Syed Zainulabeuddin, Leal Walter S
Honorary Maeda-Duffey Lab, Department of Entomology, University of California-Davis, Davis, CA 95616, USA.
Chem Senses. 2007 Oct;32(8):727-38. doi: 10.1093/chemse/bjm040. Epub 2007 Jun 14.
A single type of olfactory sensilla on maxillary palps in many species of mosquitoes houses a very sensitive olfactory receptor neuron (ORN) for carbon dioxide reception. We performed extensive single sensillum recordings from this peg sensillum in Culex quinquefasciatus and have characterized the response threshold and kinetics for CO(2) reception, with a detection threshold less than the CO(2) concentration in the atmosphere. This ORN responded in a tonic mode to lower concentrations of CO(2), whereas higher concentrations generated a phasic-tonic mode of action potential firing. Sensillum potentials accurately represented the response magnitude and kinetics of carbon dioxide-elicited excitatory responses. Stimulation of these ORNs with human breath, a complex mixture of mosquito kairomones and up to 4.5% CO(2), elicited excitatory responses that were reliably detected by CO(2)-sensitive ORNs. Another ORN housed in these sensilla responded to 1-octen-3-ol and to various plant-derived compounds, particularly floral and green leaf volatiles. This ORN showed remarkable sensitivity to the natural enantiomer, (R)-(-)-1-octen-3-ol, rivaling pheromone-detecting ORNs in moths. Maximum neuronal response was elicited with a 10 ng dose. A biological, ecological role of maxillary palps in detection of plant- and nectar-related sources is proposed.
在许多种类的蚊子中，上颌触须上的单一类型嗅觉感器容纳了一个对二氧化碳接收非常敏感的嗅觉受体神经元（ORN）。我们对致倦库蚊的这种栓状感器进行了广泛的单感器记录，并表征了二氧化碳接收的反应阈值和动力学，其检测阈值低于大气中的二氧化碳浓度。该ORN对较低浓度的二氧化碳以紧张性模式做出反应，而较高浓度则产生动作电位发放的相位 - 紧张性模式。感器电位准确地反映了二氧化碳引发的兴奋性反应的幅度和动力学。用人呼出的气体（一种包含蚊子利它素和高达4.5%二氧化碳的复杂混合物）刺激这些ORN，会引发兴奋性反应，这些反应能被对二氧化碳敏感的ORN可靠地检测到。这些感器中容纳的另一个ORN对1 - 辛烯 - 3 - 醇和各种植物衍生化合物有反应，特别是花香和绿叶挥发物。该ORN对天然对映体（R）-（-）-1 - 辛烯 - 3 - 醇表现出显著的敏感性，可与蛾类中检测信息素的ORN相媲美。10纳克剂量可引发最大神经元反应。本文提出了上颌触须在检测与植物和花蜜相关来源中的生物学和生态学作用。
