Search

Introduction: In August 2023, hybrid sturgeons (Acipenser baerii♀×Acipenser schrenckii♂) cultured in Sichuan, China, showed infectious disease symptoms, including ulcers, liver and spleen nodules, and high mortality rates. Methods: Pathogenic bacteria were isolated from the liver of diseased sturgeons and analyzed for their phenotypic and molecular traits. Furthermore, iridovirus-specific TaqMan real-time PCR (RT-PCR) analyses were conducted. The histopathological characteristics were analyzed using paraffin sectioning and transmission electron microscopy (TEM). Transcriptome sequencing was performed to elucidate the impact of pathogen exposure and immune response profiles in infected sturgeon. Results: Pathogenic bacteria isolation and phylogenetic analyses of the 16S rRNA gene confirmed that the isolated bacteria clustered within the Nocardia seriolae group. The TaqMan RT-PCR assay was performed to detect the presence of white sturgeon iridovirus (WSIV), indicating a weakly positive signal. Histopathological examination revealed severe damage to various tissues, and a notable presence of bacteria was observed through acid-fast staining. Transmission electron microscopy analysis showed the presence of abundant bacteria and virus particles, indicating cellular invasion and subsequent damage. In summary, the disease in hybrid sturgeons was diagnosed as infection of N. seriolae and WSIV. To investigate the immune response of hybrid sturgeons to this infection, spleen transcriptomes were analyzed. Numerous immune-related genes and pathways, including the "Toll-like receptor", "B-cell receptor", and "T-cell receptor" signaling pathways, were altered in response to pathogenic threats. Significantly downregulated of key components of TCR and BCR signaling pathways, such as ZAP70 , BTK , and CD79A , suggested a temporary inhibition of these pathways critical for cellular immunity post-infection. Gene set enrichment analysis revealed significant suppression of the apoptosis signaling pathway and activation of autophagy and mitophagy signaling pathways following infection. Specifically, in the death receptor-mediated apoptosis signaling pathway, downregulation of TNFα , TRAIL , CASP6 , and CASP8 was observed, while several genes in the autophagy and mitophagy pathways showed upregulated expression post-infection. Discussion: We report the initial occurrence of N. seriolae infection in cultured sturgeons. These findings could provide a theoretical basis for diagnosing and preventing this disease, as well as enhance the understanding of host-pathogen interactions in fish. [ABSTRACT FROM AUTHOR]

Background/Objectives: Interferon regulatory factors (IRFs) are multifunctional transcription factors that play important roles in the transcriptional regulation of interferons and in the immune response to pathogens. Therefore, studying the interferon system in fish is highly relevant in the prevention and treatment of viral diseases. Methods: In this study, five IRF genes (IRF1, IRF4, IRF5, IRF7 and IRF9) were identified and characterized in Hucho bleekeri, and their expression profiles were determined after LPS and Poly(I:C) treatment. Results: These IRFs have typical DNA-binding domains and IRF-association domains. Amino acid sequence comparison revealed high homology between these IRFs and those of other vertebrates, with the highest homology being with other salmonid fish. Phylogenetic analysis revealed that these IRFs are divided into four subfamilies (IRF1, IRF3, IRF4 and IRF5), with both IRF4 and IRF9 belonging to the IRF4 subfamily. IRF genes were widely expressed in all of the tested tissues, with IRF1, IRF4 and IRF9 being highly expressed in the spleen and kidney and IRF5 and IRF7 highly expressed in the gonads. IRF1, IRF4 and IRF5 expression was induced at different time points post-LPS challenge. IRF7 and IRF9 expression in the spleen and head kidney was not significantly altered by LPS induction. Poly(I:C) treatment altered IRF expression more significantly than LPS treatment. Poly(I:C) significantly altered the spleen and head kidney expression of all five IRFs. Conclusions: These findings reveal the potential role of IRFs in the antiviral response of H. bleekeri and provide a reference for examining signal transduction pathways in the interferon system in fish. [ABSTRACT FROM AUTHOR]

Long-term coal mining activities have led to severe heavy metal pollution in the soil environment of coal mining areas, posing significant threats to both ecological environments and human health. In this study, surface soil samples were collected from the overlying soil of coal gangue and the surrounding areas of the Panyi coal mine in Huainan. The concentrations of Cd, Zn, Cu, Ni, and Pb elements were determined. A self-organizing map (SOM) and an absolute principal component score multiple linear regression (APCS-MLR) receptor model were employed for the quantitative analysis of the soil's heavy metal pollution sources and contributions. Additionally, this study focused on the analysis of the pathways of the relatively serious pollution of Cd. The results revealed that the average concentrations of heavy metals (Cd, Pb, Zn, Cu, Cr, and Ni) in the study area were 4.55, 0.59, 1.54, 0.69, 0.59, and 0.71 times the local soil background values, respectively. The concentrations of Cd and Zn exceeded the risk screening values at some sampling points, with exceedance rates of 44% and 8%, respectively, indicating a relatively serious Cd contamination. The sources of heavy metals in the soil in the study area were classified into four categories: mining activities, agricultural activities, weathering of natural matrices, and other unknown sources, with average contributions of 55.48 percent, 24.44 percent, 8.91 percent and 11.86 percent, respectively. Based on the spatial distribution of Cd, it was inferred that atmospheric deposition is one of the important pollution pathways of Cd in the study area. Cd profile distribution patterns and a surface water pollution survey showed that the farmland areas were affected by the irrigation water pathway to some extent. The vertical distribution of heavy metal content in the forest area showed a strong disorder, which was related to the absorption function of plant roots. The results of this study can help to improve the environmental management of heavy metal pollution so as to protect the ecological environment and human health. [ABSTRACT FROM AUTHOR]