1、人们如何辨别自己气味发布时间：2013-01-25文章出自：译言原文链接：点击查看你在一组指纹中你不大可能辨认出你自己的指纹，但是你的大脑能认出你的气味。第一次，科学家们已发现人类能辨认自己的气味，这些气味其实是一种微小粒子（主要组织相容性复合体蛋白即 MHC），与动物通过气味选择其配偶的行为一样。这一发现表明人类也具有这种区分他人的潜力。 “这绝对是令人激动的首创”Frank Zufall 说，他是德国汉堡 Saarland 大学医学院神经生物学家，尽管他没参与此研究，“这种实验以前从未对人类做过” 。 MHC 多肽是种蛋白质，存在于人体几乎所有细胞表面，其作用是帮助免疫系统区分我们自己的细
2、胞。那一种组合的 MHC 多肽即一种 MHC 类型这是个体独有的，当有病菌或外来细胞侵入时，它能帮助我们辨认出。在过去 20 年的研究中，科学家发现这种粒子在动物中可促进交流，包括鼠类和鱼。例如棘鱼会选择与自己不同 MHC 类型的配偶。后来在 1995 年，研究者进行了现在著名的“汗味 t 恤实验”，得出结论女性喜欢不同于自己 MHC 基因类型的男性的气味。但是还没有实验能清晰表明对 MHC 蛋白的生理反应。在这新实验中，来自德国 Freiburg 市 Max Planck 研究所免疫与实验胚胎学院的生物学家 Thomas Boehm 和同事首先测试女性能否辨别出在实验室中制作出来的她们自己的
3、气味。洗过澡后，22 位女实验对象在她们腋下涂上 2 种气味不同的物质，然后选择出她们喜欢的一种。每个参与者都要重复 2 至 6 次这种实验。结果表明只有在不吸烟的女性及没有感冒的时候，她们会选择含有自己 MHC 蛋白质的合成气味。这项研究没确定女性喜欢他人身上的何种气味，但是过去关于香水的研究表明人们喜欢不同于自己的气味。 研究者想知道这种选择的根本原因是否是大脑对于蛋白质的反应。所以下一步他们利用功能性磁共振成像来观测 19 位女性嗅不同物质时她们脑部的变化，这些物质以气溶胶形态喷向她们鼻子。“可以肯定，又一次表明大脑对自己及异己多肽（一种蛋白质）的反应明显不同”，Boehm 说，“在大脑
4、的一个特定区域，只对包含有类似自己的 MHC 粒子的多肽有反应。”大脑对所有异己的 MHC 蛋白质都有类似反应，表明任何对其他人气味的选择其实是对异己的选择，而不是对某一特定的 MHC 的选择。 来自瑞士 Lausanne 大学的生物学家 Claus Wedekind，是在其独创的臭 t 恤研究领域里的领军人物，他说此研究结果和他过去十年的研究结果相当一致，“在我们刚刚开始研究臭t 恤时，我一度认为人们会选择不同的 MHC 类型，但是基于最近的研究，表明人们实际上仅仅能区分自己和异己的 MHC。这个新论文自然证明了这一观点。” 以往香水的研究表明，不同的气味香水可以放大不同的体味-桃味可能与你
5、的体味最搭，然而香草味最适合你好友。Boehm 认为他们在区分自己和异己气味方面的新发现（可以在Proceedings of the Royal Society B 网上找到），可帮助研究者理解为什么人们会喜欢喷与众不同的香水。他说，人们会选择一种能放大自己 MHC 的香水，但是喜欢其他人不同于自己 MHC 的气味的香水。然而在感知 MHC 蛋白的生理学上还有很多疑问。研究者不知道在鼻子中哪部分接收器感知 MHC 蛋白，因为人类没有像动物那样可以嗅出 MHC 蛋白的犁鼻器。“我们很想继续这个研究来确定到底是人体哪个接收器辨认 MHC 蛋白”，Boehm 说。 Zufall 说“ 人体产生的其他
6、分子也能影响体味及气味喜好。”“个体内的微生物- 我们体内及体表的细菌和我们的体味及气味喜好也有关”，Wedekind 说，“我们还不知道整个生理过程，但这是个好开端”。 How People Smell Themselves 发布时间：2013-01-25文章出自：Wired原文链接：点击查看You might not be able to pick your fingerprint out of an inky lineup, but your brain knows what you smell like. For the first time, scientists have show
7、n that people recognize their own scent based on their particular combination of major histocompatibility complex (MHC) proteins, molecules similar to those used by animals to choose their mates. The discovery suggests that humans can also exploit the molecules to differentiate between people. “This
8、 is definitely new and exciting, ” says Frank Zufall, a neurobiologist at Saarland Universitys School of Medicine in Homburg, Germany, who was not involved in the work. “This type of experiment had never been done on humans before.” MHC peptides are found on the surface of almost all cells in the hu
9、man body, helping inform the immune system that the cells are ours. Because a given combination of MHC peptidescalled an MHC typeis unique to a person, they can help the body recognize invading pathogens and foreign cells. Over the past 2 decades, scientists have discovered that the molecules also f
10、oster communication between animals, including mice and fish. Stickleback fish, for example, choose mates with different MHC types than their own. Then, in 1995, researchers conducted the now famous “sweaty T-shirt study, ” which concluded that women prefer the smell of men who have different MHC ge
11、nes than themselves. But no studies had shown a clear-cut physiological response to MHC proteins. In the new work, Thomas Boehm, a biologist at the Max Planck Institute of Immunobiology and Epigenetics in Freiburg, Germany, and colleagues first tested whether women can recognize lab-made MHC protein
