Hapten-antibody complexes prepared at equivalence with the bivalent hapten bis-DNP-octamethylene-diamine and purified rabbit anti-DNP antibody were fractionated by Sepharose gel-filtration and the fractions examined by electron microscopy. Individual fractions were tested for whole-complement fixation and C1 fixation. Dimer forms did not show this type of biological activity, while fractions co...

The methodology, characteristics and application of the sensitive C(2)H(2)-C(2)H(4) assay for N(2) fixation by nitrogenase preparations and bacterial cultures in the laboratory and by legumes and free-living bacteria in situ is presented in this comprehensive report. This assay is based on the N(2)ase-catalyzed reduction of C(2)H(2) to C(2)H(4), gas chromatographic isolation of C(2)H(2) and C(2...

1.1 Biological nitrogen fixation and nitrogen nutrition in soybean plants Biological nitrogen fixation is one of the most important processes for ecosystem to access available N for all living organisms. Although N2 consists 78% of atmosphere, but the triple bond between two N atoms is very stable, and only a few group of prokaryotes can fix N2 to ammonia by the enzyme nitrogenase. Annual rate ...

Picoplankton populations dominate the planktonic community in surface oligotrophic ocean. Yet, their strategies acquisition and partitioning of organic inorganic sources nitrogen (N) carbon (C) are poorly described. Here, we measured at single-cell level uptake dissolved C (C-fixation), C-leucine, N-leucine, nitrate (NO3?), ammonium (NH4+), N-urea pigmented nonpigmented picoplankton groups six ...

Biochar application can influence soil nitrogen (N) cycle through biological and abiotic processes. However, studies on comprehensive examination of the effects biochar microbially mediated N-cycling processes (N mineralization, nitrification, denitrification, fixation) N fate (i.e., plant uptake, N2O emission, leaching) are warranted. Therefore, aim this study was to examine transformation, mi...

Marine primary producers adapted over eons to the changing chemistry of the oceans. Because a number of metalloenzymes are necessary for N assimilation, changes in the availability of transition metals posed a particular challenge to the supply of this critical nutrient that regulates marine biomass and productivity. Integrating recently developed geochemical, biochemical, and genetic evidence,...

In many environments, biological nitrogen fixation can alleviate nitrogen limitation. The high rates of N(2) fixation often observed in cyanobacterial mats suggest that N(2) fixation may be an important source of N. In this study, organisms expressing nifH were identified in a Lyngbya sp.- and two Microcoleus chthonoplastes-dominated cyanobacterial mats. The pattern of nitrogenase activity was ...

The Neotropics harbor some of the most diversified woody species in world, and to understand nutrient dynamics these ecosystems, it is crucial role plant taxonomy. In addition, biological nitrogen (N) fixation (BNF) tropics one key processes affecting global N cycle. Our objective was (i) investigate taxonomy sampling site as predictors foliar carbon (C) concentration its stable isotopes (i.e.,...

Biological di-nitrogen fixation (N(2)) is the dominant natural source of new nitrogen to land ecosystems. Phosphorus (P) is thought to limit N(2) fixation in many tropical soils, yet both molybdenum (Mo) and P are crucial for the nitrogenase reaction (which catalyzes N(2) conversion to ammonia) and cell growth. We have limited understanding of how and when fixation is constrained by these nutri...