Most plants obtain nitrogen through nitrogen-fixing bacteria and microbial decomposition of plant and animal material. Many vascular plants are able to form close symbiotic associations with endophytic fungi. Metarhizium is a common plant endophyte found in a large number of ecosystems. This abundant soil fungus is also a pathogen to a large number of insects, which are a source of nitrogen. It...

The stable isotope of nitrogen, N 15, has been employed extensively as a tracer in studies of nitrogen transformations in animals and bacteria, and its use has yielded much information difficult or impossible to obtain otherwise. The extension of this method to studies involving the higher plants, however, has been very limited. Hevesy and coworkers (1) studied the absorption of ammonium ions l...

Isotopic labeling experiments were performed to better understand the electrochemical reduction of carbon dioxide on nitrogen-doped porous carbon electrodes. By using nonequilibrated solutions of selectively labeled initial carbon sources (i.e., 13CO2 and H13CO3-), bicarbonate anion was identified as the predominant source of the carbon monoxide reduction product.

Aged rats are more sensitive to injury, possibly through an impairment of nitrogen and glutamine (Gln) metabolisms mediated by glucocorticoids. We studied the metabolic kinetic response of adult and old rats during glucocorticoid treatment. The male Sprague-Dawley rats were 24 or 3 mo old. Both adult and old rats were divided into 7 groups. Groups labeled G3, G5, and G7 received, by intraperito...

A new 3D pulse sequence correlates backbone amide proton and nitrogen with alpha proton resonances selectively for glycine residues in a fully doubly labeled (15N, 13C) protein. The excitation of multiple quantum coherences provides optimized resolution and sensitivity. Degenerate alpha proton groups can be promptly recognized. Correlation of guanidine NH groups to delta protons of arginine sid...

Background: The in vivo quality of milk protein fractions has seldom been studied in humans. Objective: Our objective was to compare the postprandial utilization of dietary nitrogen from 3 [N]-labeled milk products: micellar caseins (MC), milk soluble protein isolate (MSPI), and total milk

Stable isotope tracing is a powerful method for interrogating metabolic enzyme activities across the metabolic network of living cells. However, most studies of mammalian cells have used (13)C-labeled tracers only and focused on reactions in central carbon metabolism. Cellular metabolism, however, involves other biologically important elements, including nitrogen, hydrogen, oxygen, phosphate an...