Department of Zoology, University of British Columbia, 6270 University Blvd., Vancouver, BC, V6T 1Z4 Canada.
J Fish Biol. 2014 Apr;84(4):982-95. doi: 10.1111/jfb.12339.
The main finding of this study was that measuring maximum heart rate during incremental warming was an effective tool to estimate upper thermal limits in three small cyprinid Danio species, which differed significantly. Arrhenius breakpoint temperature for maximum heart rate, purportedly an index of optimum temperature, was 21·2 ± 0·4, 20·1 ± 0·4 and 18·9 ± 0·8° C (mean ± s.e.) for zebrafish Danio rerio, pearl danio Danio albolineatus and glowlight danio Danio choprae, respectively. The temperature where cardiac arrhythmias were first induced during warming (T(arr)) was 36·6 ± 0·7, 36·9 ± 0·8 and 33·2 ± 0·8° C (mean ± s.e.) and critical thermal maximum (T(Cm)) was 39·9 ± 0·1, 38·9 ± 0·1 and 37·2 ± 0·1° C (mean ± s.e.) for D. rerio, D. albolineatus and D. choprae, respectively. The finding that T(arr) was consistently 3-4° C lower than T(Cm) suggests that collapse of the cardiac life support system may be a critical trigger for upper temperature tolerance. The upper thermal limits established here, which correlate well with a broad natural environmental temperature range for D. rerio and a narrow one for D. choprae, suggest that upper thermal tolerance may be a genetic trait even among closely related species acclimated to common temperatures.
本研究的主要发现是，在递增升温过程中测量最大心率是估计三种小型鲤科鱼类（差异显著）上限热限的有效工具。最大心率的 Arrhenius 断点温度，据称是最佳温度的指标，分别为斑马鱼 Danio rerio、珍珠 Danio albolineatus 和霓虹 Danio choprae 的 21.2±0.4°C、20.1±0.4°C 和 18.9±0.8°C。在升温过程中首次诱发心律失常的温度（T(arr)）分别为 36.6±0.7°C、36.9±0.8°C 和 33.2±0.8°C（均值±s.e.），临界热最大值（T(Cm)）分别为 39.9±0.1°C、38.9±0.1°C 和 37.2±0.1°C（均值±s.e.）。T(arr)始终比 T(Cm)低 3-4°C 的发现表明，心脏生命支持系统的崩溃可能是上限温度耐受性的一个关键触发因素。这里建立的上限热限与斑马鱼 D. rerio 的广泛自然环境温度范围和霓虹 Danio choprae 的狭窄范围相关良好，表明上限热耐受性可能是一种遗传特征，即使在适应常见温度的密切相关物种中也是如此。
