Franco Marcela, Contreras Carolina, Place Ned J, Bozinovic Francisco, Nespolo Roberto F
Facultad de Ciencias Naturales y Matemáticas, Universidad de Ibagué, Carrera 22 Calle 67, Ibagué, Colombia.
Instituto de Ciencias Ambientales y Evolutivas, Universidad Austral de Chile, Casilla 567, Campus Isla Teja, Valdivia 5090000, Chile.
Comp Biochem Physiol A Mol Integr Physiol. 2017 Jan;203:233-240. doi: 10.1016/j.cbpa.2016.09.025. Epub 2016 Oct 2.
Mammals of the Neotropics are characterized by a marked annual cycle of activity, which is accompanied by several physiological changes at the levels of the whole organism, organs and tissues. The physiological characterization of these cycles is important, as it gives insight on the mechanisms by which animals adjust adaptively to seasonality. Here we studied the seasonal changes in blood biochemical parameters in the relict South American marsupial Dromiciops gliroides ("monito del monte" or "little mountain monkey"), under semi-natural conditions. We manipulated thermal conditions in order to characterize the effects of temperature and season on a battery of biochemical parameters, body mass and adiposity. Our results indicate that monitos experience an annual cycle in body mass and adiposity (measured as leptin levels), reaching a maximum in winter and a minimum in summer. Blood biochemistry confirms that the nutritional condition of animals is reduced in summer instead of winter (as generally reported). This was coincident with a reduction of several biochemical parameters in summer, such as betahydroxybutyrate, cholesterol, total protein concentration and globulins. Monitos seem to initiate winter preparation during autumn and reach maximum body reserves in winter. Hibernation lasts until spring, at which time they use fat reserves and become reproductively active. Sexual maturation during summer would be the strongest energetic bottleneck, which explains the reductions in body mass and other parameters in this season. Overall, this study suggests that monitos anticipate the cold season by a complex interaction of photoperiodic and thermal cues.
新热带界的哺乳动物具有明显的年度活动周期，同时在整个生物体、器官和组织水平上伴随着若干生理变化。这些周期的生理特征很重要，因为它能让我们深入了解动物如何通过适应性调整来适应季节性变化。在此，我们研究了南美有袋类动物残留种格氏侏袋貂（“山地小兽”或“小山猴”）在半自然条件下血液生化参数的季节性变化。我们通过控制热条件来确定温度和季节对一系列生化参数、体重和肥胖程度的影响。我们的研究结果表明，侏袋貂的体重和肥胖程度（以瘦素水平衡量）呈现年度周期变化，冬季达到最大值，夏季达到最小值。血液生化分析证实，动物的营养状况在夏季而非冬季下降（与一般报道情况相反）。这与夏季一些生化参数的降低相吻合，如β-羟基丁酸、胆固醇、总蛋白浓度和球蛋白。侏袋貂似乎在秋季开始为冬季做准备，冬季时身体储备达到最大值。冬眠持续到春季，此时它们利用脂肪储备并进入繁殖活跃期。夏季的性成熟可能是最严重的能量瓶颈，这解释了该季节体重和其他参数下降的原因。总体而言，这项研究表明，侏袋貂通过光周期和热信号的复杂相互作用来提前迎接寒冷季节。
