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Rhizobium meliloti is known to use betaines synthesized by its host, Medicago sativa, as osmoprotectants and sources of energy. It is shown in the present report that the symbiotic megaplasmid (pSym) of R. meliloti RCR2011 encodes functions essential to the catabolism of three betaines, trigonelline (nicotinic acid N-methylbetaine), stachydrine (proline(More)
Our objectives were to identify substances produced by plant roots that might act as nutritional mediators of specific plant-bacterium relationships and to delineate the bacterial genes responsible for catabolizing these substances. We discovered new compounds, which we call calystegins, that have the characteristics of nutritional mediators. They were(More)
Calystegines, polyhydroxy nortropane alkaloids, are a recently discovered group of plant secondary metabolites believed to influence rhizosphere ecology as nutritional sources for soil microorganisms and as glycosidase inhibitors. Evidence is presented that calystegines mediate nutritional relationships under natural conditions and that their biological(More)
The traditional separation of the producers of research evidence in academia from the users of that evidence in healthcare organisations has not succeeded in closing the gap between what is known about the organisation and delivery of health services and what is actually done in practice. As a consequence, there is growing interest in alternative models of(More)
Stachydrine (proline betaine) can be used by Sinorhizobium meliloti as a source of carbon and nitrogen. Catabolism depends on an initial N-demethylation, after which the resultant N-methyl proline enters general metabolism. Deletion and insertion mutagenesis demonstrated that the information necessary for catabolism is carried on the symbiotic plasmid(More)
Hole dynamics in noble metals (Cu and Au) is investigated by means of first-principles many-body calculations. While holes in a free-electron gas are known to live shorter than electrons with the same excitation energy, our results indicate that d holes in noble metals exhibit longer inelastic lifetimes than excited sp electrons, in agreement with(More)
The alkaloid extract from roots of naturally growing Convolvulus arvensis, purified by ion-exchange chromatography, showed significant inhibitory activity toward beta-glucosidase and alpha-galactosidase. The demonstrated occurrence of polyhydroxy-nortropane alkaloids, the calystegins, in C. arvensis and their structural similarity to known polyhydroxy(More)
We have investigated the hole dynamics at copper surfaces by high-resolution angle-resolved photoemission experiments and many-body quasiparticle GW calculations. Large deviations from a free-electron-like picture are observed both in the magnitude and the energy dependence of the lifetimes, with a clear indication that holes exhibit longer lifetimes than(More)
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