Development of a spotted sea bass (Lateolabrax maculatus) bulbus arteriosus cell line and its application to fish virology and immunology.

The bulbus arteriosus tissue of teleosts, which is located at the forefront of the heart, is used to reduce the pulse pressure. In this study, we constructed a permanent cell line (LmAB) for the first time using bulbus arteriosus tissue from spotted sea bass (Lateolabrax maculatus). This cell line has been passaged more than 80 times. Currently, it can be subcultured in L-15 medium with 8 % fetal bovine serum added. The optimal fetal bovine serum concentration and culture temperature for LmAB cells at 62 passages are 20 % and 28 °C, respectively. This cell line consists predominantly of epithelial-like cells. We used 18S rRNA gene sequencing to confirm that LmAB cells originated from spotted sea bass. Karyotype analysis revealed that 43 % of LmAB cells in passage 63 had 48 chromosomes. Exogenous plasmid transfection revealed that LmAB cells can express the green fluorescent protein gene with a transfection efficiency of up to 40 %, indicating that these cells can be used for in vitro genetic research. LmAB cells showed susceptibility to nervous necrosis virus, largemouth bass ulcer syndrome virus, and infectious spleen and kidney necrosis virus, which results in severe cytopathic effects. PCR analysis verified that these viruses can replicate in LmAB cells, and analysis of cytoskeletal F-actin patterns verified that infected cells exhibit serious changes in their actin cytoskeleton. LmAB cells infected with these three viruses showed increased expressions of interferon signaling pathway genes (IFNd, IFNγ-rel, and ISG15), indicating that the host interferon signaling pathway participates in the antiviral immune response. These findings indicate that our newly developed LmAB cell line is a valuable resource for future research in genetics, virology, and immunology.

Type II interferons (IFN-γ and IFN-γrel) activate downstream genes through various potential receptor combinations to exert antiviral functions in spotted sea bass (Lateolabrax maculatus).

Type II interferons (IFNs) exert antiviral functions by binding to receptors and activating downstream signaling pathways. However, our understanding of the antiviral functions and the receptor complex model of type II IFNs in teleost fish remains limited. In this study, we determined the functions of type II IFNs (LmIFN-γ and LmIFN-γrel) in Lateolabrax maculatus and assessed their antiviral ability mediated by their combination with different cytokine receptor family B members (LmCRFB6, LmCRFB13, and LmCRFB17). After infection with largemouth bass ulcer syndrome virus (LBUSV), the expression levels of LmIFNs and LmCRFBs increased significantly in vitro and in vivo. Incubation or injection with LmIFNs-His activated the expressions of LmISG15, LmMx, and LmIRF1. LmIFN-γ and LmIFN-γrel both bound to the extracellular domains of the three CRFBs via Pull-down. Furthermore, LmIFN-γ combined with LmCRFB6, LmCRFB6+LmCRFB13, and LmCRFB6+LmCRFB13+LmCRFB17 and LmIFN-γrel combined with all combinations containing LmCRFB17 induced the transcription of downstream genes and reduced the number of LBUSV copies. Therefore, type II IFNs (LmIFN-γ and LmIFN-γrel) contribute to enhanced antiviral immunity in L. maculatus and that ligand-receptor combinations effectively suppress virus replication. These findings provide a reference for future studies of the signal transduction mechanism of type II IFNs in teleost fish.

Nitrogen addition stimulates soil aggregation and enhances carbon storage in terrestrial ecosystems of China: A meta-analysis.

China is experiencing a high level of atmospheric nitrogen (N) deposition, which greatly affects the soil carbon (C) dynamics in terrestrial ecosystems. Soil aggregation contributes to the stability of soil structure and to soil C sequestration. Although many studies have reported the effects of N enrichment on bulk soil C dynamics, the underlying mechanisms explaining how soil aggregates respond to N enrichment remain unclear. Here, we used a meta-analysis of data from 76N manipulation experiments in terrestrial ecosystems in China to assess the effects of N enrichment on soil aggregation and its sequestration of C. On average, N enrichment significantly increased the mean weight diameter of soil aggregates by 10%. The proportion of macroaggregates and silt-clay fraction were significantly increased (6%) and decreased (9%) by N enrichment, respectively. A greater response of macroaggregate C (+15%) than of bulk soil C (+5%) to N enrichment was detected across all ecosystems. However, N enrichment had minor effects on microaggregate C and silt-clay C. The magnitude of N enrichment effect on soil aggregation varied with ecosystem type and fertilization regime. Additionally, soil pH declined consistently and was correlated with soil aggregate C. Overall, our meta-analysis suggests that N enrichment promotes particulate organic C accumulation via increasing macroaggregate C and acidifying soils. In contrast, increases in soil aggregation could inhibit microbially mediated breakdown of soil organic matter, causing minimal change in mineral-associated organic C. Our findings highlight that atmospheric N deposition may enhance the formation of soil aggregates and their sequestration of C in terrestrial ecosystems in China.

