Search

This study aimed to investigate the efficiency of the secondary metabolites (SMs) produced by a co-culture of Trichoderma harzianum TW21990 and Burkholderia vietnamiensis B418 in the control of Colletotrichum siamense CM9. A fermentation filtrate of B418 + TW21990 co-culture (BT21) produced a notable increase in the inhibition rate of CM9 compared to those of TW21990 and B418 monocultures, which reached 91.40% and 80.46% on PDA plates and strawberry leaves, respectively. The BT21 fermentation broth exhibited high control efficiency on strawberry root rot of 68.95% in a pot experiment, which was higher than that in the monocultures and fluazinam treatment. In addition, BT21 treatment promoted strawberry root development, improved antioxidative enzyme activities in the leaves and roots, and enhanced the total chlorophyll content of the strawberry leaves. UHPLC-MS/MS analysis of fermentation filtrates was performed to elucidate SM variations, revealing 478 and 795 metabolites in BT21 co-culture in positive and negative ion modes, respectively. The metabolomic profiles suggested abundant SMs with antagonistic capabilities and growth-promoting effects: 3-(propan-2-yl)-octahydropyrrolo [1,2-a]pyrazine-1,4-dione (cyclo(L-Pro-L-Val)), 3-[(4-hydroxyphenyl)methyl]-octahydropyrrolo[1,2-a]pyrazine-1,4-dione (cyclo(L-Pro-L-Tyr)), 3-indoleacetic acid (IAA), 2-hydroxycinnamic acid, 4-aminobutyric acid (GABA), bafilomycin B1, and DL-indole-3-lactic acid (ILA) were significantly enhanced in the co-culture. Overall, this study demonstrates that a co-culture strategy is efficient for inducing bioactive SMs in T. harzianum and B. vietnamiensis, which could be exploited as a novel approach for developing biocontrol consortia.

The acceleration of the nitrogen cycle and the nitrogen excess observed in some coastal waters has increased interest into understanding the biochemical and molecular basis of nitrogen metabolism in various microorganisms. To investigate nitrogen metabolism of a novel heterotrophic nitrification and aerobic denitrification bacterium Klebsiella aerogenes strain (B23) under nitrogen-rich conditions, we conducted physiological and transcriptomic high-throughput sequencing analyses on strain B23 cultured on potassium nitrate–free or potassium nitrate–rich media. Overall, K. aerogenes B23 assimilated 82.47% of the nitrate present into cellular nitrogen. Further, 1,195 differentially expressed genes were observed between K. aerogenes B23 cultured on potassium nitrate–free media and those cultured on potassium nitrate-rich media. Gene annotation and metabolic pathway analysis of the transcriptome were performed using a series of bioinformatics tools, including Gene Ontology, Kyoto Encyclopedia of Genes and Genomes, and Non-Redundant Protein Database annotation. Accordingly, the nitrogen metabolism pathway of K. aerogenes B23 was analyzed; overall, 39 genes were determined to be involved in this pathway. Differential expression analysis of the genes involved in the nitrogen metabolism pathway demonstrated that, compared to the control, FNR, NarK/14945, fdx, gshA, proB, proA, gapA, argH, artQ, artJ, artM, ArgR, GAT1, prmB, pyrG, glnS, and Ca1 were significantly upregulated in the nitrogen-treated K. aerogenes B23; these genes have been established to be involved in the regulation of nitrate, arginine, glutamate, and ammonia assimilation. Further, norV, norR, and narI were also upregulated in nitrogen-treated K. aerogenes B23; these genes are involved in the regulation of NO metabolism. These differential expression results are important for understanding the regulation process of key nitrogen metabolism enzyme genes in K. aerogenes B23. Therefore, this study establishes a solid foundation for further research into the expression regulation patterns of nitrogen metabolism–associated genes in K. aerogenes B23 under nitrogen-rich conditions; moreover, this research provides essential insight into how K. aerogenes B23 utilizes nutritional elements.

