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Life-cycle and genome of OtV5, a large DNA virus of the pelagic marine unicellular green alga Ostreococcus tauri.

Derelle E, Ferraz C, Escande ML, Eychenié S, Cooke R, Piganeau G, Desdevises Y, Bellec L, Moreau H, Grimsley N - PLoS ONE (2008)

Bottom Line: OtV5 is a lytic phycodnavirus which unexpectedly does not degrade its host chromosomes before the host cell bursts.OtV5 carries at least one predicted gene whose protein closely resembles its host counterpart and several other host-like sequences, suggesting that horizontal gene transfers between host and viral genomes may occur frequently on an evolutionary scale.Fifty seven percent of the 268 predicted proteins present no similarities with any known protein in Genbank, underlining the wealth of undiscovered biological diversity present in oceanic viruses, which are estimated to harbour 200Mt of carbon.

View Article: PubMed Central - PubMed

Affiliation: Université Pierre et Marie Curie-Paris 06, Laboratoire Arago, Banyuls-sur-Mer, France.

ABSTRACT
Large DNA viruses are ubiquitous, infecting diverse organisms ranging from algae to man, and have probably evolved from an ancient common ancestor. In aquatic environments, such algal viruses control blooms and shape the evolution of biodiversity in phytoplankton, but little is known about their biological functions. We show that Ostreococcus tauri, the smallest known marine photosynthetic eukaryote, whose genome is completely characterized, is a host for large DNA viruses, and present an analysis of the life-cycle and 186,234 bp long linear genome of OtV5. OtV5 is a lytic phycodnavirus which unexpectedly does not degrade its host chromosomes before the host cell bursts. Analysis of its complete genome sequence confirmed that it lacks expected site-specific endonucleases, and revealed the presence of 16 genes whose predicted functions are novel to this group of viruses. OtV5 carries at least one predicted gene whose protein closely resembles its host counterpart and several other host-like sequences, suggesting that horizontal gene transfers between host and viral genomes may occur frequently on an evolutionary scale. Fifty seven percent of the 268 predicted proteins present no similarities with any known protein in Genbank, underlining the wealth of undiscovered biological diversity present in oceanic viruses, which are estimated to harbour 200Mt of carbon.

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Related in: MedlinePlus

Assays for the presence of lytic viruses.A: Marine samples from Thau Lagoon (43° 24′N, 3° 36′E) incubated with the host strain OTH95 (isolated from the same place 14 years previously). Ticked boxes indicate lysis, crossed no lysis, and diamonds show mock-inoculated host cells. B: Viral lysis plaques in a plated gel of host cells.
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pone-0002250-g001: Assays for the presence of lytic viruses.A: Marine samples from Thau Lagoon (43° 24′N, 3° 36′E) incubated with the host strain OTH95 (isolated from the same place 14 years previously). Ticked boxes indicate lysis, crossed no lysis, and diamonds show mock-inoculated host cells. B: Viral lysis plaques in a plated gel of host cells.

Mentions: The presence or absence of viruses in water samples was assayed by filtering the water to eliminate bacterial cells and protists, then mixing the filtrate with cultures of the host, O. tauri. Lysis of the host cells was usually observed about 1 week after inoculation (Figure 1A). By mixing a sufficient number of host cells (typically about 108 cells) in culture medium with 1 or 10 ml of seawater before plating in the soft gel, individual plaques could be visualized in a growing green lawn on the plate (Figure 1B, see the materials and methods [M&M] section).


Life-cycle and genome of OtV5, a large DNA virus of the pelagic marine unicellular green alga Ostreococcus tauri.

Derelle E, Ferraz C, Escande ML, Eychenié S, Cooke R, Piganeau G, Desdevises Y, Bellec L, Moreau H, Grimsley N - PLoS ONE (2008)

Assays for the presence of lytic viruses.A: Marine samples from Thau Lagoon (43° 24′N, 3° 36′E) incubated with the host strain OTH95 (isolated from the same place 14 years previously). Ticked boxes indicate lysis, crossed no lysis, and diamonds show mock-inoculated host cells. B: Viral lysis plaques in a plated gel of host cells.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2386258&req=5

pone-0002250-g001: Assays for the presence of lytic viruses.A: Marine samples from Thau Lagoon (43° 24′N, 3° 36′E) incubated with the host strain OTH95 (isolated from the same place 14 years previously). Ticked boxes indicate lysis, crossed no lysis, and diamonds show mock-inoculated host cells. B: Viral lysis plaques in a plated gel of host cells.
Mentions: The presence or absence of viruses in water samples was assayed by filtering the water to eliminate bacterial cells and protists, then mixing the filtrate with cultures of the host, O. tauri. Lysis of the host cells was usually observed about 1 week after inoculation (Figure 1A). By mixing a sufficient number of host cells (typically about 108 cells) in culture medium with 1 or 10 ml of seawater before plating in the soft gel, individual plaques could be visualized in a growing green lawn on the plate (Figure 1B, see the materials and methods [M&M] section).

Bottom Line: OtV5 is a lytic phycodnavirus which unexpectedly does not degrade its host chromosomes before the host cell bursts.OtV5 carries at least one predicted gene whose protein closely resembles its host counterpart and several other host-like sequences, suggesting that horizontal gene transfers between host and viral genomes may occur frequently on an evolutionary scale.Fifty seven percent of the 268 predicted proteins present no similarities with any known protein in Genbank, underlining the wealth of undiscovered biological diversity present in oceanic viruses, which are estimated to harbour 200Mt of carbon.

View Article: PubMed Central - PubMed

Affiliation: Université Pierre et Marie Curie-Paris 06, Laboratoire Arago, Banyuls-sur-Mer, France.

ABSTRACT
Large DNA viruses are ubiquitous, infecting diverse organisms ranging from algae to man, and have probably evolved from an ancient common ancestor. In aquatic environments, such algal viruses control blooms and shape the evolution of biodiversity in phytoplankton, but little is known about their biological functions. We show that Ostreococcus tauri, the smallest known marine photosynthetic eukaryote, whose genome is completely characterized, is a host for large DNA viruses, and present an analysis of the life-cycle and 186,234 bp long linear genome of OtV5. OtV5 is a lytic phycodnavirus which unexpectedly does not degrade its host chromosomes before the host cell bursts. Analysis of its complete genome sequence confirmed that it lacks expected site-specific endonucleases, and revealed the presence of 16 genes whose predicted functions are novel to this group of viruses. OtV5 carries at least one predicted gene whose protein closely resembles its host counterpart and several other host-like sequences, suggesting that horizontal gene transfers between host and viral genomes may occur frequently on an evolutionary scale. Fifty seven percent of the 268 predicted proteins present no similarities with any known protein in Genbank, underlining the wealth of undiscovered biological diversity present in oceanic viruses, which are estimated to harbour 200Mt of carbon.

Show MeSH
Related in: MedlinePlus