取食刺激剂对棉铃虫在含苏云金杆菌饲料上的取食行为和死亡率的影响(英文)

苏云金杆菌在非致死剂量下对棉铃虫有强的抑食作用 ,且随着浓度的增加 ,抑食作用有进一步加强的趋势。棉铃虫取食刺激剂不仅对棉铃虫具诱引作用 ,可增加幼虫的取食时间和取食量 ,而且可减轻苏云金杆菌对棉铃虫的抑食作用。苏云金杆菌浓度越低 ,取食刺激剂的效果越好。非选择性实验中 ,加入取食刺激剂可使苏云金杆菌致死中浓度降低 4 1%。但在选择性实验中 ,幼虫死亡率无显著提高。     

棉铃虫在4个辣椒品种上的寄主适合度

在室内条件下,比较了棉铃虫幼虫对辣味程度依次下降的豫优鲜辣2号、豫艺绿冠、豫艺墨秀大椒和豫甜椒12号4个辣椒品种果实的嗜食性、食物转化率和利用率及种群增长情况。结果表明：（1）棉铃虫幼虫的取食选择性、对食物的近似消化率和利用率在4个辣椒品种之间存在明显差异。其中初孵、3龄和5龄幼虫对4个辣椒品种果实的选择性规律基本一致,在豫甜椒12号品种上幼虫出现的百分率和取食量比率均最大;随着辣椒品种辣味程度的降低,5龄幼虫在其上的取食时间和休息时间依次增加,活动时间则依次降低;取食4个辣椒品种的果实后,6龄幼虫的相对生长率、相对取食量和食物转化率差异不显著,但取食豫甜椒12号与豫优鲜辣2号和豫艺绿冠之间的近似消化率和食物利用率差异达显著水平。（2）室内271 ℃ 、70 %-80 % RH和16 L：8 D光周期条件下,棉铃虫在4个辣椒品种上均能完成其世代周期,随着辣椒品种辣味程度的增加,1龄幼虫和整个世代的发育历期依次延长,且在豫甜椒12号与豫优鲜辣2号之间差异达显著水平。其中在豫优鲜辣2号上棉铃虫的世代发育历期最长（27.86 d）,其次为豫艺绿冠（27.23 d）,再次为豫艺墨秀大椒（26.83 d）,在豫甜椒12号上的发育历期最短（25.85 d）;棉铃虫在4个辣椒品种上的世代存活率分别为豫优鲜辣2号为21.67%、豫艺绿冠为23.33%、豫艺墨秀大椒为23.33%、豫甜椒12号为35.00%;取食4个品种辣椒后,棉铃虫的蛹重差异不显著,其中雌蛹重分别为取食豫甜椒12号品种的为249.3 mg,取食豫艺墨秀大椒的为244.7 mg,取食豫艺绿冠的为243.4 mg,取食豫优鲜辣2号的雌蛹最轻,为209.4 mg。雄蛹重与雌蛹表现出的规律基本一致,但取食同一品种的雌蛹重均高于雄蛹重。（3）棉铃虫的种群净增殖率和内禀增长率在豫优鲜辣2号品种上最低,在豫甜椒12号品种上最高。以上结果表明,随着4个辣椒品种辣味程度的增加,棉铃虫在其上的寄主适合度则依次降低,其寄主适合度顺序为：豫甜椒12号＞豫艺墨秀大椒＞豫艺绿冠＞豫优鲜辣2号。     

