs when the CS flavor is mixed with a naturally preferred (e.g., sweet) or avoided (e.g., bitter) US flavor. Flavor preferences and aversions are also produced by USs that have postoral positive (e.g., nutritious) or negative (e.g., toxic) actions. These types of learning appear to involve different behavioral and neural mechanisms as indicated by differences in conditioned responses, effective temporal parameters, resistance to extinction, and neurochemical mechanisms. New evidence indicates that flavor-nutrient preference learning can occur before weaning and influence food selection after weaning. Flavor conditioning not only affects food choice, but can also significantly increase food acceptance, that is, total consumption. Thus, from an early age, learning processes shape the feeding behavior of animals. While primarily serving an adaptive function, learning may play a role in biasing individuals towards excessive intake and weight gain. © 2006 Wiley Periodicals, Inc. Dev Psychobiol 48: 380,388, 2006. [source]

    Perceived quality of maternal care in childhood and structure and function of mothers' brain

    Pilyoung Kim
    Animal studies indicate that early maternal care has long-term effects on brain areas related to social attachment and parenting, whereas neglectful mothering is linked with heightened stress reactivity in the hippocampus across the lifespan. The present study explores the possibility, using magnetic resonance imaging, that perceived quality of maternal care in childhood is associated with brain structure and functional responses to salient infant stimuli among human mothers in the first postpartum month. Mothers who reported higher maternal care in childhood showed larger grey matter volumes in the superior and middle frontal gyri, orbital gyrus, superior temporal gyrus and fusiform gyrus. In response to infant cries, these mothers exhibited higher activations in the middle frontal gyrus, superior temporal gyrus and fusiform gyrus, whereas mothers reporting lower maternal care showed increased hippocampal activations. These findings suggest that maternal care in childhood may be associated with anatomy and functions in brain regions implicated in appropriate responsivity to infant stimuli in human mothers. [source]

    Neural plasticity and human development: the role of early experience in sculpting memory systems

    Charles A. Nelson
    The concept of sensitive or critical periods in the context of memory development is examined in this paper. I begin by providing examples of the role of experience in influencing sensory, linguistic and emotional functioning. This is followed by a discussion of the role of experience in influencing cognitive functioning, particularly memory. Based on this discussion, speculation is offered that the infant's proclivity for novelty, which makes its appearance shortly after birth, provides critical input into a nervous system that will eventually be set up to learn and remember for the entire lifespan. Because learning and memory are fundamental to the survival of our species, those aspects of the nervous system that permit the encoding and retention of new information are remarkably malleable from the outset, even in the face of some types of neural trauma. This flexibility is retained for many years so long as the learning and memory ,system' is challenged. The implications of this model are discussed in the context of those life events that might undermine the longevity of memory systems. [source]

    Targeting Alzheimer's disease: Is there a light at the end of the tunnel?

    David Gurwitz
    Abstract The prevalence of Alzheimer's disease (AD) is on the rise in developed nations as a consequence of longer human lifespan. Current costs to society are alarming, and are projected to become even more demanding on future health budgets. Considering the relative success of Parkinson's disease pharmacotherapy, the success of AD therapy has been disappointing. Quite a few novel and promising AD drug targets are presented in this special issue of Drug Development Research. These are built on countless research studies, by many bright minds, carried out over the last several decades. However, the answer to the growing AD threat must include reliable and accurate tools, presently lacking, for its early diagnosis in at-risk individuals. Drug Dev. Res. 56:45,48, 2002. © 2002 Wiley-Liss, Inc. [source]

    Ten-Year Echo/Doppler Determination of the Benefits of Aerobic Exercise after the Age of 65 Years

