Citrate utilization plasmids have previously been identified in atypical Escherichia coli isolates. A different citrate-utilizing (Cit+) variant of E. coli K-12 arose as a consequence of two chromosomal mutations (B. G. Hall, J. Bacteriol. 151:269-273, 1982). The processes controlling the transport of citrate in both a Cit+ chromosomal mutant and a Cit+ plasmid system were studied. Both systems...

We previously reported that glucose can be released from GLUT2-null hepatocytes through a membrane traffic-based pathway issued from the endoplasmic reticulum. Here, we further characterized this glucose release mechanism using biosynthetic labeling protocols. In continuous pulse-labeling experiments, we determined that glucose secretion proceeded linearly and with the same kinetics in control ...

Nicotinic acid adenine dinucleotide phosphate (NAADP) has been shown to release intracellular Ca(2+) in several types of cells. We have used Ca(2+)-sensitive fluorescent dyes (Fura-2, Fluo-4) to measure intracellular Ca(2+) in astrocytes in culture and in situ. Bath-applied NAADP elicited a reversible and concentration-dependent Ca(2+) rise in up to 90% of astrocytes in culture (EC(50)=7 microM...

BACKGROUND/AIMS The effect of four secondary metabolites isolated from sponge Spongionella, gracilins H, A, L and tetrahydroaplysulphurin-1 on Calcium ion (Ca2+) fluxes were studied in SH-SY5Y neuroblastoma cells. METHODS AND RESULTS These compounds did not modify cytosolic baseline Ca2+-levels. Nevertheless, when cytosolic Ca2+-influx through store operated calcium channels (SOC channels) wa...

To characterize the regulatory pathways involved in the inhibition of cell differentiation induced by the impairment of mitochondrial activity, we investigated the relationships occurring between organelle activity and myogenesis using an avian myoblast cell line (QM7). The inhibition of mitochondrial translation by chloramphenicol led to a potent block of myoblast differentiation. Carbonyl cya...

AIMS Mitochondrial cardiomyopathy is associated with deleterious remodelling of cardiomyocyte Ca(2+) signalling that is partly due to the suppressed expression of the sarcoplasmic reticulum (SR) Ca(2+) buffer calsequestrin (CASQ2). This study was aimed at determining whether CASQ2 downregulation is directly caused by impaired mitochondrial function. METHODS AND RESULTS Mitochondrial stress wa...

The genome of Chlamydia trachomatis, one of the most prominent human pathogens, contains two structural genes coding for proteins, herein called Npt1Ct and Npt2Ct (nucleoside phosphate transporters 1 and 2 of C. trachomatis), exhibiting 68 and 61% similarity, respectively, to the ATP/ADP transporter from the intracellular bacterium Rickettsia prowazekii at the deduced amino acid level. Hydropat...

Mitochondria are localized to regions of the cell where ATP consumption is high and are dispersed according to changes in local energy needs. In addition to motion directed by molecular motors, mitochondrial distribution in neuronal cells appears to depend on the docking of mitochondria to microtubules and neurofilaments. We examined interactions between mitochondria and neurofilaments using fl...

Mycoplasma mobile glides on surfaces at up to 7 microm/s by an unknown mechanism. We studied the energetics that power gliding by using a novel, growth medium-free system. We found that cells could glide in defined media if the glass substrate is preconditioned by exposure to horse serum. The active component that potentiates gliding is sensitive to proteinase K treatment. We used the defined m...

Proline-dependent oxygen uptake in corn mitochondria (Zea mays L. B73 x Mo17 or Mo17 x B73) occurs through a proline dehydrogenase (pH optimum around 7.2) bound to the matrix side of the inner mitochondrial membrane. Sidedness was established by determining the sensitivity of substrate-dependent ferricyanide reduction to antimycin and FCCP (P-trifluoromethoxycarbonylcyanide phenylhydrazone). Pr...