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The CXC chemokine receptors (CXCRs) are members of the seven transmembrane (7‐TM) G‐protein‐coupled receptor superfamily that involves innate and adaptive immune systems. In this study, CXCR3a and CXCR3b from Nile tilapia (Oreochromis niloticus) were cloned and identified, designated as OnCXCR3a and OnCXCR3b. The open reading frames of OnCXCR3a and OnCXCR3b were 1074 and 1080 bp, encoding the predicted proteins of 357 and 359 amino acids, respectively. Multiple alignment analysis of OnCXCR3a‐ and OnCXCR3b‐deduced protein sequences with the mammalian and bird sequences indicated the presence of typical structural features of chemokine receptors, including a 7‐TM domain and conserved motifs. Quantitative real‐time PCR analysis revealed that OnCXCR3a and OnCXCR3b were constitutively expressed in a wide range of tissues. When stimulated with Streptococcus agalactiae, Aeromonas hydrophila, polyinosinic:polycytidylic acid and lipopolysaccharide in vivo or in vitro on leukocytes, the mRNA levels of OnCXCR3a and OnCXCR3b were significantly upregulated. Overall, these results indicated that OnCXCR3s might be involved in host immune responses in Nile tilapia. [ABSTRACT FROM AUTHOR]

The gas-phase propylene epoxidation for noble metal system as a green process has confronted a great challenging task in metal utilization and stability. In this work, we realize the enhancement of Au capture efficiency and high-dispersed Au nanoparticles by supports modification and interfacial regulation to construct Au–Fe–TS-1 interface coupling structure. The Au capture efficiency of the optimum catalyst arrived at 69% and it displayed a 7.3% C3H6 conversion with a PO selectivity of 89.9%, giving a H2 efficiency of about 25.7%. Then some typical characterizations systematically elucidate that Fe is not only incorporated into TS-1 framework and captures Au species with high dispersion and stability, but also inhibits the losing of Ti species. Furthermore, Fe-modified catalysts change the property of Au active site and maintain lower apparent activation energy. This report may provide a new strategy to design advanced catalysts for enhancing metal utilization efficiency by the construction of interface coupling structure. [ABSTRACT FROM AUTHOR]

The gas-phase propylene epoxidation for noble metal system as a green process has confronted a great challenging task in metal utilization and stability. In this work, we realize the enhancement of Au capture efficiency and high-dispersed Au nanoparticles by supports modification and interfacial regulation to construct Au–Fe–TS-1 interface coupling structure. The Au capture efficiency of the optimum catalyst arrived at 69% and it displayed a 7.3% C3H6 conversion with a PO selectivity of 89.9%, giving a H2 efficiency of about 25.7%. Then some typical characterizations systematically elucidate that Fe is not only incorporated into TS-1 framework and captures Au species with high dispersion and stability, but also inhibits the losing of Ti species. Furthermore, Fe-modified catalysts change the property of Au active site and maintain lower apparent activation energy. This report may provide a new strategy to design advanced catalysts for enhancing metal utilization efficiency by the construction of interface coupling structure. [ABSTRACT FROM AUTHOR]

We have successfully constructed electron‐rich Bi and Mo species with a highly degree of dispersion and hierarchical pore texture by introducing Cu/SiO2 as a bi‐functional modifier for MoO3‐Bi2SiO5/SiO2. Characterization techniques suggest the Bi species was modified by Cu with a Bi‐O−Cu coordination structure, and copper species became a capture site for Mo species that improved the dispersity and interface bonding strength of Mo and regulated electron structure of Bi and Mo species, synchronously. Additionally, the hierarchical pore was constructed by compositing Cu/SiO2 with Bi2SiO5/SiO2 support. [ABSTRACT FROM AUTHOR]

We have successfully constructed electron‐rich Bi and Mo species with a highly degree of dispersion and hierarchical pore texture by introducing Cu/SiO2 as a bi‐functional modifier for MoO3‐Bi2SiO5/SiO2. Characterization techniques suggest the Bi species was modified by Cu with a Bi‐O−Cu coordination structure, and copper species became a capture site for Mo species that improved the dispersity and interface bonding strength of Mo and regulated electron structure of Bi and Mo species, synchronously. Additionally, the hierarchical pore was constructed by compositing Cu/SiO2 with Bi2SiO5/SiO2 support. [ABSTRACT FROM AUTHOR]