    ECHOCARDIOGRAPHY, Issue 1 2010
    Alexander J. Muster M.D.
    As the human lifespan becomes progressively extended, potential health-related effects of intense aerobic exercise after age 65 need evaluation. This study evaluates the cardiovascular (CV), pulmonary, and metabolic effects of competitive distance running on age-related deterioration in men between 69 (±3) and 77 (±2) years (mean ± SD). Twelve elderly competitive distance runners (ER) underwent oxygen consumption and echo/Doppler treadmill stress testing (Balke protocol) for up to 10 years. Twelve age-matched sedentary controls (SC) with no history of CV disease were similarly tested and the results compared for the initial three series of the study. CV data clearly separated the ER from SC. At entry, resting and maximal heart rate, systolic/diastolic blood pressure, peak oxygen consumption (VO2max), and E/A ratio of mitral inflow were better in the ER (P < 0.05 vs. SC). With aging, ER had a less deterioration of multiple health parameters. Exceptions were VO2max and left ventricular diastolic function (E/A, AFF, IVRT) that decreased (P < 0.05, Year 10 vs. Year 1). Health advantages of high-level aerobic exercise were demonstrated in the ER when compared to SC. Importantly, data collected in ER over 10 years confirm the benefit of intensive exercise for slowing several negative effects of aging. However, the normative drop of exercise capacity in the seventh and eighth decades reduces the potential athleticism plays in prevention of CV events. (Echocardiography 2010;27:5-10) [source]

    Comparative life-history traits in a fig wasp community: implications for community structure

    1. Whether life-history traits can determine community composition and structure is an important question that has been well explored theoretically, but has received scant empirical attention. Life-history traits of a seven-member community of galler and parasitoid fig wasp species (Chalcidoidea), developing within the inflorescences (syconia) of Ficus racemosa (Moraceae) in India, were determined and used to examine community structure and ecology. 2. Gallers were pro-ovigenic (all eggs are mature upon adult emergence) whereas parasitoids were synovigenic (eggs mature progressively during adult lifespan). Initial egg load was correlated with body size for some species, and there was a trade-off between egg number and egg size across all species. Although all species completed their development and left the syconium concurrently, they differed in their adult and pre-adult lifespans. Providing sucrose solutions increased parasitoid lifespan but had no effect on the longevity of some galler species. While feeding regimes and body size affected longevity in most species, an interaction effect between these variables was detected for only one species. 3. Life-history traits of wasp species exhibited a continuum in relation to their arrival sequence at syconia for oviposition during syconium development, and therefore reflected their ecology. The largest number of eggs, smallest egg sizes, and shortest longevities were characteristic of the earliest-arriving galling wasps at the smallest, immature syconia; the converse characterised the later-arriving parasitoids at the larger, already parasitised syconia. Thus life history is an important correlate of community resource partitioning and can be used to understand community structure. 4. This is the first comprehensive study of life-history traits in a fig wasp community. The comparative approach revealed constraints and flexibility in trait evolution. [source]

    Sexual selection did not contribute to the evolution of male lifespan under curtailed age at reproduction in a seed beetle

    Abstract. 1. Sexual selection is a powerful evolutionary force that is hypothesised to play an important role in the evolution of lifespan. Here we test for the potential contribution of sexual selection to the rapid evolution of male lifespan in replicated laboratory populations of the seed beetle, Callosobruchus maculatus. 2. For 35 generations, newly hatched virgin male beetles from eight different populations were allowed to mate for 24 h and then discarded. Sexual selection was removed in half of these populations by enforcing random monogamy. 3. Classic theory predicts that because of sexual competition, males from sexually selected lines would have higher age-specific mortality rates and shorter lifespan than males from monogamous lines. 4. Alternatively, condition-dependent sexual selection may also favour genes that have positive pleiotropic effects on lifespan and ageing. 5. Males from all eight populations evolved shorter lifespans compared with the source population. However, there was no difference in lifespan between males from populations with or without sexual selection. Thus, sexual selection did not contribute to the evolution of male lifespan despite the fact that such evolution did occur in our study populations. [source]

