禽类味觉系统研究进展

文章基于哺乳动物的味觉系统,分析了家禽味觉的结构和功能,着重从不同类型的味觉受体的研究进展进行了综述,并指出了今后禽类味觉的研究方向。     

嗅觉与味觉对动物采食作用研究进展

良好的采食行为是动物机体维持生长发育和提高生产性能的基础,而嗅觉和味觉是动物采食过程中最重要的两种感官感受,它们分别由嗅觉受体和味觉受体基因决定,这些受体基因家族是哺乳动物基因组中较大的基因家族,不仅在感觉器官中表达,还广泛表达于呼吸、消化、生殖等系统中。作者对中国羊肉消费和羊的饲养情况,当前嗅觉、味觉及其受体基因的最新研究进展,嗅觉和味觉在动物采食中的作用和机制,以及嗅觉和味觉在畜禽养殖中的应用进行了综述,为研究嗅觉和味觉在动物采食尤其是羊上的作用提供参考。     

昆虫味觉受体研究进展

化学感受受体在昆虫的觅食、食物选择、交配和产卵等行为中发挥着重要作用。随着果蝇、按蚊、蜜蜂、赤拟谷盗和家蚕等昆虫基因组测序的完成。各物种中完整化学感受受体（包括嗅觉受体和味觉受体）得以鉴定,并从中鉴定出与气味识别、食物选择密切相关的受体基因,如果蝇的二氧化碳受体基因DmGr21a和DmGr63a,糖受体DmGr5a,以及冈比亚按蚊识别人类气味的AgOrl等。其中,昆虫的味觉受体功能与昆虫食物选择、大量取食直接相关。本文就目前昆虫基因组中味觉受体的鉴定、进化、表达和功能等方面的研究进展进行了综述。对味觉受体功能的研究,将有助于我们认识昆虫味觉编码的分子基础和神经调控网络,也是研究昆虫与植物相互关系的热点。     

调味剂对动物嗅觉、味觉、肠道功能的调控研究进展

饲料的适口性是动物对饲料的气味及口感等的综合感知,在一定程度上影响动物的采食量,而动物的采食量与生产性能有较高的正相关。气味的感知主要源于鼻腔内嗅觉神经的突起,口感的感知主要由口腔内的味觉受体来完成,主要味觉受体包括甜味受体、鲜味受体和苦味受体等。食物进入胃肠道后,胃肠道上的味觉受体感应程度可影响并调节动物对食物的吸收率和采食行为。本文主要介绍了近年来有关鼻腔的嗅觉受体、口腔内的味觉受体和胃肠道内味觉受体和信号传递等相关研究,并就调味剂在动物生产上的应用进行综述,为调味剂的应用及相关研究提供一定借鉴。     

哺乳类动物胃肠道内味觉受体的信号研究

胃肠道内容物的分子识别对食物的消化、摄取量的控制、胰岛素的分泌、新陈代谢等起到重要作用。这些过程很有可能受到激素/中枢神经通路的介导。但是,有关于胃肠道的味觉识别机制还不清楚。本文综述了最新的研究结果,表明了舌上皮组织的特异性味觉受体细胞的化学感应机制在内分泌细胞中也发挥作用,用来感知肠腔内容物的化学组成。     

味觉的细胞生物学研究进展

味蕾是咪感觉器官。在哺乳动物中味蕾主要分布在舌上皮中。味蕾中存在基细胞、亮细胞、暗细胞和中间细胞四种类型,蕾内神经纤维和蕾周神经纤维共同支配味蕾。利用免疫组织化学技术,能在功能上对味细胞和味觉神经纤维进行分类和鉴定。味蕾组织染色方法在舌面拓扑学和味觉系统发育研究中起着重要作用。分离出单个的味蕾细胞是研究受体细胞传导味觉机理的手段。味蕾组织培养对于研究味觉神经支配提供了有效的模型。文章介绍了味觉细胞生物学研究中的两个热点争议问题：味蕾细胞分化路线和味感觉细胞的鉴定,并探讨了形成分歧的原因。     

营养物质的感官感受——动物嗅觉和味觉研究进展

生物进化让哺乳动物和鸟类具备敏锐的味觉和嗅觉器官,确保它们具有自己寻找食物的能力.外周化学感受被认为是动物对食物营养价值进行评估的系统.动物进食过程中产生了嗅觉、味觉和触觉的感官感受.嗅觉帮助动物对食物挥发性物质进行鉴别,这些挥发性物质是植物必需营养物质的衍生物.嗅觉的生物学比较显示灵长类和鸟类相对于非灵长类的哺乳动物...     

