cAMP is a second messenger in a variety of chemosensory receptors, including taste buds and glucose-sensitive pancreatic beta-cells. cAMP is modulated during taste transduction, yet the significance of cAMP changes and the taste cell types in which they occur (Type I glial-like; Type II Receptor; Type III Presynaptic) remain unclear. I developed techniques to image real-time changes in intracellular cAMP in taste cells using genetically-encoded cAMP reporters. This FRET-based reporter permits one to measure single-cell cAMP levels with excellent spatial and temporal resolution (Zaccolo & Pozzan 2002, Science 295:1711). Using a biolistic approach I have transfected rat fungiform taste buds with cAMP reporter plasmids. Focal application of bitter tastant to living fungiform tastebuds in situ produced a decrease in [cAMP]i within individual taste receptor cells. These results are qualitatively similar to previous biochemical measurements from homogenized taste tissue (Yan et al. 2001, Am J Physiol Cell Physiol 280:C742) but are now allowing us to examine the cAMP response in individual, identified cells. I next explored the effect of elevating cAMP on calcium levels, using Fura-2 imaging of isolated mouse vallate taste buds. Elevating [cAMP]i in taste buds evoked calcium responses in presynaptic/Type III taste cells, which do not express GAD1. cAMP induced responses were generated by calcium influx. Using pharmacological antagonists, I determined that the calcium influx triggered by cAMP is through L-type calcium channels, whereas influx following depolarization is primarily through P/Q-type calcium channels. Consistent with these data, single cell RT-PCR showed that the L-type subunit (alpha 1C) was expressed primarily in GAD-negative Presynaptic cells, while the P/Q-type (alpha 1A) was expressed in all Presynaptic cells. Thus, cAMP may modulate the function of synapses in some taste cells. Finally, we have developed a mouse strain expressing a cAMP reporter in a tissue-specific and tetracycline-inducible manner. We crossed this mouse with another strain expressing tet-activator in beta cells of the pancreas. Such islets responded to increasing concentrations of glucose (5.5 to 35mM) with an increase in cAMP levels. The half maximum of 9mM glucose for the cAMP response corresponds well with reported glucose concentrations that elicit insulin release from whole islets. Stimulating pancreatic islets with glucose is known to drive calcium influx into beta-cells. When we simultaneously imaged both second messengers, we found that cAMP changes precede and are independent of calcium changes. In conclusion, these studies have outlined novel potential functions for cAMP signaling in the transduction of both primary tastant and plasma glucose information. In addition, the flexibility of the tet-system will enable cAMP reporter expression in numerous cell types, including those which mediate gustatory transduction.

Taste, or gustation, has long been considered a primitive, and even non-rational, perceptual sense. Taste, as a subject of academic research, has been given very little attention; especially, when contrasted to other human perceptual senses. The knowledge of how people express and discuss their perceptions and sensations of tastes, and, specifically, the descriptions of tastes of chocolate, is very limited. Furthermore, the terminological inconsistency in the vocabulary of chocolate tasting, with the risk of misunderstanding or miscommunication, suggests that a basic method for representing tastes is needed. This thesis presents a study of how people actually express the perception or sensation of tasting, and specifically when tasting chocolate. This study also explores the possibility of crafting a method for use when describing the tastes of chocolate. The study was carried out by holding two tasting workshops. The first one was concerned with recording conversations about tasting chocolate. Participants were asked to taste different kinds of chocolates and, freely, discuss what they perceived and sensed. In the second workshop the participants were asked to describe the tastes of chocolate using predetermined vocabulary and formatted questionnaires. The results of this study are linguistic semantic analyses of the different words that were used, and also a proposal for a prototypical method to use when tasting chocolate.

This paper focuses on how interior decoration and taste was seen and taught in relation to the vision of the ideal home in 1940s Sweden. Two phenomena that are focused on are surveys of how people actually lived, and the attempts made to alter that way of living. The activities of Svenska Slöjdföreningen (SSF, the Swedish Society of Industrial Design) is used as a prism for discerning the discourse on domestic interior reform, and the study consists of a close reading and analysis based on archival material and publications linked to SSF. Part of the archival material consists of survey protocols and photograph, of Swedish homes, from a survey into “dwelling habits” initiated by the Association of Swedish Architects (SAR) and the SSF. In the late 1930s and early 1940s, these kinds of surveys were made in order to analyse the standard of living, and the usage of homes and furniture with the aim to find adequate ways of building better housing, of producing better furniture, and of educating people to be more modern and enlightened consumers and home-makers. Based on these findings, courses were given on how to furnish and decorate the home. Through courses in how to furnish and decorate the home, the ideal home was to become real. I mean that the concept of “taste” was almost as important as the concept of “home” in the vision of what modern Swedish society should be like, but that manifesting “good taste” in the home in the 1940s meant something more than merely creating an aesthetically pleasing or beautiful interior. Taste was, above all, seen as an indicator of the degree of modernity and social awareness of people.

