Physiological and gene expression profiles of leg muscle provide insights into molting-dependent growth of Chinese mitten crab (Eriocheir sinensis)

Abstract

Molting is a common and periodic process in crustaceans, which make crustacean withdraw from intricate and old exoskeleton, and get an increased body weight after molting. However, the underlying molecular mechanism of internal impetus and physiological features of molting process which impact muscle growth and development is unclear. In this study, the osmotic pressure of hemolymph, histological section, moisture of walking leg muscle, and comparative transcriptome were conducted in Eriocheir sinensis among different molting stages. Osmotic pressure and moisture analysis revealed that a hypertonic environment arose at pre-molt stage, which may induce the initiation of water uptake. The explosive water uptake mainly took place at post-molt stage leading to dramatic weight gain. Comparative transcriptome analysis revealed a total of 2264 differentially expressed genes between pre-molt and post-molt, including 1387 up-regulated genes at pre-molt stage, which negatively regulate muscle growth and development (eg. POMT, NEB2, ZCI2A, and MSTN), and 877 up-regulated genes at post-molt stage which are associated with positive regulation in muscle growth and proliferation (eg. TITIN, mTOR, XRCC, and ICCR). GO enrichment analysis further illustrated that many genes act on proteolysis, ion transport, and transmembrane transport which help with the maintenance of a hypertonic environment in the hemolymph at pre-molt stage. Meanwhile, differentially expressed genes at post-molt stage were enriched in DNA repair and DNA replication indicating the activated muscle growth and development process. Our results provided novel insights into the genetic interplay of osmoregulation, water uptake, and muscle development in E. sinensis during molting.

Keywords

• Eriocheir sinensis
• Water uptake
• Osmotic pressure
• Moisture
• Comparative transcriptome