昆虫嗅觉相关蛋白的研究进展

嗅觉是昆虫产生行为的重要物质基础,阐明昆虫嗅觉机理有助于调控昆虫行为和进行害虫治理。近年来,许多与嗅觉相关的生物活性分子和相关基因的发现和克隆,对揭示嗅觉机理具有重要作用。作者针对近年来研究较多的气味结合蛋白、化学感受蛋白、气味受体、气味降解酶以及感觉神经元膜蛋白等,就其生化特性、表达部位、分子结构、生理功能等进行了综述。     

蜜蜂嗅觉相关蛋白的研究进展

蜜蜂是一类营社会性生活的昆虫,蜂群中的蜂王、工蜂和雄蜂相互依存,各司其职,共同维持着群体严密有序的生活。其中,嗅觉系统在它们的生存和繁衍过程中起到重要的作用。昆虫对气味物质的感受过程是非常复杂的,需要有多种蛋白的参与。研究蜜蜂的化学感受机制可以帮助我们更深入地了解蜜蜂特有的行为及生物学特性。本文重点综述了与蜜蜂嗅觉相关的3种蛋白质的生化特性、分子结构、基因表达及其生理功能等方面的研究进展,以期为今后开展相关研究工作提供理论参考。     

寄生蜂嗅觉蛋白研究进展

寄生蜂对外界环境中气味的识别过程尤为复杂,需要很多组织器官参与,嗅觉系统在寄生蜂选择寄主、识别定位寄主和寄生过程中发挥着重要的作用。常见的嗅觉相关蛋白有气味结合蛋白、化学感受蛋白、气味受体等,本文从嗅觉蛋白的鉴定、结构特征与分类、表达定位、系统发育、功能研究等方面综述了寄生蜂嗅觉蛋白的国内外研究进展,为更多寄生蜂嗅觉相关蛋白的鉴定及其功能研究提供参考。     

稻飞虱嗅觉相关基因及功能的研究进展

稻飞虱是我国及亚洲各水稻产区的重大害虫,在我国成灾危害的种类主要为白背飞虱Sogatella furcifera、褐飞虱Nilaparvata lugens、灰飞虱Laodelphax striatellus.稻飞虱不仅通过韧皮部吸取汁液而且传播多种水稻病毒,对我国水稻每年产量巨大损失.目前,稻飞虱对多种常用化学杀虫剂产生了较高的抗性.因此,急需寻找新的绿色防治方法.当前,"反向化学生态"是化学防治的理想替代方案之一,即通过研究昆虫重要的嗅觉基因功能,揭示嗅觉感受机制,从而找到对昆虫具有吸引作用的小分子化合物,制备诱芯进行田间诱集的绿色防控方法.已有研究证实,嗅觉感受在稻飞虱对水稻植株的定位及危害中发挥重要作用,近年有关稻飞虱嗅觉感受分子机制研究方面也取得不少进展.本文对此进行综述和展望,以期为推动基于嗅觉感受的稻飞虱绿色防控技术的研发提供参考.     

昆虫嗅觉相关可溶性蛋白的研究进展

昆虫在长期进化过程中形成了一套高度敏感的嗅觉系统,通过该系统昆虫可以完成寻觅配偶、定位寄主及选择产卵位点等多种行为。在昆虫嗅觉系统中的可溶性蛋白主要有气味结合蛋白(odorant-binding protein, OBP)和化学感受蛋白(chemosensory protein, CSP)。OBP可以特异性结合并运输疏水性的气味分子相应的受体,是昆虫化学识别过程的第一步,具有十分重要的作用。CSP与OBP的结构和功能类似,主要参与化合物的识别和运输,尽管没有直接的证据表明CSP也参与了昆虫的化学感受过程,但已有研究发现,CSP在昆虫嗅觉系统中发挥着重要的作用。本文主要从分子特性、蛋白结构、表达模式、生理功能等方面分别对昆虫的OBP和CSP进行了概述,为深入的研究两者的功能提供理论参考,进而为以昆虫嗅觉系统为靶标的害虫防治提供新的思路。     

昆虫嗅觉相关蛋白的结构和功能

昆虫在长期进化的过程中形成了复杂的嗅觉系统,气味剂结合蛋白(odorant binding proteins,OBPs)、嗅觉受体(olfactory receptors,ORs)是其最主要的组分.其主要作用是结合外围挥发性的气味分子并将信号传递给细胞内的第二信使.OBPs和ORs的结构、功能、表达、进化是昆虫行为与进化关系的重要研究领域和研究热点.本文主要总结了近年来昆虫OBPs和ORs的结构特点、生理功能、表达特点、遗传进化等方面研究的最新进展,对OBPs和ORs的研究趋势进行了展望,为昆虫嗅觉系统进化研究及寻找害虫防治新途径提供参考信息.     

