College of Life Sciences, Frontier Science Center for Immunology and Metabolism, Hubei Key Laboratory of Cell Homeostasis, Wuhan University, Wuhan 430072, China.
College of Plant Protection, Northwest A&F University, Yangling 712100, China.
Proc Natl Acad Sci U S A. 2023 Feb 21;120(8):e2218183120. doi: 10.1073/pnas.2218183120. Epub 2023 Feb 13.
Vertebrate Tas2r taste receptors detect bitter compounds that are potentially poisonous. Previous studies found substantial variation in the number of genes across vertebrates, with some frog species carrying the largest number. Peculiar among vertebrates, frogs undergo metamorphosis, often associated with a dietary shift between tadpoles and adults. A possible explanation for the large size of frog families could be that distinct sets of genes are required for tadpoles and adults, suggesting differential expression of genes between tadpoles and adults. To test this hypothesis, we first examined 20 amphibian genomes and found that amphibians generally possess more genes than do other vertebrate clades. We next focused on the American bullfrog () to examine the expression of its genes in herbivorous tadpoles and insectivorous adult frogs. We report that close to one fifth of its 180 genes are differentially expressed (22 genes enriched in adults and 11 in tadpoles). Tuning properties were determined for a subset of differentially expressed genes by a cell-based functional assay, with the adult-enriched gene set covering a larger range of ligands compared to the tadpole-enriched subset. These results suggest a role of genes in the ontogenetic dietary shift of frogs and potentially initiate a new avenue of ontogenetic analysis of diet-related genes in the animal kingdom.
脊椎动物 Tas2r 味觉受体能检测到潜在有毒的苦味化合物。之前的研究发现，脊椎动物之间基因数量存在很大差异，一些青蛙物种携带的基因数量最多。在脊椎动物中比较特殊的是，青蛙经历变态发育，通常伴随着从蝌蚪到成蛙的饮食转变。青蛙科如此庞大的一个可能的解释是，蝌蚪和成蛙可能需要不同的基因集合，这表明基因在蝌蚪和成蛙之间存在差异表达。为了验证这一假说，我们首先检查了 20 种两栖动物的基因组，发现与其他脊椎动物分支相比，两栖动物通常拥有更多的基因。接下来，我们专注于美洲牛蛙 ()，以研究其基因在食草蝌蚪和成食昆虫蛙之间的表达情况。我们报告说，它的 180 个基因中接近五分之一（22 个基因在成蛙中富集，11 个在蝌蚪中富集）呈现差异表达。通过基于细胞的功能测定对一部分差异表达基因的调谐特性进行了测定，与富集在蝌蚪中的亚组相比，富集在成蛙中的基因集覆盖了更大范围的配体。这些结果表明基因在青蛙的个体发育饮食转变中起作用，并可能为动物王国中与饮食相关的基因的个体发育分析开辟新途径。
