Single-cell transcriptome, phagocytic activity and immunohistochemical analysis of crucian carp (Carassius auratus) in response to Rahnella aquatilis infection

Multi-omics analysis of miRNA-mediated intestinal microflora changes in crucian carp Carassius auratus infected with Rahnella aquatilis

“…Very recently, the integration of miRNA and mRNA analyses revealed the potential roles of the identified known miRNAs that are involved in the regulation of glycometabolism-related pathways in common carp Cyprinus carpio ( 26 ). Previous studies revealed that mucosal immune responses in crucian carp include the TLR, NOD-like receptor (NLR), and complement and coagulation pathways ( 20 , 27 , 28 ). However, there are few transcriptome analyses of miRNAs (e.g., miR-17, miR-26a, miR-144, and miR-146a) related to the involvement in the mucosal immune response of miRNA and the intestinal microflora regulation function in crucian carp ( 20 ).…”

“…Recently, intensive culture of commercial fish such as crucian carp has increased the severity and frequency of diseases in China ( 27 , 29 – 32 ). Crucian carp have fast growth rates, high nutritional quality, and good palatability and have become an important freshwater economically farmed fish in China ( 33 , 34 ).…”

“…Crucian carp have fast growth rates, high nutritional quality, and good palatability and have become an important freshwater economically farmed fish in China ( 33 , 34 ). In recent years, crucian carp were infected with bacteria and caused diseases more frequently due to the high-density culture ( 27 , 30 – 32 ). More recently, R. aquatilis has been recognized as an emerging bacterial pathogen, and more and more infections were detected in fish, which have demonstrated that R. aquatilis caused clinical enteritis and septicemia ( 30 – 32 , 35 , 36 ), and frequent outbreaks of its infections have caused severe economic losses to fish farmers in China ( 27 , 30 – 32 , 36 , 37 ).…”

“…In recent years, crucian carp were infected with bacteria and caused diseases more frequently due to the high-density culture ( 27 , 30 – 32 ). More recently, R. aquatilis has been recognized as an emerging bacterial pathogen, and more and more infections were detected in fish, which have demonstrated that R. aquatilis caused clinical enteritis and septicemia ( 30 – 32 , 35 , 36 ), and frequent outbreaks of its infections have caused severe economic losses to fish farmers in China ( 27 , 30 – 32 , 36 , 37 ). The innate immune system involved different signaling pathways that were regulated by complex mechanisms, of which the mucosal immunity (i.e., intestine, gills, and skin) was the host’s first line of defense against pathogen infection ( 38 – 41 ).…”

“…Bacterial diseases, especially bacterial enteritis, are a major problem in crucian carp Carassius auratus , which has caused large economic losses ( 3 ). In previous studies by our group, a new pathogenic R. aquatilis KCL-5 strain was isolated from diseased crucian carp ( 27 , 30 – 32 ). Subsequently, we detailedly studied the mucosal immunity (skin and gill) response of bacterial septicemia of crucian carp through multi-omics analysis ( 20 , 28 , 41 ).…”