During the winter of 2006 we measured nifH gene abundances, dinitrogen (N(2)) fixation rates and carbon fixation rates in the eastern tropical and sub-tropical North Atlantic Ocean. The dominant diazotrophic phylotypes were filamentous cyanobacteria, which may include Trichodesmium and Katagnymene, with up to 10(6) L(-1)nifH gene copies, unicellular group A cyanobacteria with up to 10(5) L(-1)n...

[1] Nutrients are supplied to the mixed layer of the open ocean by either atmospheric deposition or mixing from deeper waters, and these nutrients drive nitrogen and carbon fixation. To evaluate the importance of atmospheric deposition, we estimate marine nitrogen and carbon fixation from present‐day simulations of atmospheric deposition of nitrogen, phosphorus, and iron. These are compared wit...

The Calvin cycle is the initial pathway of photosynthetic carbon fixation, and several of its reaction steps are suggested to exert rate-limiting influence on the growth of higher plants. Plastid fructose 1,6-bisphosphate aldolase (aldolase, EC 4.1.2.13) is one of the nonregulated enzymes comprising the Calvin cycle and is predicted to have the potential to control photosynthetic carbon flux th...

The ratio of l*C : 13C was measured for Emiliania huxleyi cells grown under a range of irradiances in batch culture. Based on the assumption that HCO, was the carbon source, the maximum discrimination against 13C in the decalcified E. huxleyi cells was 24.6?& at 4.8 mol photons m-* d-l and the minimum discrimination was 17.9?& at 0.5 mol photons m-* d-l. In calcified cells, the range of 13C iso...

a sensitive and simple method for simultaneous preconcentration of trace heavy metal ions in some cerealand vegetable samples has been reported. the method is based on the adsorption of cu2+, fe3+, zn2+ and pb2+on 2-(2-nitro-phenylazo)-naphthalen-1-ol (npn) loaded on activated carbon (ac). the adsorbed metals onactivated carbon were eluted using 3 ml 4 mol l−1 nitric acid. the influences of the...

A sensitive and simple method for simultaneous preconcentration of trace heavy metal ions in some cerealand vegetable samples has been reported. The method is based on the adsorption of Cu2+, Fe3+, Zn2+ and Pb2+on 2-(2-nitro-phenylazo)-naphthalen-1-ol (NPN) loaded on activated carbon (AC). The adsorbed metals onactivated carbon were eluted using 3 ml 4 mol L−1 nitric acid. The influences of the...

A thermophilic cyanobacterium named Thermosynechococcus CL–1 (TCL–1) was cultivated in the flat plate photobioreactors under strong illumination with dense culture to examine the effects of nutrient concentrations on the biomass production, CO2 fixation, and the potential as the feedstock for bioethanol production. The results show that concentrations of Na, NO3, and CaCl2•2H2O, should be decre...

A mathematical model is developed which can be used to predict in vivo carbon isotope fractionations associated with carbon fixation in plants in terms of diffusion, CO(2) hydration, and carboxylation components. This model also permits calculation of internal CO(2) concentration for comparison with results of gas-exchange experiments. The isotope fractionations associated with carbon fixation ...

In vivo CO(2) fixation and in vitro phosphoenolpyruvate (PEP) carboxylase levels have been measured in lupin (Lupinus angustifolius L.) root nodules of various ages. Both activities were greater in nodule tissue than in either primary or secondary root tissue, and increased about 3-fold with the onset of N(2) fixation. PEP carboxylase activity was predominantly located in the bacteroid-containi...

BACKGROUND Although outdoor cultivation systems have been widely used for mass production of microalgae at a relatively low cost, there are still limited efforts on outdoor cultivation of carbohydrate-rich microalgae that were further used as feedstock for fermentative bioethanol production. In particular, the effects of seasonal changes on cell growth, CO2 fixation, and carbohydrate production...