CAREER: Mechanisms and tradeoffs of dietary specialization in mammalian herbivores

职业：哺乳动物食草动物饮食专业化的机制和权衡

• 批准号: 0236402
• 负责人: Maria Denise Dearing
• 金额: $ 51.07万
• 依托单位: University of Utah
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-03-01 至 2010-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0236402&HistoricalAwards=false
• 关键词: CAREER; Mechanisms; tradeoffs; dietary; specialization

Limitations of the detoxification system in processing plant toxins are implicated as the mechanism explaining the paucity of dietary specialization among mammalian herbivores. In fact, little is known about how wild herbivores metabolize plant toxins and how detoxification restricts dietary specialization. Detoxification constraints are of current interest given that the toxin concentrations of many plants will double within the next century due to rising atmospheric CO2 levels. The overarching goals of the research are to understand the mechanisms that permit and tradeoffs associated with dietary specialization in herbivorous woodrats (Neotoma). Specialist woodrats are predicted to absorb lower concentrations of plant toxins compared to generalists. The research examines 3 mechanisms that may decrease toxin absorption: 1) tannin-binding proteins 2) p-glycoproteins and 3) intestinal detoxification. Specialists and generalists will be compared to determine how they differ with respect to these mechanisms. Biochemical and pharmacological methods will be employed. In addition, theory predicts that specialists have detoxification systems that are more efficient in processing plant toxins in their diet compared to generalist herbivores processing the same compounds. However, the superior ability that specialists have in processing toxins from their diet is predicted to compromise their efficiency to biotransform novel toxins, which are not contained in their normal diet. The potential tradeoffs of dietary specialization will be addressed by comparing 1) maximal levels of novel toxins that specialists and generalists can ingest; 2) capacities of detoxification pathways (functionalization and glucuronidation) using probe drugs; and 3) surveying the detoxification systems of generalists and specialists with DNA microarrays. For the education component, an intensive course is proposed for mid-level students (sophomore-junior) to train them in various aspects of research by using this research project as the example and opportunity. This course, "Scientific Immersion", will be offered in the fall semester each year to a maximum of five students.

处理植物毒素的解毒系统的局限性被认为是解释哺乳动物食草动物缺乏饮食专门化的机制。事实上，人们对野生食草动物如何代谢植物毒素以及解毒如何限制饮食专门化知之甚少。由于大气中二氧化碳浓度上升，许多植物的毒素浓度将在下个世纪内翻倍，因此解毒限制引起了当前的关注。该研究的总体目标是了解草食性林鼠（Neotoma）饮食专业化的允许和权衡机制。与通才相比，专家预计林鼠吸收的植物毒素浓度较低。该研究探讨了 3 种可能减少毒素吸收的机制：1) 单宁结合蛋白 2) p-糖蛋白和 3) 肠道解毒。将比较专家和通才，以确定他们在这些机制方面有何不同。将采用生物化学和药理学方法。 此外，理论预测，与处理相同化合物的通才食草动物相比，专家的解毒系统在处理饮食中的植物毒素方面更有效。 然而，专家们处理饮食中毒素的卓越能力预计会损害他们生物转化新毒素的效率，而这些毒素并不包含在他们的正常饮食中。饮食专业化的潜在权衡将通过比较来解决：1）专家和通才可以摄入的新型毒素的最大水平； 2）使用探针药物的解毒途径（功能化和葡萄糖醛酸化）的能力； 3) 利用 DNA 微阵列调查通才和专家的解毒系统。 在教育部分，建议为中级学生（大二至大三）开设强化课程，以本研究项目为范例和机会，对他们进行各个研究方面的培训。 这门“科学沉浸”课程将在每年秋季学期向最多五名学生提供。