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Biomedical subjects

Y C Zee

Publications and source records attributed to Y C Zee.

At least 19 recordsLinked to original sources
PubMed1994

Degradation of rRNA in Salmonella strains: a novel mechanism to regulate the concentrations of rRNA and ribosomes.

We have previously shown that the 23S rRNA of Salmonella strains is highly fragmented by specific enzyme cleavages. In this article, we report that 23S rRNA of Salmonella strains is rapidly degraded as the cells enter the stationary phase. More than 90% of the 23S rRNA is degraded when the cells reach the stationary phase. The rate of degradation of 23S rRNA correlated with its degree of fragmentation. This degradation is probably mediated by newly synthesized protein factor(s), since treatment with chloramphenicol or rifampin inhibits the rRNA degradation. We propose that degradation of 23S rRNA is a novel mechanism in the regulation of the bacterial 23S rRNA and ribosome concentration and that this additional regulatory mechanism provides some selective advantage to cells.

Cell Division↗
PubMed1993

Comparison of herpesvirus isolates from falcons, pigeons and psittacines by restriction endonuclease analysis.

Field isolates of herpesviruses recovered from falcon, pigeon, and psittacine birds were compared by restriction endonuclease (RE) analysis using four separate enzymes. Pigeon and falcon herpesviruses had strikingly similar DNA cleavage patterns, while DNA cleavage pattern of virus isolates from a double-yellow headed Amazon and an African grey parrot had different genomic patterns to both the pigeon and falcon herpesviruses. These findings support the field observations that pigeon herpesvirus causes a fatal herpesviral infection in the livers of pigeon-eating falcons.

Animals↗
PubMed1992

Diversity of cleavage patterns of Salmonella 23S rRNA.

The recent discovery of the phenomenon that some prokaryotes fragment their 23S rRNA during post-transcriptional processing of precursor rRNA has been shown to be particularly prevalent among strains and species of Salmonella. Some strains of Salmonella cleaved 23S rRNA at multiple sites producing several fragments. The cleavage patterns of 23S rRNA differed among Salmonella strains and sometimes among the rRNA operons in the same strain. Fragmentation of 23S rRNA was not observed in strains of the closely related species Escherichia coli. Fragmentation of 23S rRNA occurred in Brucella and Agrobacterium but the cleavage pattern was not as diverse as that demonstrated in Salmonella. Introduction of cleavage sites into precursor 23S rRNA of Salmonella is probably a recent evolutionary event.

Blotting, Northern↗
PubMed1991

Complete nucleotide and deduced amino acid sequence of genome segment 5 encoding the outer capsid protein, VP5, of a U.S. isolate of bluetongue virus serotype 11.

The complete nucleotide sequence of the RNA genome segment coding for the outer capsid protein, VP5, of the United States prototypic strain of bluetongue virus (BTV) serotype 11 was determined from two overlapping cDNA clones. The genome segment was found to be 1638 nucleotides in length with a single open reading frame coding for a 526 amino acid protein of MW 59,278 and having a net charge of -4.0 at neutral pH. Comparisons of the predicted amino acid sequence of VP5 of BTV 11 with those of the United States serotypes 2, 10, and 13 and two isolates of BTV 1 from Australia and South Africa confirmed earlier reports that VP5 is a conserved protein with no clear regions of variability. A computer generated consensus sequence suggested VP5 of BTV 2 to be representative of the average VP5 sequences reported thus far.

Amino Acid Sequence↗
PubMed1990

A diagnostic method to detect alcelaphine herpesvirus-1 of malignant catarrhal fever using the polymerase chain reaction.

A sensitive diagnostic method specific for alcelaphine herpesvirus-1, causative agent of malignant catarrhal fever, has been developed. Based on the nucleotide sequence of the alcelaphine herpesvirus-1 genomic DNA, a pair of 30 nucleotide primers was selected and synthesized for detecting the virus genome using the polymerase chain reaction (PCR). The virus genome was detected in crude cell lysate using the amplification reaction.

Animals↗
PubMed1990

Nucleotide sequence of a 3.5 kilobase fragment of malignant catarrhal fever virus strain WC11.

A 3.5 kilobase DNA fragment of the malignant catarrhal fever virus (MCFV), strain WC11, was mapped with a number of restriction enzymes, subcloned and sequenced. The fragment was subcloned into plasmid vector, pUC19, for direct sequencing. A complete open reading frame of 2,058 base pairs and a partial open reading frame of 630 base pairs were identified. The sequence of 3,389 nucleotides was compared to other herpesviruses. A 310 base pairs sequence in gene A was 57% homologous to a sequence in reading frame BXLF1 of Epstein-Barr virus strain B95-8.

Amino Acid Sequence↗
PubMed1990

Unique ribosome structure of Leptospira interrogans is composed of four rRNA components.

