Wilson R S, James R S, Johnston I A
Department of Zoology and Entomology, The University of Queensland, St. Lucia, Australia.
J Comp Physiol B. 2000 Mar;170(2):117-24. doi: 10.1007/s003600050266.
Among amphibians, the ability to compensate for the effects of temperature on the locomotor system by thermal acclimation has only been reported in larvae of a single species of anuran. All other analyses have examined predominantly terrestrial adult life stages of amphibians and found no evidence of thermal acclimatory capacity. We examined the ability of both tadpoles and adults of the fully aquatic amphibian Xenopus laevis to acclimate their locomotor system to different temperatures. Tadpoles were acclimated to either 12 degrees C or 30 degrees C for 4 weeks and their burst swimming performance was assessed at four temperatures between 5 degrees C and 30 degrees C. Adult X. laevis were acclimated to either 10 degrees C or 25 degrees C for 6 weeks and their burst swimming performance and isolated muscle performance was determined at six temperatures between 5 degrees C and 30 degrees C. Maximum swimming performance of cold-acclimated X. laevis tadpoles was greater at cool temperatures and lower at the highest temperature in comparison with the warm-acclimated animals. At the test temperature of 12 degrees C, maximum swimming velocity of tadpoles acclimated to 12 degrees C was 38% higher than the 30 degrees C-acclimation group, while at 30 degrees C, maximum swimming velocity of the 30 degrees C-acclimation group was 41% faster than the 12 degrees C-acclimation group. Maximum swimming performance of adult X. laevis acclimated to 10 degrees C was also higher at the lower temperatures than the 25 degrees C acclimated animals, but there was no difference between the treatment groups at higher temperatures. When tested at 10 degrees C, maximum swimming velocity of the 10 degrees C-acclimation group was 67% faster than the 25 degrees C group. Isolated gastrocnemius muscle fibres from adult X. laevis acclimated to 10 degrees C produced higher relative tetanic tensions and decreased relaxation times at 10 degrees C in comparison with animals acclimated to 25 degrees C. This is only the second species of amphibian, and the first adult life stage, reported to have the capacity to thermally acclimate locomotor performance.
在两栖动物中，通过热驯化来补偿温度对运动系统影响的能力仅在一种无尾目动物的幼体中被报道过。所有其他分析主要研究的是两栖动物的陆生成年阶段，并未发现热驯化能力的证据。我们研究了完全水生的非洲爪蟾幼体和成体使运动系统适应不同温度的能力。将幼体分别在12摄氏度或30摄氏度下驯化4周，并在5摄氏度至30摄氏度之间的四个温度下评估它们的爆发式游泳表现。将成年非洲爪蟾分别在10摄氏度或25摄氏度下驯化6周，并在5摄氏度至30摄氏度之间的六个温度下测定它们的爆发式游泳表现和离体肌肉表现。与温暖驯化的动物相比，冷驯化的非洲爪蟾幼体在低温时的最大游泳表现更好，在最高温度时则更低。在12摄氏度的测试温度下，适应12摄氏度的幼体的最大游泳速度比适应30摄氏度的组高38%，而在30摄氏度时，适应30摄氏度的组的最大游泳速度比适应12摄氏度的组快41%。适应10摄氏度的成年非洲爪蟾在较低温度下的最大游泳表现也比适应25摄氏度的动物高，但在较高温度下，处理组之间没有差异。在10摄氏度测试时，适应10摄氏度的组的最大游泳速度比25摄氏度组快67%。与适应25摄氏度的动物相比，适应10摄氏度的成年非洲爪蟾的离体腓肠肌纤维在10摄氏度时产生更高的相对强直张力并缩短了舒张时间。这是被报道具有热驯化运动表现能力的第二种两栖动物，也是第一个成年阶段。