昆虫嗅觉受体功能的研究进展

嗅觉对昆虫的生存和繁殖至关重要。近年来对昆虫嗅觉识别的分子机制研究表明,嗅觉受体主要包括气味受体和离子型受体,它们在气味分子的识别过程中发挥关键和核心作用。为系统了解昆虫嗅觉受体功能的研究现状,本文综述了气味受体和离子型受体的发现历程、结构特征、表达定位,重点描述了气味受体和离子型受体的功能研究及其研究方法,力求为嗅觉受体研究和昆虫行为调控研究提供基础和参考。     

昆虫嗅觉结合蛋白研究进展

嗅觉结合蛋白是嗅觉系统的第一个参与者,主要表达在嗅觉外周系统淋巴液中,负责识别、结合和转运气味和信息素分子到达嗅觉受体.近些年,随着各种生物新技术的应用,大量昆虫嗅觉结合蛋白被鉴定出来,其各种不同功能得到揭示.本文对近年来嗅觉结合蛋白的分子特征、蛋白结构、功能和应用等方面的研究进展进行总结和综述.总的来说,嗅觉结合蛋白...     

昆虫嗅觉受体的研究进展

昆虫的嗅觉对昆虫的栖息地选择、觅食、群集、趋避、繁殖以及信息传递等行为具有重要的影响。对昆虫嗅觉机理的深入研究和嗅觉信号传导途径的完整阐述,是探索农业害虫的专一性防治的基础。嗅觉受体(olfactory receptors,Ors)是G蛋白偶联受体(G protein-coupled receptor)的一种,是嗅觉系统的关键成分。近年来嗅觉受体的研究日益受到关注。本文对昆虫嗅觉的基本过程、基因结构和表达调控特征、蛋白分子结构、生理功能、分布部位和相关配体的研究等进行了综述。     

昆虫化学感受蛋白(CSPs)的功能研究概述

昆虫的嗅觉系统与其各项生命活动息息相关,化学感受蛋白(CSPs)是嗅觉系统中的重要组成部分,可以结合气味或信息素分子,并传递给嗅觉受体,完成嗅觉相关功能。随着分子生物学技术和测序手段的不断发展,越来越多的昆虫CSPs得到鉴定。CSPs在昆虫体内广泛分布于触角、跗节、下颚须等化学感受器官,同时也在表皮、腹部、体躯等非感受器官大量表达,具有感知化学分子的功能并且与昆虫生长、发育、繁殖等生理功能及昆虫对杀虫剂的抗性相关。本文通过从CSPs的发现和命名、分子特性、结构及分布等方面展开综述,着重介绍CSPs的气味分子识别作用机制、抗药性机制及功能分类,以期为今后利用CSPs作为靶标防治害虫提供参考。     

Molecular biology of insect olfaction:recent progress and conceptual models

Insects have an enormous impact on global public health as disease vectors and as agricultural enablers as well as pests and olfaction is an important sensory input to their behavior. As such it is of great value to understand the interplay of the molecular components of the olfactory system which, in addition to fostering a better understanding of insect neurobiology, may ultimately aid in devising novel intervention strategies to reduce disease transmission or crop damage. Since the first discovery of odorant receptors in vertebrates over a decade ago, much of our view on how the insect olfactory system might work has been derived from observations made in vertebrates and other invertebrates, such as lobsters or nematodes. Together with the advantages of a wide range of genetic tools, the identification of the first insect odorant receptors in Drosophila melanogaster in 1999 paved the way for rapid progress in unraveling the question of how olfactory signal transduction and processing occurs in the fruitfly. This review intends to summarize much of this progress and to point out some areas where advances can be expected in the near future.     

Bioinformatic analysis of gene encoding odorant binding protein (OBP) 1, OBP2, and chemosensory proteins in Grapholita molesta

In this study, odorant binding proteins (OBPs) and chemosensory protein (CSP), which are associated with the sensitivity of Grapholita molesta, were comprehensively analysed using bioinformatics. The full-length cDNAs of GmolOBP1, GmolOBP2, and GmolCSP were downloaded and their open reading frames (ORFs) were analysed. Their physicochemical properties were determined and their structures and functions were predicted. Additionally, a phylogenetic tree was constructed to investigate the evolutionary relationships among GmolOBP1, GmolOBP2, GmolCSP, and 14 other insect proteins. GmolOBP1, GmolOBP2 and GmolCSP were composed of 164, 161, and 127 amino acids. GmolOBP1 and GmolOBP2 contained 7 and 6 cysteine residues forming 3 disulphide bonds. The transmembrane, hydrophobic, and signal peptide regions overlapped in GmolOBP1 and GmolCSP and were located in the extracellular environment. GmolCSP showed more coiled coils and a smaller cavity in the three-dimensional structure than GmolOBP1 and GmolOBP2. In the phylogenetic tree, GmolOBP1, GmolOBP2, and GmolCSP were in different clusters or sub-clusters. In conclusion, GmolOBP1 and GmolOBP2 shared some common properties with other OBPs. Additionally, GmolOBP1, GmolOBP2, and GmolCSP may have evolved independently.     

