Epidermal growth factor levels in mouse submaxillary glands following chronic isoproterenol treatment.
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Animals↗
Biomedical subjects
V D Winston
Publications and source records attributed to V D Winston.
An improved plaque assay for viruses infecting poikilothermic cells; use of ultralow-gelling-temperature agarose.
The conventional plaque assay for viruses infecting poikilothermic cells is difficult because the cells are easily damaged at temperatures needed to keep the agarose overlay from solidifying prematurely. A modification of the assay in which these problems were solved by use of a new type of agarose (SeaPrep 15/45) that remains liquid above 15 degrees C, was developed. Use of this agarose made it easy to obtain smooth agar overlays without the risk of thermal damage to the cells.
Animals↗
A simple program which processes liquid scintillation counting data from samples containing both 125I and 3H under conditions of varying quench.
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Iodine Radioisotopes↗
Isolation and characterization of polyoma uncoating intermediates from the nuclei of infected mouse cells.
A method was developed which enabled the efficient recovery of polyoma uncoating intermediates from the nuclei of infected cells at early times after infection (15 min to 12 h). Cells were infected with radiolabeled virus and lysed with the detergent Nonidet P-40. The nuclei were then collected and sonicated, and the products were analyzed on sucrose gradients. The uncoating intermediate sedimented at 190S and was a viral DNA-protein complex closely associated with a structure of host origin. The host material associated with the 190S uncoating intermediate was determined by polyacrylamide gel electrophoresis and visualized by electron microscopy. The amount of 190S uncoating intermediate found in the nucleus increased with time after infection. The viral DNA was predominantly for I. All of the viral proteins were present in the 190S uncoating intermediate in amounts similar to those found in viral DNA-protein complex cores.
Animals↗
Effect of butylated hydroxytoluene on Newcastle disease virus.
A study was done to examine the effects of butylated hydroxytoluene (BHT) on purified Newcastle disease virus (NDV). Treatment of the virus with 50 microgram of BHT/ml caused 92% inactivation of the virion infectivity. Virion adsorption to chicken-embryonated cells was inhibited 32% and synthesis of intracellular hemagglutinin was inhibited 29%. Electron microscopy of the BHT-treated virions revealed virion envelope damage. Chicken-embryonated cells treated with 25 microgram of BHT/ml before NDV infection demonstrated 65% inhibition of NDV progeny production.
Butylated Hydroxytoluene↗
Characterization of a DNA-protein complex and capsomere subunits derived from polyoma virus by treatment with ethyleneglycol-bis-N,N'-tetraacetic acid and dithiothreitol.
Treatment of polyoma virions with ethyleneglycol-bil-N,N'-tetraacetic acid (EGTA) and dithiothreitol (DTT) at pH 8.5 resulted in the dissociation of the virions into a DNA-protein complex and individual structural capsomere subunits. The sedimentation value of the DNA-protein complex in sucrose gradients was approximately 48S, and it had a density of 1.45 g/cm3 in equilibrium CsCl gradients. Alkaline sucrose analysis of the DNA within this DNA-protein complex demonstrated that approximately 75% of the DNA is component 1. The proteins associated with the DNA were dissociated by treatment with either NaCl or the anionic detergent Sarkosyl. VP1 and the histone proteins VP 4--7 were the major proteins associated with the DNA. Treatment of the DNA-protein complex with alkaline pH resulted in the specific removal of FP1. Electron microscopy of the 48S DNA-protein complex demonstrated that it is a very tightly coiled structure that is slightly larger than the intact virion. Treatment of the complex with either NaCl or with pH 10.5 buffer resulted in the loss of protein and subsequent loosening of the DNA-protein complex such that the DNA could be visualized. The capsomere subunits released as a result of the EGTA-DTT treatment sedimented as 18S, 12S, and 5S subunits in sucrose gradients. Electrophoretic analysis of the isolated capsomeres demonstrated that VP1, VP2, and VP3 were present in each species, although the ratios of the proteins varied. In addition to the structural proteins, histones VP 4--7 were found to be predominantly associated with the 5S capsomere subunit.
Capsid↗
Dissociation of polyoma virus by the chelation of calcium ions found associated with purified virions.
Analysis of polyoma virions by X-ray fluorometry demonstrated that calcium (Ca2+) was associated with the purified virion. Treatment of purified virions with ethyleneglycol-bis-N,N'-tetraacetic acid (EGTA), which chelates Ca2+, and the reducing agent dithiothreitol caused the virions to dissociate. Electron microscopy revealed that the virions were dissociated to the capsomere level. Incubation of polyoma virions with 150 mM NaCl, 10 mM EGTA, and 3 mM dithiothreitol was optimum for the dissociation reaction. The pH for the dissociation reaction ranged from 7.5 to 10.5. Cesium chloride density gradient centrifugation indicated that both EGTA and dithiothreitol were necessary for dissociation to occur; neither reagent alone dissociated the virus. The major protein product of the dissociated viral particles sedimented at 12S. Relationships between these experiments and the alkaline carbonate-bicarbonate dissociation of polyoma are discussed.
Calcium↗