棉铃虫在4个辣椒品种上的寄主适合度

在室内条件下,比较了棉铃虫幼虫对辣味程度依次下降的豫优鲜辣2号、豫艺绿冠、豫艺墨秀大椒和豫甜椒12号4个辣椒品种果实的嗜食性、食物转化率和利用率及种群增长情况。结果表明:(1)棉铃虫幼虫的取食选择性、对食物的近似消化率和利用率在4个辣椒品种之间存在明显差异。其中初孵、3龄和5龄幼虫对4个辣椒品种果实的选择性规律基本一致,在豫甜椒12号品种上幼虫出现的百分率和取食量比率均最大;随着辣椒品种辣味程度的降低,5龄幼虫在其上的取食时间和休息时间依次增加,活动时间则依次降低;取食4个辣椒品种的果实后,6龄幼虫的相对生长率、相对取食量和食物转化率差异不显著,但取食豫甜椒12号的近似消化率和食物利用率与豫优鲜辣2号和豫艺绿冠之间差异达显著水平。(2)室内(27±1) ℃ 、70%-80% RH和16 L∶8 D光周期条件下,棉铃虫在4个辣椒品种上均能完成其世代周期,随着辣椒品种辣味程度的增加,1龄幼虫和整个世代的发育历期依次延长,且在豫甜椒12号与豫优鲜辣2号之间差异达显著水平。其中在豫优鲜辣2号上棉铃虫的世代发育历期最长(27.86 d),其次为豫艺绿冠(27.23 d),再次为豫艺墨秀大椒(26.83 d),在豫甜椒12号上的发育历期最短(25.85 d);棉铃虫在4个辣椒品种上的世代存活率分别为豫优鲜辣2号为21.67%、豫艺绿冠为23.33%、豫艺墨秀大椒为23.33%、豫甜椒12号为35.00%;取食4个辣椒品种后,棉铃虫的蛹重差异不显著,其中雌蛹重分别为取食豫甜椒12号品种的为249.3 mg,取食豫艺墨秀大椒的为244.7 mg,取食豫艺绿冠的为243.4 mg,取食豫优鲜辣2号的雌蛹最轻,为209.4 mg。雄蛹重与雌蛹表现出的规律基本一致,但取食同一品种的雌蛹重均高于雄蛹重。(3)棉铃虫的种群净增殖率和内禀增长率在豫优鲜辣2号品种上最低,在豫甜椒12号品种上最高。以上结果表明,随着4个辣椒品种辣味程度的增加,棉铃虫在其上的寄主适合度则依次降低,其寄主适合度顺序为:豫甜椒12号>豫艺墨秀大椒>豫艺绿冠>豫优鲜辣2号。     

棉铃虫低龄幼虫对花香挥发物的联系性学习

鳞翅目昆虫的寄主选择主要是成虫的任务,但幼虫也可以精细调节取食部位。低龄幼虫记忆一些与食物伴随的化学信息能够提高适合度。当幼虫被迫离开寄主植物后,最好是搜索与此前取食过的寄主气味相似的植物,以便节省寄主转移的生理代谢成本。棉铃虫幼虫嗜食作物花器,因此推测花香挥发物可以代表幼虫食物的典型化学信息。采用人工饲料为无条件刺激,在条件化训练开始时,使初孵幼虫取食时暴露在7种花香挥发物下,随后7 d逐日测试低龄幼虫学习表现。结果发现,在7次测试中,苯乙醛选择频次有3次显著多于对照,芳樟醇条件化组在2次测定中处理被选频次显著或极显著多于对照,苯乙醇条件化组仅1次对处理选择频次显著多于对照,其他4种挥发物无论训练时间长短均不能造成嗅觉偏好性的改变,说明棉铃虫在取食过程中是选择性采集食物关键化学信息。然而,无经历组无论训练时间如何均不对苯乙醛表现出嗅觉偏好性,证实气味偏好性的改变并非生理性成熟所致。总之,和同种的成虫以及若虫期比较活泼的其他种类相比,棉铃虫低龄幼虫嗅觉联系性学习表现较差,并且嗅觉偏好性变化与条件化训练时长没有明确关系,结合棉铃虫的生态学习性讨论了可能的原因。     

