Many fluorophores present inside the living cells such as NADH + H(+), tryptophan, pyridoxine, and riboflavin fluoresce at specific excitation and emission wavelength combinations. Since these key intracellular metabolites are involved in cell
growth and metabolism, their concentration change at any time inside the cell could reflect the changes in cell metabolic activity. NADH + H(+) spectrofluorometry was used for on-line characterization of physiological state during batch cultivation of poly-beta-hydroxybutyric acid (PHB) production by Wautersia eutropha. The culture fluorescence increased with an increase in the biomass concentration with time. A linear correlation between cell mass concentration and net NADH + H(+) fluorescence was established during active growth phase (13 to 38 h) of batch Z-DEVD-FMK cultivation. The rate of AZD6738 cost change of culture fluorescence (dF/dt) exhibited a gradual increase during the predominantly growth phase of batch cultivation (till 20 h).
Thereafter, a sudden drop in the dF/dt rate and its leveling was recorded indicating major changes in culture metabolism status which synchronized with the start-up of accumulation of PHB. After 48 h, yet another decrease in the rate of change of fluorescence (dF/dt) was observed primarily due to severe substrate limitation in the reactor. On-line NADH + H(+) fluorescence signal and its rate (dF/dt) could therefore be used to distinguish the growth, product formation, and nutrient depletion stage (the metabolic state marker) during the batch
cultivation of W. eutropha.”
“Systemic RNAi in Caenorhabditis elegans requires the widely conserved transmembrane protein SID-1 to transport RNAi silencing signals between cells. When expressed in Drosophila S2 cells, C. elegans SID-1 enables passive dsRNA uptake from the culture medium, suggesting that SID-1 functions as a channel for the transport of double-stranded RNA (dsRNA). Here we show that nucleic acid transport by SID-1 is specific for dsRNA and that addition of dsRNA to SID-1 HDAC inhibitor review expressing cells results in changes in membrane conductance, which indicate that SID-1 is a dsRNA gated channel protein. Consistent with passive bidirectional transport, we find that the RNA induced silencing complex (RISC) is required to prevent the export of imported dsRNA and that retention of dsRNA by RISC does not seem to involve processing of retained dsRNA into siRNAs. Finally, we show that mimics of natural molecules that contain both single-and double-stranded dsRNA, such as hairpin RNA and pre-microRNA, can be transported by SID-1. These findings provide insight into the nature of potential endogenous RNA signaling molecules in animals.”
“Purpose Therapeutic hypothermia has become the standard treatment for unconscious patients in cardiac arrest.