Incorporation of [32P]phosphate into nucleotides of the dorsal root ganglia of regenerating rat sciatic nerve

β-Glucose-1-Phosphate, a Possible Mediator for Polysaccharide Formation in Maltose-Assimilating Lactococcus lactis

Homolactic fermentation of glucose and heterolactic fermentation of maltose with Lactococcus lactis 65.1 were confirmed. When moles of glucose were compared, the uptake rates of the two carbon sources were similar. The intracellular concentration of fructose-1,6-diphosphate (FDP) in maltose-assimilating cells was half of that in glucose-assimilating cells. Similarly, formation of FDP and lactate from maltose by extracts of maltose-grown cells was half of that formed from glucose by extracts of glucose-grown cells, indicating a difference in the utilization of the two carbon sources for energy metabolism. Concentrations of adenine nucleotides were similar in both types of cells. Glucose-1-phosphate was found in extracts of maltose-grown cells given maltose and, in addition, an inducible and low β-specific phosphoglucomutase activity was observed. β-Glucose-1-phosphate was not metabolized by cell extracts to either FDP or lactate, suggesting an alternative metabolic route. The amount of [ 14 C]maltose incorporated into the cell material of maltose-grown cells was four times greater than that of [ 14 C]glucose incorporated into the cell material of glucose-grown cells. The intracellular concentration of UTP was lower in maltose-assimilating cells than in glucose-assimilating cells. Cells grown on maltose were more spherical and less fragile than cells grown on glucose.

Intracellular compartmentation of diadenosine tetraphosphate (Ap4A) and dTTP in rat liver

1. The intracellular compartmentation of diadenosine tetraphosphate (Ap4A) and of dTTP was studied in rat liver cells using non-aqueous glycerol for the isolation of cell nuclei. 2. This method allows a stepwise removal of cytoplasm from the nuclei. 3. The decrease in Ap4A or dTTP during the process was compared to the simultaneous decrease in RNA, which was taken to represent the cytoplasm. 4. In regenerating liver excised 24 hr after partial hepatectomy, Ap4A was almost equally distributed between the nucleus and cytoplasm. 5. In livers from unoperated control rats, the nuclear concentration of Ap4A was slightly elevated compared to that of whole cells. dTTP was only investigated in regenerating liver. 6. Significantly higher concentrations were found in the nuclear fractions. 7. The purest nuclei contained about 26% of whole cell levels of dTTP, while their RNA values had decreased to 7% of the whole cell RNA. 8. Considering that the liver cell nucleus comprises about 7% of the entire cell mass, a nuclear dTTP concentration of 26% indicates significantly higher dTTP levels in the nuclear compartment than in the cytoplasm of regenerating rat liver cells.

Herpes simplex virus latent infection: reactivation and elimination of latency after neurectomy

Section of the sciatic nerve during the period of herpes simplex virus (HSV) latent infection was performed to evaluate residual latency in mouse dorsal root ganglion. In control mice without sciatic neurectomy, latency was present in 90-100%, while in those which underwent a neurectomy procedure, latent infection was surprisingly decreased to 28-50%. To investigate the hypothesis that the decrease of latency resulted from HSV reactivation and replication (with subsequent neuron destruction), groups of mice were treated with acyclovir to inhibit HSV reactivation, after having undergone a neurectomy procedure. Acyclovir treatment largely prevented the neurectomy-related elimination of latency and supported the hypothesized mechanism.

Periodate-methylamine degradation of ribonucleotides in rat liver extracts in comparison to extracts of cultured cells

Periodate-methylamine degradation of ribonucleotides, which enables separation of deoxyribonucleotides in cell extracts by high-performance liquid chromatography, was tested on the acid-soluble fraction of L1210 cells, Ehrlich ascites tumor (ELD) cells, liver tissue, and liver cell nuclei. It was shown that dTTP, dCTP, and dATP could be clearly separated in L1210 and ELD extracts. In samples from liver tissue, however, dTTP coeluted with another compound, the dCTP peak often eluted very close to another peak, and only dATP separated quite satisfactorily. Furthermore, extracts from liver cell nuclei, isolated in glycerol, were not directly susceptible to periodate oxidation. This problem can be avoided by use of a different procedure for the isolation of cell nuclei.