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Photoperiod and dietary lipids both influence thermal physiology and the pattern of torpor of heterothermic mammals. The aim
of the present study was to test the hypothesis that photoperiod-induced physiological changes are linked to differences in
tissue fatty acid composition of deer mice, Peromyscus maniculatus (∼18-g body mass). Deer mice were acclimated for >8 weeks to one of three photoperiods (LD, light/dark): LD 8:16 (short photoperiod),
LD 12:12 (equinox photoperiod), and LD 16:8 (long photoperiod). Deer mice under short and equinox photoperiods showed a greater
occurrence of torpor than those under long photoperiods (71, 70, and 14%, respectively). The duration of torpor bouts was
longest in deer mice under short photoperiod (9.3 ± 2.6 h), intermediate under equinox photoperiod (5.1 ± 0.3 h), and shortest
under long photoperiod (3.7 ± 0.6 h). Physiological differences in torpor use were associated with significant alterations
of fatty acid composition in ∼50% of the major fatty acids from leg muscle total lipids, whereas white adipose tissue fatty
acid composition showed fewer changes. Our results provide the first evidence that physiological changes due to photoperiod
exposure do result in changes in lipid composition in the muscle tissue of deer mice and suggest that these may play a role
in survival of low body temperature and metabolic rate during torpor, thus, enhancing favourable energy balance over the course
of the winter. 相似文献
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The severity, duration and amplitude of extreme weather events are forecast to intensify with current climate trends, over
both long (e.g. seasonal) and short (e.g. daily) time-scales. As such, the predictability of food supplies for many small
endotherms is likely to become increasingly important. Numerous small mammals and birds combat food shortages using torpor,
a controlled reduction in metabolic rate and body temperature that helps lower their daily energy requirements. As such, torpor
often has been cited as a key feature allowing some small endotherms to survive highly unpredictable climates, such as tropics
or dry deserts, but mensurative demonstrations of this are lacking. We have shown here that when a small desert marsupial,
the fat-tailed dunnart (Sminthopsis crassicaudata), is offered unpredictable levels of daily food, they increase frequency of daily torpor and length of bouts compared with
animals offered ad libitum food, but this was not found for animals offered a 70% food-restricted diet. Our data suggest that
simple food restriction may not be sufficient for evaluating the efficacy of torpor as a strategy for managing unpredictable
climates. 相似文献
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