A mutant strain of Bradyrhizobium japonicum USDA110 lacking isocitrate dehydrogenase activity was created to determine whether this enzyme was required for symbiotic nitrogen fixation with soybean (Glycine max cv. Williams 82). The isocitrate dehydrogenase mutant, strain 5051, was constructed by insertion of a streptomycin resistance gene cassette. The mutant was devoid of isocitrate dehydrogen...

In the present study, carbon species including organic carbon (OC), elemental carbon (EC), and water-soluble organic carbon (WSOC) concentration in PM2.5 were assessed at an urban site of Tehran, Iran during March to June 2014. The PM2.5 samples were collected using an frmOMNITM Ambient Air Sampler. Thermal gravimetric analysis (TGA) was used to analyze OC and EC. The results showed that PM2.5 ...

Warm Neptuneand sub-Neptune-sized exoplanets in orbits smaller than Mercury’s are thought to have experienced extensive atmospheric evolution. Here we propose that a potential outcome of this atmospheric evolution is the formation of helium-dominated atmospheres. The hydrodynamic escape rates of Neptuneand sub-Neptune-sized exoplanets are comparable to the diffusion-limited escape rate of hydro...

The rates of inorganic carbon accumulation and carbon fixation in light by the unicellular cyanobacterim Coccohloris peniocystis have been determined. Cells incubated in the light in medium containing H14CO3- were rapidly separated from the medium by centrifugation through silicone oil into a strongly basic terminating solution. Samples of these inactivated cells were assayed to determine total...

Anthropogenic and biophysical contributions to increasing atmospheric CO2 growth rate and airborne fraction M. R. Raupach, J. G. Canadell, and C. Le Quéré Global Carbon Project, CSIRO Marine and Atmospheric Research, Canberra, Australia School of Environmental Sciences, University of East Anglia, Norwich, UK British Antarctic Survey, Cambridge, UK Received: 2 June 2008 – Accepted: 4 June 2008 –...

Increasing concentrations of atmospheric carbon dioxide are projected to lead to an increase in sea surface temperatures, potentially impacting marine ecosystems and biogeochemical cycling. Here we conducted an indoor mesocosm experiment with a natural plankton community taken from the Baltic Sea in summer. We induced a plankton bloom via nutrient addition and followed the dynamics of the diffe...

Measurements of the N2 produced by denitrification, a better understanding of non-canonical pathways for N2 production such as the anammox reaction, better appreciation of the multiple environments in which denitrification can occur (e.g. brine pockets in ice, within particles outside of suboxic water, etc.) suggest that it is unlikely that the oceanic denitrification rate is less than 400 Tg N...