Hepatopancreas immune response during molt cycle in the mud crab, Scylla paramamosain

Zhanning Xu,Shengkang Li,An Liu,Haihui Ye,Guizhong Wang

doi:10.1038/s41598-020-70139-2

Abstract

Molt is a critical developmental process in crustaceans. Recent studies have shown that the hepatopancreas is an important source of innate immune molecules, yet hepatopancreatic patterns of gene expression during the molt cycle which may underlie changes in immune mechanism are unknown. In this study, we performed Illumina sequencing for the hepatopancreas of the mud crab, Scylla paramamosain during molt cycle (pre-molt stage, post-molt stage, and inter-molt stage). A total of 44.55 Gb high-quality reads were obtained from the normalized cDNA of hepatopancreas. A total of 70,591 transcripts were assembled; 55,167 unigenes were identified. Transcriptomic comparison revealed 948 differentially expressed genes (DEGs) in the hepatopancreas from the three molt stages. We found that genes associated with immune response patterns changed in expression during the molt cycle. Antimicrobial peptide genes, inflammatory response genes, Toll signaling pathway factors, the phenoloxidase system, antioxidant enzymes, metal-binding proteins and other immune related genes are significantly up-regulated at the post-molt stage and inter-molt stage compared with the pre-molt stage, respectively. These genes are either not expressed or are expressed at low levels at the pre-molt stage. To our knowledge, this is the first systematic transcriptome analysis of genes capable of mobilizing a hepatopancreas immune response during the molt cycle in crustaceans, and this study will contribute to a better understanding of the hepatopancreas immune system and mud crab prophylactic immune mechanisms at the post-molt stage.

Highlights

In crustaceans, molt is an essential characteristic of the organism’s development; in order to grow, the animal must shed the old exoskeleton and construct a new one[1,2,3,4]
We found classifications of differentially expressed genes (DEGs) from Gene Ontology (GO), Clusters of Orthologous Groups (COG) and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases, which were involved in energy metabolism, growth development, osmotic pressure regulation and immune-related processes, this phenomenon demonstrated the major physiological changes happen during molt cycle in S. paramamosain
Compared with pre-molt stage, a large number of genes were up-regulated at the post-molt stage and the inter-molt stage, which further showed that the hepatopancreas is an important organ involved in molt cycle in S. paramamosain

Summary

Introduction

Molt is an essential characteristic of the organism’s development; in order to grow, the animal must shed the old exoskeleton and construct a new one[1,2,3,4]. Several researchers have described studies of molt susceptibility to pathogenic infections. Tumburu et al.[8] have shown that pesticide-virus interactions lead to increasingly higher susceptibility to acute toxicity at post-molt stage in L. vannamei. These studies indicate that crustaceans display susceptibility to pathogenic infections that vary during the molt cycle. At post-molt stage, in light of the soft body, lack of exoskeleton protection, and susceptibility to various pathogens, crustaceans may mobilize the body’s immune d efense[4]. Cond.[2] Inter-molt stage Pre-molt stage Post-molt stage immune responses in the hepatopancreas at three molt stages in the mud crab, S. paramamosain to understand the mechanism of immune defense during the crustacean molt cycle

Methods

Results

Conclusion