Immunosenescence in wild animals:Meta-analysis and outlook

Immunosenescence, the decline in immune defense with age, is an important mortality source in elderly humans but little is known of immunosenescence in wild animals. We systematically reviewed and meta-analysed evidence for age-related changes in immunity in captive and free-living populations of wild species (321 effect sizes in 62 studies across 44 species of mammals, birds and reptiles). As in humans, senescence was more evident in adaptive (acquired) than innate immune functions. Declines were evident for cell function (antibody response), the relative abundance of naive immune cells and an in vivo measure of overall immune responsiveness (local response to phytohaemagglutinin injection). Inflammatory markers increased with age, similar to chronic inflammation associated with human immunosenescence. Comparisons across taxa and captive vs free-living animals were difficult due to lack of overlap in parameters and species measured. Most studies are cross-sectional, which yields biased estimates of age-effects when immune function co-varies with survival. We therefore suggest longitudinal sampling approaches, and highlight techniques from human cohort studies that can be incorporated into ecological research. We also identify avenues to address predictions from evolutionary theory and the contribution of immunosenescence to age-related increases in disease susceptibility and mortality

Response surface analysis on the effect of temperature and pH on Growth and proteolytic activity of thermophilic Bacillus sp

Proteolytic activity and cell biomass of thermophilic Bacillus sp. strain were evaluated at various levels of initial pH and temperature by applying response surface methodology. The mineral medium containing yeast extract (0.01%) and starch (1%) was used throughout the experiment. The results of statistical analysis revealed the polynomial model with high coefficient of determination (R² = 0.8) for the biomass and total proteolytic activity of the strain studied. This model showed a satisfactory adjustment of the statistic model with the experimental data. The p values showed that the temperature and pH had significant effect on biomass and proteolytic activity (P<0.05) of strain tested. The highest proteolytic activity (2.333 U/ml/h) of the Bacillus sp. was predicted at 41º C and pH 4.8. The high biomass values were observed at broad range of temperature and pH.<br>Atividade proteolítica total e biomassa de uma linhagem de Bacillus sp. termofílico foram analisados em vários níveis de pH inicial e temperatura utilizando a metodologia de superfície de resposta. O meio mineral com extrato de levedura (0.01%) e amido (1%) foi utilizado no experimento. Os resultados de análise estatística da metodologia de resposta de superfície definiram um modelo polinomial para a biomassa e atividade proteolítica da linhagem de Bacillus sp. com alto coeficiente de determinação (R² = 0.8), mostrando um ajuste satisfatório do modelo estatístico obtido com os dados experimentais. Os valores de p mostraram que a temperatura e pH tiveram efeito significante em biomassa e atividade total (P <0.05) da linhagem testada. A atividade proteolítica mais alta (2.368 U/ml/h) da linhagem de Bacilus sp. foi prevista pelas curvas de superfície de resposta em temperatura a 41º C e pH igual a 4.8. Os valores de biomassa altos foram previstos para ampla faixa de temperatura e pH