School of Biological Sciences, University of Wollongong, Wollongong, Australia.
PLoS One. 2013 Sep 3;8(9):e73781. doi: 10.1371/journal.pone.0073781. eCollection 2013.
All organisms age, the rate of which can be measured by demographic analysis of mortality rates. The rate of ageing is thermally sensitive in ectothermic invertebrates and we examined the effects of temperature on both demographic rates of ageing and on cellular senescence in the blowfly, Calliphora stygia. The short lifespan of these flies is advantageous for demographic measurements while their large body size permits individual-based biochemical characterisation. Blowflies maintained at temperatures from 12°C to 34°C had a five to six-fold decrease in maximum and average longevity, respectively. Mortality rates were best described by a two-phase Gompertz relation, which revealed the first-phase of ageing to be much more temperature sensitive than the second stage. Flies held at low temperatures had both a slower first-phase rate of ageing and a delayed onset of second-phase ageing, which significantly extended their longevity compared with those at high temperatures. Blowflies that were transferred from 29°C to 15°C had higher first-phase mortality rates than those of flies held at constant 15°C, but their onset of second-phase ageing was deferred beyond that of flies held constantly at this temperature. The accumulation of fluorescent AGE pigment, a measure of cellular oxidative damage, increased steadily over time in all blowflies, irrespective of the temporal pattern of mortality. Pigment accumulated steadily during periods of 'negligible senescence', as measured by minimal rate of mortality, and the rate of accumulation was significantly affected by temperature. Thus accumulation of AGE pigment is more representative of chronological age than a reflection of biological age or a cause of mortality.
所有生物都会衰老，衰老的速度可以通过对死亡率的人口统计学分析来衡量。在变温无脊椎动物中，衰老的速度对温度敏感，我们研究了温度对衰老的人口统计学速度和粉纹夜蛾（Calliphora stygia）细胞衰老的影响。这些苍蝇的寿命很短，有利于人口统计学测量，而它们的体型较大则允许进行基于个体的生化特征描述。将苍蝇保持在 12°C 至 34°C 的温度下，最大和平均寿命分别减少了五到六倍。死亡率最好用两段式 Gompertz 关系来描述，这表明第一阶段的衰老比第二阶段对温度更敏感。在低温下饲养的苍蝇，第一阶段的衰老速度较慢，第二阶段的衰老开始时间也较晚，与高温下饲养的苍蝇相比，它们的寿命显著延长。从 29°C 转移到 15°C 的苍蝇的第一阶段死亡率高于在 15°C 下保持恒定的苍蝇，但它们的第二阶段衰老开始时间被推迟，超过了在该温度下保持恒定的苍蝇。荧光 AGE 色素的积累，是衡量细胞氧化损伤的一个指标，在所有的苍蝇中都随着时间的推移而稳步增加，与死亡率的时间模式无关。色素在死亡率最小的“可忽略衰老”期间稳定积累，积累的速度受到温度的显著影响。因此，AGE 色素的积累更能代表实际年龄，而不是反映生物年龄或导致死亡率的原因。
