Ultrafine carbon nanoparticles activate inflammasome signaling and cell death in murine macrophages

Carbon black (CB) is the primary nanoparticulate component of air pollution from fossil fuel combustion. This work examines the cellular impact of ultrafine carbon (carbon black, CB) nanoparticles, that range in size down to 30 nm, upon murine macrophages. The size analysis of the carbon black nanoparticles was performed using atomic force microscopy (AFM) and transmission electron microscopy (TEM) techniques. RAW246.7 macrophage cells were exposed to CB doses ranging from 50 – 200 ug/ml in complete media. Analysis of cell survival over time revealed elevated rates of significant nuclear degradation and cell lifting after 48 hours of exposure, and in a dose dependent pattern. Live cell imaging of cells exposed to nanoparticles revealed a visible uptake of nanoparticles with accumulation over time. To assess inflammasome signaling, both caspase-1 activation and IL-1b production were observed in whole cell lysates. Caspase-1 activation was measured as the appearance of the active (cleaved) form of the protease appearing in immunoblot analysis. The analysis revealed significant activation of caspase-1 with 48-hour CB exposures at doses of 100-200 ug/ml. Similarly, levels of IL-1b were significantly induced by CB exposure, with maximal induction observed after a 48 hour exposure. Macrophage cells were assessed for accumulation of LC3, a marker for autophagosome vesicle accumulation. Immunoblot analysis revealed a significant accumulation of LC3 in response to CB exposure and in response to chloroquine, which inhibits autophagosome/lysosome fusion. Taken together, these results support a model in which CB exposure activates the inflammasome and disrupts autophagy in macrophages

Heteromeles arbutifolia associated Post-Fire Soil Microbiome Recovery and Respiration in a Chaparral Ecosystem

The purpose of this post-Woolsey Fire project is to examine the relationship between soil respiration in areas of cool burns and hot burns relative to individuals of Heteromeles Arbutifolia. It was hypothesized that the soil subjected to a cooler burn would have greater respiration rates due to increased survival of microorganisms compared to a hotter burn. An Li-6800 CO2 Flux Chamber was used to collect measurements for several replicates. Significance was detected in the “Day 3” data, with the soil respiration higher at the cool burn site. Temperature and soil flux also varied directly. In the future experiments including increasingly comprehensive data are recommended for further investigation on the success of soil respiration