Working harder to stay alive: Metabolic rate increases with age in Drosophila simulans but does not correlate with life span

The hypothesis that metabolic rate is inversely correlated with life span has long been debated. Another area of controversy has been the relationship between metabolic rate and aging. In most molecular studies key aspects of cellular metabolism have been shown to decline with age. Less attention ha...

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Bibliographic Details
Published in:Journal of insect physiology 2007-12, Vol.53 (12), p.1300-1306
Main Authors: Melvin, Richard G., Van Voorhies, Wayne A., Ballard, J. William O.
Format: Article
Language:English
Subjects:
age
Aging
Aging - physiology
Animals
Basal Metabolism
carbon dioxide
Drosophila - genetics
Drosophila - metabolism
Drosophila simulans
energy metabolism
Energy Metabolism - physiology
gene dosage
insect aging
Life span
longevity
Longevity - physiology
Male
Metabolic rate
mitochondrial DNA
mitochondrial DNA copy number
mtDNA
Oxidative phosphorylation
Oxygen Consumption
physical activity
senescence
walking
walking speed
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Summary:The hypothesis that metabolic rate is inversely correlated with life span has long been debated. Another area of controversy has been the relationship between metabolic rate and aging. In most molecular studies key aspects of cellular metabolism have been shown to decline with age. Less attention has been focused on metabolic rate as an organism ages. We studied the survival of three Drosophila simulans fly lines and measured whole organism metabolic rate, mitochondrial DNA copy number and walking speed. Metabolic rate as assayed by CO 2 production did not correlate with median lifespan but increased by 0.43–1.14%/d. In contrast, mitochondrial DNA copy number decreased by 0.56–1.06%/d. Physical activity, as assayed by mean walking speed, did not change with age but was positively correlated with mitochondrial DNA copy number. One explanation for these data is that metabolic rate was increased, in the face of a reduced mitochondrial DNA copy number and capacity for oxidative metabolism, to maintain a constant bioenergetic demand (physical activity). Alternatively, metabolic rate may increase to provide energy for the repair of cellular damage or due to a shift in metabolic substrate use over time.
ISSN:0022-1910
1879-1611
DOI:10.1016/j.jinsphys.2007.07.006