A comparative analysis of the transcriptome in skeletal muscle of different growth stages in the Chinese Giant Salamander ( <i>Andrias davidianus</i> )

To understand the molecular mechanisms underlying its growth in Chinese giant salamander (CGS), transcriptome analysis of the skeletal muscle from five different growth stages at year 0.5 (0.5Y), year 1 (1Y), year 2 (2Y), year 3 (3Y), and year 4 (4Y) were performed. Five libraries were constructed, resulting in the identification of 59,850 unigenes in skeletal muscle by assembly. Unigenes exhibited a length distribution ranging from 201 to 96,350 bp, with an average length of 346 bp. Totally, 20,328 (33.96%) unigenes were successfully annotated to the Nr, TF, Swiss-Prot, Pfam, eggNOG, GO, and KEGG databases. Among these unigenes, 15,467 were found to contain SSRs loci, representing 25.84% of the total unigenes. The average inter-locus distance for SSR was determined to be 3,134 bp. A total of 696 differentially expressed genes (DEGs) with co-expression were identified. Furthermore, it was found that 13 myosin heavy chain family genes are involved in the muscle regulation of CGS. Of them, six DEGs were confirmed for their accuracy by real-time qPCR. GO enrichment showed that DEGs were associated with cytoplasm, nucleus, ATP binding, and metal ion binding in terms of biological processes. KEGG enrichments showed that DEGs were enriched to 275 signaling pathways including cardiac muscle contraction, RNA transport, AMPK signaling pathway, regulation of actin cytoskeleton, calcium signaling pathway, Glycolysis/Gluconeogenesis. Our results contribute to improve and enrich the annotation information of CGS transcriptome, and also provide theoretical basis and data support for the further exploration and verification of related gene functions for elucidating molecular regulatory mechanism behind growth differences between individuals of CGS.