Fluoride effects on 31P NMR spectra of macrophages

Itaconate biosynthesis in Aspergillus terreus

Itaconate biosynthesis was studied in intact cells of high-yield (RC4') and low-yield (CM85J) strains of the fungus Aspergillus terreus by methods (tracers, nuclear magnetic resonance spectroscopy, and mass spectroscopy) that did not interfere with metabolism. Itaconate formation in RC4' required de novo protein biosynthesis. Krebs cycle intermediates increased in both strains during the production of itaconic acid. The Embden-Meyerhof-Parnas pathway and the Krebs cycle were shown to be involved in this biosynthesis by using 14C- and 13C-labelled substrates and nuclear magnetic resonance spectroscopy. A metabolic pathway for itaconate formation from glucose in A. terreus is proposed.

31P NMR study of intracellular pH during the respiratory burst of macrophages

The metabolic events occurring during the respiratory burst of macrophages previously primed in vivo with lipopolysaccharide were studied by 31P nuclear magnetic resonance, using the P388D1 cell line as a model of the mature macrophages. Using perchloric acid extracts, the presence of phosphocreatine was shown in the primed cells, indicating that in control P388 D1 macrophages, in which no phosphocreatine was seen, in vivo maturation was incomplete. The cells primed in vivo exhibited greater maturation than the control cells, as well as greater creatine kinase activity. Perfusion of gel-embedded macrophages allowed the monitoring of phosphorylated metabolite peak intensities and of the intracellular pH. After the respiratory burst of the primed macrophages had been triggered by concanavalin A, these intensities did not alter significantly, but the intracellular pH decreased. 31P NMR spectra reflected transient acidification in the primed cells, possibly due to the formation of endocytic vesicles and their fusion with lysosomes.