All known ribosomes of procaryotic organisms are made up of three rRNA components that are 23, 16, and 5S in size. We now report that in some Leptospira interrogans strains, the classical 23S rRNA is further processed to generate 14 and 17S rRNAs. This processing step was previously known to occur only in some eucaryotes and in a small group of procaryotes. The implications of this finding are discussed.

Leptospira interrogans↗
PubMed1989

Comparison of genomes of malignant catarrhal fever-associated herpesviruses by restriction endonuclease analysis.

The restriction endonuclease DNA cleavage patterns of eight isolates of malignant catarrhal fever-associated herpesviruses were examined using the restriction endonucleases HindIII and EcoRI. The eight viruses could be assigned to two distinct groups. Virus isolates from a blue wildebeest, a sika deer and an ibex had restriction endonuclease DNA cleavage patterns that were in general similar to each other. The restriction pattern of these three viruses was distinct from the other five. Of these five, four were isolated from a greater kudu, a white tailed wildebeest, a white bearded wildebeest, and a cape hartebeest. The fifth isolate C500, was isolated from a domestic cow with malignant catarrhal fever. These five viruses had similar DNA cleavage patterns.

Animals↗
PubMed1988

Enhancement of allergic lung sensitization in mice by ozone inhalation.

Inhaled ozone was found to exert an enhancing effect for allergic lung sensitization when mice contracted an aerosolized allergen. The animals were exposed to ozone concentrations of 0.24, 0.16, 0.13, and 0.10 ppm. After 4 days of continuous ozone exposure, the mice had allergen contact from an aerosolized solution of ovalbumin. The animals were then maintained in ambient air for several days before the cycle of ozone and aerosolized allergen was repeated over four allergen contact cycles. Mice were rested in ambient air for a week after the last allergen contact, and they were then tested for allergic sensitization by the intravenous injection of 2 mg of ovalbumin to induce anaphylactic shock in allergic individuals. The control groups of mice were maintained in ambient air throughout the experiment, but they experienced identical allergen contact with the ozone-exposed mice. The phenomenon of allergic enhancement from ozone inhalation was detected at 0.24, 0.16, and 0.13 ppm of ozone. The enhancing effect disappeared at 0.10 ppm of ozone. The study indicated a potential for increasing the number of allergically sensitized individuals when various allergens are inhaled during periods of high ozone exposure with the consequent adverse changes on respiratory membranes. The significance to human health of the allergic enhancement phenomenon by ozone needs investigation.

Aerosols↗
PubMed1988

Cloning and characterization of a genomic probe for malignant catarrhal fever virus.

A genomic probe specific for malignant catarrhal fever (MCF) virus was cloned by using purified viral DNA from MCF-virus strain WCll. Restriction endonuclease analysis of the purified viral DNA was used to identify the cloned viral genomic fragment. Dot blot hybridization by use of the genomic probe (pRP-5) indicated that the probe hybridized specifically with WCll-MCF virus, as well as with one other isolate of MCF-associated herpesvirus. Hybridization also was observed to a non-MCF virus strain of bovine herpesvirus.

Animals↗
PubMed1987

Enzyme-linked immunosorbent assay for the detection of antibodies to bovine virus diarrhea virus in sera from border disease virus-infected sheep.

An enzyme-linked immunosorbent assay (ELISA) was established for the rapid detection of specific antibodies against the causative agent of border disease in ovine sera. Polyethylene-glycol concentrated, equilibrium density gradient purified bovine virus diarrhea virus was used as test antigen. The optimal amount of antigen was 0.5 microgram/well, and the optimal concentration of conjugate was at 1/4,000 dilution. A total of 20 ovine serum samples, which had been collected from animals with or without border disease, were compared by ELISA and serum neutralization test for the detection of border disease-specific antibodies. ELISA was shown to be equally specific but less time-consuming and easier to perform than serum neutralization test. A positive correlation (r = 0.60) between the two tests was found.

Animals↗
PubMed1986

Neutralizing monoclonal antibodies directed to infectious bovine rhinotracheitis virus.

Infectious bovine rhinotracheitis virus (IBRV) has been shown in this report to have thirty-three polypeptides. Ten of the eleven polypeptides which can be labeled with (3H)-glucosamine are located on the surface of the virus since they can be surface labeled with sodium boro(3H)hydride. In order to define the immunologically important viral proteins, monoclonal antibodies were prepared against the virus and selected for their ability to neutralize infectivity. Four such hybridoma lines were obtained for characterization of the antigens that elicit neutralizing antibodies. The viral polypeptides were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and the specificity of each monoclonal antibody was determined by "Western" blot analysis and/or by immunoprecipitation of (35S)-methionine and (3H)-glucosamine labeled infected cell lysates by the monoclonal antibodies. One monoclonal antibody reacted with two glycoproteins, gp135 and gp78a, on the "Western" blot but immunoprecipitated three glycoproteins, gp135, gp78a, and gp54 from labeled infected cell lysates. The other three monoclonal antibodies immunoprecipitated a single glycoprotein, gp78b, from (3H)-glucosamine labeled infected cell lysates but not from (35S)-methionine labeled infected cell lysates.