植物次生物质对烟青虫和棉铃虫食物利用及中肠解毒酶活性的影响

用分别添加0-5%(干重比)棉酚、烟碱、番茄苷和辣椒素4种植物次生物质的人工饲料饲养烟青虫Helicoverpa assulta和棉铃虫H. armigera 5龄幼虫48 h,测定这些次生物质对烟青虫和棉铃虫的营养效应和中肠谷胱甘肽S-转移酶（GST）及羧酸酯酶（CarE）活性的影响。结果表明：在实验浓度下,棉酚可显著降低烟青虫的相对消化率,但对棉铃虫却有助食作用;番茄苷抑制烟青虫的取食和生长,对其近似消化率和食物利用率也有显著的抑制作用,但食物转化率有明显升高,对棉铃虫的各营养指标无显著影响;烟碱对烟青虫和棉铃虫的相对生长率均无影响;辣椒素使烟青虫的取食量有大幅度的提高,对棉铃虫的取食量无影响,但引起其相对消化率的提高。由此可见,棉铃虫对4种次生物质有普遍的适应性,而烟青虫只对寄主植物所含的烟碱和辣椒素有较好的适应性。烟青虫和棉铃虫幼虫中肠CarE活性不受4种次生物质的影响,烟碱和辣椒素对烟青虫GST有显著的诱导作用,番茄苷对烟青虫GST活性则有抑制作用,4种次生物质对棉铃虫GST均无显著影响。     

关于棉铃虫食性和营养的某些特点

本工作选用棉花不同器官所含有的几种化学成分作为嗅觉和味觉刺激剂, 测验棉铃虫对它们的反应;结果表明一至三龄的幼虫对甲醇三甲基胺、香草酸等的趋性不同, 四龄幼虫对不同的糖类、氨基酸等的取食反应也各不一。这说明幼虫对食料植物中的个别化学成分有感觉辨识的能力。用不同品种的海岛棉、陆地棉、以及棉花和其它锦葵科植物杂交所产生的后代的叶片来试验棉铃虫对它们的趋性和取食反应, 结果表明当有选择的机会时幼虫对陆地棉和一定品种海岛棉有较强的趋性, 对某些杂交后代的趋性很弱。在不能选择的条件下棉铃虫在一定时间内对不同种类或品种的棉叶的取食量也不相同, 并对原来的食料植物可形成条件化。 曾对棉花不同器官的含水量、含氮物质和糖类进行了测定, 同时分别用叶、蕾和铃将新孵化的幼虫饲养到老熟。幼虫取食不同器官时的累积食量、发育速度、死亡率, 和变成的蛹的重量均有明显的差别。当以大叶为食时幼虫的总食量超过以嫩叶为食时的一倍以上;以铃为食时总食量可为以嫩叶为食时的数倍。这种差异可能是因铃中水分和含糖量较高, 对幼虫的取食发生强烈的助长作用所造成的。因此, 同株植物上含糖和含水缺多的器官对棉铃虫似乎有较好的营养效应, 而这种效应可能是通过糖类等的味觉刺激来增加取食量所造成。     

转Bt棉花对蜘蛛生长发育及捕食行为的影响

室内评价了取食转Bt棉叶的棉铃虫幼虫对草间钻头蛛和八斑鞘腹蛛生长发育的影响.并通过捕食功能反应评价了取食了Bt棉叶的棉铃虫幼虫对成熟草间钻头蛛捕食行为的影响.室内饲养实验结果表明草间钻头蛛、八斑鞘腹蛛取食用转Bt棉叶处理的棉铃虫幼虫与取食普通棉叶处理的棉铃虫幼虫的发育历期、成蛛体重都没有显著差异.捕食功能反应实验结果表明草间钻头蛛对棉铃虫幼虫的捕食功能反应符合HollingⅡ型圆盘方程,两组不同猎物饲养成熟的草间钻头蛛对同种处理的棉铃虫幼虫的捕食行为没有显著差异.综合考虑：转Bt棉对蜘蛛生长发育、捕食能力没有显著的负作用.     