Plasma cells are terminally differentiated antibody-secreting B lymphocytes that contribute to humoral immunity by producing large numbers of antibodies. Increasing evidence suggests that teleost fish B cells share certain characteristics with mammalian B1 B cells, including antibody-secreting, phagocytic, and antigen-presenting capacities. However, the difference between mature B cells and plasma cells remains unclear. In this study, we found that, based on their light-scattering characteristics, tilapia anterior kidney (AK) leukocytes can be categorized into two IgM + B-cell subsets: the lymphoid (L) gate and granulocyte-monocyte/macrophage (G-M) subsets. G-M gate cells are more numerous than L-gate cells and have higher mean fluorescence, but lower forward scatter and side scatter. We analyzed the morphological and ultrastructural features of sorted IgM + cells and found that L-gate IgM + cells have a high nucleus-cytoplasm ratio and lymphocyte-like morphology, whereas G-M gate IgM + cells have a small nucleus, more abundant endoplasmic reticulum, and a larger number of mitochondria, and have a plasma cell-like or macrophage-like morphology. To further characterize the cell types, we examined the specific patterns of expression of B-cell- and T-cell-related genes. We found that B-cell-specific genes were expressed by both L-gate and G-M gate IgM + cells, and that G-M gate IgM + cells secreted extremely high levels of IgM. However, T-cell-related genes were highly expressed only in L-gate IgM - cells. These results suggest that G-M gate IgM + cells are similar to plasma-like cells, with high antibody-secreting capacity. Given that G-M gate cells include the granulocyte, monocyte, and macrophage cell types, but not B cells, monocyte/macrophage markers were used to investigate the cell types further. A macrophage receptor with a collagenous structure was frequently observed, and macrophage-expressed gene-1 was highly expressed, in the G-M gate IgM + cells. Phagocytic capacity, as determined by ingestion of beads or bacteria, was significantly higher in G-M gate IgM + cells than in L-gate IgM + cells, as was antigen-processing capacity. Our findings show that tilapia AK leukocytes can be divided into two IgM + B-cell subsets and that G-M gate IgM + cells resemble plasma-like cells, having high antibody-secreting, phagocytic, and antigen-presenting capacities. Thus, this study increases our understanding of the functions of teleost fish plasma-like cells., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Wu, Yang, Gao, Li and Ye.)

Present investigation was carried out to study toxicological damages of copper exposure and mitigation of its adverse effects with β-glucan administration in IgM + B cells which processes multiple roles similar to macrophages in Nile tilapia (Oreochromis niloticus). IgM + B cells were pretreated with β-glucan (25 μg/mL) for 24 h before exposed to cupric oxide nanoparticles (CuO NPs) or cupric chloride (Cu ions) at the doses of 0, 5, 10, and 20 μg/mL for 24 h, respectively. Our results demonstrated that β-glucan increased reduced glutathione (GSH) to against oxidative damage from CuO NPs and Cu ions exposure in IgM + B cells. The apoptosis process through mitochondrial signaling pathway was depressed in IgM + B cells since the mitochondrial membrane potential (ΔΨm) was protected from copper exposure by β-glucan treatment. Furthermore, the inhibition on phagocytic abilities of IgM + B cells caused by copper exposure could be enhanced with β-glucan treatment via evaluation of microspheres and bioparticles uptake and LPS-induced NO production. Importantly, β-glucan might participate in immunomodulation in IgM + B cells through B cell antigen receptor (BCR) to suppress toxicological effect derived from copper exposure. Taken together, this study provides more information on the toxicological damages in IgM + B cells upon copper exposure and explains the molecular mechanism to reverse adverse effects caused by copper exposure with β-glucan administration., (Copyright © 2022. Published by Elsevier Ltd.)

Copper (Cu), as an essential micronutrient in human and animal metabolism, easily spreads and excessively accumulates in rearing water, which make it more susceptible to fish farms and threatens the health of aquatic animals. In this issue, the protective effect of vitamin C against oxidative damage caused by copper exposure was studied in monocytes/macrophages (MO/MФ) and IgM + B cells of Nile tilapia (Oreochromis niloticus), the cell types possessing phagocytic activities. The significant increase of ROS level and up-regulation of proinflammatory factors accompanied by depletion of GSH and down-regulation of antioxidative molecules in MO/MФ and IgM + B cells, when stressed with CuO NPs or Cu ions, indicated the induction of oxidative damage due to the toxicological effects with copper exposure. Copper induced cell apoptosis through mitochondrial-dependent pathway in these two cell populations was demonstrated with disruption of mitochondrial membrane potential (ΔΨm) and activation of apoptosis factor. Furthermore, the phagocytic abilities for microspheres and bioparticle uptake significantly decreased in these two cell populations upon CuO NPs or Cu ions; meanwhile, antigen presentation of MO/MФ and antibody production of IgM + B cells were also inhibited. However, vitamin C supplementation reversed all these biochemical indices, as well as cell apoptosis and phagocytic abilities in MO/MФ and IgM + B cells that were induced by CuO NPs or Cu ions. In conclusion, these results revealed that vitamin C exerts cytoprotective effects against oxidative damage through its antioxidant properties and may be of therapeutic use in preventing toxicological effects caused by copper exposure., (Copyright © 2022. Published by Elsevier B.V.)