来自Rockefeller大学的科学家通过研究发现，在神经生物学水平上而言，人类和苍蝇的嗅觉系统是很相似的，这和我们之前预料的很不一样。研究结果发表在了3月19日的在线版《美国国家科学院院刊》（PNAS）上。
要询问一个人他闻到了什么味道是一件很容易的事情——例如味道有多强烈？或者它像什么的味道？——但是对于昆虫来说就很困难了。文章的第一作者，Leslie Vosshall副教授的博士后Andreas Keller表示：“对于这些昆虫是如何对气味作出反应的行为细节并不清楚。”为此，Keller设计了一个实验来观察单个的苍蝇暴露于不同气味之下时是如何作出反应的。结果他和Vosshall发现，苍蝇和人类判断气味强度的方式是一致的，但是判断品质方面却有所不同。
苍蝇的嗅觉系统和人类的类似，都是由很多神经细胞构成的，它们形成气味感受器。每个感受器识别一些气味，因此这些神经细胞结合起来就产生了我们人类以及苍蝇的嗅觉。每种动物的感受器数量是不同的——老鼠大约1200个，人类大约400个，而果蝇为61个。Vosshall和Keller希望了解为什么人类和果蝇发展出了数量如此不同的气体感受器。
Vosshall说：“在不同物种中，感受器数量对于气体感官的影响并不十分清楚。我们发现尽管确定强度方面人类和苍蝇类似，但是在气味种类判断上还是有差异的。”或许在两者的嗅觉系统中产生了基本的变化，这导致了以上差异的形成。
部分英文原文：
Published online before print March 19, 2007, 10.1073/pnas.0605321104
PNAS | March 27, 2007 | vol. 104 | no. 13 | 5614-5619
Influence of odorant receptor repertoire on odor perception in humans and fruit flies
Andreas Keller, and Leslie B. Vosshall*
Laboratory of Neurogenetics and Behavior, The Rockefeller University, 1230 York Avenue, Box 63, New York, NY 10021
Edited by Jeffrey C. Hall, Brandeis University, Waltham, MA, and approved February 16, 2007 (received for review June 26, 2006)
The olfactory system is thought to recognize odors with multiple odorant receptors (ORs) that are activated by overlapping sets of odorous molecules, ultimately generating an odor percept in the brain. We investigated how the odor percept differs between humans and Drosophila melanogaster fruit flies, species with very different OR repertoires. We devised high-throughput single fly behavior paradigms to ask how a given OR contributes to the odor percept in Drosophila. Wild-type flies showed dose- and stimulus-dependent responses to 70 of 73 odors tested, whereas mutant flies missing one OR showed subtle behavioral deficits that could not be predicted from the physiological responses of the OR. We measured human and fly judgments of odor intensity and quality and found that intensity perception is conserved between species, whereas quality judgments are species-specific. This study bridges the gap between the activation of olfactory sensory neurons and the odor percept.
behavior | Drosophila | genetics | olfaction | psychophysics
Author contributions: A.K. designed research; A.K. performed research; A.K. and L.B.V. analyzed data; and A.K. and L.B.V. wrote the paper.
