Is Diet Shifting Facilitated by Modulation of Intestinal Nutrient Uptake? Test of an Adaptational Hypothesis in Yellow-Rumped Warblers
Is Diet Shifting Facilitated by Modulation of Intestinal Nutrient Uptake? Test of an Adaptational Hypothesis in Yellow-Rumped Warblers
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DOI：
10.1086/639580
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发表时间：
1997-03
期刊：
影响因子：
--
通讯作者：
D. Afik;B. W. Darken;W. Karasov
中科院分区：
文献类型：
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作者：
D. Afik;B. W. Darken;W. Karasov
黄腰莺（Dendroica coronata）是许多季节性改变饮食的鸟类之一。使用它们，我们测试了D-葡萄糖和氨基酸L-亮氨酸的摄取将分别随着碳水化合物和蛋白质的饮食水平的增加而增加的预测，并且整个小肠的介导摄取能力将与每日食物摄入的营养负荷相匹配。用水果、昆虫和种子配制的三种半合成饲料喂养鸡7 d。体外介导的D-葡萄糖摄取受饮食影响，但与我们的先验预测相反，吃水果的人吃碳水化合物最高的饮食摄取率最低。在低浓度（0.01 mmol L-亮氨酸）下，昆虫和食籽动物的Na+依赖性L-亮氨酸摄取较高，这与对膳食蛋白质适应的预测一致，尽管膳食脂肪也可能起作用。介导的D-葡萄糖摄取量在小肠长度上的总和只能解释估计的全动物吸收率的一小部分。因此，我们拒绝碳水化合物的预测，但建议我们的结果是符合经济设计的另一种解释。
Yellow-rumped warblers (Dendroica coronata) are one of many avian species that change their diet seasonally. Using them, we tested the predictions that uptake of D-glucose and the amino acid L-leucine will increase as dietary levels of carbohydrate and protein, respectively, are increased and that mediated uptake capacity of the entire small intestine will match nutrient loads from daily food intake. Birds were fed three semisynthetic diets, formulated from fruit, insects, or seeds, for 7 d. Mediated D-glucose uptake in vitro was affected by diet, but contrary to our a priori prediction, fruit eaters eating the diet highest in carbohydrates had the lowest uptake rate. Na⁺-dependent L-leucine uptake at a low concentration (0.01 mmol L⁻¹) was higher in insect and seed eaters, which is consistent with the prediction of adaptation to dietary protein, though dietary fat may also play a role. Mediated D-glucose uptake summed over small intestine length could explain only a small percentage of the estimated whole-animal absorption rate. We thus reject the predictions for carbohydrate but suggest an alternative interpretation of our results that is consistent with economical design.