Nitrogen is one of the most important limiting factors for plant growth. However, as ammonium is readily converted into ammonia (NH3) when soil pH rises above 8.0, this activity depletes the availability of ammonium (NH4(+)) in alkaline soils, consequently preventing the growth of most plant species. The perennial wild grass Puccinellia tenuiflora is one of a few plants able to grow in soils wi...

Previous experiments have revealed a much greater efficiency of ammonium utilization by bean plants (Phaseolus vulgaris L.) when the acidity of the ambient medium was maintained at near-neutral conditions with carbonates or hydroxides. The present investigation, in which (15)N-labeled ammonium was used, permitted an assessment of the origin of nitrogen in tissue nitrogen pools with and without ...

PURPOSE Previous studies from our laboratory have suggested that pooling of ammonium in tumor tissues may be caused by its inefficient removal due to the poor vasculature commonly found in tumors. The purpose of these experiments was to validate the relationship between tumor ammonium ion concentration and tumor blood flow, and to determine whether large concentrations of ammonium ion detected ...

We have investigated the thermodynamics and kinetics of ammonium nitrate/water and mixed ammonium nitrate/succinic acid/water microparticles. The water activity of ammonium nitrate microparticles is determined as a function of composition down to 12% relative humidity by accounting for the rapid evaporation of ammonia and nitric acid. Both the observed deliquescence and water activities for amm...

Introduction Conclusions References

background: quaternary ammonium compounds (qac), which contain benzalkonium chloride as the most widely used agent, are employed as wound and skin antiseptics, as well as disinfectants in hospitals. the resistance mechanism to disinfectants is usually determine by genes which are related to resistance to quaternary ammonium compounds, namely, qace, qacδe1, qacδe1 that are found in gram-negative...

the microalgae, dunaliella salina was isolated from maharlu salt lake, south east of shiraz, iran. the isolated strain was identified by both morphological and physiological markers. the complete its region (its1 + its2) including the 5.8s rdna gene used as molecular marker confirmed our identification. growth and cell proliferation, total chlorophyll and carotenoid contents were determined in ...

Nitrogen metabolism of planktonic populations in coastal waters of the southern Scotia Sea was studied in February-March 1981 aboard R/V M e l d l e . In spite of the high concentration of nitrate present in these waters (21 to 29 FM), up to 93 % of phytoplankton nitrogen was assimilated in the form of ammonium, with the overall mean being 78 %. Time course experiments showed that uptake of nit...

Ammonium uptake in plant roots is mediated by AMT/MEP/Rh-type ammonium transporters. Out of five AMTs being expressed in Arabidopsis roots, four AMT1-type transporters contribute to ammonium uptake, whereas no physiological function has so far been assigned to the only homolog belonging to the MEP subfamily, AMT2;1. Based on the observation that under ammonium supply, the transcript levels of A...

The brain ammonium production is detoxified by astrocytes, the gut ammonium production is detoxified by hepatic cells, and the renal ammonium production plays a major role in renal acid excretion. As a result of ammonium handling in these organs, the ammonium and pH values are strictly regulated in plasma. Up until recently, it was accepted that mammalian cell transmembrane ammonium transport w...