藉由比較高達美的美學與康德判斷力批判中的品味(鑑賞)概念，探討此一概念對於現代人的意義。 / This dissertation attempts to discuss the implication of “taste”in Kant's Critique of Judgment and in Gadamer's Aesthetic.

La incidència sobre el suro de defectes sensorials amb descriptors de florit-humitat és un dels principals problemes amb què s'enfronta la indústria surera. Els principals compostos relacionats amb aquest defecte son cloroanisoles, metoxipirazines, geosmina i metilisoborneol. Aquesta recerca s'ha fet amb l'objectiu principal d'aprofundir en els mètodes de determinació de compostos volàtils en suro. S'ha desenvolupat una metodologia basada en la microextracció en fase sòlida i la cromatografia de gasos per a l'anàlisi conjunta d'aquests compostos en macerats de suro. El fet que la majoria dels compostos d'interès tingui un origen microbià ha fet necessari completar les anàlisis químiques amb mètodes de detecció i aïllament dels microorganismes susceptibles de produir-los. S'ha utilitzat un mètode per a l'estudi de la diversitat de fongs i bacteris en mostres de suro basat en l'estudi de marcadors genètics mitjançant l'anàlisi en gradients electroforètics desnaturalitzants. Per últim s'ha avaluat la capacitat de producció de defectes sensorials per microorganismes aïllats de suro utilitzant tècniques olfactomètriques. / The incidence of musty-earthy sensory deviations on cork is one of the main problems that the cork industry faces. The main compounds related to this defect are chloroanisoles, methoxypyrazines, geosmin and methylisoborneol. The aim of this research work was to develop analytical methods to simultaneously determine a large set of volatile compounds in cork samples. A methodology based on solid phase microextraction (SPME) and gas chromatography for the determination of TCA, 3-isopropyl-2-methoxypyrazine, geosmin and methylisoborneol in cork aqueous macerates has been developed and validated. Moreover, the microbial origin of most of these compounds makes necessary to complement the chemical analysis with the detection and isolation of microorganisms that may be involved in the production of off-odours. Regular fingerprinting techniques for the analysis of microbial diversity such as Denaturing Gradient Gel Electrophoresis (DGGE) have been applied to the study of microorganism potentially responsible for off-odour formation in cork, in order to complement the chemical characterization of the volatile fraction. Finally we have evaluated the off-odour production capacity of microorganisms isolated from cork using olfactometry techniques.