Perceived social support and suicide ideation in Chinese rural left-behind children: A possible mediating role of depression.

OBJECTIVE: Psychologically distressed rural Chinese left-behind children (LBC) are at an increased risk of suicide. However, within this population, suicide and potential associated factors are severely under-discussed. This study primarily aims to explore the association between perceived social support and suicide ideation (SI), and to discuss the possible mediating role of depression in this association. METHOD: A population representative sampling survey was carried out with 2,898 LBC in southwest China. Relevant information was collected by means of face-to-face interviews. Binary and ordinal logistic regression models were employed to screen factors associated with perceived social support, depression and SI. Path analysis was applied to estimate the direct and indirect associations between social support and SI. RESULTS: Multivariate logistic regression models revealed that, among the four sources, perceived social support from relatives living together, friends, and parents, but not teachers, was inversely associated with SI in LBC. Moreover, depression and SI were strongly associated with each other: Compared with non-depressed LBC, depressed LBC were 6.76 (95%CI: 3.85, 11.87) times more likely to report prominent SI. Path analysis revealed that it is possible that the association between perceived social support and SI was almost entirely mediated by depression. CONCLUSIONS: Perceived social support from relatives living together, friends, and parents may be a protective factor against SI among rural Chinese LBC. Intervention strategies and measures that are targeted towards improving social support, especially cultivating closeness between LBC and their grandparents, could be effective in reducing SI in LBC.

Induced biotransformation of lead (II) by Enterobacter sp. in SO4-PO4-Cl solution.

Pb is a toxic heavy metal in contaminated soil and water, resulted from industrial activities, mine exploration, etc. Phosphate solubilizing bacteria are able to secrete organic acids and further to enhance the solubility of phosphates. Enterobacter. sp and geological fluorapatite (FAp) were applied to investigate the biotransformation of Pb2+ in solution with SO42-, PO43-, and Cl- species by ICP-OES, ATR-IR, XRD, and SEM. Enterobacter. sp can lower pH of the medium to ∼4. Meanwhile, >90% mobile Pb (declining from 1000 to 30 ppm) was immobilized via the combination of Enterobacter. sp and FAp. With the addition of FAp and Pb, pyromorphite was precipitated, but with relatively low content. In contrast, abundant anglesite mineral was formed in such weakly acidic system. These anglesite crystals can even absorb phosphates particles onto their surface. Additionally, geochemical modeling confirms the formation of anglesite and cerussite under weekly acidic and alkalic condition respectively, especially when H2PO4- concentration <10-8 mM. Furthermore, the presence of Cl- in solution leads to the formation of chloropyromorphite when H2PO4- concentration >10-12 mM, especially under neutral environment. This study explored the biotransformation of Pb in SO4-PO4-Cl aqueous system and hence provided guidance on bioremediation of Pb by bacteria and FAp.

Lead immobilization by geological fluorapatite and fungus Aspergillus niger.

Phosphate solubilizing fungi have high ability to secrete organic acids. In this study, fungus Aspergillus niger and geological fluorapatite were applied in lead remediation in aqueous solution. Formation and morphology of the lead minerals, e.g., pyromorphite and lead oxalate, were investigated by SEM, XRD, and ATR-IR. The total quantity of organic acids reached the maximum at the sixth day, which improved the concentration of soluble P up to ∼370mg/L from ∼0.4mg/L. The organic acids, especially the oxalic acid, enhance the solubility of fluorapatite significantly. The stable fluoropyromorphite [Pb5(PO4)3F] is precipitated with the elevated solubility of fluorapatite in the acidic environment. Furthermore, A. niger grows normally with the presence of lead cations. It is shown that >99% lead cations can be removed from the solution. However, immobilization caused by the precipitation of lead oxalate cannot be ignored if the fungus A. niger was cultured in the Pb solution. This study elucidates the mechanisms of lead immobilization by FAp and A. niger, and sheds its perspective in lead remediation, especially for high Pb concentration solution.