寄主植物轮换饲养和次生代谢物交叉涂布对棉铃虫取食的影响

食物混合通常对多食性昆虫的生长表现有积极的影响,然而此前的研究对象主要是成虫期和幼虫期迁移能力较强的种类。某些鳞翅目种类尽管是多食性的,但其幼虫个体因时空隔离的原因,并无机会自由选择食料寄主。采用寄主叶片轮换饲养和次生代谢物交叉涂布两种方法研究了多食性棉铃虫幼虫的取食行为,供试寄主植物包括烟草、辣椒、番茄和棉花,次生代谢物采用自然浓度进行交叉涂布。结果表明,食物混合并没有造成幼虫总体摄食量的显著增加。其中,烟草和水合烟碱能显著抑制棉铃虫对其他寄主叶碟的取食,而辣椒及(E)-辣椒素对其他寄主叶碟的被食量均无影响。番茄叶片轮换饲养不影响棉铃虫对与其轮换的其他寄主叶片的被食量,但α-番茄苷涂布在辣椒和棉花叶碟上则对棉铃虫有显著拒食作用。棉花-烟草轮换饲养组中的烟草被食量显著大于烟草非轮换组中的烟草被食量,但(+)-棉酚涂布处理却能显著抑制棉铃虫对烟草的摄食。两种生物测定方法均未发现棉花与辣椒存在显著性相互影响。总之,棉铃虫可能是以耐受式的对策适应寄主植物次生代谢物的,符合相称性形态构成假说,即扩散能力较差的鳞翅目幼虫个体并不需要进化出同时应对来自两种或两种以上的寄主植物次生代谢物的适应机制。     

去甲斑蝥素对小菜蛾幼虫的拒食作用及取食行为的影响

去甲斑蝥素(NCTD)是斑蝥素(CTD)的衍生物,可人工合成。去甲斑蝥素对害虫有毒杀作用。为明确它是否有拒食作用及其作用方式,本研究以小菜蛾幼虫为供试昆虫,采用叶碟浸液法对试虫拒食作用及取食量、取食选择、取食次数和持续时间等取食行为进行了生物测定。拒食作用结果显示,2-48 h内NCTD处理组的幼虫取食量明显低于对照组且两者差距随时间逐渐增加,拒食率与剂量呈显著正相关,增加剂量会增加拒食率。行为研究结果显示,小菜蛾处理组试虫的单次平均取食时长明显减少,仅为对照组的70. 6%,而持续取食次数和试探次数均明显增多,分别是对照组的1. 4倍和1. 9倍。结果表明,NCTD对小菜蛾幼虫的拒食作用主要表现在降低试虫的取食量,减少取食时间,增加试探次数。     

茉莉酸甲酯处理对棉铃虫生长和解毒能力的影响

【目的】为明确茉莉酸甲酯（methyl jasmonate, MeJA）的不同处理方式对昆虫生长和解毒代谢能力的影响,以及MeJA熏蒸处理昆虫对植物防御和昆虫解毒代谢之间关系的影响。【方法】本文比较了取食MeJA和MeJA熏蒸等两种处理对棉铃虫Helicoverpa armigera 3龄末幼虫生长和解毒代谢酶活性的影响,并系统研究了经MeJA熏蒸处理的棉铃虫3龄末幼虫,再取食经MeJA喷雾处理的棉叶,其中肠解毒酶活性的变化。【结果】取食MeJA和MeJA熏蒸两种不同处理,对棉铃虫幼虫的生长及解毒能力的影响有所不同。取食含2.9 μg/g MeJA的人工饲料显著抑制了棉铃虫的生长,同时诱导棉铃虫幼虫P450活性增加了1.92倍,而MeJA熏蒸虽然没有影响棉铃虫幼虫的生长,但MeJA熏蒸处理使棉铃虫幼虫P450活性和羧酸酯酶活性分别增加了2.94倍和1.16倍。经MeJA熏蒸处理后的棉铃虫幼虫,再取食正常的或经MeJA喷雾处理的棉叶,其幼虫P450活性显著增加,其中经MeJA熏蒸处理的棉铃虫,再取食经MeJA喷雾处理的棉叶,其P450酶显示了最高活性。【结论】MeJA熏蒸处理棉铃虫,不仅使棉铃虫中与P450酶相关的解毒能力显著增加,而且增加了棉铃虫对于MeJA所诱导的棉花防御反应的解毒能力。     

