作者: John P. Whiteman , Henry J. Harlow , George M. Durner , Eric V. Regehr , Bryan C. Rourke
关键词: Sea ice 、 Annual cycle 、 Muscle atrophy 、 Animal science 、 Foraging 、 Biology 、 Endocrinology 、 Myosin 、 Internal medicine 、 Predation 、 Habitat 、 Atrophy
摘要: When reducing activity and using stored energy during seasonal food shortages, animals risk degradation of skeletal muscles, although some species avoid or minimize the resulting atrophy while experiencing these conditions hibernation. Polar bears may be deprived relatively inactive winter (when pregnant females hibernate hunting success declines for other demographic groups) as well summer sea ice retreats from key foraging habitats). We investigated muscle in samples biceps femoris collected free-ranging polar Southern Beaufort Sea (SBS) throughout their annual cycle. Atrophy was most pronounced April-May a result deprivation previous winter, with muscles exhibiting reduced protein concentration, increased water content, lower creatine kinase mRNA. These feeding spring seal prey becomes more available), initiating period recovery. During following melt late summer, ~30% SBS abandon retreating land; August, 'shore' exhibited no atrophy, indicating that they had fully recovered deprivation. individuals subsequently scavenged whale carcasses deposited by humans October, retained good condition. In contrast, ~70% follow north into deep less prey. 'ice' fast; loss rapid changes myosin heavy-chain isoforms response to activity. findings indicate that, unlike hibernation, without cannot mitigate atrophy. Consequently, prolonged fasting climate change-induced creates greater abilities travel hunt.