Phototrophic growth of the moderate halotolerant Rhodobacter capsulatus strain E1F1 in media containing up to 0.3 M NaCl was dependent on the nitrogen source used. In these media, increased growth rates and growth levels were observed in the presence of reduced nitrogen sources such as ammonium and amino acids. When the medium contained an oxidized nitrogen source (dinitrogen or nitrate), incre...

The specific activities of nitrate reductase, nitrite reductase, glutamine synthetase, glutamate synthase, and glutamate dehydrogenase were determined in intact protoplasts and intact chloroplasts from Chlamydomonas reinhardtii. After correction for contamination, the data were used to calculate the portion of each enzyme in the algal chloroplast. The chloroplast of C. reinhardtii contained all...

in order to study the effect of different levels of nitrogen and copper on yield and nutrients concentrations and nitrate in broccoli head, an experiment was conducted based on a factorial combinations of five levels of nitrogen (0, 100, 200, 300 and 400 kg/ha) and three levels of copper (0, 2.5 and 5 kg/ha) that were applied to soil as ammonium sulfate and copper sulfate respectively, in three...

We previously showed that the selective accumulation of phosphoenolpyruvate carboxylase (PEPC) in photosynthetically maturing maize (Zea mays L.) leaf cells induced by nitrate supply to nitrogen-starved plants was primarily a consequence of the level of its mRNA (B Sugiharto, K Miyata, H Nakamoto, H Sasakawa, T Sugiyama [1990] Plant Physiol 92: 963-969). To determine the specificity of inorgani...

We measured nitrogen transformations and loss following forest clearing in a relatively fertile tropical forest site. Nitrogen mineralization, nitrification, and amounts of ammonium and nitrate increased substantially in surface soils during the 6 mo following burning, then returned to background levels. The nitrogen content of microbial biomass declined to half its original value 6 mo after cl...

Two varieties of maize (Zea mays L.) grown in fields in black soils of northeast China were tested to study the dynamic changes of nitrogen metabolism and antioxidant enzyme activity in tassels of maize. Results showed that antioxidant enzyme activity in tassels of maize increased first and then decreased with the growing of maize, and reached peak value at shedding period. Pattern of proline w...

The discharge of excess nitrogen to streams and rivers poses an existential threat to both humans and ecosystems. A seminal study of headwater streams across the United States concluded that in-stream removal of nitrate is controlled primarily by stream chemistry and biology. Reanalysis of these data reveals that stream turbulence (in particular, turbulent mass transfer across the concentration...

Bacillus subtilis can use either nitrate or nitrite as a sole source of nitrogen. The isolation of the nasABCDEF genes of B. subtilis, which are required for nitrate/nitrite assimilation, is reported. The probable gene products include subunits of nitrate/nitrite reductases and an enzyme involved in the synthesis of siroheme, a cofactor for nitrite reductase.

Inorganic nitrogen is an essential nutrient for photosynthetic organisms. Its efficient use in nature involves adaptation of the organisms to the availability of the nitrogen supply, to changing environmental conditions, and to the provision of carbon and other nutrients. The unicellular alga Chlamydomonas provides a useful model to identify not only each of the components participating in the ...

BACKGROUND Presently, health costs associated with nitrate in drinking water are uncertain and not quantified. This limits proper evaluation of current policies and measures for solving or preventing nitrate pollution of drinking water resources. The cost for society associated with nitrate is also relevant for integrated assessment of EU nitrogen policies taking a perspective of welfare optimi...