Reduction of saltiness and bitterness after a chlorhexidine rinse

Chronic rinsing with chlorhexidine, an oral-antiseptic, has been shown to decrease the saltiness of NaCl and the bitterness of quinine. The effect of acute chlorhexidine on taste has not been investigated. The purpose of the present study was to examine the effect of acute chlorhexidine rinses on taste intensity and quality of 11 stimuli representing sweet, salt, sour, bitter and savory. All stimuli were first matched for overall intensity so the effects of chlorhexidine would be directly comparable across compounds. As a control treatment, the bitter taste of chlorhexidine digluconate (0.12%) was matched in intensity to quinine HCl, which was found to cross-adapt the bitterness of chlorhexidine. Subjects participated in four experimental conditions: a pre-test, a quinine treatment, a chlorhexidine treatment, and a post-test condition, while rating total taste intensity and taste qualities in separate test sessions. Relative to the quinine treatment, chlorhexidine was found to decrease the salty taste of NaCl, KCl and NH4Cl, and not to significantly affect the tastes of sucrose, monosodium glutamate (MSG), citric acid, HCl and the taste of water. The bitter taste of urea, sucrose octa-acetate and quinine were suppressed after chlorhexidine rinses relative to water rinses, but were only marginally suppressed relative to quinine rinses. Potential mechanisms are discussed.     

Responses of Primate Taste Cortex Neurons to the Astringent Tastant Tannic Acid

In order to advance knowledge of the neural control of feeding,we investigated the cortical representation of the taste oftannic acid, which produces the taste of astringency. It isa dietary component of biological importance particularly toarboreal primates. Recordings were made from 74 taste responsiveneurons in the orbitofrontal cortex. Single neurons were foundthat were tuned to respond to 0.001 M tannic acid, and representeda subpopulation of neurons that was distinct from neurons responsiveto the tastes of glucose (sweet), NaCl (salty), HCI (sour),quinine (bitter) and monosodium glutamate (umami). In addition,across the population of 74 neurons, tannic acid was as wellrepresented as the tastes of NaCI, HCI quinine or monosodiumglutamate. Multidimensional scaling analysis of the neuronalresponses to the tastants indicates that tannic acid lies outsidethe boundaries of the four conventional taste qualities (sweet,sour, bitter and salty). Taken together these data indicatethat the astringent taste of tannic acid should be consideredas a distinct taste quality, which receives a separate representationfrom sweet, salt, bitter and sour in the primate cortical tasteareas. Chem. Senses 21: 135–145, 1996.     

Autonomic nervous system responses associated with primary tastes

The hedonic dimension of the taste sensation plays a crucial role in the control of many taste-mediated responses related to food ingestion or rejection. The purpose of this study was to evaluate the emotional reactivity associated with each primary taste (sweet, salty, sour and bitter) through analysis of the variations of autonomic nervous system (ANS) parameters. Thirty-four healthy non-smoker volunteer subjects (17 males and 17 females, mean age = 28 years) participated in the experiment. Taste stimuli were solutions of 0.3 M sucrose (sweet), 0.15 M NaCl (salty), 0.02 M citric acid (sour) and 0.00015 M quinine sulfate (bitter). Evian mineral water was used as the diluent and control (neutral taste). Throughout the test, five ANS parameters (skin potential and skin resistance, skin blood flow and skin temperature, and instantaneous heart rate) were simultaneously and continuously recorded. Results of the ANOVA evidenced a significant effect of primary taste on skin resistance amplitude (P: < 0.001) and duration (P: < 0.0001), skin temperature amplitude (P: < 0.001), skin blood flow amplitude (vasoconstriction) (P: < 0.0001) and instantaneous heart rate increase (P: < 0.0001). Skin resistance and cardiac responses were the most relevant ANS parameters to distinguish among the taste solutions. The four primary tastes could be associated with significantly different ANS responses in relation to their hedonic valence: the pleasantly connoted and innate-accepted sweet taste induced the weakest ANS responses whereas the unpleasant connoted tastes (salty, sour and bitter) induced stronger ANS responses, the innate-rejected bitter taste inducing the strongest ones. Such a neurovegetative characterization of each primary taste could provide references for the hedonic analysis of the more complex gustative sensation attached to foods.     

