Transcriptome analysis of axolotl oropharyngeal explants during taste bud differentiation stages

Transcriptome analyses reveal differentially expressed genes associated with development of the palatal organ in bighead carp (Hypophthalmichthys nobilis)

The palatal organ is a filter-feeding related organ and occupies a considerable proportion of the head of bighead carp (Hypophthalmichthys nobilis), a large cyprinid fish intensive aquaculture in Asia. In this study, we performed RNA-seq of the palatal organ during growth periods of two (M2), six (M6) and 15 (M15) months of age after hatching. The numbers of differentially expressed genes (DEGs) were 1384, 481 and 1837 for M2 VS M6, M6 VS M15 and M2 VS M15 respectively. The following signaling pathways of energy metabolism and cytoskeleton function were enriched, including ECM-receptor interaction, Cardiac muscle contraction, Steroid biosynthesis and PPAR signaling pathway. Several members of collagen family (col1a1, col2a1, col6a2, col6a3, col9a2), Laminin gamma 1 (lamc1), integrin alpha 1 (itga1), Fatty acid binding protein 2 (fads2) and lipoprotein lipase (lpl), and Protein tyrosine kinase 7 (Ptk7) are candidate genes for growth and development of basic tissues of the palatal organ. Furthermore, taste-related genes such as fgfrl1, fgf8a, fsta and notch1a were also identified, which may be involved in the development of taste buds of the palatal organ. The transcriptome data obtained in this study provide insights into the understanding functions and development mechanisms of palatal organ, and potential candidate genes that may be related to the genetic modulation of head size of bighead carp.

Transcriptome dataset for RNA-seq analysis of axolotl embryonic oropharyngeal endoderm explants

Animal nutrition and toxin deterrence rely on the ability to taste, which occurs through columnar taste cells clustered within taste buds. Taste buds in mammals are located within specialized tissues, called papillae. However, taste buds in fish and amphibians, such as axolotls (Ambystoma mexicanum), are not housed in papillae, rather they are embedded within the pharyngeal epithelium. This simplified tissue level organization, along with the ability of cultured oropharyngeal explants from early embryos to produce taste buds on the same time-line as embryos, make the axolotl an excellent model to identify molecules specifically involved in taste bud cell differentiation. We performed de novo transcriptomic analysis on RNA sequences from three different stages of oropharyngeal explants: stages 37/38, 39, and 41. RNA-seq data from 17 total samples representing these stages were pooled to generate a de novo assembly of the transcriptome using a Trinity pipeline. From 27.9Gb of raw sequences, we identified 21,244 transcripts. To our knowledge, this is the first published assembly of axolotl oropharyngeal endoderm explants. This data and transcriptome assembly relate to the research article “Transcriptome Analysis of Axolotl Oropharyngeal Explants During Taste Bud Differentiation Stages” (Kohli et al. 2020). This RNA-seq data and transcriptome assembly provide information on genes expressed in the oropharyngeal endoderm and will be valuable in the identification of taste bud development genes.