Deletion of Plasma Membrane Malate Transporters Increased Lipid Accumulation in the Oleaginous Fungus Mucor circinelloides WJ11.

Malate as an important intermediate metabolite, its subcellular location, and concentration have a significant impact on fungal lipid metabolism. Previous studies showed that the mitochondrial malate transporter plays an important role in lipid accumulation in Mucor circinelloides by manipulating intracellular malate concentration. However, the role of plasma membrane malate transporters in oleaginous fungi remains unexplored. Therefore, in this work, two plasma membrane malate transporters "2-oxoglutarate:malate antiporters" (named SoDIT-a and SoDIT-b) of M. circinelloides WJ11 were deleted, and the consequences in growth capacity, lipid accumulation, and metabolism were analyzed. The results showed that deletion of sodit-a or/and sodit-b reduced the extracellular malate, confirming that the products of both genes participate in malate transportation. In parallel, the lipid contents in mutants increased approximately 10-40% higher than that in the control strain, suggesting that the defect in plasma membrane malate transport results in an increase of malate available for lipid biosynthesis. Furthermore, transcriptional analysis showed that the expression levels of multiple key genes involved in the lipid biosynthesis were also increased in the knockout mutants. To the best of our knowledge, this is the first report that demonstrated the association between plasma membrane malate transporters and lipid accumulation in M. circinelloides.

Effect of Ca/P ratio on the structural and corrosion properties of biomimetic CaP coatings on ZK60 magnesium alloy.

Magnesium and its alloys have attracted much attention as metallic biodegradable implants for their excellent biocompatibility and mechanical properties. However, magnesium has a poor corrosion resistance, causing its rapid degrading in vivo via an electrochemical reaction, which has become a major obstacle to their applications in implants. In this work, CaP coating was successfully coated on the ZK60 magnesium alloys by a simple hydrothermal deposition method. The mechanisms of the hydrothermal reactions of CaP coatings on Mg substrate are described in details. The effect of Ca/P ratio in the hydrothermal solution on the phase composition, microstructure and biodegradation properties of CaP coatings on ZK60 alloys was investigated by varying the Ca/P ratio from 0.83 to 4.18. The morphology of the CaP coating changed significantly with the Ca/P ratio. Biodegradation behavior of the CaP coating magnesium was characterized by anodic polarization and immersion tests in a simulated body fluid. It is revealed that the corrosion resistance of ZK60 magnesium alloy was greatly improved with the biomimetic CaP coatings, and the ZK60 alloy with CaP coating deposited at Ca/P ratio of 1.67 has the best corrosion resistance, which indicates that the CaP coatings are promising for improving the biodegradation properties of Mg-based orthopedic implants and devices.

[TLR-4 involvement in pyroptosis of mice with pulmonary inflammation infected by Actinobacillus pleuropneumoniae].

OBJECTIVE: Pyroptosis is a caspase-1 dependent programmed cell death and involves pathogenesis of infectious diseases by releasing many pro-inflammatory cytokines to induced inflammation. TLR-4 plays an important role in mediating pathogenesis of some infectious diseases. In this study, we detected the expression of TLR-4 and some molecules (e. g caspase-1, TNF-α, IL-1ß, IL-6, IL-18 ) related with pyroptosis to determine its involvement and mechanisms of pulmonary inflammation in mice infected by A. pleuropneumoniae. METHODS: Mice were intranasally infected by A. pleuropneumoniae and killed 48 hours post infection. Pulmonary gross lesion and histological pathology by H-E were observed. Expression levels of caspase-1 , caspase-3, TNF-α, IL-1ß, IL-6, IL-18, and TLR-4 in lung of mice were detected by RT-PCR and qPCR. RESULTS: Serious pulmonary hemorrhage and inflammation in infected mice were observed. Expression levels of caspase-1, caspase-3, TNF-α, IL-1ß, IL-6, IL-18 and TLR-4 increased, and expression levels of caspase-3 were not changed in lung of infected mice. CONCLUSION: TLR-4 might be involved in pulmonary inflammation of mice infected by A. pleuropneumoniae. After induced by activated TLR-4 some cells in this lesion expressed pro-inflammatory cytokines. These cytokines would induce pulmonary inflammation. This lesion might involve pyroptosis with caspase-1 expression.