Taste perception with age: generic or specific losses in supra-threshold intensities of five taste qualities?

The influence of ageing on supra-threshold intensity perception of NaCl, KCl, sucrose, aspartame, acetic acid, citric acid, caffeine, quinine HCl, monosodium glutamate (MSG) and inosine 5'-monophosphate (IMP) dissolved in water and in 'regular' product was studied in 21 young (19-33 years) and 21 elderly (60-75 years) persons. While the relative perception (intensity discrimination) seems to be remarkably resistant to the effect of ageing, the absolute perception (intensity rating) decreased with age for all tastants in water, but only for the salty and sweet tastants in product. When assessed while wearing a nose clip, only the perception of salty tastants was diminished with age. The slopes of the psychophysical functions were flatter in the elderly than in the young for the sweet, bitter and umami tastants in water, and for the sour tastants in product only. The age effects found were almost exclusively generic and never compound-specific within a taste. This study indicates that the relevance of determining intensities of tastants dissolved in water for the 'real life' perception of taste in complex food is rather limited.     

(+)-(S)-alapyridaine--a general taste enhancer?

N-(1-Carboxyethyl)-6-hydroxymethyl-pyridinium-3-ol inner salt (alapyridaine), recently identified in heated sugar/amino acid mixtures as well as in beef bouillon, has been shown to exhibit general taste-enhancing activities, although tasteless on its own. Differing from other taste enhancers reported so far, racemic (R/S)-alapyridaine and, to an even greater extent (+)-(S)-alapyridaine, the physiologically active enantiomer, are able to enhance more than one basic taste quality. The threshold concentrations for the sweet taste of glucose and sucrose, for the umami taste of monosodium L-glutamate (MSG) and guanosine-5'-monophosphate (GMP), as well as the salty taste of NaCl, were significantly decreased when alapyridaine was present. In contrast, perception of the bitter tastes of caffeine and L-phenylalanine, as well as of sour-tasting citric acid, was unaffected. Furthermore, alapyridaine was shown to intensify known taste synergies such as, for example, the enhancing effect of L-arginine on the salty taste of NaCl, as well as that of GMP on the umami taste of MSG. The activity of (+)-(S)-alapyridaine could be observed not only in solutions of single taste compounds, but also in more complex tastant mixtures; for example, the umami, sweet and salty taste of a solution containing MSG, sucrose, NaCl and caffeine was significantly modulated, thus indicating that alapyridaine is a general taste enhancer.     

Enhancement of retronasal odors by taste

Psychophysical studies of interactions between retronasal olfaction and taste have focused most often on the enhancement of tastes by odors, which has been attributed primarily to a response bias (i.e., halo dumping). Based upon preliminary evidence that retronasal odors could also be enhanced by taste, the present study measured both forms of enhancement using appropriate response categories. In the first experiment, subjects rated taste ("sweet," "sour," "salty," and "bitter") and odor ("other") intensity for aqueous samples of 3 tastants (sucrose, NaCl, and citric acid) and 3 odorants (vanillin, citral, and furaneol), both alone and in taste-odor mixtures. The results showed that sucrose, but not the other taste stimuli, significantly increased the perceived intensity of all 3 odors. Enhancement of tastes by odors was inconsistent and generally weaker than enhancement of odors by sucrose. A second experiment used a flavored beverage and a custard dessert to test whether the findings from the first experiment would hold for the perception of actual foods. Adding sucrose significantly enhanced the intensity of "cherry" and "vanilla" flavors, whereas adding vanillin did not significantly enhance the intensity of sweetness. It is proposed that enhancement of retronasal odors by a sweet stimulus results from an adaptive sensory mechanism that serves to increase the salience of the flavor of nutritive foods.     

