The sense of taste helps humans to obtain information and form a picture of the world by recognizing chemicals in their environments. Over the past decade, large advances have been made in understanding the mechanisms of taste detection and mimicking its capability using artificial sensor devices. However, the detection capability of previous artificial taste sensors has been far inferior to that of animal tongues, in terms of its sensitivity and selectivity. Herein, we developed a bioelectronic tongue using heterodimeric human sweet taste receptors for the detection and discrimination of sweeteners with human-like performance, where single-walled carbon nanotube field-effect transistors were functionalized with nanovesicles containing human sweet taste receptors and used to detect the binding of sweeteners to the taste receptors. The receptors are heterodimeric G-protein-coupled receptors (GPCRs) composed of human taste receptor type 1 member 2 (hTAS1R2) and human taste receptor type 1 member 3 (hTAS1R3), which have multiple binding sites and allow a human tongue-like broad selectivity for the detection of sweeteners. This nanovesicle-based bioelectronic tongue can be a powerful tool for the detection of sweeteners as an alternative to labor-intensive and time-consuming cell-based assays and the sensory evaluation panels used in the food and beverage industry. Furthermore, this study also allows the artificial sensor to exam the functional activity of dimeric GPCRs.

Mutations in COCH cause autosomal dominant non-syndromic hearing loss with variable degrees of clinical onset and vestibular malfunction. We selected eight uncharacterized mutations and performed immunocytochemical and Western blot analyses to track cochlin through the secretory pathway. We then performed a comprehensive analysis of clinical information from DFNA9 patients with all 21 known COCH mutations in conjunction with cellular and molecular findings to identify genotype-phenotype correlations. Our studies revealed that five mutants were not secreted into the media: two vWFA domain mutants, which were not transported from the ER to Golgi complex and formed high-molecular-weight aggregates in cell lysates; and three LCCL domain mutants, which were detected as intracellular dimeric cochlins. Mutant cochlins that were not secreted and accumulated in cells result in earlier age of onset of hearing defects. In addition, individuals with LCCL domain mutations show accompanying vestibular dysfunction, whereas those with vWFA domain mutations exhibit predominantly hearing loss. This is the first report showing failure of mutant cochlin transport through the secretory pathway, abolishment of cochlin secretion, and formation and retention of dimers and large multimeric intracellular aggregates, and high correlation with earlier onset and progression of hearing loss in individuals with these DFNA9-causing mutations.

In this study, we developed a human taste receptor protein, hTAS2R38-functionalized carboxylated polypyrrole nanotube (CPNT)-field effect transistor (FET) as a nanobioelectronic tongue (nbe-tongue) that displayed human-like performance with high sensitivity and selectivity. Taster type (PAV) and nontaster type (AVI) hTAS2R38s were expressed in Escherichia coli (E. coli) at a high level and immobilized on a CPNT-FET sensor platform. Among the various tastants examined, PAV-CPNT-FET exclusively responded to target bitterness compounds, phenylthiocarbamide (PTC) and propylthiouracil (PROP), with high sensitivity at concentrations as low as 1 fM. However, no significant changes were observed in the AVI-CPNT-FET in response to the target bitter tastants. This nbe-tongue exhibited different bitter-taste perception of compounds containing thiourea (N-C═S) moieties such as PTC, PROP, and antithyroid toxin in vegetables, which corresponded to the haplotype of hTAS2R38 immobilized on CPNTs. This correlation with the type of receptor is very similar to the human taste system. Thus, the artificial taste sensor developed in this study allowed for the efficient detection of target tastants in mixture and real food sample with a human-like performance and high sensitivity. Furthermore, our nbe-tongue could be utilized as a substitute for cell-based assays and to better understand the mechanisms of human taste.

BackgroundHereditary hearing loss is one of the most common heterogeneous disorders, and genetic variants that can cause hearing loss have been identified in over sixty genes. Most of these hearing loss genes have been detected using classical genetic methods, typically starting with linkage analysis in large families with hereditary hearing loss. However, these classical strategies are not well suited for mutation analysis in smaller families who have insufficient genetic information.MethodsEighty known hearing loss genes were selected and simultaneously sequenced by targeted next-generation sequencing (NGS) in 8 Korean families with autosomal dominant non-syndromic sensorineural hearing loss.ResultsFive mutations in known hearing loss genes, including 1 nonsense and 4 missense mutations, were identified in 5 different genes (ACTG1, MYO1F, DIAPH1, POU4F3 and EYA4), and the genotypes for these mutations were consistent with the autosomal dominant inheritance pattern of hearing loss in each family. No mutational hot-spots were revealed in these Korean families.ConclusionTargeted NGS allowed for the detection of pathogenic mutations in affected individuals who were not candidates for classical genetic studies. This report is the first documenting the effective use of an NGS technique to detect pathogenic mutations that underlie hearing loss in an East Asian population. Using this NGS technique to establish a database of common mutations in Korean patients with hearing loss and further data accumulation will contribute to the early diagnosis and fundamental therapies for hereditary hearing loss.

Mutations in the DFNA5 gene are known to cause autosomal dominant non-syndromic hearing loss (ADNSHL). To date, five DFNA5 mutations have been reported, all of which were different in the genomic level. In this study, we ascertained a Korean family with autosomal dominant, progressive and sensorineural hearing loss and performed linkage analysis that revealed linkage to the DFNA5 locus on chromosome 7. Sequence analysis of DFNA5 identified a 3-bp deletion in intron 7 (c.991-15_991-13del) as the cause of hearing loss in this family. As the same mutation had been reported in a large Chinese family segregating DFNA5 hearing loss, we compared their DFNA5 mutation-linked haplotype with that of the Korean family. We found a conserved haplotype, suggesting that the 3-bp deletion is derived from a single origin in these families. Our observation raises the possibility that this mutation may be a common cause of autosomal dominant progressive hearing loss in East Asians.