Most organisms rely on their olfactory system to detect and analyze olfactory cues in the environment, cues that are subsequently utilized in the context of behavior. Odorants are recognized by olfactory sensory neurons (OSNs), which are located in the olfactory epithelia of vertebrates or in the dendrites of olfactory sensory cells within the sensilla on the antennal surface of insects (Buck and Axel 1991; Carlson 2001; Chess et al. 1992; Vosshall et al. 2000). The OSNs express odorant receptors (ORs), which are related to seven transmembrane G-protein-coupled receptors (GPCR) and transduce odorant binding to cellular excitation (see also Chapter 7). The olfactory system of the genetic model organism, the fruit fly , has been the focus of numerous investigations. has two pairs of olfactory organs, the antennae and the maxillary palps. Each antenna contains about 1200 OSNs housed in a total of 410 olfactory sensilla covering the antenna, while the maxillary palp has about 120 OSNs and 60 olfactory sensilla (Laissue and Vosshall 2007). The sensilla are of three morphological types: basiconic sensilla, trichoid sensilla, and coeloconic sensilla (Venkatesh and Singh 1984). Across insects, there is a beautiful diversity of sensillar morphologies, including pore plate sensilla, campaniform sensilla, sensilla ampullacea, and more (Kleineidam and Tautz 1996; Steinbrecht 1996). In recent studies, the OR gene family of has been identified and shown to comprise 62 defned members (Table 2.1) (Clyne et al. 1999; Gao and Chess 1999; Vosshall et al. 1999). Several studies have been dedicated to characterize the molecular receptive ranges of identified ORs (Dobritsa et al. 2003; Hallem and Carlson 2006; Pelz et al. 2006).
大多数生物体依靠其嗅觉系统来检测和分析环境中的嗅觉线索，这些线索随后会在行为中被利用。气味分子由嗅觉感觉神经元（OSN）识别，嗅觉感觉神经元位于脊椎动物的嗅觉上皮中，或者位于昆虫触角表面感器内嗅觉感觉细胞的树突中（Buck和Axel，1991年；Carlson，2001年；Chess等人，1992年；Vosshall等人，2000年）。嗅觉感觉神经元表达气味受体（OR），气味受体与七个跨膜G蛋白偶联受体（GPCR）相关，并将气味分子结合转化为细胞兴奋（另见第7章）。遗传模式生物果蝇的嗅觉系统一直是众多研究的焦点。果蝇有两对嗅觉器官，触角和下颚须。每根触角包含约1200个嗅觉感觉神经元，分布在覆盖触角的总共410个嗅觉感器中，而下颚须有大约120个嗅觉感觉神经元和60个嗅觉感器（Laissue和Vosshall，2007年）。感器有三种形态类型：锥形感器、毛形感器和腔锥形感器（Venkatesh和Singh，1984年）。在昆虫中，感器形态多种多样，包括孔板感器、钟形感器、壶形感器等等（Kleineidam和Tautz，1996年；Steinbrecht，1996年）。在最近的研究中，果蝇的气味受体基因家族已被鉴定，显示由62个确定的成员组成（表2.1）（Clyne等人，1999年；Gao和Chess，1999年；Vosshall等人，1999年）。几项研究致力于表征已鉴定气味受体的分子感受范围（Dobritsa等人，2003年；Hallem和Carlson，2006年；Pelz等人，2006年）。
