Apoptosis of host cells plays an important role in modulating the pathogenesis of many infectious diseases.It has been reported that Leptospira interrogans, the causal agent of leptospirosis, induces apoptosis in macrophages and hepatocytes. However, the molecular mechanisms responsible for host cell death remained largely unknown. Here we demonstrate that L. interrogans induced apoptosis in a macrophage-like cell line, J774A.1, and primary murine macrophages in a time-and dose-dependent manner. Apoptosis was associated with the activation of cysteine aspartic acid-specific proteases (caspase-3, caspase-6, and caspase-8), the increased expression of Fas-associated death domain (FADD), and the cleavage of the caspase substrates poly(ADP-ribose) polymerase (PARP) and nuclear lamina protein (lamin A and lamin C). Caspase-9 was activated to a lesser extent, whereas no release of cytochrome c from mitochondria was detectable. Inhibition of caspase-8 impaired L. interrogans-induced caspase-3 and -6 activation, as well as PARP and lamin A/C cleavage and apoptosis, suggesting that apoptosis is initiated via caspase-8 activation. Furthermore, caspase-3 was required for the activation of caspase-6 and seemed to be involved in caspase-9 activation through a feedback amplification loop. These data indicate that L. interrogans-induced apoptosis in macrophages is mediated by caspase-3 and -6 activation through a FADD-caspase-8-dependent pathway, independently of mitochondrial cytochrome c-caspase-9-dependent signaling.
The development of semiconductor photoanodes is of great practical interest for the realization of photoelectrochemical (PEC) water splitting. Herein, MXene quantum dots (MQD) were grafted on a BiVO 4 substrate, then a MoO x layer by combining an ultrathin oxyhydroxide oxygen evolution cocatalyst (OEC) was constructed as an integrated photoanode. The OEC/ MoO x /MQD/BiVO 4 array not only achieves a current density of 5.85 mA cm À 2 at 1.23 V versus a reversible hydrogen electrode (vs. RHE), but also enhances photostability. From electrochemical analysis and density functional theory calculations, high PEC performance is ascribed to the incorporation of MoO x /MQD as hole transfer layers, retarding charge recombination, promoting hole transfer and accelerating water splitting kinetics. This proof-of-principle work not only demonstrates the potential utilization of hole transfer layers, but also sheds light on rational design and fabrication of integrated photoanodes for feasible solar energy conversion.
Biomass-derived acid-resistant Co@NC is used as a bifunctional catalyst for biomass-derived FA dehydrogenation and biomass-derived vanillin hydrodeoxygenation.
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