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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

Total number of viral community samples that resulted in an infection for each host strain. Colors correspond to the number of replicates that were lysed and the corresponding range of infectious units based on most probable number tables for each infectious cross. Infectious units ml-1 of seawater were calculated assuming 100% retention of infectivity and accounting for the effect of concentrating virus from 20 L of seawater and volume of viral concentrates added to host cultures in crosses.
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Figure 4: Total number of viral community samples that resulted in an infection for each host strain. Colors correspond to the number of replicates that were lysed and the corresponding range of infectious units based on most probable number tables for each infectious cross. Infectious units ml-1 of seawater were calculated assuming 100% retention of infectivity and accounting for the effect of concentrating virus from 20 L of seawater and volume of viral concentrates added to host cultures in crosses.

Mentions: Pseudo-nitzschia isolates ranged widely in their susceptibility to infection by the viral communities (Figure 4). Thirteen host strains showed no detectable signs of infection from any environmental virus community. The remaining 28 strains were infected at least once, and ranged from being infected by one viral community to up to 10 viral communities. Five Pseudo-nitzschia hosts, P. pungens GH29, P. pungens PC45, P. australis GH31, P. pungens GH23, and P. pungens GH20 were infected by 5 or more viral communities, and accounted for 48% of the total infectious crosses observed. In some cases replicates displayed variable survival within one host-virus community cross, suggesting the infecting virus or viruses were present at too low a concentration to successfully infect all wells. Based on MPN calculations, bounds of infectious units ml-1 of whole seawater could be put on infectious crosses where between 1 and 4 replicates died (e.g., 1 replicate death = 2–11 infectious units ml-1, 4 replicates death = 13–34 infectious units ml-1) (Figure 4). The samples in crosses that resulted in infection in all five replicates had titers that were at least 23 infectious units ml-1 but the upper bound of infectious units was unknown. Hosts infected by more communities had infectious crosses suggesting more infectious units ml-1 (linear regression R2 = 0.536, p < 0.01). In the most infected host, for example, P. pungens GH20, all five replicates died in 8 out of the 10 infectious crosses (Figure 4).


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

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

Total number of viral community samples that resulted in an infection for each host strain. Colors correspond to the number of replicates that were lysed and the corresponding range of infectious units based on most probable number tables for each infectious cross. Infectious units ml-1 of seawater were calculated assuming 100% retention of infectivity and accounting for the effect of concentrating virus from 20 L of seawater and volume of viral concentrates added to host cultures in crosses.
© Copyright Policy
Related In: Results  -  Collection

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

Figure 4: Total number of viral community samples that resulted in an infection for each host strain. Colors correspond to the number of replicates that were lysed and the corresponding range of infectious units based on most probable number tables for each infectious cross. Infectious units ml-1 of seawater were calculated assuming 100% retention of infectivity and accounting for the effect of concentrating virus from 20 L of seawater and volume of viral concentrates added to host cultures in crosses.
Mentions: Pseudo-nitzschia isolates ranged widely in their susceptibility to infection by the viral communities (Figure 4). Thirteen host strains showed no detectable signs of infection from any environmental virus community. The remaining 28 strains were infected at least once, and ranged from being infected by one viral community to up to 10 viral communities. Five Pseudo-nitzschia hosts, P. pungens GH29, P. pungens PC45, P. australis GH31, P. pungens GH23, and P. pungens GH20 were infected by 5 or more viral communities, and accounted for 48% of the total infectious crosses observed. In some cases replicates displayed variable survival within one host-virus community cross, suggesting the infecting virus or viruses were present at too low a concentration to successfully infect all wells. Based on MPN calculations, bounds of infectious units ml-1 of whole seawater could be put on infectious crosses where between 1 and 4 replicates died (e.g., 1 replicate death = 2–11 infectious units ml-1, 4 replicates death = 13–34 infectious units ml-1) (Figure 4). The samples in crosses that resulted in infection in all five replicates had titers that were at least 23 infectious units ml-1 but the upper bound of infectious units was unknown. Hosts infected by more communities had infectious crosses suggesting more infectious units ml-1 (linear regression R2 = 0.536, p < 0.01). In the most infected host, for example, P. pungens GH20, all five replicates died in 8 out of the 10 infectious crosses (Figure 4).

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