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Pseudo-nitzschia Challenged with Co-occurring Viral Communities Display Diverse Infection Phenotypes.

Carlson MC, McCary ND, Leach TS, Rocap G - Front Microbiol (2016)

Bottom Line: Diatom-virus dynamics were explored by sampling every month at two coastal and estuarine locations in Washington state, USA resulting in 41 new isolates of the pennate diatom Pseudo-nitzschia and 20 environmental virus samples.Isolates that were infected by the most viral communities also had the highest maximum observed viral titers (as high as 16000 infectious units ml(-1)).The interactions between Pseudo-nitzschia and the viral communities highlight the diversity of diatoms and emphasize the complexity and variability of diatom-virus dynamics in the ocean.

View Article: PubMed Central - PubMed

Affiliation: School of Oceanography, University of Washington Seattle, WA, USA.

ABSTRACT
Viruses are catalysts of biogeochemical cycling, architects of microbial community structure, and terminators of phytoplankton blooms. Viral lysis of diatoms, a key group of eukaryotic phytoplankton, has the potential to impact carbon export and marine food webs. However, the impact of viruses on diatom abundance and community composition is unknown. Diatom-virus dynamics were explored by sampling every month at two coastal and estuarine locations in Washington state, USA resulting in 41 new isolates of the pennate diatom Pseudo-nitzschia and 20 environmental virus samples. We conducted a total of 820 pair-wise crosses of the Pseudo-nitzschia isolates and viral communities. Viral communities infected Pseudo-nitzschia isolates in 8% of the crosses overall and 16% of crosses when the host and viral communities were isolated from the same sample. Isolates ranged in their permissivity to infection with some isolates not infected by any viral samples and others infected by up to 10 viral communities. Isolates that were infected by the most viral communities also had the highest maximum observed viral titers (as high as 16000 infectious units ml(-1)). Titers of the viral communities were host dependent, as titers for one viral sample on eight different hosts spanned four orders of magnitude. Sequencing of the Pseudo-nitzschia Internal Transcribed Spacer 1 (ITS1) of the revealed multiple subgroups of hosts with 100% ITS1 identities that were infected by different viral communities. Indeed, we repeatedly isolated groups of isolates with identical ITS1 sequences from the same water sample that displayed different viral infection phenotypes. The interactions between Pseudo-nitzschia and the viral communities highlight the diversity of diatoms and emphasize the complexity and variability of diatom-virus dynamics in the ocean.

No MeSH data available.


Related in: MedlinePlus

Locations of sampling. Penn Cove, located in the Puget Sound estuary, and Grays Harbor located on the coast of Washington state, USA. Inset map of North America shows the region of sampling.
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Figure 1: Locations of sampling. Penn Cove, located in the Puget Sound estuary, and Grays Harbor located on the coast of Washington state, USA. Inset map of North America shows the region of sampling.

Mentions: Samples were collected at Penn Cove, Washington (48.2397, -122.6795) and Grays Harbor, Washington (46.7625, -124.0898) (Figure 1) monthly from April 2013 to April 2014 except from November to February, when sampling occurred at Penn Cove in November and January and at Grays Harbor in December and February. Approximately 15 L of surface water was filtered through triplicate 3.0 and 0.2 μm 147 mm polyethersulfone filters (Millepore) with a peristaltic pump within 2 h of sampling. The filters were frozen at -80°C for molecular analysis. The viruses in the filtrate were precipitated by adding iron chloride (1 g L-1) and incubating for 12 h at 13°C in the dark (John et al., 2011). The iron-precipitated viruses were collected by filtering on to 2.0 and 0.2 μm 147 polycarbonate filters (Millepore). The viruses were resuspended from both filters by incubating them with 0.2 M ascorbate-0.25 M EDTA-Mg2-0.25 M Tris-HCL for at least 24 h with periodic shaking (John et al., 2011). The resuspended viruses were purified to remove Fe-EDTA complexes by adding 10% poly ethylene glycol (PEG) and 2% NaCl final concentrations and incubating at 4°C for 24 h. The samples were then spun at 12000 × g for 20 min at 4°C to pellet the viruses. The supernatant was removed and the pellet washed three times with modified SM buffer (0.4 M NaCl, 0.02 M MgSO4, 0.05 M Tris, pH 7.5). The pellet was resuspended in 2 ml SM buffer, spun, and again washed three times with modified SM buffer. The final pellet was resuspended in 20 ml SM buffer. The PEG was removed according to Colombet and Sime-ngando (2012) by adding 1 M KCl and incubating the samples on ice for 20 min. The solution was centrifuged at 8000 × g for 10 min at 4°C and the supernatant containing the viruses was removed. The purified virus concentrates were stored at 4°C.


