Life's timekeeper is a 'free-running' intracellular oscillator synchronised across all cells. It runs throughout life splitting lifespan into equal length phases. During the maturational period it controls the overall rate of progression whereas in the post-maturational period it controls the overall rate of ageing. This includes the rate of senescence and hence time to death. As such life's timekeeper equates maturational and post-maturational time, hence explains the tight correlation between these time periods that has existed throughout mammalian evolution.
Laboratory study was conducted on the biology of the phorid fly Megaselia sacalaris. The influence of 3 constant temperatures and various larval densities was researched in the laboratory as these relate to mean life stage rate of development and survival. Flay development on a synthetic diet at 25 degrees C. 75=2% RH and 18 hr photophase was used as the standard. Mean times for development and survival were egg incubation 16.3 h (97.6%); larval period 7.3 days (97.6%); pupal period 9.8 days (95.8%, 91.6%); adult longevity 29.9 days, 24.8 days. Fecundity was 664.8 eggs.
For the evolution of life histories, the trade-off between survival and reproduction is fundamental. Because sexes optimize fitness in different ways, this trade-off is expected to be resolved differently by males and females. Consequently, the sexes are predicted to respond differently to changes in resource availability. In fruit flies, research on dietary restriction has focused largely on females maintained in the absence of males, thereby neglecting sexual interactions that affect reproductive behavior of both sexes under more natural conditions.
It is well known that dietary restriction (DR) may substantially affect the life span (LS) of various model organisms including Drosophila melanogaster. In our recent studies, it has been revealed that the reduction of the content of main nutrients in larval medium may lead to an increase of flies' LS. Analysis of these data suggested that the most likely candidate for such long-term adaptive changes is insects' epigenome (i.e., persistent changes in the activity of genes that are not related to changes in the DNA structure).
Adult dietary restriction (DR) extends lifespan, but the mechanisms that underlie this effect are not well understood. Many DR studies have demonstrated that lifespan extension tends to be accompanied by a reduction in female fecundity - a correlation widely interpreted as evidence that DR triggers an adaptive re - allocation of resources from reproduction to somatic maintenance. Yet, recent evidence suggests that survival and fecundity need not always trade off under DR, calling the re-allocation hypothesis into question.
A time-resolved record of inhabited water depth, metabolic rate and trophic behaviour of the orange roughy Hoplostethus atlanticus was recovered from combined stable-isotope analyses of otolith and muscle tissue. The results demonstrate that H. atlanticus from the north-east Atlantic Ocean have a complex life history with three distinct depth-stratified life stages. Early juvenile H. atlanticus occupy relatively shallow habitats, juvenile H. atlanticus show a deep-demersal phase, rising at sexual maturity, and adult H. atlanticus exploit increasingly deep habitats with increasing age.
The outcome of the Phase IIb trial of RTS,S (a vaccine comprising the polypeptides RTS and S) in young Mozambican children consolidated hopes that effective vaccination against malaria is a step nearer, and even elicited a generous promise of commitment from the Chancellor of the Exchequer of the UK. However, it seems that both optimism and generosity should be moderated by the failure of this vaccine to induce meaningful protection against infection by Plasmodium falciparum and that we should await confirmation of its efficacy in diminishing the incidence of severe malaria.
Social organization correlates with longevity across animal taxa. This correlation has been explained by selection for longevity by social evolution. The reverse causality is also conceivable but has not been sufficiently considered. We constructed a simple, spatially structured population model of asexually reproducing individuals to study the effect of temporal life history structuring on the evolution of cooperation. Individuals employed fixed strategies of cooperation or defection towards all neighbours in a basic Prisoner's Dilemma paradigm.
The infectivity of Plasmodium falciparum gametocytes after exposure in vitro to quinine, artesunate, and primaquine was assessed in Anopheles dirus, a major vector of malaria in Southeast Asia. Mature gametocytes (stage 5) of a Thai isolate of P. falciparum were exposed to the drugs for 24 h in vitro before membrane feeding to A. dirus. After 10 days, the mosquito midguts were dissected and the oocysts were counted.
The American Journal of Tropical Medicine and Hygiene
Patient data from eight clinical trials were pooled and analyzed to study the efficacy and safety of the six-dose versus four-dose regimen of artemether-lumefantrine (coartemether; Coartem) in children weighing 5-25 kg. A total of 544 patients with uncomplicated P. falciparum malaria (six-dose: 343; four-dose: 201), matched for demographic and baseline characteristics and individual coartemether doses were included in the analysis.