Key Laboratory of Freshwater Fish Reproduction and Development, Ministry of Education, School of Life Sciences, Southwest University, Chongqing 400715, China.
Wudu Bayi High School, Wudu, Longnan, Gansu 746000, China.
J Exp Biol. 2018 Apr 20;221(Pt 8):jeb174474. doi: 10.1242/jeb.174474.
The metabolic-level boundaries (MLB) hypothesis proposes that metabolic level mediates the relative influence of surface area (SA)- versus volume-related metabolic processes on the body-mass scaling of metabolic rate in organisms. The variation in the scaling of SA may affect how metabolic level affects the metabolic scaling exponent. This study aimed to determine the influence of increasing metabolic level at a higher temperature on the metabolic scaling exponent of the goldfish and determine the link between metabolic scaling exponents and SA parameters of both gills and body. The SA of gills and body and the resting metabolic rate (RMR) of the goldfish were assessed at 15°C and 25°C, and their mass scaling exponents were analyzed. The results showed a significantly higher RMR, with a lower scaling exponent, in the goldfish at a higher temperature. The SA of the gills and the total SA of the fish (TSA) were reduced with the increasing temperature. The scaling exponent of RMR () tended to be close to that of the TSA at a higher temperature. This suggests that temperature positively affects metabolic level but negatively affects The findings support the MLB hypothesis. The lower scaling exponent at a higher temperature can be alternatively explained as follows: the higher viscosity of cold water impedes respiratory ventilation and oxygen uptake and reduces metabolic rate more in smaller individuals than in larger individuals at lower temperature, thus resulting in a negative association between temperature and .
代谢水平边界（MLB）假说提出，代谢水平介导了表面积（SA）与体积相关代谢过程对生物体代谢率与体重之间关系的相对影响。SA 比例的变化可能会影响代谢水平对代谢比例指数的影响。本研究旨在确定在较高温度下增加代谢水平对金鱼代谢比例指数的影响，并确定代谢比例指数与鳃和身体的 SA 参数之间的联系。在 15°C 和 25°C 下评估了金鱼的鳃和身体的 SA 以及静止代谢率（RMR），并分析了它们的质量比例指数。结果表明，金鱼在较高温度下具有更高的 RMR 和更低的比例指数。随着温度的升高，鳃和鱼的总 SA（TSA）的比例降低。RMR 的比例指数（）在较高温度下趋于接近 TSA 的比例指数。这表明温度对代谢水平有积极影响，但对代谢率的表面积比（）有负面影响。研究结果支持 MLB 假说。较高温度下较低的比例指数可以用以下方式解释：冷水的较高粘度会阻碍呼吸通气和氧气摄取，并在较低温度下导致较小个体的代谢率降低幅度大于较大个体，从而导致温度与之间呈负相关。