Pseudo-nitzschia Challenged with Co-occurring Viral Communities Display Diverse Infection Phenotypes.

Carlson MC, McCary ND, Leach TS, Rocap G - Front Microbiol (2016)

Locations of sampling. Penn Cove, located in the Puget Sound estuary, and Grays Harbor located on the coast of Washington state, USA. Inset map of North America shows the region of sampling.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4837327&req=5

Figure 1: Locations of sampling. Penn Cove, located in the Puget Sound estuary, and Grays Harbor located on the coast of Washington state, USA. Inset map of North America shows the region of sampling.
Mentions: Samples were collected at Penn Cove, Washington (48.2397, -122.6795) and Grays Harbor, Washington (46.7625, -124.0898) (Figure 1) monthly from April 2013 to April 2014 except from November to February, when sampling occurred at Penn Cove in November and January and at Grays Harbor in December and February. Approximately 15 L of surface water was filtered through triplicate 3.0 and 0.2 μm 147 mm polyethersulfone filters (Millepore) with a peristaltic pump within 2 h of sampling. The filters were frozen at -80°C for molecular analysis. The viruses in the filtrate were precipitated by adding iron chloride (1 g L-1) and incubating for 12 h at 13°C in the dark (John et al., 2011). The iron-precipitated viruses were collected by filtering on to 2.0 and 0.2 μm 147 polycarbonate filters (Millepore). The viruses were resuspended from both filters by incubating them with 0.2 M ascorbate-0.25 M EDTA-Mg2-0.25 M Tris-HCL for at least 24 h with periodic shaking (John et al., 2011). The resuspended viruses were purified to remove Fe-EDTA complexes by adding 10% poly ethylene glycol (PEG) and 2% NaCl final concentrations and incubating at 4°C for 24 h. The samples were then spun at 12000 × g for 20 min at 4°C to pellet the viruses. The supernatant was removed and the pellet washed three times with modified SM buffer (0.4 M NaCl, 0.02 M MgSO4, 0.05 M Tris, pH 7.5). The pellet was resuspended in 2 ml SM buffer, spun, and again washed three times with modified SM buffer. The final pellet was resuspended in 20 ml SM buffer. The PEG was removed according to Colombet and Sime-ngando (2012) by adding 1 M KCl and incubating the samples on ice for 20 min. The solution was centrifuged at 8000 × g for 10 min at 4°C and the supernatant containing the viruses was removed. The purified virus concentrates were stored at 4°C.

Bottom Line: Diatom-virus dynamics were explored by sampling every month at two coastal and estuarine locations in Washington state, USA resulting in 41 new isolates of the pennate diatom Pseudo-nitzschia and 20 environmental virus samples.Isolates that were infected by the most viral communities also had the highest maximum observed viral titers (as high as 16000 infectious units ml(-1)).The interactions between Pseudo-nitzschia and the viral communities highlight the diversity of diatoms and emphasize the complexity and variability of diatom-virus dynamics in the ocean.

View Article: PubMed Central - PubMed

Affiliation: School of Oceanography, University of Washington Seattle, WA, USA.

ABSTRACT
Viruses are catalysts of biogeochemical cycling, architects of microbial community structure, and terminators of phytoplankton blooms. Viral lysis of diatoms, a key group of eukaryotic phytoplankton, has the potential to impact carbon export and marine food webs. However, the impact of viruses on diatom abundance and community composition is unknown. Diatom-virus dynamics were explored by sampling every month at two coastal and estuarine locations in Washington state, USA resulting in 41 new isolates of the pennate diatom Pseudo-nitzschia and 20 environmental virus samples. We conducted a total of 820 pair-wise crosses of the Pseudo-nitzschia isolates and viral communities. Viral communities infected Pseudo-nitzschia isolates in 8% of the crosses overall and 16% of crosses when the host and viral communities were isolated from the same sample. Isolates ranged in their permissivity to infection with some isolates not infected by any viral samples and others infected by up to 10 viral communities. Isolates that were infected by the most viral communities also had the highest maximum observed viral titers (as high as 16000 infectious units ml(-1)). Titers of the viral communities were host dependent, as titers for one viral sample on eight different hosts spanned four orders of magnitude. Sequencing of the Pseudo-nitzschia Internal Transcribed Spacer 1 (ITS1) of the revealed multiple subgroups of hosts with 100% ITS1 identities that were infected by different viral communities. Indeed, we repeatedly isolated groups of isolates with identical ITS1 sequences from the same water sample that displayed different viral infection phenotypes. The interactions between Pseudo-nitzschia and the viral communities highlight the diversity of diatoms and emphasize the complexity and variability of diatom-virus dynamics in the ocean.

No MeSH data available.


Related in: MedlinePlus