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A Puga

Publications and source records attributed to A Puga.

67 records · Page 4Linked to original sources
PubMed1982

Homology between murine and human cellular DNA sequences and the terminal repetition of the S component of herpes simplex virus type 1 DNA.

DNA from trigeminal ganglia of mice latently infected with herpes simplex virus type 1 was cloned in bacteriophage lambda Charon 27. Three recombinant clones that cross-hybridize to each other and hybridize to the S-segment terminal repeat region of the herpesvirus genome were obtained. The region of homology maps within a 1.1 kb Sma l fragment approximately 400 bp from the S-segment terminal repeat terminus, outside the domain of the a sequences. The insert DNAs in these clones, as well as the Sma l fragment of viral DNA that contains the region of homology, hybridize to uninfected mouse brain DNA with a pattern indicative of the presence of repeated sequences, and also hybridize to discrete Eco Rl fragments of human DNA. These recombinant clones contain intermediate repetitive mouse genomic DNA sequences related to a small region of the viral S-segment terminal repeat, and those sequences are evolutionarily conserved in mammalian DNA.

Animals↗
PubMed1980

Herpes simplex virus DNA sequences in the CNS of latently infected mice.

It has been amply documented that herpes simplex virus (HSV) persists in sensory ganglia of the peripheral nervous system (PNS). In contrast, HSV latency in the central nervous system (CNS) has not been well characterized. Corneal inoculation of virus results in a productive viral infection in the CNS during the first week after inoculation, indicating that the virus can progress from the PNS to the CNS. During latency, HSV has been found by co-cultivation of CNS tissue in only a very small fraction of inoculated mice. We have used here molecular hybridization techniques to analyse the fate of viruses that reach the CNS by anatomical pathways. We show that 6 days after corneal inoculation of HSV-1 a productive viral infection was present in brain tissue as well as in peripheral ganglia in at least 90%F of the inoculated mice. The mortality during this acute phase was only 2%. In the survivors, latent HSV could be recovered by explantation from 95% of the trigeminal ganglia, but only 5% of the brain tissue explants of the same mice yielded infectious virus. However, HSV DNA sequences were detected in the brains of 30% of mice which harboured latent HSV in their trigeminal ganglia. These results suggest that viruses that progress from the PNS into the CNS are not eliminated, but are capable of establishing a latent infection in the CNS that cannot be reactivated by explantation techniques.

Animals↗
PubMed1973

Difference between functional and structural integrity of messenger RNA.

Messenger RNA molecules that are structurally stable, as measured by their ability to hybridize to DNA, may nevertheless be considerably less stable in retaining their ability to function in protein synthesis. The structure of the majority of the mRNA of phage S13 decays with a half-life of 10.6 +/- 0.5 min. In contrast, much of the function of the mRNA that is involved in synthesis of a capsid protein (product of the F gene) decays rapidly with a half-life of 1.4 +/- 0.8 min; a residual amount of function decays with a half-life of 14.0 +/- 4.0 min. The measurements were made in the presence of rifampicin, which was used to prevent the formation of new mRNA. A proposed model for the functional decay is based on the polycistronic nature of the mRNA. Degradation of the mRNA would proceed in two steps: the first step would be a fast attack at a region near the 5'-terminus of each molecule that would eliminate the function of the proximal message; the second step would be a slow attack on the remaining messenger molecule precipitating a subsequent rapid degradation of the physical structure.

Carbon Isotopes↗
PubMed1969

Synthesis of replicative form deoxyribonucleic acid and messenger ribonucleic acid by gene IV mutants of bacteriophage S13.

Gene IV mutants of bacteriophage S13 are known to be blocked in infectious replicative form (RF) DNA synthesis, producing only a small fraction of the RF formed by wild-type phage. This investigation shows that gene IV mutants form only parental RF and are blocked in the synthesis of any progeny RF, either infectious or noninfectious. This was determined by density labeling of RF in cells treated with mitomycin C to suppress host deoxyribonucleic acid (DNA) synthesis. RF synthesis was also studied in untreated cells, using methylated albumin columns to separate RF from host DNA. In this case it was also found that synthesis of progeny RF by gene IV mutants is negligible. It has been found by DNA-ribonucleic acid (RNA) hybridization experiments that gene IV mutants form at least as much or more messenger RNA than wild-type phage. Therefore, parental RF alone can form messenger RNA in appreciable amounts.

Bacteriophages↗
PubMedDate not supplied

Stable expression of mouse Cyp1a1 and human CYP1A2 cDNAs transfected into mouse hepatoma cells lacking detectable P450 enzyme activity.

Using the mouse hepatoma Hepa-1c1c7 c37 mutant cell line that exhibits negligible benzo[a]pyrene hydroxylase (Cyp1a1) and acetanilide 4-hydroxylase (Cyp1a2) enzyme activities, we developed stable transfectants of plasmids containing the murine Cyp1a1 (cytochrome P(1)450) and the human CYP1A2 (P(3)450) cDNAs. We show that the assay measuring metabolism of ethoxyfluorescein ethyl ester (EFEE) was invaluable in screening large numbers of individual cell lines for high Cyp1a1 enzyme activity. Nine different plasmid constructs containing various combinations of promoter and enhancer sequences were compared, including: the Drosophila heat shock promoter, the mouse mammary tumor virus long terminal repeat (MMTV LTR) carrying the glucocorticoid-responsive element (GRE), enhancer sequences from simian virus 40 (SV40) and herpes simplex virus type 1 (HSV-1), and the aromatic hydrocarbon-responsive domain (AhRD) of the murine Cyp1a1 gene. Interestingly, only those constructs containing the AhRD produced high levels of Cyp1a1 enzyme activity. In contrast, high levels of CYP1A2 activity were obtained with plasmids carrying the HSV-1 enhancer, as well as the AhRD. These studies suggest that the AhRD, which responds to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), provides a post-transcriptional signal necessary for the induction of functional Cyp1a1 enzyme activity. Although untransfected c37 cells exhibit markedly elevated levels of endogenous Cyp1a1 mRNA, the expression of exogenous Cyp1a1 or CYP1A2 enzyme activity in these cells decreases the concentration of this endogenous Cyp1a1 mRNA to negligible levels and restores Cyp1a1 mRNA inducibility by TCDD; these data indicate that the functional product of either the Cyp1a1 gene or the CYP1A2 gene might have a role in an autoregulatory loop controlling the constitutive expression of the Cyp1a1 gene. The cell lines described herein should be valuable in assessing the contribution of these two P450 enzymes to the processes of cytotoxicity, mutagenesis, and carcinogenesis.

Animals↗