Site du LPSC

International audienc

Le calcul pour le LHC au LPSC

International audienc

Magnetogenic Probes for in vitro and in vivo detection of enzymes by magnetic resonance imaging

National audienc

Magnetogenic Probes for in vitro and in vivo detection of enzymes by magnetic resonance imaging

National audienc

Semisynthetic biosensors for mapping cellular concentrations of nicotinamide adenine dinucleotides

We introduce a new class of semisynthetic fluorescent biosensors for the quantification of free nicotinamide adenine dinucleotide (NAD+) and ratios of reduced to oxidized nicotinamide adenine dinucleotide phosphate (NADPH/NADP+) in live cells. Sensing is based on controlling the spatial proximity of two synthetic fluorophores by binding of NAD(P) to the protein component of the sensor. The sensors possess a large dynamic range, can be excited at long wavelengths, are pH-insensitive, have tunable response range and can be localized in different organelles. Ratios of free NADPH/NADP+ are found to be higher in mitochondria compared to those found in the nucleus and the cytosol. By recording free NADPH/NADP+ ratios in response to changes in environmental conditions, we observe how cells can react to such changes by adapting metabolic fluxes. Finally, we demonstrate how a comparison of the effect of drugs on cellular NAD(P) levels can be used to probe mechanisms of action

LA RÉACTION 9Be(n, nn) αα A 15 MeV

La réaction 9Be(n, nn) αα étudiée à 15 MeV, par spectrométrie à double temps de vol, a lieu par une suite de réactions à deux corps et non par un processus quasi élastique. Les niveaux du 9Be de 4 à 10 MeV et leur désintégration sont étudiés. L'influence d'une résonance à deux corps par une troisième est discutée.The 9Be(n, nn) αα reaction is analysed at 15 MeV by double time-of-flight spectrometry. The results show a sequential process of two-body reactions. The decay of the 4 to 10 MeV 9Be levels is observed and the shift of the 8Be (2 +) free resonance by a third particle is discussed