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Nature：果蝇大脑内存在“热敏元件”
苍蝇不像人类可以改变环境温度，为了生存它们需要选择温度合适的地方活动，美国布兰迪斯大学大学研究认为果蝇体内有类似热敏元件的组织。研究结果发表在11日《自然》杂志上。
生物学家Paul Garrity和他的同事们发现，果蝇大脑内有4个大型热感应神经元细胞，它们将在环境温度高于理想温度的时候被激活，温度改变通过细胞膜上的dTrpA1离子通道，该离子通道本身就担任着温度传感的职责。
果蝇能使用脑内的传感器测量环境温度。大型动物使用外围神经元监控周围环境温度，而普遍的看法是像果蝇这样的小型生物也是如此。研究人员通过使用多种追踪方式，希望能在果蝇身上找到热敏感应外围神经元，可是最终数据表明，温度传感的关键不在外围神经元，而在果蝇的大脑。
研究数据显示dTrpA1离子通道可能像火警预报一样工作。当果蝇大脑内温度过高，dTrpA1激活内部传感，让它们寻找温度更适宜的地方。
尽管环境温度广泛影响着人类和动物行为，我们对动物们选择适宜温度的神经中枢工作原理却知之甚少。这项研究使得科学家们在探知神经元细胞如何帮助果蝇寻找合适的温度以确保生存的进度上迈出了重要的一步。反之，这些神经元通路也能成为攻击和扰乱动物热敏行为的武器，可以应用于农业害虫和传播疟疾、登革热等疾病的蚊子等的防治。
全球变暖使大量昆虫、鱼类、鸟类和哺乳类动物不得不去寻找温度更适宜的生存环境，明白动物神经中枢对温度变换的感应机制，能够更好地理解动物应对环境变化的措施。此外，控制这一温度感应机制的蛋白质与人类的疼痛、炎症有关，深入研究这些蛋白质的工作原理将在新的治疗方法和药物研究方面做出重要贡献。
原始出处：
Nature 11 June 2008 | doi:10.1038/nature07001
An internal thermal sensor controlling temperature preference in Drosophila
Fumika N. Hamada1, Mark Rosenzweig1, Kyeongjin Kang1, Stefan R. Pulver1, Alfredo Ghezzi1, Timothy J. Jegla2 & Paul A. Garrity1
National Center for Behavioral Genomics, Volen Center for Complex Systems, Biology Department, Brandeis University MS-008, 415 South Street, Waltham, Massachusetts 02454, USA
Department of Cell Biology and Institute for Childhood and Neglected Diseases, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA
Correspondence to: Paul A. Garrity1 Correspondence and requests for materials should be addressed to P.A.G. (Email: pgarrity@brandeis.edu).
Animals from flies to humans are able to distinguish subtle gradations in temperature and show strong temperature preferences1, 2, 3, 4. Animals move to environments of optimal temperature and some manipulate the temperature of their surroundings, as humans do using clothing and shelter. Despite the ubiquitous influence of environmental temperature on animal behaviour, the neural circuits and strategies through which animals select a preferred temperature remain largely unknown. Here we identify a small set of warmth-activated anterior cell (AC) neurons located in the Drosophila brain, the function of which is critical for preferred temperature selection. AC neuron activation occurs just above the fly's preferred temperature and depends on dTrpA1, an ion channel that functions as a molecular sensor of warmth. Flies that selectively express dTrpA1 in the AC neurons select normal temperatures, whereas flies in which dTrpA1 function is reduced or eliminated choose warmer temperatures. This internal warmth-sensing pathway promotes avoidance of slightly elevated temperatures and acts together with a distinct pathway for cold avoidance to set the fly's preferred temperature. Thus, flies select a preferred temperature by using a thermal sensing pathway tuned to trigger avoidance of temperatures that deviate even slightly from the preferred temperature. This provides a potentially general strategy for robustly selecting a narrow temperature range optimal for survival. |
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