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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

Pseudo-nitzschia isolates obtained and community composition at (A,C) Penn Cove and (B,D) Grays Harbor from April 2013 to April 2014. Time of sampling is shown in Julian day and monthly increments on the x-axis. Solid lines are water temperature and dashed lines are nitrate concentration. Pseudo-nitzschia species are colored by phylogenetic clade (Lundholm et al., 2002, Guannel, unpublished data) with members of clade 1 represented by warm colors and clade 2 represented by cool colors. Unidentifiable ARISA fragments are represented in grayscale. Black bars represent ARISA fragments for isolated Pseudo-nitzschia with no species identification. ∗ indicates months with no detectable Pseudo-nitzschia by ARISA or in net tows.
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Figure 2: Pseudo-nitzschia isolates obtained and community composition at (A,C) Penn Cove and (B,D) Grays Harbor from April 2013 to April 2014. Time of sampling is shown in Julian day and monthly increments on the x-axis. Solid lines are water temperature and dashed lines are nitrate concentration. Pseudo-nitzschia species are colored by phylogenetic clade (Lundholm et al., 2002, Guannel, unpublished data) with members of clade 1 represented by warm colors and clade 2 represented by cool colors. Unidentifiable ARISA fragments are represented in grayscale. Black bars represent ARISA fragments for isolated Pseudo-nitzschia with no species identification. ∗ indicates months with no detectable Pseudo-nitzschia by ARISA or in net tows.

Mentions: Samples for viral communities and Pseudo-nitzschia isolates were taken every month from April 2013 to April 2014 (except for December and February in Penn Cove and November and January in Grays Harbor) at two sites (Figure 1). Penn Cove is a shallow (20 m depth) inlet in the Puget Sound estuary and Grays Harbor is located on the Pacific coast of Washington State. In total, 20 environmental virus communities were sampled and 41 Pseudo-nitzschia strains were isolated. Pseudo-nitzschia were isolated successfully during summer months when water temperatures were warm (13–17°C), nutrient concentrations were low (<6 μM NO3-) and Pseudo-nitzschia was abundant enough to be found in net tow samples (Figures 2A,B). Nitrate concentrations were positively correlated with phosphate and silicate concentrations at Grays Harbor and Penn Cove, respectively (p < 0.001). Only in June 2013 in Penn Cove was Pseudo-nitzschia a dominant member of the phytoplankton community overall.


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

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

Pseudo-nitzschia isolates obtained and community composition at (A,C) Penn Cove and (B,D) Grays Harbor from April 2013 to April 2014. Time of sampling is shown in Julian day and monthly increments on the x-axis. Solid lines are water temperature and dashed lines are nitrate concentration. Pseudo-nitzschia species are colored by phylogenetic clade (Lundholm et al., 2002, Guannel, unpublished data) with members of clade 1 represented by warm colors and clade 2 represented by cool colors. Unidentifiable ARISA fragments are represented in grayscale. Black bars represent ARISA fragments for isolated Pseudo-nitzschia with no species identification. ∗ indicates months with no detectable Pseudo-nitzschia by ARISA or in net tows.
© Copyright Policy
Related In: Results  -  Collection

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

Figure 2: Pseudo-nitzschia isolates obtained and community composition at (A,C) Penn Cove and (B,D) Grays Harbor from April 2013 to April 2014. Time of sampling is shown in Julian day and monthly increments on the x-axis. Solid lines are water temperature and dashed lines are nitrate concentration. Pseudo-nitzschia species are colored by phylogenetic clade (Lundholm et al., 2002, Guannel, unpublished data) with members of clade 1 represented by warm colors and clade 2 represented by cool colors. Unidentifiable ARISA fragments are represented in grayscale. Black bars represent ARISA fragments for isolated Pseudo-nitzschia with no species identification. ∗ indicates months with no detectable Pseudo-nitzschia by ARISA or in net tows.
Mentions: Samples for viral communities and Pseudo-nitzschia isolates were taken every month from April 2013 to April 2014 (except for December and February in Penn Cove and November and January in Grays Harbor) at two sites (Figure 1). Penn Cove is a shallow (20 m depth) inlet in the Puget Sound estuary and Grays Harbor is located on the Pacific coast of Washington State. In total, 20 environmental virus communities were sampled and 41 Pseudo-nitzschia strains were isolated. Pseudo-nitzschia were isolated successfully during summer months when water temperatures were warm (13–17°C), nutrient concentrations were low (<6 μM NO3-) and Pseudo-nitzschia was abundant enough to be found in net tow samples (Figures 2A,B). Nitrate concentrations were positively correlated with phosphate and silicate concentrations at Grays Harbor and Penn Cove, respectively (p < 0.001). Only in June 2013 in Penn Cove was Pseudo-nitzschia a dominant member of the phytoplankton community overall.

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