PubMed Health⌕ Search

Biomedical subjects

G A Gentry

Publications and source records attributed to G A Gentry.

52 records · Page 3Linked to original sources
PubMed1972

Protein kinase activity in equine herpesvirus.

A protein kinase which is intimately associated with equine herpesvirus (equine abortion virus) was found by using adenosine triphosphate-gamma-(32)P as a phosphate donor and virus protein as an acceptor. Consistent demonstration of the activity requires prior removal of phosphohydrolase. The kinase activity requires Mg(2+), is not stimulated by cyclic adenosine monophosphate, but is enhanced by added protamine or arginine-rich histone. The labeled product is resistant to ribonuclease, deoxyribonuclease, and chloroform-methanol but is sensitive to Pronase. Other tests suggest that serine and threonine residues are the acceptor sites. In the in vitro reaction, the incorporation represents an average of approximately 4,500 phosphate residues per virion, and all 17 virus protein bands resolved by polyacrylamide gel electrophoresis appear to be labeled.

Adenosine Triphosphate↗
PubMed1969

Mycoplasmal deoxyribonuclease activity in virus-infected L-cell cultures.

Cell-free extracts of Mycoplasma hominis and medium from 72-hr broth cultures had deoxyribonuclease activity like that of deoxyribonuclease I. Mg(++) stimulated activity, and the pH optimum was between 8.0 and 9.0. Double-stranded or heatdenatured deoxyribonucleic acid (DNA) served as a substrate, and oligonucleotides were produced. Cell-free extracts of L cells infected with M. hominis or M. hominis plus equine abortion virus (equine herpes virus, EAV) had greatly increased activity over that of extracts of L cells or of L cells infected with EAV alone. In the absence of M. hominis, however, extracts had little activity, most of which was in virus-infected cell cultures. Activity was found in the culture medium only in those systems in which M. hominis was present. It is concluded that M. hominis can contribute significant deoxyribonuclease activity to virus-infected as well as virusfree cell cultures. Perhaps the most interesting question arising concerns the ability of EAV, a DNA virus, to replicate successfully despite the presence of deoxyribonuclease activity at the site of replication (the nucleus).

Cell-Free System↗
PubMed1968

Kinetics of viral deoxyribonucleic acid, protein, and infectious particle production and alterations in host macromolecular syntheses in equine abortion (herpes) virus-infected cells.

Infection of exponential-phase suspension cultures of mouse fibroblast cells (L-M) with equine abortion virus (EAV) resulted in inhibition of cell growth and marked alterations in host metabolic processes. The synthesis of deoxyribonucleic acid (DNA) and ribonucleic acid was inhibited within 4 hr after infection and was suppressed by more than 90% by the time of maximal virus replication (14 to 18 hr). The overall rate of protein synthesis, however, was similar in uninfected and virus-producing cells as determined by measurements of net protein and isotope incorporation. The time course of viral DNA and protein synthesis and assembly into mature virus was determined with the inhibitors 5-fluorodeoxyuridine (FUdR) and cycloheximide, respectively. Thus, viral DNA synthesis was essentially completed at 14 hr, and viral protein and infectious virus synthesis was completed at 18 hr. Although the number of plaque-forming units (PFU) produced by FUdR-treated cells (10(3) to 10(4) PFU/ml) was at least 3 logs less than that produced by untreated cells, the yield of physical particles (as determined by electron microscopy) was approximately the same at 30 hr after infection. Besides being relatively non-infective, the particles produced in FUdR-treated cells appeared morphologically incomplete as they contained little or no nucleoid material.

Abortion, Veterinary↗
PubMed1965

Lability of host-cell DNA in growing cell cultures due to Mycoplasma.

In HeLa-cell cultures chronically infected with Mycoplasma, (PPLO) host-cell DNA is unstable as detected by incorporation of H(3)-or C1 i-thymidine into DNA and subsequent release into the medium as acidsoluble radioactivity. This characteristic can be transmitted to PPLO-free cultures of strain L cells by inoculation with preparations of PPLO from the HeLa cells, although chronically infected cultures of L cells continue to multiply. In addition, virus preparations also may carry PPLO contamination through numerous passages.

Carbon Isotopes↗
PubMedDate not supplied

Phylogeny of immune recognition: fine specificity of fish immune repertoires to cytochrome C.

Using the structurally defined protein antigen cytochrome C, studies were conducted in an attempt to delineate the fine specificities of channel catfish immune repertoires. We have previously reported that species variants of cytochrome C were cross-stimulatory to peripheral blood leukocytes (PBL) from catfish immunized with the pigeon variant. Molecular database analyses revealed the existence of overlapping epitopes that appear to define the specificity of the immune response to a "family" of closely related antigens. To further explore these observations, studies were conducted to determine the contribution of peptide 81-104 to the immunogenicity of cytochrome C. Current data showed that peptide 81-104 and intact cytochrome C were stimulatory to PBL from fish previously immunized with the native molecule. In contrast, PBL from fish previously primed with the peptide 81-104 responded only to the immunizing peptide as well as to some, but not all, variants of the peptide 81-104. The differences in the stimulatory capacities of the peptide variants appeared to correlate with amino acid substitutions at various positions of the peptide and changes in their predicted secondary structures.

Amino Acid Sequence↗