Geosmin is an odorous secondary metabolite produced by some cyanobacteria during growth and released from the cells. Little is known about the biosynthesis of geosmin and the gene(s) required for its production have not been characterized. During late August and early September geosmin episodes due to planktonic cyanobacteria frequently occur in the northwest basin of Lake Ontario waters resulting in taste and odour episodes in drinking water that serves more than 5 million people. At high concentrations geosmin evades traditional drinking water treatment and reaches the tap. These episodes often elicit consumer concern and are wrongly construed to reflect impaired drinking water safety. Water quality managers in the region have generally been unable to prevent or control taste and odour episodes via a proactive approach due to the lack of knowledge of cyanobacterial communities in offshore waters as well as the inability to predict when geosmin will reach intake pipes due to downwelling, the process by which the surface waters mix with the hypolimnion. This study evaluated denaturing gradient gel electrophoresis (DGGE) as a molecular tool for proactive monitoring of potential taste and odour-causing cyanobacteria in environmental samples. The 16S rRNA gene was assessed for its ability to distinguish among geosmin-producing and non-producing strains. This study also examined the evolutionary relationships among geosmin-producing cyanobacteria using the full-length 16S rRNA gene and compared phylogenies with current taxonomy. <br /><br /> A DGGE standard using the V3 hypervariable region of the 16S rRNA gene was developed using geosmin-producing and non-producing isolates of cyanobacteria. Included in the standard was the suspected primary contributor to Lake Ontario taste and odour, <em>Anabaena lemmermannii</em> Richter. This standard was then applied to various environmental collections from Lake Ontario (August 2005) to examine the cyanobacterial community composition. DGGE profiles were consistent with the presence of <em>An. lemmermannii</em> at locations with increased geosmin concentrations (determined using gas chromatography-mass spectrometry), supporting hypothesis that <em>An. lemmermannii</em> is the primary contributor to northwestern Lake Ontario taste and odour. In addition, the application of DGGE in the identification of potential geosmin-producing species of cyanobacteria was deemed to be a potentially useful approach to monitoring cyanobacterial communities in source waters. The 16S rRNA-V3 region alone did not distinguish among geosmin-producing and non-producing strains, however with additional data (actual geosmin concentration) it was showed relationships. <br /><br /> In the phylogenetic analyses, geosmin-producing cyanobacteria did not group monophyletically and it was not possible to state that a single evolutionary event has led to the acquisition of the geosmin-producing trait. Phylogenies also showed that the taxonomy of the Cyanobacteria is largely unresolved. All five Sections (bacteriological classification)/four orders (Komárek & Anagnostidis classification) were paraphyletic, however the heterocystous cyanobacteria (Sections IV and V/Nostocales and Stigonematales) grouped separately from the non-heterocystous cyanobacteria (Sections I, III/Chroococcales and Oscillatoriales). Although both systems of classification compared in this study were similar, nomenclature and groupings were occasionally different among the groups. This demonstrates the incongruity between bacteriologists and phycologists and emphasizes the need for a consensus system of classification for the Cyanobacteria.

Geosmin is an odorous secondary metabolite produced by some cyanobacteria during growth and released from the cells. Little is known about the biosynthesis of geosmin and the gene(s) required for its production have not been characterized. During late August and early September geosmin episodes due to planktonic cyanobacteria frequently occur in the northwest basin of Lake Ontario waters resulting in taste and odour episodes in drinking water that serves more than 5 million people. At high concentrations geosmin evades traditional drinking water treatment and reaches the tap. These episodes often elicit consumer concern and are wrongly construed to reflect impaired drinking water safety. Water quality managers in the region have generally been unable to prevent or control taste and odour episodes via a proactive approach due to the lack of knowledge of cyanobacterial communities in offshore waters as well as the inability to predict when geosmin will reach intake pipes due to downwelling, the process by which the surface waters mix with the hypolimnion. This study evaluated denaturing gradient gel electrophoresis (DGGE) as a molecular tool for proactive monitoring of potential taste and odour-causing cyanobacteria in environmental samples. The 16S rRNA gene was assessed for its ability to distinguish among geosmin-producing and non-producing strains. This study also examined the evolutionary relationships among geosmin-producing cyanobacteria using the full-length 16S rRNA gene and compared phylogenies with current taxonomy. <br /><br /> A DGGE standard using the V3 hypervariable region of the 16S rRNA gene was developed using geosmin-producing and non-producing isolates of cyanobacteria. Included in the standard was the suspected primary contributor to Lake Ontario taste and odour, <em>Anabaena lemmermannii</em> Richter. This standard was then applied to various environmental collections from Lake Ontario (August 2005) to examine the cyanobacterial community composition. DGGE profiles were consistent with the presence of <em>An. lemmermannii</em> at locations with increased geosmin concentrations (determined using gas chromatography-mass spectrometry), supporting hypothesis that <em>An. lemmermannii</em> is the primary contributor to northwestern Lake Ontario taste and odour. In addition, the application of DGGE in the identification of potential geosmin-producing species of cyanobacteria was deemed to be a potentially useful approach to monitoring cyanobacterial communities in source waters. The 16S rRNA-V3 region alone did not distinguish among geosmin-producing and non-producing strains, however with additional data (actual geosmin concentration) it was showed relationships. <br /><br /> In the phylogenetic analyses, geosmin-producing cyanobacteria did not group monophyletically and it was not possible to state that a single evolutionary event has led to the acquisition of the geosmin-producing trait. Phylogenies also showed that the taxonomy of the Cyanobacteria is largely unresolved. All five Sections (bacteriological classification)/four orders (Komárek & Anagnostidis classification) were paraphyletic, however the heterocystous cyanobacteria (Sections IV and V/Nostocales and Stigonematales) grouped separately from the non-heterocystous cyanobacteria (Sections I, III/Chroococcales and Oscillatoriales). Although both systems of classification compared in this study were similar, nomenclature and groupings were occasionally different among the groups. This demonstrates the incongruity between bacteriologists and phycologists and emphasizes the need for a consensus system of classification for the Cyanobacteria.