Antibodies, Monoclonal↗
PubMed1985

Enzyme-linked immunosorbent assay for the detection of antibodies to bovine viral diarrhea virus in bovine sera.

A specific and sensitive enzyme-linked immunosorbent assay (ELISA) was established for the detection of antibodies to bovine viral diarrhea virus (BVDV) in bovine sera. Polyethylene-glycol concentrated, equilibrium density gradient purified BVDV was used as test antigen at an optimal amount of 1 microgram/well, whereas the optimal concentration of conjugate was at 1/2000 dilution. The standardized test encountered no non-specific reaction with test sera at a starting dilution of 1/10. A total of 50 bovine serum samples was assayed for the presence of antibodies against BVDV by ELISA and serum neutralization test (SNT). A positive correlation between the 2 tests was found. However, ELISA could be as much as 500-fold more sensitive than SNT in detecting low levels of BVDV antibodies.

Abortion, Veterinary↗
PubMed1985

Duration of maternally derived antibodies against equine influenza in newborn foals.

Serum antibody concentrations against influenza A-equi-1 virus and A-equi-2 virus were measured in a group of 18 foals from birth to 4 months of age. More than 50% of the foals were seronegative to A-equi-1 virus infection by 4 weeks of age, with titers of less than or equal to 1:16. For A-equi-2 virus, more than 50% of the foals were seronegative by 2 weeks of age, with titers of less than or equal to 1:8. Passively derived antibodies against influenza A-equi-1 virus and A-equi-2 virus in foals obtained from recently vaccinated mares and from mares not vaccinated within 6 months before foaling were low in titer. The duration of passively derived antibodies was also short-lived.

Animals↗
PubMed1984

Comparison of the genomes of pseudorabies (Aujeszky's disease) virus strains by restriction endonuclease analysis.

The DNA of pseudorabies virus (PRV) strains from the United States and Taiwan and attenuated vaccine strains from Romania were compared by restriction endonuclease analysis. Electrophoretically separated PRV DNA fragments of KpnI and BamHI digests demonstrated cleavage pattern variations which clearly distinguished the 3 Taiwan isolates from all other strains, as well as from each other. One type of variation involved the loss or gain of restriction endonuclease cleavage sites. Examples of this type of variation were clearly observed in fragment patterns of the Taiwan isolates. Another type of variation that occurred at higher frequency for fragments mapping in the repeat and repeat-unique joint regions of the PRV genome involved sequence additions or deletions from existing fragments. This second type of variation occurred in most of the strains analyzed.

Animals↗
PubMed1984

Morphology of bovine viral diarrhea virus.

The morphology of bovine viral diarrhea virus (BVDV) was studied by electron microscopy. The NADL strain of BVDV was plaque purified 3 times, concentrated by polyethylene glycol precipitation, and purified by centrifugation to equilibrium in continuous potassium tartrate density-gradients. The virus was examined by negative-stain electron microscopy in the presence or absence of specific antiserum. The density of BVDV was between 1.101 g/cm3 and 1.174 g/cm3, with the peak at maximum infectivity at 1.122 g/cm3. Oval to pleomorphic viral particles, 120 ( +/- 30) nm in diameter, were enriched in the peak of maximum infectivity. The detailed structure of virions was revealed: a 5- to 7-microns thick unit membrane-like envelope layer with numerous projecting knobs, 4 to 5 nm in diameter, surrounding an interior core-like structure. Viral particles measuring 120 ( +/- 30) nm were found in large aggregates in the presence of specific antiserum.

Animals↗
PubMed1983

Identification of envelope and nucleocapsid proteins of infectious bovine rhinotracheitis virus by SDS-polyacrylamide gel electrophoresis.

Infectious bovine rhinotracheitis (IBR) virus was purified by rate zonal and isopycnic centrifugation in potassium tartrate gradients. Viral nucleocapsids were isolated from purified virions by treatment with the nonionic detergent Triton X-100 followed by high speed centrifugation. This treatment was shown to produce a suspension of 74% completely de-enveloped nucleocapsids, 24% incompletely de-enveloped nucleocapsids, and 2% whole virions. The viral nucleocapsids contained DNA and banded at a density of 1.25 g/cm3. Analysis of the viral polypeptides by gradient SDS-polyacrylamide gel electrophoresis revealed that 33 virion proteins, ranging in molecular weight from 13,000 to 275,000 dalton, were present in the complete virus particle. Detergent treatment of the virus quantitatively removed two of the major proteins (vp8, 90,000 dalton, and vp13, 73,000 dalton) and partially removed eleven other proteins. Fifteen viral polypeptides appeared to remain firmly associated with the viral nucleocapsids.

Animals↗