果蝇被水果味吸引并不奇怪。最近的研究工作显示，果蝇还能嗅到二氧化碳并作出反应。二氧化碳是果蝇在野外可能会碰到的发酵中的水果的一种标记物。现在，果蝇还被发现能够通过其吻部的一组专门的神经元“尝”到以碳酸水形式存在的二氧化碳。这一新颖的味觉模式有可能帮助果蝇获得由微生物所产生的营养物质。

原文摘要:

The detection of carbonation by the Drosophila gustatory system

Walter Fischler1,2, Priscilla Kong1,2, Sunanda Marella1,2 & Kristin Scott1,2

There are five known taste modalities in humans: sweet, bitter, sour, salty and umami (the taste of monosodium glutamate). Although the fruitfly Drosophila melanogaster tastes sugars, salts and noxious chemicals, the nature and number of taste modalities in this organism is not clear. Previous studies have identified one taste cell population marked by the gustatory receptor gene Gr5a that detects sugars, and a second population marked by Gr66a that detects bitter compounds1, 2, 3, 4. Here we identify a novel taste modality in this insect: the taste of carbonated water. We use a combination of anatomical, calcium imaging and behavioural approaches to identify a population of taste neurons that detects CO2 and mediates taste acceptance behaviour. The taste of carbonation may allow Drosophila to detect and obtain nutrients from growing microorganisms. Whereas CO2 detection by the olfactory system mediates avoidance5, CO2 detection by the gustatory system mediates acceptance behaviour, demonstrating that the context of CO2 determines appropriate behaviour. This work opens up the possibility that the taste of carbonation may also exist in other organisms.