Dietary Specialization in Mammals: Constraints and Costs of Detoxification of Plant Secondary Compounds

哺乳动物的饮食专门化：植物次生化合物解毒的限制和成本

• 批准号: 0079865
• 负责人: Maria Denise Dearing
• 金额: $ 16万
• 依托单位: University of Utah
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-08-15 至 2003-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0079865&HistoricalAwards=false
• 关键词: Dietary; Specialization; Mammals; Constraints; Costs

Mammals that consume plants run the risk of being poisoned by naturally occurring toxins produced by plants. Little experimental work exists on the mechanisms mammals employ to deal with plant toxins, or how specialized species such as the koala are capable of consuming plants that are toxic to other species. The proposed research interfaces with ecology, chemistry, physiology and pharmacology to address mechanisms by which herbivores detoxify plant toxins as well as the costs of detoxification. The PI will investigate how woodrat herbivores that specialize on one species of toxic plant differ in detoxification physiology from generalist woodrats that consume a variety of plant species. Woodrats are a model system for this problem because the diversity of specialists and generalists woodrats is unparalleled by any other genus of mammalian herbivores. Thus far, the PI has found that specialist herbivores are capable of tolerating higher doses of toxins than generalists. Contrary to conventional wisdom, specialists do not appear to have unique detoxification pathways compared to generalists but rather systems with a greater capacity. Preliminary results suggest that specialists are able to deal with high toxin loads because they can eliminate toxins faster than generalists. These studies will further investigate how specialists and generalists differ in detoxification abilities and will address issues on costs and constraints of dietary specialization. For example, are specialists more efficient than generalists in processing toxins? Do specialist herbivores trade-off the ability to detoxify a wide range of toxins in exchange for enhanced processing of a subset of toxins? In this century, mammalian herbivores will confront profound detoxification challenges. Novel toxins (eg dioxins, PCBs) are being added to the environment at unprecedented rates. Moreover, in the next 50 years, levels of CO2 in the atmosphere are predicted to double due to extensive burning of fossil fuels. Many species of plants grown under elevated levels of CO2 are substantially inferior in nutritional quality in that they are lower in protein and contain up to twice the toxin concentration as plants grown under current CO2 concentrations. Will mammalian herbivores be aversely impacted by such a radical change in the nutritional quality of their food, particularly the increase in toxins? The results of this research on detoxification processes of wild herbivores will provide vital insights on how herbivores will be affected by this change in nutritional quality of food.

食用植物的哺乳动物有被植物产生的天然毒素毒害的风险。 关于哺乳动物处理植物毒素的机制，或者像考拉这样的特殊物种如何能够食用对其他物种有毒的植物，几乎没有实验工作。 拟议的研究与生态学，化学，生理学和药理学接口，以解决草食动物解毒植物毒素的机制以及解毒的成本。 PI将研究专门研究一种有毒植物的食草林鼠在解毒生理学方面与食用各种植物物种的多面手林鼠有何不同。 林鼠是这个问题的模型系统，因为林鼠的专家和多面手的多样性是任何其他哺乳类食草动物都无法比拟的。 到目前为止，PI已经发现，专业食草动物比通才能够耐受更高剂量的毒素。 与传统观点相反，专家似乎没有独特的解毒途径相比，通才，而是系统具有更大的能力。 初步结果表明，专家能够处理高毒素负荷，因为他们可以比通才更快地消除毒素。 这些研究将进一步调查专家和通才在解毒能力方面的差异，并将解决饮食专业化的成本和限制因素问题。 例如，在处理毒素方面，专家是否比通才更有效率？ 专业食草动物是否会权衡各种毒素的解毒能力，以换取对一部分毒素的强化处理？ 在这个世纪，哺乳类食草动物将面临深刻的解毒挑战。 新的毒素（如二恶英，多氯联苯）正在以前所未有的速度添加到环境中。 此外，在未来50年内，由于化石燃料的广泛燃烧，大气中的二氧化碳水平预计将翻一番。 许多种在高水平的CO2下生长的植物在营养品质上实质上是低劣的，因为它们的蛋白质含量较低，并且含有高达在当前CO2浓度下生长的植物的两倍的毒素浓度。 食草哺乳动物是否会因食物营养质量的急剧变化，特别是毒素的增加而受到严重影响？这项关于野生食草动物解毒过程的研究结果将为食草动物如何受到食物营养质量变化的影响提供重要的见解。