Institut für Genetik, Universität zu Köln, Zülpicher Strasse 47a, Köln, Germany.
Chem Senses. 2011 May;36(4):357-65. doi: 10.1093/chemse/bjq138. Epub 2011 Jan 17.
Chemosensory systems in vertebrates employ G protein-coupled receptors as sensors. In mammals, several families of olfactory and gustatory receptors as well as specific G alpha proteins coupling to them have been identified, for example, gustducin for taste. Orthologous receptor families have been characterized in fish, but the corresponding G alpha genes have not been well investigated so far. We have performed a comprehensive search of several lower vertebrate genomes to establish the G alpha protein family in these taxa and to identify those genes that may be involved in chemosensory signal transduction in fish. We report that gustducin is absent from the genomes of all teleost and amphibian species analyzed, presumably due to independent gene losses in these lineages. However, 2 other G alpha genes, Gi1b and G14a, are expressed in zebrafish taste buds and 4 G proteins, Go1, Go2, Gi1b, and Golf2, were detected in the olfactory epithelium. Golf2, Gi1b, and G14a are expressed already shortly after hatching, consistent with the physiological and behavioral responses of larvae to odorants and tastants. Our results show general similarity to the mammalian situation but also clear-cut differences and as such are essential for using the zebrafish model system to study chemosensory perception.
脊椎动物的化学感觉系统使用 G 蛋白偶联受体作为传感器。在哺乳动物中，已经鉴定出了几种嗅觉和味觉受体家族以及与之偶联的特定 G 蛋白α亚基，例如味觉中的 gustducin。在鱼类中也已经描述了同源的受体家族，但迄今为止，相应的 G 蛋白α基因尚未得到很好的研究。我们对几种低等脊椎动物的基因组进行了全面搜索，以确定这些分类群中的 G 蛋白α家族，并鉴定那些可能参与鱼类化学感觉信号转导的基因。我们报告说， gustducin 缺失于所有分析的硬骨鱼和两栖动物物种的基因组中，可能是由于这些谱系中的独立基因丢失。然而，在斑马鱼的味蕾中表达了另外 2 个 G 蛋白α基因 Gi1b 和 G14a，并且在嗅觉上皮中检测到 4 个 G 蛋白，Go1、Go2、Gi1b 和 Golf2。Golf2、Gi1b 和 G14a 在孵化后不久就开始表达，与幼虫对气味和味觉刺激的生理和行为反应一致。我们的结果与哺乳动物的情况总体相似，但也存在明显的差异，因此对于使用斑马鱼模型系统研究化学感觉感知至关重要。
