Data are presented showing the distribution of 14C and tritium from radioactive tracer experiments with ribose-lI%, uniformly labeled riboseJ4C, ribose-1-3H, ribose-3-3H, uniformly labeled adenosine14C, and adenosineJ4C following their incorporation into the pyrrolopyrimidine nucleoside antibiotic, toyocamycin, elaborated by Streptomyces rimosus. The data clearly show that carbon 2, but not car...

In vivo studies with L-[13N]glutamate in the Walker 256 carcinosarcoma implanted under the renal capsule of female Sprague-Dawley rats demonstrate that uptake of glutamate and the rate of incorporation of the nitrogen label from this amino acid into metabolites is slower in the tumor than in nontumorous kidney tissue. Glutamate dehydrogenase, glutaminase, and alanine aminotransferase activities...

Urea is the major nitrogen form supplied as fertilizer in agricultural plant production but also an important nitrogen metabolite in plants. We report the cloning and functional characterization of AtDUR3, a high-affinity urea transporter in plants. AtDUR3 contains 14 putative transmembrane-spanning domains and represents an individual member in Arabidopsis that belongs to a superfamily of sodi...

Methods. Adult female rats and rabbits were killed with overdose of sodium pentobarbital, and the extraocular muscles were rapidly frozen in isopentane cooled with liquid nitrogen. Serial transverse frozen sections were cut and labeled respectively with monoclonal antibodies specific for various isofonns of myosin heavy chain, and monoclonal antibodies specific for the fast isoform of the sarco...

During senescence and at times of stress, plants can mobilize needed nitrogen from chloroplasts in leaves to other organs. Much of the total leaf nitrogen is allocated to the most abundant plant protein, Rubisco. While bulk degradation of the cytosol and organelles in plants occurs by autophagy, the role of autophagy in the degradation of chloroplast proteins is still unclear. We have visualize...

Increasing diffuse nitrate loading of surface waters and groundwater has emerged as a major problem in many agricultural areas of the world, resulting in contamination of drinking water resources in aquifers as well as eutrophication of freshwaters and coastal marine ecosystems. Although empirical correlations between application rates of N fertilizers to agricultural soils and nitrate contamin...

15 15 The dynamics of freshly released and N labeled dissolved organic nitrogen (DO N) in the , 94 mm planktonic assemblages of coastal waters and the effects of herbivorous copepods on 15 1 those dynamics were assessed by applying NH under laboratory conditions. At the same time, 4 1 the rate of NH uptake and regeneration in the , 94 mm planktonic assemblages, and the rates of 4 1 15 ingestion...

Short term (2-hour) incorporation of nitrogen from nitrate, glutamine, or asparagine was studied by supplying them as unlabeled ((14)N) tracers to growing pea (Pisum sativum L.) leaves, which were previously labeled with (15)N, and then following the elimination of (15)N from various amino components of the tissue. Most components had active and inactive pools. Ammonia produced from nitrate was...

Plants form symbiotic associations with endophytic bacteria within tissues of leaves, stems, and roots. It is unclear whether or how plants obtain nitrogen from these endophytic bacteria. Here we present evidence showing nitrogen flow from endophytic bacteria to plants in a process that appears to involve oxidative degradation of bacteria. In our experiments we employed Agave tequilana and its ...

The capacity for nitrate reduction, as measured by nitrate reductase activity (NRA), was generally low for a range of plant communities in Australia (coastal heathland, rainforest, savanna woodland, monsoon forest, mangrove, open Eucalyptus forest, coral cay open forest) and only a loose relationship existed between NRA and leaf nitrogen concentration. This suggests that nitrate ions are not th...