哺乳动物味觉感受器T1Rs受体家族及信号转导机制的研究进展

味觉受体第一家族（T1Rs）是一类能感知甜味和鲜味的受体家族,它包括T1R1,T1R2,T1R3三个成员。T1R2＋T1R3以异二聚体形式共表达参与甜味识别,而T1R1＋T1R3也以异二聚体形式共表达参与鲜味识别。良好的味觉能促进牛的食欲,促进生长发育,但目前关于牛的T1Rs受体家族的研究并不多见,有必要对这个受体家族做进一步探索。本文从甜味和鲜味两个方面对这一受体家族的分子结构及信号转导机制的最新研究进展做简要综述。     

α-味蛋白与味觉感受

α-参兜鞍是一种transducins样味觉特异性G蛋白,它在从鱼到人类的多种脊椎动物物种的味细胞内均有表达,是脊椎动物味觉感受中重要的调控因子之一。多方面研究显示,α-参兜鞍在苦、甜、鲜味信号转导中发挥着作用。敲除了α-参兜鞍的小鼠对苦、甜、鲜味刺激的行为学和电生理反应都有下降;分子生物学研究也发现,α-参兜鞍与介导苦、甜、鲜味信号转导的G蛋白偶联受体(G protein-coupledreceptors,GPCRs)存在不同程度地共表达。α-参兜鞍参与的信号转导途径中仍存在许多问题,这些均需要更加深入细致地研究。文章综述了α-参兜鞍在味觉信号转导中的研究进展。     

昆虫化学感受受体的研究进展

化学感受这一重要的生化过程对于昆虫的生存来说是十分必要的,昆虫的化学感受受体家族由气味(嗅觉)受体和味觉受体组成。嗅觉可以识别挥发性的化学物质,使昆虫发现食物、寻找配偶和逃避敌害;而味觉能识别可溶性刺激物,以引起觅食、交配和产卵等行为。文章主要介绍了昆虫气味受体及味觉受体家族的特性,以及目前对多种昆虫化学感受受体超家族的研究进展。     

Taste

Taste has a dual role. Like other senses it informs the individual about the external world, but unlike other senses it connects that perception with information about the internal environment. The principal function of taste is similar in all higher species. Molecules act on specialized sensory cells (= taste cells) in various regions of the oral cavity thus triggering signals, which are relayed to the cortex via afferent nerves, the caudal hindbrain and the thalamus. Taste afferents also reach the hypothalamus and the limbic system. The taste of food triggers physiological and behavioral reactions in man and animals. Stimulation of taste cells immediately elicits salivation, secretion of gastric acid and pancreatic juice as well as secretion of gastrointestinal and pancreatic hormones. Innate and learned taste preferences or aversions play an important role in food selection and taste aversions are considered to be reliable indicators of malaise. Neural signals from the periphery or humoral factors which are sensed by receptors in the central nervous system both can change the acceptance of a certain taste. Endogenous opiates in the brain seem to play a special role in the modulation of taste perception. The amygdala is apparently a brain area which is particularly important for taste perception.     

苦味受体的生物学特征、信号转导机制及苦味剂和苦味抑制剂对苦味受体的影响

苦味受体(bitter taste receptors,TAS2Rs)是一种G-蛋白偶联受体(GPCR),由30个基因组成的基因家族编码。苦味可使动物远离有毒有害物质,当动物尝到苦味物质时,会刺激舌头的味蕾中味觉受体细胞表达TAS2Rs,进而引发下游一系列信号转导反应,最终通过鼓索神经和舌咽神经将信息整合传到大脑,使动物产生厌恶的感觉,从而选择拒绝摄入这些苦味物质。本文就TAS2Rs的生物学特征、信号转导机制及苦味剂和苦味抑制剂对苦味受体的影响进行简要综述。     

动物甜味受体研究进展及猪饲料甜味剂的选择

动物的味觉识别是通过口腔味觉细胞中的味觉受体来启动。味觉受体T1R家族中的T1R2和T1R3以异构体方式发挥甜味识别作用,其中T1R2起主导作用,T1R3对T1R2结合位点构象起调节作用。猪与人在甜味受体基因序列上存在种族差异,导致猪与人在味觉感觉上存在明显不同,对人很甜的一些人工甜味剂(如索马甜、甜蜜素、NHDC、阿斯巴甜等)不能被猪识别,其对猪不能起到甜味作用。     