    Age-dependent clutch size in a koinobiont parasitoid

    Jelmer A. Elzinga
    Abstract., 1. The Lack clutch size theory predicts how many eggs a female should lay to maximise her fitness gain per clutch. However, for parasitoids that lay multiple clutches it can overestimate optimal clutch size because it does not take into account the future reproductive success of the parasitoid. 2. From egg-limitation and time-limitation models, it is theoretically expected that (i) clutch size decreases with age if host encounter rate is constant, and (ii) clutch size should increase with host deprivation and hence with age in host-deprived individuals. 3. Clutch sizes produced by ageing females of the koinobiont gregarious parasitoid Microplitis tristis Nees (Hymenoptera: Braconidae) that were provided daily with hosts, and of females ageing with different periods of host deprivation were measured. 4. Contrary to expectations, during the first 2 weeks, clutch size did not change with the age of the female parasitoid, neither with nor without increasing host-deprivation time. 5. After the age of 2 weeks, clutch size decreased for parasitoids that parasitised hosts daily. The decrease was accompanied by a strong decrease in available eggs. However, a similar decrease occurred in host-deprived parasitoids that did not experience egg depletion, suggesting that egg limitation was not the only factor causing the decrease in clutch size. 6. For koinobiont parasitoids like M. tristis that have low natural host encounter rates and short oviposition times, the costs of reproduction due to egg limitation, time limitation, or other factors are relatively small, if the natural lifespan is relatively short. 7. Koinobiont parasitoid species that in natural situations experience little variation in host density and host quality might not have strongly evolved the ability to adjust clutch size. [source]

    Parasitism by the mite Trombidium breei on four U.K. butterfly species

    L. Conradt
    Abstract 1. The incidence of parasitism by larvae of the mite species Trombidium breei was reported in one population of the lycaenid butterfly Polyommatus icarus, four populations of the satyrine butterfly Maniola jurtina, one population of the satyrine butterfly Aphantopus hyperanthus, and two populations of the satyrine butterfly Pyronia tithonus, as well as on one specimen of the dipteran Alophorus hemiptera. A considerable proportion of butterflies (11-50%) was infested in all study populations. 2. The pattern of infestation was examined in detail in M. jurtina. Males had a significantly higher incidence of infestation than females, and middle-aged butterflies had a higher incidence of infestation than old or young butterflies. The incidence of infestation peaked in the middle of the flight season, and this seasonal effect was independent of the effect of butterfly age. 3. Using a model based on capture-recapture data, it was estimated that a hypothetical ideal male M. jurtina that lives exactly the mean expected lifespan of 9-10 days has an approximately 75% chance of becoming infested with mites at least once during its lifetime, a mean time to first infestation of 3-4 days, and an average infestation persistence time of 2-3 days. 4. Capture-recapture data failed to show any effect of mite infestation on the lifespan or within-habitat movement rate of M. jurtina. 5. In experiments in which individual butterflies were taken out of their normal habitat and released, M. jurtina and P. tithonus that were infested with mite larvae did not differ from uninfested individuals in the efficiency with which they returned to suitable habitat. Thus, parasitism by T. breei larvae had no detectable effects on flight performance or orientation ability. 6. The results suggest that trombidiid mite larvae have limited potential in the biological control of insect pests. [source]

    Lifespan is unrelated to investment in reproduction in populations of mammals and birds in captivity

    ECOLOGY LETTERS, Issue 10 2007
    Robert E. Ricklefs
    Abstract We examined the relationship between number of offspring produced to a certain age and subsequent longevity in captive zoo populations of 18 species of mammal and 12 species of bird. The age cut-offs in each analysis were set to include 50%, 75% and 90% of the offspring produced in each of the population samples. Only one of 68 regressions was significant, and its slope was positive. In addition, we examined the relationship between age at first reproduction up to a certain age and longevity after that age, generally 5 years (3,8), among 17 species of mammal and 12 species of bird. Only one of these regressions had a significantly positive slope, indicating that early reproduction rarely reduces lifespan. Overall, we found no evidence that producing offspring in a zoo environment influences the age at death. Thus, although trade-offs might apply in natural populations under resource limitation, neither pregnancy, growth of the foetus and lactation in mammals, nor egg production in birds, reduces lifespan in the absence of such stress. If genetically based or other intrinsic antagonistic pleiotropy underlies the evolution of senescence, it was not evident in our analyses. [source]