Clinical and Evolutionary Significance of the Taste and Oral Digestion of Starch

描述（由申请人提供）：拟议工作的目的是阐明淀粉摄入量的进化差异导致的遗传变异如何影响当今食用西方饮食的人的淀粉口味和消化、葡萄糖吸收和血糖。为了实现这一目标，将测试唾液淀粉酶基因（AMY 1）的拷贝数（CNV）增加增加摄入淀粉后血糖升高的速率的假设（目标1）。此外，研究人员将测试淀粉味存在于人类中的假设，并确定口服淀粉暴露是否会影响唾液淀粉酶水平（目标2）。对于目标1，研究人员将检查淀粉摄入后个体的血糖谱。将使用蛋白质印迹法和酶活性测定法分析唾液样本的唾液淀粉酶水平和酶功能。将通过高效液相色谱法（HPLC）评估淀粉酶水解产生的淀粉分解特征。最后，研究人员将通过定量PCR（qPCR）、纤维荧光原位杂交（FISH）和基因分型来评估AMY 1的遗传变异，包括基因拷贝数和单核苷酸多态性（SNP）。对于目标2，研究人员将确定受试者是否能够独立于强度区分淀粉和单糖的味道（2a），以及口服淀粉是否会比单糖更能增加唾液淀粉酶的释放（2b;口服调节）。最后，他们还将检查将受试者置于高或低淀粉饮食的影响，以确定唾液淀粉酶水平是否根据淀粉摄入量上调或下调（2c;口服和口服后调节）。将按照目标1评估唾液淀粉酶。 公共卫生相关性：在进化上，有效的淀粉代谢可能有助于在营养不良和/或肠道不适发作期间的生存，这可能导致营养吸收不良。然而，在当今食物过量和高淀粉摄入的状态下，AMY 1基因的拷贝数增加可能导致胰岛素抵抗和非胰岛素依赖型糖尿病（NIDDM）的风险，这些疾病与碳水化合物代谢改变有关。因此，有可能使用高AMY 1基因拷贝数和唾液淀粉酶水平作为风险因素来识别胰岛素抵抗和糖尿病风险的个体。

DESCRIPTION (provided by applicant): The objective of the proposed work is to elucidate how genetic variations resulting from evolutionary differences in starch intake influence starch taste and digestion, glucose absorption, and blood sugar in people consuming a Western diet today. To achieve this goal, the hypothesis that increased copy number (CNVs) of the salivary amylase gene (AMY1) increases the rate at which blood glucose rises after ingesting starch will be tested (Aim 1). Furthermore, the researchers will test the hypothesis that starch taste exists in humans and determine if oral starch exposure affects salivary amylase levels (Aim 2). For Aim 1, the researchers will examine an individuals' blood glucose profile following starch ingestion. Saliva samples will be analyzed for salivary amylase levels and enzyme functionality using Western blots and enzymatic activity assays. The starch breakdown profile resulting from amylase hydrolysis will be assessed via high performance liquid chromatography (HPLC). Finally, the researchers will assess genetic variation in AMY1, including the number of gene copies and single nucleotide polymorphisms (SNPs), through quantitative PCR (qPCR), fiber fluorescence in situ hybridization (FISH), and genotyping. For Aim 2, the researchers will determine if subjects can discriminate the taste of starch from simpler sugars independent of intensity (2a) and if oral exposure to starch will increase the release of salivary amylase more so than simpler sugars (2b; oral regulation). Finally, they will also examine the effects of placing subjects on a high or low starch diet to determine if salivary amylase levels are up or down-regulated depending on starch intake (2c; oral and post-oral regulation). Salivary amylase will be assessed as in Aim 1. PUBLIC HEALTH RELEVANCE: Evolutionarily, efficient starch metabolism may have contributed to survival during bouts of malnutrition and/or intestinal malaise, which can lead to nutrient malabsorption. However, in today's state of food excess and high starch ingestion, it is possible that increased copy number of the AMY1 gene contributes to the risk of insulin resistance and non-insulin dependent diabetes (NIDDM), disorders associated with altered carbohydrate metabolism. Therefore, it may be possible to use high AMY1 gene copy number and salivary amylase levels as risk factors to identify individuals at risk for insulin resistance and diabetes.