title: Purification and some properties of a double-stranded DNA containing virus-like particle from Uronema gigas, a filamentous eucaryotic green alga.
abstract: A scheme has been developed for the recovery and purification of about 50% of the 390-nm-diameter virus-like particles (VLPs) present in filtered medium in which Uronema gigas was grown for 6 to 10 weeks. Purification was assayed by electron microscopy of negatively stained samples. Yield of VLPs was low, for example 150 mug from 8 liters of medium. The purified VLP had the following properties:A260/A280 = 1.14 to 1.21;s(20,w) = 6340 +/- 300 S; buoyant density in sucrose, 1.30 g/ml. One major polypeptide (MW = 45,000) and up to nine minor polypeptides (MW = 26,000 to 64,000) were detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The nucleic acid associated with the VLP was double-stranded DNA with a buoyant density of 1.719 g/ml in cesium chloride and 1.436 g/ml in cesium sulfate. Molecules of the DNA were linear with a length of 4 to 36 mum (MW = 8 to 72 x 10(6)). No modal length was observed. These properties distinguish this VLP from other groups of viruses with dsDNA genomes.
authors.affiliation: Departments of Botany and Plant Science, University of British Columbia, B. C., Canada.
authors.forename: A
authors.initials: A
authors.lastname: Cole
authors.forename: J A
authors.initials: JA
authors.lastname: Dodds
authors.forename: R I
authors.initials: RI
authors.lastname: Hamilton