Relevance of positive selection on human salivary amylase gene

该奖项是作为NSF社会、行为和经济学博士后研究奖学金(SPRF)计划的一部分提供的。SPRF计划的目标是为学术界、工业界或私营部门和政府的科学职业生涯培养有前途的、早期职业博士水平的科学家。SPRF奖项包括在知名科学家的赞助下进行两年的培训，并鼓励博士后研究员进行独立研究。国家科学基金会致力于促进科学界所有阶层的科学家参与其研究方案和活动，包括那些来自代表性不足的群体的科学家；博士后阶段被认为是实现这一目标的专业发展的一个重要水平。每个博士后研究员都必须解决推动各自学科领域向前发展的重要科学问题。在内华达大学拉斯维加斯分校Alyssa Crittenden博士的赞助下，这项博士后奖学金奖支持一位早期职业科学家研究唾液淀粉酶基因(AMY1)拷贝数增加的正选择对人类在食物消费的口腔阶段消化淀粉的能力的影响。这个项目解决了有关唾液α淀粉酶(SAA)对淀粉消费的重要性的悬而未决的问题。口服SAA是消化淀粉类食物的第一步。然而，人类通过烹饪使食物降解变得外在，从而消除了对口服消化的需要，这会分解淀粉等大分子。然而，尚不清楚咀嚼过程中的SaA活动是否与人类消化淀粉有关。重要的是，目前还没有研究探索生和熟淀粉中SAA活性的比率变化。人类独一无二地拥有多个AMY1拷贝数，标志着饮食中淀粉摄入量的转变。这种饮食变化影响人类健康，因为它与对富含淀粉的饮食的耐受性有关。该项目将有助于对人类SAA基因适应的理解。此外，了解AMY1变异对不同种族和地域人群的营养获取的影响有助于为代谢性疾病预防的饮食治疗策略提供信息。该项目使用多学科方法来回答有关饮食适应如何影响健康的公开问题。这项拟议的研究有三个阶段--体外建模阶段、人类参与者试验阶段和现场工作阶段。第一阶段将通过测量不同短时间间隔内的还原糖副产物，研究暴露于SAA的淀粉消化作为AMY1拷贝数的函数。组织学检测将通过淀粉的形态变化来显示SAA活性。第二阶段将通过口服淀粉溶液在短时间间隔内研究受试者的口服淀粉消化。排出的溶液将以类似的方式测量还原糖分。将使用淀粉酶α1的酶联免疫吸附试验试剂盒在刺激的唾液中测量酶的数量，并使用从口腔拭子中提取的DNA使用数字聚合酶链式反应来测量参考单一拷贝基因的基因拷贝数。这些数据将与医疗和饮食历史数据相结合，帮助发现影响SAA生产和活动的因素。第三阶段需要实地工作，以量化分配给口腔加工淀粉类食物的咀嚼时间。这些都是有价值的数据，可以用来说明以未经广泛机械或热处理的食物为生的人类咀嚼的背景。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This award was provided as part of NSF's Social, Behavioral and Economic Sciences Postdoctoral Research Fellowships (SPRF) program. The goal of the SPRF program is to prepare promising, early career doctoral-level scientists for scientific careers in academia, industry or private sector, and government. SPRF awards involve two years of training under the sponsorship of established scientists and encourage Postdoctoral Fellows to perform independent research. NSF seeks to promote the participation of scientists from all segments of the scientific community, including those from underrepresented groups, in its research programs and activities; the postdoctoral period is considered to be an important level of professional development in attaining this goal. Each Postdoctoral Fellow must address important scientific questions that advance their respective disciplinary fields. Under the sponsorship of Dr. Alyssa Crittenden at University of Nevada, Las Vegas, this postdoctoral fellowship award supports an early career scientist investigating the impact of positive selection for increased copy number of the salivary amylase gene (AMY1) on the ability for humans to digest starch during the oral phase of food consumption. This project tackles unanswered questions regarding the significance of salivary alpha amylase (sAA) for starch consumption. Oral activity of sAA is the first step towards digestion of starchy foods. Yet humans have removed the need for oral digestion by externalizing food degradation through cooking, which breaks down large molecules such as starch. However it is unknown whether sAA activity during chewing is relevant for humans to digest starch. Importantly, no research exists that explores rate variation of sAA activity on raw versus cooked starch. Humans uniquely possess multiple copy numbers of AMY1, signaling a shift in dietary intake of starch. Such dietary shifts impact human health as it relates to tolerance of starch-rich diets. This project will contribute towards an understanding of human sAA genetic adaptations. Furthermore, understanding the impact of AMY1 variation on nutritional acquisition among ethnically and geographically diverse human populations helps inform dietary therapeutic strategies for metabolic disease prevention. This project uses a multidisciplinary approach to answer open questions about how dietary adaptation impacts health. The proposed research has three phases - an in-vitro modeling phase, a human participant trial phase, and a field work phase. Phase I will investigate starch digestion from exposure to sAA as a function of AMY1 copy number by measuring the reducing sugar byproducts across varying short time intervals. Histological assays will show sAA activity via the morphological changes to starch. Phase II will investigate oral starch digestion in human participants over short time intervals via oral manipulation of a starch solution. The expelled solution will similarly be measured for reducing sugars. Enzyme quantity will be measured on stimulated saliva using an ELISA kit for Amylase Alpha 1, and gene copy number will be measured using digital PCR against a reference single copy gene using DNA extracted from buccal swabs. These data will be combined with medical and dietary history data to help discover factors that influence the production and activity of sAA. Phase III entails field work to quantify chewing time allocated for orally processing starchy foods. These are valuable data to contextualize chewing for humans that subsist from foods that have not undergone extensive mechanical or thermal processing.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.