大熊猫苦味受体基因的适应性进化与功能研究

The perception of bitter taste, as a defensive mechanism against ingestion of toxins, has long been conceived to play a vital role in animal's adaptation to environment. Giant pandas are known partly for their being a carnivore but highly specialized feeding on bamboos, and it was speculated that discrimination of bitter compounds in the bamboo should be essential for the survive of the giant panda. Most recently, it has been indicated that bitter taste receptor genes T2R 3 and T2R49 may play potential roles in adaptation to local environments for giant pandas. However, the molecular mechanism underlying adaptive evolution of bitter taste receptor genes and functional roles they may have in defending bitter compounds remain largely unknown for the giant panda. In this proposal, we aim to investigate polymorphism of bitter taste receptor genes and their potential roles in adaptation to diet in the giant panda. The underlying mechanisms of bitter taste receptor genes in adaptive evolution will be explored. Furthermore, the physiological response to bitter compounds such as quercetin or chloroquine, which are enriched in bamboo, of bitter taste receptor gene will be examined by ectopic expression. Our projects will shed light on adaptive mechanism of bitter taste receptor genes in evolution of the giant panda, and will contribute to the conservation and management of the captive giant pandas.

对食物的适应是动物适应环境最重要的环节之一。大熊猫属食肉目，但特化以竹子为食。由于苦味刺激较之其它味觉更易被察觉，对竹子中苦味物质的适应在大熊猫食性的进化中显得尤为重要。大熊猫主食竹种类较多，苦味成分复杂，大熊猫的苦味受体基因（T2Rs）也应存在相应的适应性变异。最新的研究结果表明，大熊猫的T2R3和T2R49在种群水平上受到了明显的定向选择，提示其对苦味成分的识别应具有重要功能。为验证上述假设，本课题拟对大熊猫T2Rs的变异及其受到的选择压力进行研究，探讨大熊猫食性进化过程中T2Rs适应性进化的分子机制；进一步地，将适应性进化中检测到的具有潜在功能的T2Rs，通过异位表达从细胞水平上研究大熊猫T2Rs对主食竹中苦味物质的功能反应。通过本研究，不仅能够深入了解苦味感知在大熊猫食性进化中的作用，还可以进一步丰富适应性进化的理论体系，并为更有效地制定大熊猫保护管理策略提供相关科学依据。