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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

Titers of infectious units over time in Julian days with monthly increments at (A) Penn Cove and (B) Grays Harbor. Each of the nine strains was crossed with each of the Penn Cove or Grays Harbor viral communities. Cool colors are hosts isolated from Penn Cove, warm colors are hosts isolated from Grays Harbor. Error bars are 95% confidence intervals from 5 well MPN tables. Values below the limit of detection of 1.8 infectious units ml-1 are not shown.
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Figure 5: Titers of infectious units over time in Julian days with monthly increments at (A) Penn Cove and (B) Grays Harbor. Each of the nine strains was crossed with each of the Penn Cove or Grays Harbor viral communities. Cool colors are hosts isolated from Penn Cove, warm colors are hosts isolated from Grays Harbor. Error bars are 95% confidence intervals from 5 well MPN tables. Values below the limit of detection of 1.8 infectious units ml-1 are not shown.

Mentions: More detailed changes in viral abundance over time were quantified by measuring titers on Pseudo-nitzschia strains that represented a range of susceptibilities to the viral communities. Host strains P. pungens PC45 and P. pungens GH20 were infected by 5 and 10 of the 20 viral communities respectively, while P. sp 1 GH10, P. pungens GH30, and P. pungens GH34 were infected by 2 or 3 of the 20 viral communities and P. pungens PC62, P. pungens PC40, and P. australis GH28 were each infected by a single viral community. Viral titers were determined for each of these nine hosts with every viral community. Measures of viral abundance varied by time and by host (Figures 5A,B). Abundance of viruses infecting host strain P. pungens PC45 was high, with three occurrences of above 300 infectious units ml-1 of whole seawater, all in summer months. The highest viral infectivity of over 104 infectious units ml-1 seawater was observed on this strain crossed with the July Penn Cove viral community (Figure 5A). Interestingly, PC45 was isolated from the same water sample. However, strain P. pungens PC40, isolated at the same time from the same water sample as PC45, had four orders of magnitude lower viral abundance when crossed with the same July Penn Cove virus community (Figure 5A). This viral community did not infect the other six host strains on which titers were performed. In contrast to the high viral titers on PC45 in the summer at both locations, strain P. pungens GH20 had the highest titers in the fall and winter months at both locations. Host strains PC45 and GH20 that were infected by a high number of viral samples (Figure 4) also had the highest maximum observed titers, 16000 and 540 infectious units ml-1, respectively, compared with less infected strains like PC40 and GH28, which had lower maximum titers, 2 and 7.8 infectious units ml-1 respectively.


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

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

Titers of infectious units over time in Julian days with monthly increments at (A) Penn Cove and (B) Grays Harbor. Each of the nine strains was crossed with each of the Penn Cove or Grays Harbor viral communities. Cool colors are hosts isolated from Penn Cove, warm colors are hosts isolated from Grays Harbor. Error bars are 95% confidence intervals from 5 well MPN tables. Values below the limit of detection of 1.8 infectious units ml-1 are not shown.
© Copyright Policy
Related In: Results  -  Collection

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

Figure 5: Titers of infectious units over time in Julian days with monthly increments at (A) Penn Cove and (B) Grays Harbor. Each of the nine strains was crossed with each of the Penn Cove or Grays Harbor viral communities. Cool colors are hosts isolated from Penn Cove, warm colors are hosts isolated from Grays Harbor. Error bars are 95% confidence intervals from 5 well MPN tables. Values below the limit of detection of 1.8 infectious units ml-1 are not shown.
Mentions: More detailed changes in viral abundance over time were quantified by measuring titers on Pseudo-nitzschia strains that represented a range of susceptibilities to the viral communities. Host strains P. pungens PC45 and P. pungens GH20 were infected by 5 and 10 of the 20 viral communities respectively, while P. sp 1 GH10, P. pungens GH30, and P. pungens GH34 were infected by 2 or 3 of the 20 viral communities and P. pungens PC62, P. pungens PC40, and P. australis GH28 were each infected by a single viral community. Viral titers were determined for each of these nine hosts with every viral community. Measures of viral abundance varied by time and by host (Figures 5A,B). Abundance of viruses infecting host strain P. pungens PC45 was high, with three occurrences of above 300 infectious units ml-1 of whole seawater, all in summer months. The highest viral infectivity of over 104 infectious units ml-1 seawater was observed on this strain crossed with the July Penn Cove viral community (Figure 5A). Interestingly, PC45 was isolated from the same water sample. However, strain P. pungens PC40, isolated at the same time from the same water sample as PC45, had four orders of magnitude lower viral abundance when crossed with the same July Penn Cove virus community (Figure 5A). This viral community did not infect the other six host strains on which titers were performed. In contrast to the high viral titers on PC45 in the summer at both locations, strain P. pungens GH20 had the highest titers in the fall and winter months at both locations. Host strains PC45 and GH20 that were infected by a high number of viral samples (Figure 4) also had the highest maximum observed titers, 16000 and 540 infectious units ml-1, respectively, compared with less infected strains like PC40 and GH28, which had lower maximum titers, 2 and 7.8 infectious units ml-1 respectively.

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