carnation is considered as the world's third most important cut flower. tissue culture techniques offer suitable method for micropropagation of this ornamental plant. however, one of the problems during in vitro culture of carnation is vitrification. ratio of ammonium to nitrate and agar concentrations in the medium affect this phenomenon. therefore, in this study the effect of these factors on...

Moving bed biofilm reactors (MBBRs) were placed at two wastewater treatment plants, where they constantly fed with effluent and intermittently primary wastewater. Each reactor was subjected to different feast/famine periods flow rates of wastewater, thus the organic nutrient loads (chemical oxygen demand(COD), ammonium(NH4-N)) resulted in feast-famine conditions applied biomass. In batch experi...

We assessed the extent to which plants can acquire amino acids when supplied as single N-sources or when plants have access to a mixture of aminoand inorganic N sources. Because the uptake of different N-sources is temperaturedependent, the effects of temperature on amino-N uptake were also tested. Lolium perenne (perennial rye-grass) was grown hydroponically at 11 ∞ C or 21 ∞ C. Uptake of N wa...

Ammonium transporter (AMT) proteins of the AMT family mediate the transport of ammonium across plasma membranes. To investigate whether AMTs are regulated at the posttranscriptional level, a gene construct consisting of the cauliflower mosaic virus 35S promoter driving the Arabidopsis (Arabidopsis thaliana) AMT1;1 gene was introduced into tobacco (Nicotiana tabacum). Ectopic expression of AtAMT...

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...

The resistance of Listeria monocytogenes to cadmium and arsenic has been used extensively for strain subtyping. However, limited information is available on the prevalence of such resistance among isolates from the environment of food-processing plants. In addition, it is not known whether the resistance of such isolates to heavy metals may correlate with resistance to quaternary ammonium compo...

The western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), is a major pest of corn (Zea mays L.) in North America and has evolved resistance to crop rotation by ovipositing in alternate crops such as soybeans [Glycine max (L.) Merr.]. Through experiments with plants grown in the greenhouse and the field, we tested whether soybeans with resistance to the soybe...

To investigate nitrogen assimilation and translocation in Zea mays L. colonized by the vesicular-arbuscular mycorrhizal (VAM) fungus Glomus fasciculatum (Thax. sensu Gerd.), we measured key enzyme activities, 15N incorporation into free amino acids, and 15N translocation from roots to shoots. Glutamine synthetase and nitrate reductase activities were increased in both roots and shoots compared ...

BACKGROUND Despite the large stocks of organic nitrogen in soil, nitrogen availability limits plant growth in many terrestrial ecosystems because most plants take up only inorganic nitrogen, not organic nitrogen. Although some vascular plants can assimilate organic nitrogen directly, only recently has organic nitrogen been found to contribute significantly to the nutrient budget of any plant. C...