12、s resembling their own. After showering, 22 women applied two different solutions to their armpits and decided which odor they liked better. The experiment was repeated two to six times for each participant. Women preferred to wear a synthetic scent containing their own MHC proteins, but only if the
13、y were nonsmokers and didnt have a cold. The study did not determine which scents women preferred on other people, but past studies on perfume have shown that individuals prefer different smells on themselves than on others. The researchers wanted to know whether the preferences were truly rooted in
14、 the brains response to the proteins. So next, they used functional magnetic resonance imaging to measure changes in the brains of 19 different women when they smelled the various solutions, in aerosol form puffed toward their noses. “Sure enough, there again was a clear difference between the respo
15、nse to self and non-self peptides, ” Boehm says. “There was a particular region of the brain that was only activated by peptides resembling a persons own MHC molecules.” The brain had a similar response to all non-self MHC combinations, suggesting that any preference for how other people smell is a
16、preference for non-self, not for particular MHC types. Claus Wedekind, a biologist at the University of Lausanne in Switzerland who spearheaded the original smelly T-shirt study, says the results fit well with his research over the past decade. “After our original T-shirt study, I had the impression
17、 that people had preferences between different MHC types, ” he says. “But based on later studies, it seemed that people are actually just distinguishing between self and non-self. This new paper certainly confirms this view.” Past studies on perfumes have shown that different scents amplify the natu
18、ral aromas of different MHC types peach might mesh best with your own smell, whereas vanilla might jibe with your best friends odor. Boehm says his groups new findings on distinguishing self from non-self smells, which appear online today in the Proceedings of the Royal Society B, could help researc
19、hers understand why people prefer different perfumes on themselves than on others. They might, he says, choose to wear a perfume that amplifies their own MHC peptides, but they favor perfumes on another person that amplify a non-self MHC type. But questions on the physiology of sensing MHC peptides
20、still abound. Researchers dont know which receptors in the nose actually sense MHC proteins, because humans dont have the vomeronasal organ that animals use to sniff out the molecules. “We would really like to continue this research to identify the receptors that recognize these peptides in humans,
21、” Boehm says. Other molecules the human body produces could also influence individual smells and scent preferences, Zufall says. The individuality of peoples microbiomesthe collection of microbes living in and on uscould also be linked to the bodys odor or preferences, Wedekind says. “We just dont know the full physiology yet, ” he said, “B ut this is a good start.” This story provided by ScienceNOW, the daily online news service of the journal Science.
