Viruses of symbiotic Chlorella -like algae isolated from Paramecium bursaria and Hydra viridis

Abstract

We previously reported that isolation of symbiotic Chloreila-like algae from the Florida strain ofHydra viridis induced replication of a virus (designated HVCV-1) in the algae. We now report that isolation ofsymbiotic Chlorella-like algae from four other sources of green hydra and one source ofthe protozoan Paramecium bursaria also induced virus synthesis. Algae from one of these hydra contained a virus identical to HVCV-1 (based on its rate of sedimentation, buoyant density, reaction to HVCV-1 antiserum, and DNA restriction fragments) whereas algae from the other three hydra contained. another similar, but distinct, virus (designated HVCV-2). The virus from the paramecium algae (designated PBCV-1) was distinct from both HVCV-1 and HVCV-2. The symbiotic algae in the hydra could also be distinguished ultrastructurally. Chloroplasts of both algae that produced HVCV-1 lacked a pyrenoid whereas chloroplasts of the other three symbiotic algae contained pyrenoids. Since all symbiotic eukaryotic algae we have examined have had virus, a potential viral role in symbiosis is suggested.

The Symbiotic Relationship between Bacteria and a Mesogastropod Snail, <i>Alviniconcha hessleri</i>, collected from Hydrothermal Vents of the Mariana Back-Arc Basin

“…For example, root-nodule bacteria lacking their plasmid on which symbiotic genes are located cannot construct symbiotic association with their leguminous hosts (Truchet et al, 1985). Van Etten et al (1982) suggested that viruses in zoochlorellae isolated from five sources of green hydra and protozoan Paramecium bursaria may play role in determining the acceptability of the zoochlorellae to the host.…”

Mutual Exclusion Occurs in a Chlorella-like Green Alga Inoculated with Two Viruses

“…Under these conditions about 1 x 103 plaques were recovered; viruses purified from these plaques were insensitive to PBCV-1 antiserum. Polyclonal antisera to PBCV-1, NY-2C and EPA 1 were raised against purified viruses as described previously (Van Etten et al, 1982).…”

Diversity of algal viruses in various North American freshwater environments

“…The first reports of eukaryotic phytoplankton infection came from cultivation studies of viruses that parasitise the marine alga Micromonas pusilla (Mayer & Taylor 1979) and freshwater symbiotic Chlorella-like algae (van Etten et al 1982). Since then, the majority of viruses that infect eukaryotic algae (12 out of 13 virus genera) have been assigned to the virus family Phycodnaviridae, are classified as Nucleocytoplasmic Large DNA Viruses (NCLDVs) (Iyer et al 2001), and have been cultivated from hosts belonging to the algal classes Chlorophyceae, Chrysophyceae, Dinophyceae, Phaeophyceae, Prasinophyceae, Prymnesiophyceae and Raphidophyceae (reviewed in: Brussaard 2004, Dunigan et al 2006.…”