Mechanistic Linkages for the Pace of Life, Life History, and Environment in Birds

与同等大小的哺乳动物相比，鸟类的不同之处在于它们有更高的新陈代谢率、更高的体温、更高的血糖水平和更高的终生能量消耗，所有这些特征都被认为会缩短寿命。然而，鸟类比同等大小的哺乳动物寿命更长。这一提议调查了鸟类及其细胞的代谢率如何与它们的寿命相关。作者将研究他们已经确定的热带和温带鸟类之间全动物代谢差异的潜在机制，这些物种组合具有良好的记录，独特的生活史，包括寿命。研究表明，热带鸟类的基础代谢率和高峰代谢率都很低这与它们的寿命长，繁殖率低有关，而温带鸟类的新陈代谢率高，繁殖率高，这些都与高死亡率有关。作者使用了一种综合的方法，专注于在整个生物体、细胞和分子水平上识别机制，这些机制可以解释生命史（如寿命）的差异。该项目采用热带和温带鸟类的系统发育配对比较，从分析中排除系统发育和体重因素，研究热带和温带鸟类细胞内在特性的差异，例如它们的细胞代谢率、对氧化应激和重金属毒性的抵抗力以及膜脂过氧化。由于脂质不饱和与衰老过程有关，研究人员进一步使用质谱法检查了细胞膜中的脂质种类及其不饱和程度。这项研究将培养一名博士后，并将深入了解细胞膜如何改变以影响寿命。

Joseph B. WilliamsProposal # IOS-1036914Mechanistic linkages for the pace of life, life-history, and environment in birdsIn comparison with a similar sized mammal, birds are remarkable in that they have a higher rate of metabolism, higher body temperature, higher blood glucose levels, and higher life-time energy expenditure, all traits thought to reduce life span. Yet, birds live longer than a similar-sized mammal. This proposal investigates how the metabolic rate of birds and of their cells relates to their longevity. The authors will study underlying mechanisms for differences that they have identified in whole-animal metabolism between tropical and temperate birds, species assemblages with well-documented, distinct, life-histories including life-span. They show that tropical birds have low rates of basal and peak metabolism and that this is related to long life span and low rates of reproduction, which contrasts with temperate birds which have high rates of metabolism, high rates of reproduction, all associated with high rates of mortality. The authors use an integrated approach that focuses on identifying mechanisms at the whole-organism, cellular, and molecular levels that can account for the differences in life-histories such as longevity. The project employs phylogenetically-paired comparisons of tropical and temperate birds, which factors out phylogeny and body mass from analyses, to investigate differences in intrinsic properties of cells between tropical and temperate birds, such as their cellular metabolic rates, their resistance to oxidative stress and heavy metal toxicity, and membrane lipid peroxidation. Further the investigators examine the kinds of lipids and their degree of unsaturation in cell membranes using mass spectrometry because lipid unsaturation has been related to the aging process. This investigation will train a postdoctoral fellow, and will yield insights into how cell membranes might be altered to influence life-span.