Ligand specificity of odorant receptors

Odorant receptors belong to class A of the G protein-coupled receptors (GPCRs) and detect a large number of structurally diverse odorant molecules. A recent structural bioinformatic analysis suggests that structural features are conserved across class A of GPCRs in spite of their low sequence identity. Based on this work, we have aligned the sequences of 29 ORs for which ligand binding data are available. Recent site-directed mutagenesis experiments on one such receptor (MOR174-9) provide information that helped to identify nine amino-acid residues involved in ligand binding. Our modeling provides a rationale for amino acids in equivalent positions in most of the odorant receptors considered and helps to identify other amino acids that could be important for ligand binding. Our findings are consistent with most of the previous models and allow predictions for site-directed mutagenesis experiments, which could also validate our model.     

Olfactory receptors in aquatic and terrestrial vertebrates

In species representing different levels of vertebrate evolution, olfactory receptor genes have been identified by molecular cloning techniques. Comparing the deduced amino-acid sequences revealed that the olfactory receptor gene family of Rana esculenta resembles that of Xenopus laevis, indicating that amphibians in general may comprise two classes of olfactory receptors. Whereas teleost fish, including the goldfish Carassius auratus, possess only class I receptors, the `living fossil' Latimeria chalumnae is endowed with both receptor classes; interestingly, most of the class II genes turned out to be pseudogenes. Exploring receptor genes in aquatic mammals led to the discovery of a large array of only class II receptor genes in the dolphin Stenella Coeruleoalba; however, all of these genes were found to be non-functional pseudogenes. These results support the notion that class I receptors may be specialized for detecting water-soluble odorants and class II receptors for recognizing volatile odorants. Comparing the structural features of both receptor classes from various species revealed that they differ mainly in their extracellular loop 3, which may contribute to ligand specificity. Comparing the number and diversity of olfactory receptor genes in different species provides insight into the origin and the evolution of this unique gene family. Accepted: 29 July 1998     

Sensational placodes: Neurogenesis in the otic and olfactory systems

For both the intricate morphogenetic layout of the sensory cells in the ear and the elegantly radial arrangement of the sensory neurons in the nose, numerous signaling molecules and genetic determinants are required in concert to generate these specialized neuronal populations that help connect us to our environment. In this review, we outline many of the proteins and pathways that play essential roles in the differentiation of otic and olfactory neurons and their integration into their non-neuronal support structures. In both cases, well-known signaling pathways together with region-specific factors transform thickened ectodermal placodes into complex sense organs containing numerous, diverse neuronal subtypes. Olfactory and otic placodes, in combination with migratory neural crest stem cells, generate highly specialized subtypes of neuronal cells that sense sound, position and movement in space, odors and pheromones throughout our lives.     

Structural determinants of odorant recognition by the human olfactory receptors OR1A1 and OR1A2

An interaction of odorants with olfactory receptors is thought to be the initial step in odorant detection. However, ligands have been reported for only 6 out of 380 human olfactory receptors, with their structural determinants of odorant recognition just beginning to emerge. Guided by the notion that amino acid positions that interact with specific odorants would be conserved in orthologs, but variable in paralogs, and based on the prediction of a set of 22 of such amino acid positions, we have combined site-directed mutagenesis, rhodopsin-based homology modelling, and functional expression in HeLa/Olf cells of receptors OR1A1 and OR1A2. We found that (i) their odorant profiles are centred around citronellic terpenoid structures, (ii) two evolutionary conserved amino acid residues in transmembrane domain 3 are necessary for the responsiveness of OR1A1 and the mouse ortholog Olfr43 to (S)-(-)-citronellol, (iii) changes at these two positions are sufficient to account for the differential (S)-(-)-citronellol responsiveness of the paralogs OR1A1 and OR1A2, and (iv) the interaction sites for (S)-(-)-citronellal and (S)-(-)-citronellol differ in both human receptors. Our results show that the orientation of odorants within a homology modelling-derived binding pocket of olfactory receptor orthologs is defined by evolutionary conserved amino acid positions.