The Role of microRNA-133 in Hemocyte Proliferation and Innate Immunity of Scylla paramamosain

Comparative transcriptomic and molecular biology analyses to explore potential immune responses to Vibrio parahaemolyticus challenge in Eriocheir sinensis

Vibrio parahaemolyticus is a significant pathogen affecting shrimp and crab farming, particularly strains carrying genes associated with acute hepatopancreatic necrosis syndrome. However, the immune response of Eriocheir sinensis to V. parahaemolyticus infection remains unclear. To address this knowledge gap, an experiment was conducted to establish a V. parahaemolyticus infection model. This model aimed to compare pathological damage and enzyme activity changes in E. sinensis hepatopancreas tissue at various infection time points, and to examine transcriptome changes in individuals exhibiting different clinical symptoms of infection. The results showed that intramuscular injection of 1.78 × 106 CFU/mL of V. parahaemolyticus for 24 hours resulted in a 50% mortality rate among the experimental animals. Pathological findings revealed that the infection led to a change in color of the hepatopancreas tissue from bright yellow to white, diffuse tissue cell distribution, and hepatopancreatic necrosis. Additionally, there was a significant increase in the activities of alanine aminotransferase and aspartate aminotransferase in the hepatopancreas (P < 0.01). Furthermore, the activities of superoxide dismutase, total antioxidant capacity, phenoloxidase, alkaline phosphatase, and acid phosphatase initially increased and then decreased. RNA-seq analysis revealed 11,662 differentially expressed genes compared to the susceptible group and control group, with 6,266 genes up-regulated and 5,396 genes down-regulated. When comparing the susceptible group to the disease-resistant group, 13,515 differentially expressed genes were identified, with 7,694 genes up-regulated and 5,821 genes down-regulated. Finally, comparison between the disease-resistant group and control group yielded 13,515 differentially expressed genes, with 7,631 genes up-regulated and 3,111 genes down-regulated. Differential gene enrichment analysis revealed pathways such as phagosomes, cancer pathways, proteoglycans in cancer, ribosomes, protein processing in the endoplasmic reticulum, starch and sucrose metabolism, and lysosome signaling pathways. Furthermore, 342 immune-related genes with differential expression were identified, primarily enriched in 22 pathways linked to cell signaling. These genes play a crucial role in defense against bacterial invasion and immune response regulation through various signaling pathways. Overall, this study provides valuable insights into the defense mechanisms and understanding of Chinese mitten crab immunity against bacterial infection by examining changes in mRNA, enzyme activity, and hepatopancreatic damage during infection.

Effects of Hizikia fusiforme polysaccharides on innate immunity and disease resistance of the mud crab Scylla paramamosain

In this study, we extracted the polysaccharides from Hizikia fusiforme (HFPs) and evaluated their effects on the immune response of the mud crab Scylla paramamosain. Compositional analysis revealed that HFPs were composed mainly of mannuronic acid (49.05%) and fucose (22.29%) as sulfated polysaccharides, and the sugar chain structure was β-type. These results indicated that HFPs have potential antioxidant and immunostimulation activity in vivo or in vitro assays. Through this research, we found that HFPs inhibited viral replication in white spot syndrome virus (WSSV)-infected crabs and promoted phagocytosis of Vibrio alginolyticus by hemocytes. Quantitative PCR results showed that HFPs up-regulated the expression levels of astakine, crustin, myosin, MCM7, STAT, TLR, JAK, CAP, and p53 in crab hemocytes. HFPs also promoted the activities of superoxide dismutase and acid phosphatase and the hemolymph antioxidant activities of crabs. HFPs maintained peroxidase activity after WSSV challenge, thereby providing protection against oxidative damage caused by the virus. HFPs also promoted apoptosis of hemocytes after WSSV infection. In addition, HFPs significantly enhanced the survival rate of WSSV-infected crabs. All results confirmed that HFPs improved the innate immunity of S. paramamosain by enhancing the expression of antimicrobial peptides, antioxidant enzyme activity, phagocytosis, and apoptosis. Therefore, HFPs have potential for use as therapeutic or preventive agents to regulate the innate immunity of mud crabs and protect them against microbial infection.

Expression Analysis of Moritella viscosa-Challenged Atlantic Salmon Identifies Disease-Responding Genes, MicroRNAs and Their Predicted Target Genes and Pathways

Moritella viscosa is a bacterial pathogen causing winter-ulcer disease in Atlantic salmon. The lesions on affected fish lead to increased mortality, decreased fish welfare, and inferior meat quality in farmed salmon. MicroRNAs (miRNAs) are small non-coding RNAs involved in post-transcriptional regulation by guiding the miRNA-induced silencing complex to specific mRNA transcripts (target genes). The goal of this study was to identify miRNAs responding to Moritella viscosa in salmon by investigating miRNA expression in the head-kidney and the muscle/skin from lesion sites caused by the pathogen. Protein coding gene expression was investigated by microarray analysis in the same materials. Seventeen differentially expressed guide-miRNAs (gDE-miRNAs) were identified in the head-kidney, and thirty-nine in lesion sites, while the microarray analysis reproduced the differential expression signature of several thousand genes known as infection-responsive. In silico target prediction and enrichment analysis suggested that the gDE-miRNAs were predicted to target genes involved in immune responses, hemostasis, angiogenesis, stress responses, metabolism, cell growth, and apoptosis. The majority of the conserved gDE-miRNAs (e.g., miR-125, miR-132, miR-146, miR-152, miR-155, miR-223 and miR-2188) are known as infection-responsive in other vertebrates. Collectively, the findings indicate that gDE-miRNAs are important post-transcriptional gene regulators of the host response to bacterial infection.