Greene, A. C. | Search bioRxiv

bioRxiv2025

Wildfire alters nitrogen cycling to increase soil emissions of nitric oxide (NO) and the heterogeneity of nitrous oxide (N2O) in California chaparral

Wildfires can disrupt ecosystem nitrogen (N) cycling by combusting vegetation biomass N and depositing ash that is rich in ammonium (NH4+) onto soils. Post-fire increases in NH4+ and soil physicochemical changes may promote further N loss by stimulating microbially-driven emissions of nitric oxide (NO) and nitrous oxide (N2O)--trace gases that alter air quality and climate. We hypothesized that soil NO and N2O emissions would increase with the flush of post-fire N availability and would be highest in soils that burned at medium severity due to the combination of high soil N availability and persistence of microbial activity. To test this, we established nine plots (6 burned; 3 unburned) and sampled soils seasonally over three years after wildfire in a chaparral shrubland in Southern California, USA. Wildfire significantly increased soil extractable NH4+ by an average of 10 {micro}g NH4+-N g soil-1, soil extractable NO3- by 8 {micro}g NO3--N, and soil pH by 0.5 units. Post-fire soil NO emissions significantly increased by an average 74 ng NO-N g-1 (cumulative 40-h incubations) over three years, with the highest emissions measured in year one from plots that burned at medium and high severities. No significant effects of burning were detectable for N2O emissions over three years (average {+/-} standard error; 224 {+/-} 107 ng N2O-N g-1 soil in burned plots and 30 {+/-} 17 ng N2O-N g-1 soil in unburned plots); however, we observed high fluxes only from soils that burned at medium and high severities (N2O > 3500 ng N2O-N g-1 soil). Isotopic characterization of N2O from high-emitting soils indicated contributions from diverse sources and increased N2O reduction to N2. Overall, the occurrence of high N2O fluxes and accelerated NO emissions post fire indicate wildfires interact with soil N cycling to promote burn-severity-sensitive gaseous N losses long after wildfires are extinguished.

ecology↗

bioRxiv2024

Yellow and oxidation-resistant derivatives of a monomeric superfolder GFP

Fluorescent proteins (FPs) are essential tools in biology. The utility of FPs depends on their brightness, photostability, efficient folding, monomeric state, and compatibility with different cellular environments. Despite the proliferation of available FPs, derivatives of the originally identified Aequorea victoria GFP often show superior behavior as fusion tags. We recently generated msGFP2, an optimized monomeric superfolder variant of A. victoria GFP. Here, we describe two derivatives of msGFP2. The monomeric variant msYFP2 is a yellow superfolder FP with high photostability. The monomeric variant moxGFP2 lacks cysteines but retains significant folding stability, so it works well in the lumen of the secretory pathway. These new FPs are useful for common imaging applications.

cell biology↗