饲粮中添加风味剂对猪采食量的影响及其作用机理

调控猪各个阶段的采食量是动物营养研究的热点问题。风味剂主要有香味剂、甜味剂、鲜味剂,可以改善饲粮的适口性,提高猪对饲粮的喜爱程度,也可以缓解因环境变化、饲料原料改变等应激反应导致的采食量下降。猪的嗅觉系统特别发达,灵敏度很高,味觉也要比人类敏感,因此在饲粮中添加风味剂主要通过刺激猪的嗅觉和味觉来使摄食中枢兴奋,进而促进猪采食。本文综述了饲粮中添加风味剂对猪采食量的影响及其作用机理,为相关试验提供理论依据。     

Research Progress on Effects of Olfactory and Taste on Animal Food Intake

Good food intake behavior is the basis of maintaining the growth and development of animal and improving production performance.Olfaction and taste are two important senses in the progress of animal food intake.They are determined by olfactory receptor genes and taste receptor genes respectively,which are relatively large gene family in mammalian genomes.They express not only in the sense organs,but also widely in the respiratory,digestive,reproductive and other systems.This paper analyzed the consumption of mutton and sheep breeding in China.It gave an overview of the latest research progress on the olfaction,taste and their receptor gene.Finally,the function and mechanism of olfaction and taste in animal food intake,and the utilization in livestock production were expounded.This paper provided a theoretical reference for the study of the sense of olfaction and taste in animal food feeding especially in sheep.     

Molecular evolution and deorphanization of bitter taste receptors in a vampire bat

Bats represent the largest dietary radiation in a single mammalian order, and have become an emerging model group for studying dietary evolution. Taste receptor genes have proven to be molecular signatures of dietary diversification in bats. For example, all 3 extant species of vampire bats have lost many bitter taste receptor genes (Tas2rs) in association with their dietary shift from insectivory to sanguivory. Indeed, only 8 full-length Tas2rs were identified from the high-quality genome of the common vampire bat (Desmodus rotundus). However, it is presently unknown whether these bitter receptors are functional, since the sense of taste is less important in vampire bats, which have an extremely narrow diet and rely on other senses for acquiring food. Here, we applied a molecular evolutionary analysis of Tas2rs in the common vampire bat compared with non-vampire bats. Furthermore, we provided the first attempt to deorphanize all bitter receptors of the vampire bat using a cell-based assay. We found that all Tas2r genes in the vampire bat have a level of selective pressure similar to that in non-vampire bats, suggesting that this species must have retained some bitter taste functions. We demonstrated that 5 of the 8 bitter receptors in the vampire bat can be activated by some bitter compounds, and observed that the vampire bat generally can not detect naturally occurring bitter compounds examined in this study. Our study demonstrates functional retention of bitter taste in vampire bats as suggested by cell-based functional assays, calling for an in-depth study of extra-oral functions of bitter taste receptors.     

Expression levels of taste‐related genes in palate and tongue tip,and involvement of transient receptor potential subfamily M member 5 (TRPM5) in taste sense in chickens

The elucidation of the mechanisms underlying the taste sense of chickens will contribute to improvements in poultry feeding, because the molecular mechanism of chickens’ taste sense defines the feeding behavior of chickens. Here we focused on the gene expressions in two different oral tissues of chickens – the palate, which contains many taste buds, and the tongue tip, which contains few taste buds. Using the quantitative real‐time polymerase chain reaction method, we found that the molecular markers for taste buds of chickens, that is α‐gustducin and vimentin, were expressed significantly highly in the palate compared to the tongue tip. Our analyses also revealed that transient receptor potential subfamily M member 5 (TRPM5), a cation channel involved in taste transduction in mammals, was also highly expressed in the palate compared to the tongue tip. Our findings demonstrated that the expression patterns of these genes were significantly correlated. We showed that the aversion to bitter solution was alleviated by a TRPM5 inhibitor in behavior of chickens. Taken together, our findings enabled us to develop a simple method for screening taste‐related genes in chickens. The use of this method demonstrated that TRPM5 was involved in chickens’ taste transduction, and that a TRPM5 inhibitor can alleviate chickens’ bitter taste perception of feed ingredients.