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BIOCHEMICAL AND PHYSIOLOGICAL CHARACTERIZATION OF CYANOPHAGE SM-2
Abstract
Cyanophage SM-2 infects two unicellular blue-green algae, Synechococcus elongatus UTEX 563 and Microcystis aeruginosa NRC-1 (Synechococcus sp. NRC-1) UTEX 1937. The virus has a polyhedral head 50-55 nm in diameter, a noncontractile tail 130-140 nm long and a base plate. SM-2 has a bouyant density of 1.483 g/cm('3) and DNA as its sole nucleic acid. The DNA has a bouyant density of 1.729 g/cm('3) and a guanine + cytosine (G + C) content of 69-70%. These values are very similar to those of cyanophage SM-1. Cyanophage SM-2 has 11 observable proteins, as determined by polyacrylamide gel electrophoresis, with the bulk of the protein mass concentrated at the 39,000 mw band. There appear to be no cross-reacting antibodies in antisera prepared to whole virus particles of cyanophage SM-1, SM-2 and AS-1. There is, however, immunologic cross-reactivity in antisera prepared to the 39,000 mw protein of cyanophage SM-1 and SM-2. This also indicates a close relationship between cyanophage SM-1 and SM-2. Unlike other cyanophage of unicellular blue-green algae, SM-2 requires cations for stabilization. The host blue-green algae, S. elongatus and M. aeruginosa are not capable of sufficient heterotrophic metabolism to support cell growth or presumably virus replication. It is therefore assumed that photosynthetically derived energy is used by cyanophage SM-2 for replication in host blue-green algal cells. This requirement is apparently absolute because dark incubation or photosynthetic inhibitor treatment of SM-2 infected host cells causes reductions in or the prevention of virus replication. Photosynthetically derived energy is used for virus adsorption as well as replication but virus adsorption can be enhanced in the dark by increasing the Na('+) ion concentration in the media. CO(,2) fixation by SM-2 infected host cells is first enhanced and then maintained until late in the infection cycle. During the infection process the stress placed on host cells is revealed in morphologic changes, the most recognizable being the increased adherence of extraneous material to be a "sticky" cell wall mucilage layer. Cyanophage SM-2 is, therefore, a typical virus of unicellular blue-green algae which in several ways in similar to cyanophage SM-1. SM-2, however, differs from other unicellular blue-green algal cyanophage in its requirements for cations. Cyanophage SM-2 replicates in host cells using photosynthetically derived host energy, causes elevation and maintenance of host CO(,2) fixation and causes development of a "sticky" host cell mucilage layer.
Subject Area
Microbiology
Recommended Citation
BENSON, RANDALL LEE, "BIOCHEMICAL AND PHYSIOLOGICAL CHARACTERIZATION OF CYANOPHAGE SM-2" (1981). ETD collection for University of Nebraska-Lincoln. AAI8120157.
https://digitalcommons.unl.edu/dissertations/AAI8120157