Genome-Wide Analysis of Gene Expression in Primate Taste Buds Reveals Links to Diverse Processes

Efforts to unravel the mechanisms underlying taste sensation (gustation) have largely focused on rodents. Here we present the first comprehensive characterization of gene expression in primate taste buds. Our findings reveal unique new insights into the biology of taste buds. We generated a taste bud gene expression database using laser capture microdissection (LCM) procured fungiform (FG) and circumvallate (CV) taste buds from primates. We also used LCM to collect the top and bottom portions of CV taste buds. Affymetrix genome wide arrays were used to analyze gene expression in all samples. Known taste receptors are preferentially expressed in the top portion of taste buds. Genes associated with the cell cycle and stem cells are preferentially expressed in the bottom portion of taste buds, suggesting that precursor cells are located there. Several chemokines including CXCL14 and CXCL8 are among the highest expressed genes in taste buds, indicating that immune system related processes are active in taste buds. Several genes expressed specifically in endocrine glands including growth hormone releasing hormone and its receptor are also strongly expressed in taste buds, suggesting a link between metabolism and taste. Cell type-specific expression of transcription factors and signaling molecules involved in cell fate, including KIT, reveals the taste bud as an active site of cell regeneration, differentiation, and development. IKBKAP, a gene mutated in familial dysautonomia, a disease that results in loss of taste buds, is expressed in taste cells that communicate with afferent nerve fibers via synaptic transmission. This database highlights the power of LCM coupled with transcriptional profiling to dissect the molecular composition of normal tissues, represents the most comprehensive molecular analysis of primate taste buds to date, and provides a foundation for further studies in diverse aspects of taste biology

Reduced taste function and taste papillae density in children with chronic kidney disease

Background: Taste loss may contribute to the loss of appetite in children with chronic kidney disease (CKD) and other serious medical conditions that result in malnutrition. Traditional methods for measurement of taste loss commonly use aqueous tastant solutions that can induce nausea, vomiting, or even pain in the mouth. An alternative is to measure fungiform papillae density on the anterior tongue since this correlates with taste sensitivity. Here we aimed to develop a non-invasive method for assessing papillae density on the anterior tongue and to use the method to determine if CKD patients [estimated glomerular filtrate (eGFR 89 ml/min/1.73 m2). Methods: Thirty-five healthy adults participated in the development of a method, which was assessed by 24 children, 12 of whom were CKD patients and 12 were clinical controls. Results: Similar papillae densities were found using invasive and non-invasive methods (F(1,34) = 0.647, p = 0.427). The CKD group had a significantly lower papillae density (X2 = 7.17, p = 0.007) and poorer taste sensitivity than the CC group (p = 0.0272), and the density correlated significantly with eGFR (r = 0.56, p < 0.01). Conclusions: Loss of taste in children with CKD is due to the reduced number of papillae and their taste-sensing receptor cells

Is manual dexterity essential in the selection of dental students?

Objective The purpose of this study was to determine whether basic manual dexterity (BMD) could be an important parameter in selecting students for the Degree in Dentistry (CLOPD) and to assess whether initial manual dexterity in students admitted to the CLOPD can improve with training in pre-clinical and clinical practice. Design Observational study. Setting The study was carried out at the Catholic University of Rome, in five consecutive academic years. Subjects and methods Four hundred and thirty-three subjects (262 males and 171 females) were tested (10 different exercises) in five consecutive years. Two retests were performed after three and five years respectively from the beginning of the experimentation. Main outcome measures The scores of individual exercises were averaged for each candidate, assessing the mean value of basic manual dexterity score (BMDS). Results It was possible to observe some differences among candidates coming from different types of high schools, since those having a prior university degree or a scientific high school degree proved better than those with classical or vocational high school qualifications (p < 0.05). A statistically significant improvement of BMDS has been observed in students who attended the CLOPD for at least 32 months. Conclusions Data obtained revealed that basic manual dexterity is not essential in the selection of dental students. Students who could follow training significantly improved in their manual ability. © 2007 Nature Publishing Group