Molecular Mechanisms of Dietary Modulation of Intestinal Enzymes in Birds

许多鸟类和哺乳动物是杂食性的，根据食物的可用性或营养需求的变化，吃各种各样的食物，消化酶的产生可能会随着饮食中底物的可用性而增加。当底物处于高水平时，这种调节模式最大限度地提高了底物的消化率，当底物处于低水平时，这种调节模式最大限度地降低了合成多余酶的成本。在过去nsf支持的研究的基础上，PI将测试关于肠道酶弹性的分子调控基础的假设。对鸟类消化酶调节的研究要么会加强可能出现的普遍性（如果与啮齿动物的研究一致），要么会改变目前对消化酶调节的看法。加深了解还将提高对鸟类对栖息地改变或气候变化引起的饮食变化的反应能力的预测。项目一的重点是家雀（Passer domesticus）幼雀，它们确实表现出肠道碳糖酶的灵活性，而成年麻雀则没有。目的是确定幼鱼肠道糖酶和氨基肽酶- n的饮食调节中的关键分子及其变化率，并测试糖酶表达调节机制是否在不同饮食的成鱼中被沉默。项目II侧重于比较雀形目、非雀形目和啮齿类的野生杂食性代表。目的是测试潜在基因表达调控机制及其变化率的差异。利用饲喂不同饲料的动物组织，PI将测试酶反应模式的分子机制和调节反应的时间过程。该研究支持国际合作以及博士后、研究生、本科生和高中水平的培训。这些研究的数据将在国家和国际科学会议上以及通过同行评议的出版物进行分享。

Many birds and mammals are omnivorous, eating a wide variety of foods depending on changing availability or nutritional requirements, and the production of digestive enzymes may increase with availability of substrate in the diet. This mode of regulation maximizes the digestibility of substrates when they are at high dietary levels and minimizes the cost of synthesizing excess enzyme when the substrate is at low levels. Building on past NSF-supported research, the PI will test hypotheses about the molecular regulatory basis of intestinal enzymatic flexibility. Research on digestive enzyme regulation in birds will either strengthen what may be an emerging generality (if in agreement with rodent studies) or transform current thinking about regulation of digestive enzymes. The enhanced understanding will also improve predictions about birds' abilities to respond to changes in diet that occur due to habitat alterations or climate change.Project I focuses on house sparrow (Passer domesticus) juveniles, which do exhibit intestinal carboydrase flexibility, and adults, which do not. The goal is to identify key molecular players and their rates of change in dietary modulation of intestinal carbohydrases and aminopeptidase-N in the juveniles, and test whether the carbohydrase expression regulatory machinery is silenced in the adults switched between diets. Project II focuses on comparison of wild omnivorous representatives from passerine, nonpasserine, and rodent clades. The goal is to test for differences in underlying gene expression regulatory mechanisms and their rates of change. Using tissues harvested from animals fed contrasting diets, the PI will test for molecular mechanisms underlying enzymatic patterns of response and the time-course for regulatory responses. The research supports international collaboration and also training at postdoctoral, graduate, undergraduates and high school levels. Data from these studies will be shared at national and international scientific conferences and through peer-reviewed publications.