Most studies of gustatory coding have been performed in either anesthetized or awake, passively stimulated rats. In this dissertation the influences of behavioral state on gustatory processing in awake rats are described. In the first set of experiments, the effects of non-contingent tastant delivery on the chemical tuning of single neurons were explored. Tastants were delivered non-contingently through intra-oral cannulas to restrained, non water-deprived rats while single unit responses were recorded from the gustatory cortex (GC). As the subjects' behavior progressed from acceptance to rejection of the tastants, the chemical tuning of the neurons changed as well. This suggests that the subjects' behavioral state powerfully influences gustatory processing. In the second set of experiments, rats were trained to lick for fluid reinforcement on an FR5 schedule while single unit activity was recorded from GC. In this case, the chemical tuning was much more stable. Under this paradigm, chemosensory responses were rapid (~ 150 ms) and broadly tuned. In the third study, it was found that ensembles of GC neurons could discriminate between tastants and their concentrations on a single trial basis, and such discrimination was accomplished with a combination of rate and temporal coding. Ensembles of GC neurons also anticipated the identity of the upcoming stimulus when the tastant delivery was predictable. Finally, it was found that ensembles of GC neurons could discriminate between the bitter stimuli nicotine and quinine. Nicotine is both a bitter tastant and a trigeminal stimulant, and when the acetylcholine receptors in the lingual epithelium were blocked with mecamylamine, the ensembles failed to discriminate nicotine from quinine.

<p>Gustation, also known as taste perception, is critical for the survival of most animal species. The fruit fly Drosophila melanogaster employs 68 different gustatory receptors (GRs) for the detection of sugars, bitter or toxic compounds, and pheromones. However, with a few notable exceptions, the functions of most GRs involved in feeding are unknown. Our research has focused on a cluster of highly-related Drosophila Grs, known as the Gr64 family, that have been shown to be critical for the perception of multiple sugars. Furthermore, we have demonstrated that another gene related to the Gr64 genes, Gr61a, is a sugar receptor that is narrowly tuned to a subset of pyranose sugars and may (along with the Gr64 genes) be indispensable for early fly development. </p><p>As a complementary approach to our behavioral analysis, we have examined the expression pattern of the Drosophila sugar receptors using knock-in driver alleles created by homologous recombination. As expected, most of these drivers have shown strong expression in various taste tissues. Intriguingly, some of these knock-in alleles also show expression in the maxillary palp and antenna, tissues previously thought to be involved only in olfaction. These expression patterns raise interesting questions about the true range of function of these chemosensory receptors and whether or not they might be involved in olfaction as well as gustation.</p> / Dissertation

The main objectives of this thesis are to examine the relations between people and things in American novelist Henry James's 1897 novel The Spoils of Poynton, and thus to deepen our understanding of James's engagement with material culture. Critics have tended to frame James's works in general in terms of his detachment from economic and material reality; and criticisms on the novel in particular have seen it as exemplifying the alleged detachment, interpreting the things accumulated by a female collector at Poynton, as something illusory and unsubstantial, such as a form of commodity fetishism, a Freudian fetish, or a Lacanian signifier. Contrary to the conventional view, however, this thesis argues that James, in this novel about a struggle between a mother and her son over a house and its furnishings, represents and explores physical and affective relationships between the characters and things. James, focusing on the characters' sense experience, attempts to criticize the phallocentric power of his own culture that not only excludes women from the legal right of possession but also undervalues female domestic work in spite of its support for the culture. Drawing our attention to the senses that have traditionally been thought "lower" and "feminine," and thus refusing the taxonomization and hierarchization of the senses, James expands the category of aesthetic experience. This thesis argues that in the novel, by adopting as his primary mode of writing immediate sense experience prior to philosophical abstraction, James makes clear the latent implication between cultural repudiation of the feminine and the material, on the one hand, and the political and institutionalized exclusion of women by patriarchal property law, on the other. Criticism that ignores the material urgency and presence in the novel will further replicate that patriarchal power structure.