PLCbeta2-independent behavioral avoidance of prototypical bitter-tasting ligands

Using a brief-access taste assay, we show in the present report that although phospholipase C beta2 knockout (PLCbeta2 KO) mice are unresponsive to low- and midrange concentrations of quinine and denatonium, they do significantly avoid licking higher concentrations of these aversive compounds. PLCbeta2 KO mice displayed no concentration-dependent licking of the prototypical sweetener sucrose but were similar to wild-type mice in their responses to citric acid and NaCl, notwithstanding some interesting exceptions. Although these findings confirm an essential role for PLCbeta2 in taste responsiveness to sucrose and to low- to midrange concentrations of quinine and denatonium in mice as previously reported, they importantly suggest that higher concentrations of the latter two compounds, which are bitter to humans, can engage a PLCbeta2-independent taste transduction pathway.     

The molecular biology of taste transduction

Taste cells respond to a wide variety of chemical stimuli: certain ions are perceived as salty (Na⁺) or sour (H⁺); other small molecules are perceived as sweet (sugars) and bitter (alkaloids). Taste has evolutionary value allowing animals to respond positively (to sweet carhohydrates and salty NaCl) or aversively (to bitter poisons and corrosive acids). Recently, some of the proteins involved in taste transduction have been cloned. Several different G proteins have been identified and cloned from taste tissue: gustducin is a taste cell specific G protein closely related to the transducins. Work is under way to clone additional components of the taste transduction pathways. The combination of electrophysiology, biochemistry and molecular biology is being used to characterize taste receptor cells and their sensory transduction mechanisms.     

Taste profiles from single circumvallate papillae: comparison with fungiform profiles

Two experiments were conducted to investigate the psychophysicalresponse characteristics of single circumvallate papillae. InExperiment 1, 12 circumvallate papillae in four subjects werechemically stimulated to assess identification of taste qualities.Single circumvallate papillae were found to mediate multipletaste qualities, and the taste profiles obtained from differentpapillae were similar within the same subject. Moreover, sucrose,quinine monohydrochloride and citric acid elicited unitary andcharacteristic quality responding in these papillae from allsubjects, whereas NaCl elicited predominantly sour and/or bitterresponses from three of the four subjects. Experiment 2 directly compared responses obtained from singlecircumvallate papillae with those obtained from fungiform regionsof the tongue. Data for 10 subjects showed significantly greatersour responses to citric acid and NaCl in circumvallate papillaeand significantly greater salty responses to these compoundson the anterior tongue. In addition, the taste profiles forcitric acid and NaCl were distinct for circumvallate papillae,while those from the anterior tongue were similar. These datasuggest that the bitterness and sweetness of quinine and sugar,respectively, can be identified on the basis of sensory informationarising from either circumvallate or fungiform regions, butthat differentiation of the tastes of salts and acids may dependon a comparison of the input from both regions and/or additionalinformation arising from foliate regions.     

Molecular mechanisms underlying the reception and transmission of sour taste information

Taste enables organisms to determine the properties of ingested substances by conveying information regarding the five basic taste modalities: sweet, salty, sour, bitter, and umami. The sweet, salty, and umami taste modalities convey the carbohydrate, electrolyte, and glutamate content of food, indicating its desirability and stimulating appetitive responses. The sour and bitter modalities convey the acidity of food and the presence of potential toxins, respectively, stimulating aversive responses to such tastes. In recent years, the receptors mediating sweet, bitter, and umami tastes have been identified as members of the T1R and T2R G-protein-coupled receptor families; however, the molecular mechanisms underlying sour taste detection have yet to be clearly elucidated. This review covers the molecular mechanisms proposed to mediate the detection and transmission of sour stimuli, focusing on polycystic kidney disease 1-like 3 (Pkd1l3), Pkd2l1, and carbonic anhydrase 4 (Car4).