German Donovan P, Horn Michael H, Gawlicka Anna
Department of Biological Science, California State University, Fullerton, CA, 92834-6850, USA.
Physiol Biochem Zool. 2004 Sep-Oct;77(5):789-804. doi: 10.1086/422228.
We measured the activities of eight digestive enzymes in four species of herbivorous and carnivorous prickleback fishes and determined the effects of ontogeny, diet, and phylogeny on these enzyme activities. Of the four species, Cebidichthys violaceus and Xiphister mucosus shift to a more herbivorous diet as they grow (> or =45 mm SL [standard length]), whereas Xiphister atropurpureus and Anoplarchus purpurescens remain carnivores throughout life. Digestive enzyme activities of small (30-40 mm SL) carnivorous juveniles were compared with those of larger (60-75 mm SL) wild-caught juveniles that had consumed a natural diet and larger (60-75 mm SL) juveniles raised on a high-protein animal diet. Cebidichthys violaceus and both species of Xiphister showed ontogenetic changes in digestive enzyme activities, whereas A. purpurescens did not. Despite dietary differences between X. atropurpureus and X. mucosus, these sister taxa displayed the most similar digestive enzyme activities from ontogenetic and dietary perspectives (high alpha-amylase and lipase and low trypsin and aminopeptidase activities), and both were more similar to C. violaceus, a member of the same largely herbivorous clade, than either was to A. purpurescens, a member of an adjacent, carnivorous clade. The results support the hypothesis that phylogeny influences digestive enzyme activities in these fishes. Anoplarchus purpurescens, a carnivore with a diverse diet, showed great plasticity in enzyme activity, especially trypsin and aminopeptidase, which were elevated in this species to the highest level among the four species after consuming the high-protein diet. These results support the hypothesis that fishes with relatively broad diets can modulate digestive enzyme activities in response to changes in dietary composition.
我们测量了四种食草性和肉食性杜父鱼科鱼类中八种消化酶的活性，并确定了个体发育、饮食和系统发育对这些酶活性的影响。在这四个物种中，紫罗兰色杜父鱼和黏液杜父鱼随着生长（标准长度大于或等于45毫米）会转向更食草性的饮食，而紫杜父鱼和紫拟三刺鲀终生保持肉食性。将小型（标准长度30 - 40毫米）肉食性幼鱼的消化酶活性与食用天然食物的较大型（标准长度60 - 75毫米）野生捕获幼鱼以及以高蛋白动物饲料饲养的较大型（标准长度60 - 75毫米）幼鱼的消化酶活性进行了比较。紫罗兰色杜父鱼和两种杜父鱼属鱼类在消化酶活性上表现出个体发育变化，而紫拟三刺鲀则没有。尽管紫杜父鱼和黏液杜父鱼在饮食上存在差异，但从个体发育和饮食角度来看，这两个姊妹分类单元显示出最相似的消化酶活性（高α -淀粉酶和脂肪酶活性以及低胰蛋白酶和氨肽酶活性），并且它们与同一主要食草性分支的成员紫罗兰色杜父鱼相比，都比与相邻肉食性分支的成员紫拟三刺鲀更相似。结果支持了系统发育影响这些鱼类消化酶活性的假设。紫拟三刺鲀是一种食性多样的肉食性鱼类，在酶活性方面表现出很大的可塑性，尤其是胰蛋白酶和氨肽酶，在食用高蛋白饲料后，该物种的这些酶活性在四个物种中升至最高水平。这些结果支持了饮食相对广泛的鱼类可以根据饮食组成变化调节消化酶活性的假设。
