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Average Life Expectancy (average + life_expectancy)
Selected AbstractsOntogenetic Shifts in the Ability of the Cladoceran, Moina macrocopa Straus and Ceriodaphnia cornuta Sars to Utilize Ciliated Protists as Food SourceINTERNATIONAL REVIEW OF HYDROBIOLOGY, Issue 3 2008Ram Kumar Abstract The ontogenetic diet shifts and age specific ability of the two cladoceran species Moina macrocopa and Ceriodaphnia cornuta to derive energy from ciliated protists have been investigated in laboratory. The postembryonic developmental rates and life table demography (longevity, age and size at first reproduction, fecundity and intrinsic rate of natural increase) of the cladocerans have been elucidated on algae (Chlorella vulgaris) and the ciliated protists (Tetrahymena pyriformis, Colpoda (c.f.) steini) as food. For either of the cladoceran, the somatic growth rate and average body size at first reproduction were higher with algal diet. During initial stages of development (0,5 days), either cladoceran realized higher rate of somatic growth on algal diet, subsequently ciliated protists supported significantly higher growth rate than the alga. Algal and ciliate diets did not differ in maximum body size (C. cornuta: 539,554 ,m; M. macrocopa: 1274.8,1309 ,m) reached by either of the cladocerans. The maximum body sizes were larger than size at first reproduction with either of the ciliated protists, however, with algal diet the maximum body sizes did not differ from the size at first reproduction in each case. In case of C. cornuta the generation time (20.5 ± 0.3 days on ciliate; 15.6 ± 0.17 days on algal diet), reproductive rates (net reproductive rate: 20.05 ± 3.2 on ciliate; 15.5 ± 1.2 on algal diet), and average life expectancy at hatching (27 ± 0.8 days on ciliate; 22.7 ± 0.71 days on alga) were higher, whereas the size at first reproduction (482 ,m on ciliate; 521 ,m on alga) was smaller with the ciliate than with an algal diet. The algal and the ciliate diets did not differ in survival (life expectancy at hatching: 9.2 ± 0.7 days) and fecundity (NRR: 23.6 ± 2.4) for M. macrocopa. The two ciliates used in the experiment did not differ in their performance as food source for either cladoceran species. Our results suggest that both the cladoceran species are able to utilize smaller ciliate (e.g., T. pyriformis, C. (c.f.) steini) as food; however with differential ability to derive energy from the ciliate diet and this ability is size and age structured in both cases. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Exploring mechanisms of sex differences in longevity: lifetime ovary exposure and exceptional longevity in dogsAGING CELL, Issue 6 2009David J. Waters Summary To move closer to understanding the mechanistic underpinnings of sex differences in human longevity, we studied pet dogs to determine whether lifetime duration of ovary exposure was associated with exceptional longevity. This hypothesis was tested by collecting and analyzing lifetime medical histories, age at death, and cause of death for a cohort of canine ,centenarians', exceptionally long-lived Rottweiler dogs that lived more than 30% longer than average life expectancy for the breed. Sex and lifetime ovary exposure in the oldest-old Rottweilers (age at death, , 13 years) were compared to a cohort of Rottweilers that had usual longevity (age at death, 8.0,10.8 years). Like women, female dogs were more likely than males to achieve exceptional longevity (OR, 95% CI = 2.0, 1.2,3.3; P = 0.006). However, removal of ovaries during the first 4 years of life erased the female survival advantage. In females, a strong positive association between ovaries and longevity persisted in multivariate analysis that considered other factors, such as height, body weight, and mother with exceptional longevity. A beneficial effect of ovaries on longevity in females could not be attributed to resistance against a particular disease or major cause of death. Our results document in dogs a female sex advantage for achieving exceptional longevity and show that lifetime ovary exposure, a factor not previously evaluated in women, is associated with exceptional longevity. This work introduces a conceptual framework for designing additional studies in pet dogs to define the ovary-sensitive biological processes that promote healthy human longevity. [source] Differentials in Adult Mortality and Activity Limitation by Years of Education in the United States at the End of the 1990sPOPULATION AND DEVELOPMENT REVIEW, Issue 4 2004Michael T. Molla This study examines mortality differentials and health disparities between educational groups within the 1998 adult population (ages 25 and older) in the United States. Mortality differentials are measured using average life expectancy and health disparities by expected years without activity limitation. The results indicate that for both sexes, higher education is associated with higher life expectancy. Those with higher levels of education also have higher life expectancy without activity limitation. Adults with higher education can also expect to enjoy a greater percentage of their expected lives free of any form of activity limitation. At each level of education, adult females have a higher level of activity limitation compared to adult males. At the same level of education, adult females expect to enjoy smaller percentages of their remaining lives free of activity limitation compared to adult males of the same age. [source] Strong and weak lifespan extension: what is most feasible and likely?AUSTRALASIAN JOURNAL ON AGEING, Issue 2 2006Jayne C Lucke Abstract Recent advances in biomedical science indicate that it may eventually be possible to intervene in the biological process of human ageing. This paper overviews the current state of the science of lifespan extension and promising future directions. It is uncertain whether ,strong' lifespan extension , the extension of human life beyond the maximum 122 years so far observed , will become a reality. It is more likely that cumulative effects of numerous scientific and biomedical advances in the treatment of common disease will produce ,weak' lifespan extension , the extension of average life expectancy. The practical application of molecular, genetic and nanomaterials research may also lead to advances in life expectancy. It is not too early to begin to consider the policy implications of either form of lifespan extension. [source] | ||||||||||