Molt-dependent transcriptome analysis of claw muscles in Chinese mitten crab Eriocheir sinensis.

Background: Molting is a critical developmental process for crustaceans, during which the claw muscles undergo periodic atrophy and restoration. But the mechanism underlying this special muscle reshuffle around ecdysis is not yet thoroughly understood.
Objective: To investigate the molecular mechanism underlying the muscle's reshuffle over the molting cycle of Chinese mitten crab Eriocheir sinensis.
Methods: The Illumina high-throughput sequencing technique were used to sequence the transcriptome of the whole claw muscles from Chinese mitten crab Eriocheir sinensis in three molting stages (inter-molt C stage, pre-molt D _3-4 and post-molt A-B stage); the de novo assembly, annotation and functional evaluation of the contigs were performed with bioinformatics tools.
Results: Totally 129,149 unigenes, 128,190 CDS, 33,770 SSRs and a large number of SNP sites were obtained, and 3700 and 12,771 differentially expressed genes (DEGs) were identified respectively in A-B and D _3-4 stage compared with that in C stage. The identified DEGs were enriched to 746 and 1 408 GO terms respectively in A-B and D _3-4 stage compared with C stage (p ≤ 0.05). KEGG pathway analysis showed that the DEGs were significantly enriched in 14 and 11 pathways in A-B vs C comparison and D _3-4 vs C comparison (p ≤ 0.05), respectively. These DEGs are involved in several biological processes critical for the animal's growth and development, such as gene expression, protein synthesis, muscle development, new cuticle reconstruction, oxidation-reduction process and glycolytic process.
Conclusion: The data generated in this study is the first transcriptomic resource from the muscles of Chinese mitten crab, which would facilitate to characterize key molecular processes underlying crab muscle's growth and development during the molting cycles.