ULTRASTRUCTURE OF THE INFECTION CYCLE OF CYANOPHAGE SM‐2 IN SYNECHOCOCCUS ELONGATUS (CYANOPHYCEAE)¹

Abstract

Transmission electron microscopy was used to examine the ultrastructure aspects of cyanophage SM‐2 replication in its host Synechococcus elongatus Naegeli UTEX 563. Filled virion heads were observed 10 h after infection, correlating well with the 6–8 h eclipse period for the virus. As the infection cycle proceeded from 10–50 h, additional virion heads accumulated at either end of the nucleoplasm. Of the several cyanophage that lyse unicellular bluegreen algae, this is unique to the SM‐2 system. The surrounding photosynthetic lamellae remained intact throughout the infection cycle. The nucleic acid composition of SM‐2 was determined as DNA.

Dynamics of cyanophage-like particles and algicidal bacteria causing Microcystis aeruginosa mortality

“…Previous studies have also reported that such infection by cyanophages is not strictly species-specific (Daft et al 1970;Hennes et al 1985;Leach et al 1980;Morris 1963, 1964). However, in the present study, the densities of cyanophage-like particles were below the detection limit when the densities of M. aeruginosa were low during winter (Figs.…”

“…(Leach et al 1980); Lyngbya sp., Plectonema sp., and Phormidium sp. (Daft et al 1970;Morris 1963, 1964); and M. aeruginosa (Fox et al 1976).…”

Significance of bacteriophages for controlling bacterioplankton growth in a mesotrophic lake

“…In total, Ͼ900 cells per sample were examined. Cyanobacteria containing only polyhedral bodies were excluded from counting (14). Electron micrographs of phage-infected bacteria were taken at a magnification of ϫ60,000 with AGFA Scientia 100 film.…”

Viruses in Marine Planktonic Systems

“…It should be noted that the same factor probably does not apply to cyanobacteria. Padan and Shilo (1973) and Leach et al (1980) indicate that mature intracellular cyanophage can become abundant about halfway through the infection cycle, suggesting a conversion factor of about 4. Thus given that only 1-3% of the native population appear infected (Proctor and Fuhrman, 1990), viruses may account for only 5-10% of the mortality of cyanobacteria.…”