一项针对双胞胎体味进行的研究有助于阐释气味的遗传基础。
（图片提供:Jason Hetherington/Getty Images）
你身上的气味取决于多久洗一次澡，然而准确地说，或许应该取决于你的基因，这是一项新研究取得的结果。瑞士研究人员发现，与不相干的人相比，双胞胎的体味显然闻起来要像得多。这一研究结果将为开发基于气味的疾病诊断或个体识别新工具铺平道路。
人体散发的气味源于细菌与皮肤和汗液——这种分泌物本身是无味儿的——产生的化学反应。体味在小鼠的择偶过程中扮演了一个重要角色，而一些实验表明，人类在选择配偶时，体味同样是一个需要考虑的重要因素。体味中最常见的化学物质至少包括24种羧基酸。然而领导这项新研究的瑞士Givaudan fragrance公司的生物化学家Andreas Natsch指出，科学家对于构成体味的各种羧基酸到底分泌了多少并不清楚。
为了研究遗传因素在体味中扮演的角色，Natsch和同事招募了12对同卵双胞胎，其中包括7对姐妹和5对兄弟。由于这些双胞胎都是从同一个受精卵发育而来的，因此在不发生变异的前提下，每对双胞胎都将拥有相同的基因。研究人员让这些志愿者进行了约1个小时的锻炼，同时在他们的腋窝处放置了棉花垫。锻炼之后，研究人员收回了这些棉花垫，并且利用相同的细菌酶对其进行了处理，从而确保了全部的汗样都以相同的方式进行加工。第二天，这些双胞胎再一次重复了上述实验。
接下来，研究人员利用一种结合了气相色谱分析和质谱分析的方法分离了每份汗样产生的化学物质。他们依据之前的记录检查了每种化学物质，此举旨在确保这些化学物质都是人体分泌物，而不是香水或除臭剂的延迟痕迹。通过分析每个人分泌的某种羧基酸到底有多少，研究人员鉴别出了每对双胞胎的羧基酸模式。研究表明，在同一天采自同一志愿者的体味样本最相近；而隔天采自同一志愿者的体味样本则略有不同。但是与不相干的两个人体味中的羧基酸模式相比，双胞胎的体味所呈现的羧基酸模式要相近10倍。研究人员在最新出版的英国皇家学会《界面》（Interface）杂志上报告了这一研究成果。Natsch表示：“对我而言，这并不让人感到惊讶。双胞胎看起来一样，闻起来也差不多。”
与此同时，这一发现也为其他用途敞开了大门。例如英国利物浦大学的生物学家Craig Roberts便指出，研究人员如今可以看看体味是否反映了其他生理状况。Roberts说：“这很重要，因为它将有助于疾病的非侵入式诊断，以及针对特定气味的生物认证技术的发展。”
原始出处：
Interface，10.1098/rsif.2008.0223，Fabian Kuhn, Andreas Natsch
Body odour of monozygotic human twins: a common pattern of odorant carboxylic acids released by a bacterial aminoacylase from axilla secretions contributing to an inherited body odour type
1 Analytical Chemistry, Givaudan Schweiz AG, Ueberlandstrasse 138, 8600 Duebendorf, Switzerland
2 Biosciences, Givaudan Schweiz AG, Ueberlandstrasse 138, 8600 Duebendorf, Switzerland
It is currently not fully established whether human individuals have a genetically determined, individual-specific body odour. Volatile carboxylic acids are a key class of known human body odorants. They are released from glutamine conjugates secreted in axillary skin by a specific Nα-acyl-glutamine-aminoacylase present in skin bacteria. Here, we report a quantitative investigation of these odorant acids in 12 pairs of monozygotic twins. Axilla secretions were sampled twice and treated with the Nα-acyl-glutamine-aminoacylase. The released acids were analysed as their methyl esters with comprehensive two-dimensional gas chromatography and time-of-flight mass spectrometry detection. The pattern of the analytes was compared with distance analysis. The distance was lowest between samples of the right and the left axilla taken on the same day from the same individual. It was clearly greater if the same subject was sampled on different days, but this intra-individual distance between samples was only slightly lower than the distance between samples taken from two monozygotic twins. A much greater distance was observed when comparing unrelated individuals. By applying cluster and principal component analyses, a clear clustering of samples taken from one pair of monozygotic twins was also confirmed. In conclusion, the specific pattern of precursors for volatile carboxylic acids is subject to a day-to-day variation, but there is a strong genetic contribution. Therefore, humans have a genetically determined body odour type that is at least partly composed of these odorant acids.
