Department of Ecology and Evolutionary Biology University of California—Irvine 321 Steinhaus Hall Irvine, CA 92697-2525, USA.
Rejuvenation Res. 2012 Feb;15(1):49-58. doi: 10.1089/rej.2011.1201. Epub 2012 Jan 10.
In a variety of organisms, adulthood is divided into aging and late life, where aging is a period of exponentially increasing mortality rates and late life is a period of roughly plateaued mortality rates. In this study we used ∼57,600 Drosophila melanogaster from six replicate populations to examine the physiological transitions from aging to late life in four functional characters that decline during aging: desiccation resistance, starvation resistance, time spent in motion, and negative geotaxis. Time spent in motion and desiccation resistance declined less quickly in late life compared to their patterns of decline during aging. Negative geotaxis declined at a faster rate in late life compared to its rate of decline during aging. These results yield two key findings: (1) Late-life physiology is distinct from the physiology of aging, in that there is not simply a continuation of the physiological trends which characterize aging; and (2) late life physiology is complex, in that physiological characters vary with respect to their stabilization, deceleration, or acceleration in the transition from aging to late life. These findings imply that a correct understanding of adulthood requires identifying and appropriately characterizing physiology during properly delimited late-life periods as well as aging periods.
在多种生物体中，成年期分为衰老期和晚年期，其中衰老期是死亡率呈指数增长的时期，而晚年期是死亡率大致稳定的时期。在这项研究中，我们使用了来自六个重复种群的约 57600 只黑腹果蝇，以检查在四个随衰老而下降的功能特征中从衰老到晚年的生理转变：抗干燥能力、抗饥饿能力、运动时间和负趋地性。与衰老过程中的下降模式相比，晚年时运动时间和抗干燥能力的下降速度较慢。负趋地性在晚年的下降速度比衰老期间的下降速度快。这些结果得出了两个关键发现：（1）晚年的生理学与衰老的生理学不同，衰老的特征并不是简单地延续了衰老过程中的生理趋势；（2）晚年的生理学很复杂，因为生理特征在从衰老到晚年的过渡过程中，在稳定、减速或加速方面存在差异。这些发现意味着，要正确理解成年期，就需要确定并适当描述在适当界定的晚年期和衰老期期间的生理学。
