Seasonal change in mitochondrial function and metabolic enzyme activity of different populations of the mud crab, Scylla paramamosain, from China

Abstract

Over past decades, the farming of mud crab Scylla paramamosain has expanded rapidly in China. In our previous experiments, the results showed that the mud crab S. paramamosain in China could be divided into northern and southern populations and these two populations had differences in the adaptive capacity to cultivation environmental conditions. In order to verify this, the present study measured and compared the mitochondrial function and metabolic enzyme activity of these two populations during seasonal acclimatization. It was shown that the mitochondrial respiration rates in the gill, hepatopancreas and muscle of the northern population were significantly higher than those of the southern population in winter, spring and summer although the differences in summer were less pronounced than in winter and spring. In winter and spring, both state 2 and 3 mitochondrial respiration rates measured using either succinate or pyruvate+malate as the substrate in the gill of the northern population were consistently significantly higher than those of the southern population. The measurement of metabolic enzyme activity during different seasons showed that for the mitochondrial cytochrome C oxidase in the gill, hepatopancreas and muscle, the differences in activity between the northern and southern populations were in general consistent with those of the mitochondrial function. For example, the mitochondrial cytochrome C oxidase activities in the gill of the northern population were significantly higher than those of the southern population in winter, spring and summer. However, activity of lactate dehydrogenase, pyruvate kinase and hexokinase in the muscle were slightly different between the northern and southern populations. Only in summer the lactate dehydrogenase and pyruvate kinase activities in the muscle of the southern population were significantly higher than those of the northern population. In summary, the results of the present study showed that compared to the southern population, the northern population had a better compensation mechanism in mitochondrial metabolite level during cooler seasons, which might indicate that the northern population adapts better to low temperature than the southern population. Therefore, the temperature for the farming of the southern population and northern population should be different.