Bcl-2 and Bax modulate adenine nucleotide translocase activity

Bcl-2 is a prosurvival factor that reportedly prevents the nonspecific permeabilization of mitochondrial membranes, yet enhances specific ADP/ATP exchange by these organelles. Here, we show that Bcl-2 enhances the ADP/ATP exchange in proteoliposomes containing the purified adenine nucleotide translocase (ANT) in isolated mitochondria and mitoplasts, as well as in intact cells in which mitochondrial matrix ATP was monitored continuously using a specific luciferase-based assay system. Conversely, Bax, which displaces Bcl-2 from ANT in apoptotic cells, inhibits ADP/ATP exchange through a direct action on ANT. The Bax-mediated inhibition of ADP/ATP exchange can be separated from Bax-stimulated formation of nonspecific pores by ANT. Chemotherapy-induced apoptosis caused an inhibition of ANT activity, which preceded the loss of the mitochondrial transmembrane potential and could be prevented by overexpression of Bcl-2. These data are compatible with a model of mitochondrial apoptosis regulation in which ANT interacts with either Bax or Bcl-2, which both influence ANT function in opposing manners. Bcl-2 would maintain the translocase activity at high levels, whereas Bax would inhibit the translocase function of ANT

Bcl-2 and Bax modulate adenine nucleotide translocase activity

none13Bcl-2 is a prosurvival factor that reportedly prevents the nonspecific permeabilization of mitochondrial membranes, yet enhances specific ADP/ATP exchange by these organelles. Here, we show that Bcl-2 enhances the ADP/ATP exchange in proteoliposomes containing the purified adenine nucleotide translocase (ANT) in isolated mitochondria and mitoplasts, as well as in intact cells in which mitochondrial matrix ATP was monitored continuously using a specific luciferase-based assay system. Conversely, Bax, which displaces Bcl-2 from ANT in apoptotic cells, inhibits ADP/ATP exchange through a direct action on ANT. The Bax-mediated inhibition of ADP/ATP exchange can be separated from Bax-stimulated formation of nonspecific pores by ANT. Chemotherapy-induced apoptosis caused an inhibition of ANT activity, which preceded the loss of the mitochondrial transmembrane potential and could be prevented by overexpression of Bcl-2. These data are compatible with a model of mitochondrial apoptosis regulation in which ANT interacts with either Bax or Bcl-2, which both influence ANT function in opposing manners. Bcl-2 would maintain the translocase activity at high levels, whereas Bax would inhibit the translocase function of ANT.noneBELZACQ A.S.;VIEIRA H.L.;VERRIER F.;VANDECASTEELE G.;COHEN I.;PREVOST M.C.;LARQUET E.;PARISELLI F.;PETIT P.X.;KAHN A.;R. RIZZUTO;BRENNER C.;KROEMER G.Belzacq, A. S.; Vieira, H. L.; Verrier, F.; Vandecasteele, G.; Cohen, I.; Prevost, M. C.; Larquet, E.; Pariselli, F.; Petit, P. X.; Kahn, A.; Rizzuto, Rosario; Brenner, C.; Kroemer, G

Determination of BTEX by GCMS in air of offset printing plants: comparison between conventional and ecological inks

The use of inks containing organic solvents by the offset printing process implies in the release of volatile organic compounds to the work environment. Many of these compounds such as benzene, toluene, ethylbenzene, and the xylene isomers (well known by the acronym BTEX) are extremely toxic. In this study, the BTEX concentrations were determined in two different printing plants that use distinct types of inks: the conventional and the so-called ecological, which is manufactured based on vegetal oil. Concentration ranges were 43-84, 15-3,480, 2-133, 5-459, and 2-236 μg m-3 for benzene, toluene, ethylbenzene, m + p-xylene, and o-xylene, respectively, for the conventional printing plant. At the ecological printing plant, concentration ranges were below limit of detection (<LD)-31, <LD-618, <LD-1,690, <LD-10,500, <LD-3,360 μg m-3 for benzene, toluene, ethylbenzene, m + p-xylene, and o-xylene, respectively. BTEX concentrations are lower at the ecological printing environment than in the conventional, where mineral oil-based inks are used. However, the worker who cleans the printing matrices is exposed to high concentrations of ethylbenzene and xylenes, due probably to the cleaning product's composition (containing high amounts of BTEX). Although the BTEX concentrations found in both printing work environments were below the limits considered by the Brazilian Law for Activities and Unhealthy Operations (NR-15), the exposure to such vapors characterizes risk to the workers' health for some of the evaluated samples, mainly the personal ones. © Springer Science+Business Media B.V. 2009

Experimental approaches to better understand the retention of aroma compounds in oro-naso-pharyngeal cavities

Better understanding the persistence of aroma compounds during food consumption has constituted a challenging issue in food science for a long time. Due to the complexity and the diversity of the phenomena involved, it has often been studied through in vitro approaches. The main objective of the present study was to propose a global approach to address this topic in in vivo conditions. Four simple experimental protocols were developed to differently expose the compartments of naso-oro-pharyngeal cavities to flavored gaseous samples. Assumptions on possible mechanisms (mass transfer, dilution, interactions with mucosa and/or saliva, etc.) were proposed to explain the shapes of release kinetics that were observed. Release differences appeared to be dependent on the physicochemical properties of volatile molecules, on the physiological characteristics of individuals (notably saliva properties) and on the compartment of the naso-oro-pharyngeal cavities that was considered. These achievements constitute a first step to progress in the understanding of relationships that exist between aroma release and perception