Long-term entrainment of circannual reproductive and metabolic cycles by Northern and Southern Hemisphere photoperiods in woodchucks (Marmota monax).
Long-term entrainment of circannual reproductive and metabolic cycles by Northern and Southern Hemisphere photoperiods in woodchucks (Marmota monax).
复制标题
北半球和南半球光周期对土拨鼠（Marmota monax）的年度生殖和代谢周期的长期影响。
DOI：
10.1095/biolreprod57.5.1008
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发表时间：
1997
影响因子：
3.6
通讯作者：
Tennant,B
中科院分区：
文献类型：
--
作者：
Concannon,P;Roberts,P;Baldwin,B;Tennant,B
在20-23°C的环境中，雄性旱獭17只，雌性旱獭17 - 18只，连续69个月暴露在模拟的北半球（北方）或南半球（南方）自然光周期中，每月进行一次检查。根据体重峰值、睾丸体积峰值、男性血清睾酮升高和女性血清孕酮升高的日期来评估内源性周期的光携性。在17只雄性和所有17只雌性中，有15只和所有17只雌性的北温带光周期具有同步的年周期；2只雄鼠从不训练，每隔9到11个月自由奔跑一次。35只动物中有34只在2.5年后出现了大约6个月的南方光周期。4年后，4只被困的雄性变得难治性，每隔6到10个月自由奔跑一次。光照下的北方动物在头2年的阶段提前1个月，然后有12个月的周期，持续4年。在第五年，平均而言，北方周期包括1月中旬（相对于南方动物的7月中旬）初始睾酮水平升高，3月初分娩（相对于南方动物的9月初），7月中旬体重达到峰值（相对于南方动物的1月下旬）。结果表明，土拨鼠内源的年轮周期可以被类似于中北纬地区的日光周期变化所牵引和同步6年，并且可以被中南纬地区的日光周期所重新牵引和提前6个月。
Woodchucks were exposed to simulated Northern Hemisphere (boreal) or Southern Hemisphere (austral) natural photoperiods in groups of 17 males and 17–18 females at 20–23°C for 69 mo and examined monthly. Photoentrainment of endogenous cycles was evaluated based on dates of peak body weight, peak testis volume, increased serum testosterone in males, and increased serum progesterone in females. Boreal photoperiods entrained and synchronized annual cycles in 15 of 17 males and in all 17 females; 2 males never entrained and free-ran at 9- to 11-mo intervals. Austral photoperiods phase-advanced cycles by approximately 6 mo after 2.5 yr in 34 of 35 animals. Four entrained males became refractory after 4 yr, free-running at 6- to 10-mo intervals. Photoentrained boreal animals became phaseadvanced by 1 mo during the first 2 yr, and then had 12-mo cycles for 4 yr. In Year 5, on average, boreal cycles included initial testosterone elevations in mid-January (vs. mid-July in australs), parturition in early March (vs. early September in australs), and peak body weight in mid-July (vs. late January in australs). The results confirm that endogenous circannual cycles of woodchucks can be entrained and synchronized for 6 yr by daily changes in photoperiod similar to those of midnorthern latitudes, and can be re-entrained and phase-advanced 6 mo by photoperiods of midsouthern latitudes.