Caviedes-Vidal E, Afik D, Martinez del Rio C, Karasov W H
Departamento de Bioquímica y Ciencias Biológicas, Universidad Nacional de San Luis, 5700 San Luis, Argentina.
Comp Biochem Physiol A Mol Integr Physiol. 2000 Jan;125(1):11-24. doi: 10.1016/s1095-6433(99)00163-4.
Insectivorous/frugivorous passerine species studied so far lack the ability to modulate intestinal maltase activity, in contrast to galliformes. We tested for dietary modulation of small intestine (SI) enzymes including maltase in house sparrows to understand whether the difference between the galliformes on the one hand, and the passerines on the other, reflects a phylogenetic pattern (maltase modulated in galliformes but not passerines), a dietary pattern (maltase modulated in granivores but not insectivore/frugivores), some other pattern, or chance. We also tested the prediction that intestinal peptidase activity would be increased on a high protein (HP) diet. Birds were fed three diets high in starch, protein, or lipid for 10 days. For birds on the HP diet (60.3% protein) we observed the predicted upward modulation of aminopeptidase-N activity, as compared with the lower-protein, high starch (HS) (12.8% protein) diet. In contrast, birds eating the HS diet had similar maltase and sucrase activities, and only slightly higher isomaltase activity, compared with birds eating the high protein (HP), starch-free diet. Birds eating high lipid (HL) diet had low activities of both carbohydrases and peptidase. Considering that the statistical power of our tests was adequate, we conclude that house sparrows show little or no increase in carbohydrases in response to elevated dietary carbohydrate. We cannot reject the hypothesis that maltase lability among avian species has a phylogenetic component, or that high dietary fat has a depressing effect on both carbohydrase and peptidase activities.
与鸡形目动物不同，迄今为止所研究的食虫/食果雀形目物种缺乏调节肠道麦芽糖酶活性的能力。我们对家麻雀小肠（SI）酶（包括麦芽糖酶）进行了饮食调节测试，以了解一方面鸡形目动物与另一方面雀形目动物之间的差异，是反映了系统发育模式（鸡形目动物中麦芽糖酶可调节，而雀形目动物中则不可调节）、饮食模式（谷食性动物中麦芽糖酶可调节，而食虫/食果动物中则不可调节）、其他某种模式，还是仅仅出于偶然。我们还测试了高蛋白（HP）饮食会使肠肽酶活性增加这一预测。给鸟类喂食三种分别富含淀粉、蛋白质或脂质的饲料，持续10天。与低蛋白、高淀粉（HS）（12.8%蛋白质）饮食的鸟类相比，我们观察到食用HP饮食（60.3%蛋白质）的鸟类出现了预测的氨肽酶-N活性上调。相比之下，食用HS饮食的鸟类与食用无淀粉的高蛋白（HP）饮食的鸟类相比，麦芽糖酶和蔗糖酶活性相似，异麦芽糖酶活性仅略高。食用高脂（HL）饮食的鸟类碳水化合物酶和肽酶的活性都较低。鉴于我们测试的统计效力足够，我们得出结论，家麻雀对饮食中碳水化合物增加的反应中，碳水化合物酶几乎没有增加或根本没有增加。我们不能排除这样的假设，即鸟类物种间麦芽糖酶的不稳定性具有系统发育成分，或者高饮食脂肪对碳水化合物酶和肽酶的活性都有抑制作用。
