Pseudopleuronectes yokohamae is an important marine economic fish species in northern China and is vulnerable to various pathogens during the breeding process.To investigate the viru-lence of Edwardsiella tarda on Pseudopleuronectes yokohamae and elucidate the role of miRNAs in their interaction,we conducted pathological analyses on various tissues of Pseudopleuronectes yokohamae larvae pre-and post-infection with Edwardsiella tarda.Subsequently,Illumina high-throughput sequencing was employed to identify and functionally characterize differentially ex-pressed miRNAs in liver and kidney tissues.The results demonstrated that infection with Ed-wardsiella tarda led to ulceration,hemorrhaging,significant hepatomegaly,nephromegaly,and as-cites in the abdominal cavity.Histopathological examination revealed swollen hepatocytes with vac-uolization,minor blood cell infiltration,and enlarged renal corpuscles with signs of cellular lysis.miRNA sequencing analysis indicated that 24 miRNAs were significantly upregulated and 45 miR-NAs were significantly downregulated in the liver,while in the kidney,6 miRNAs were upregulat-ed and 58 were downregulated following infection.Functional enrichment analysis revealed signifi-cant enrichment of differentially expressed miRNAs in Toll and IMD signaling pathways,HIF-1 signaling pathway,Rap1 signaling pathway,MAPK signaling pathway,and Apelin signaling path-way.These findings suggest the involvement of these miRNAs in host metabolism,pathogen rec-ognition,and immune response in the interaction between Pseudopleuronectes yokohamae and Ed-wardsiella tarda.This research lays a foundation for elucidating the mechanisms underlying bacte-rial disease susceptibility and resistance in Pseudopleuronectes yokohamae.

Pseudopleuronectes yokohamae is an important marine economic fish species in northern China and is vulnerable to various pathogens during the breeding process.To investigate the viru-lence of Edwardsiella tarda on Pseudopleuronectes yokohamae and elucidate the role of miRNAs in their interaction,we conducted pathological analyses on various tissues of Pseudopleuronectes yokohamae larvae pre-and post-infection with Edwardsiella tarda.Subsequently,Illumina high-throughput sequencing was employed to identify and functionally characterize differentially ex-pressed miRNAs in liver and kidney tissues.The results demonstrated that infection with Ed-wardsiella tarda led to ulceration,hemorrhaging,significant hepatomegaly,nephromegaly,and as-cites in the abdominal cavity.Histopathological examination revealed swollen hepatocytes with vac-uolization,minor blood cell infiltration,and enlarged renal corpuscles with signs of cellular lysis.miRNA sequencing analysis indicated that 24 miRNAs were significantly upregulated and 45 miR-NAs were significantly downregulated in the liver,while in the kidney,6 miRNAs were upregulat-ed and 58 were downregulated following infection.Functional enrichment analysis revealed signifi-cant enrichment of differentially expressed miRNAs in Toll and IMD signaling pathways,HIF-1 signaling pathway,Rap1 signaling pathway,MAPK signaling pathway,and Apelin signaling path-way.These findings suggest the involvement of these miRNAs in host metabolism,pathogen rec-ognition,and immune response in the interaction between Pseudopleuronectes yokohamae and Ed-wardsiella tarda.This research lays a foundation for elucidating the mechanisms underlying bacte-rial disease susceptibility and resistance in Pseudopleuronectes yokohamae.