Relatlimab is a type of human immunoglobulin G4 monoclonal blocking antibody. It is the world’s first Lymphocyte-Activation Gene-3 (LAG-3) inhibitor and the third immune checkpoint inhibitor with clinical application, following PD-1 and CTLA-4. Relatlimab can bind to the LAG-3 receptor which blocks the interaction between LAG-3 and its ligand to reduce LAG-3 pathway-mediated immunosuppression and promote T-cell proliferation, inducing tumor cell death. On 18 March 2022, the U.S. FDA approved the fixed-dose combination of relatlimab developed by Bristol Myers Squibb with nivolumab, under the brand name Opdualag for the treatment of unresectable or metastatic melanoma in adult and pediatric patients aged 12 and older. This study comprehensively describes the mechanism of action and clinical trials of relatlimab and a brief overview of immune checkpoint drugs currently used for the treatment of melanoma.

BackgroundMitochondrial dynamin-related protein 1 (DRP1) regulates mitochondrial division and plays an important role in maintaining hepatocyte function. However, the role of DRP1 in cadmium exposure-induced maternal liver damage in pregnant mice remains unclear. ObjectiveTo investigate the role and mechanism of DRP1 in maternal liver damage induced by cadmium exposure during pregnancy.MethodsThis study consisted of animal experiments and cell experiments. (1) Animal experiments. Mice at 14 days of gestation were randomly divided into three groups: a control group, a low-dose cadmium group (LCd group: 2.5 mg·kg−1), and a high-dose cadmium group (HCd group: 5 mg·kg−1). The pregnant mice were intraperitoneally injected with cadmium chloride (CdCl2) for 6 and 24 h in the next morning. The weights of pregnant mice, uterus, maternal liver, and fetal mice were recorded after sacrifice. Serum and liver of pregnant mice were collected, the levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in serum were detected, and liver tissues were stained with HE to observe changes in liver function and liver tissue structure. The expressions of oxidative phosphorylation-related proteins, hypoxia inducible factor-1α (HIF-1α) and DRP1 proteins in liver of pregnant mice were detected by Western blotting. (2) Cell experiments. AML12 cells were treated with CdCl2 (10 μmol·L−1) for 0, 2, 6, 12, and 24 h. The expressions of oxidative phosphorylation-related proteins, DRP1, and hypoxia inducible factor-1α (HIF-1α) proteins were detected. AML12 cells were pretreated with DRP1 inhibitor Mdivi-1 for 1 h and then CdCl2 (10 μmol·L−1) for 12 h to detect the expression of oxidative phosphorylation-related proteins and DRP1 protein. AML12 cells were treated with Hif-1α siRNA for 48 h and CdCl2 (10 μmol·L−1) for 6 h to detect the expression of HIF-1α and DRP1 proteins. ResultsThe results of animal experiments showed that cadmium exposure in pregnant mice had no effects on maternal liver weight and liver coefficient. However, the histomorphological changes and necrosis in hepatocytes were observed. Compared with the control group, the serum ALT and AST levels of pregnant mice in the LCd group were significantly increased after 6 h (P＜0.05), and the levels in the HCd group were significantly increased after 6 and 24 h (P＜0.05). Cadmium exposure during pregnancy significantly up-regulated HIF-1α and DRP1 expressions and down-regulated the expressions of oxidative phosphorylation-related proteins in maternal livers. In vitro cell experiments showed that the expressions of oxidative phosphorylation-related proteins was significantly decreased and HIF-1α and DRP1 protein expressions were significantly increased in the AML12 cells treated with CdCl2 for 6 h. Mdivi-1 pretreatment significantly antagonized the inhibitory effect of cadmium on the expressions of oxidative phosphorylation-related proteins in AML12 cells, while Hif-1α siRNA pretreatment significantly antagonized the up-regulative effect of cadmium on DRP1 expression in AML12 cells. ConclusionCadmium exposure in pregnant mice may up-regulate DRP1 expression by activating HIF-1α signaling, then inhibit oxidative phosphorylation level of hepatic cells, and ultimately lead to maternal liver damage.