The latent period of either particle is noticeably shorter than the 30 to 33 h for HaV, a large dsDNA virus infecting H. The virus-to-host ratio at the start of the experiment for OIs1 LO and HaRNAV could not be determined, because the number of phages introduced with the algal viruses was unknown. The two virus systems examined in this study were isolated from nearby areas.
In our case, two unrelated viruses, and likely many others, coexist in the same environment and compete for the same host when we might expect one virus to outcompete the other. Harris' 13 explanation for the paradox of the plankton is that the ocean is not homogeneous.
Equilibrium is rarely attained; the frequency and intensity of environmental fluctuations are high enough that competitive exclusion is disrupted 8. The paradox of the viruses can likewise be explained by heterogeneity, but in this case it may be biological variability and the inherent dynamics of phytoplankton blooms that allow two virus systems infecting the same host to coexist.
The rapid release of progeny viruses following infection and the subsequent swift propagation of OIs1 infection lend this virus a competitive advantage over HaRNAV when the host density is high.
In this manner, latent period and burst size interact with the rapidly fluctuating host densities inherent in phytoplankton blooms and may lead to one virus being temporarily favored over another on short time scales. If this variability is overlaid against complex patterns of host range 28 , 29 , 32 and decay rates of viral infectivity 9 , 33 , it seems apparent that the biological variability is great enough to allow the coexistence of viruses infecting the same host.
We are only beginning to appreciate the diversity of viruses that infect marine phytoplankton. As we continue to discover novel algal viruses and gain insight into their biology, we will be able to better comprehend their undoubtedly complex role in shaping marine microbial ecosystems. Suttle, a grant to C. National Center for Biotechnology Information , U.
Journal List Appl Environ Microbiol v. Appl Environ Microbiol. Published online Oct Janice E. Brussaard , 2 and Curtis A.
Suttle 3. Corina P. Curtis A. Author information Article notes Copyright and License information Disclaimer. Phone: Fax: E-mail: ac. Received May 24; Accepted Oct 5. This article has been cited by other articles in PMC.
Abstract We used flow cytometry to examine the process of cell death in the bloom-forming alga Heterosigma akashiwo during infection by a double-stranded DNA virus OIs1 and a single-stranded RNA virus H. Open in a separate window. RESULTS Total in vivo chl a fluorescence of the control and infected Heterosigma akashiwo cultures tracked very well with the total cell numbers for each of the cultures. Bratbak, G. Egge, and M. Viral mortality of the marine alga Emiliania huxleyi Haptophyceae and termination of algal blooms.
Brussaard, C. Optimization of procedures for counting viruses by flow cytometry. Kuipers, and M. A mesocosm study of Phaeocystis globosa population dynamics.
Regulatory role of viruses in bloom control. Harmful Algae 4 : Marie, and G. Flow cytometric detection of viruses. Methods 85 : Marie, R. Thyrhaug, and G. Flow cytometric analysis of phytoplankton viability following viral infection. Thyrhaug, D. Flow cytometric analyses of viral infection in two marine phytoplankton species, Micromonas pusilla Prasinophyceae and Phaeocystis pouchetii Prymnesiophyceae.
Cole, J. Pace, and S. Bacterial production in fresh and saltwater ecosystems: a cross system overview. Connell, J. Diversity in tropical rain forests and coral reefs. Science : Cottrell, M. Dynamics of a lytic virus infecting the photosynthetic marine picoflagellate Micromonas pusilla.
Gobler, C. Hutchins, N. Fisher, E. Cosper, and S. Guillard, R. Culture of phytoplankton for feeding marine invertebrates, p. Smith and M. Chanley ed. Plenum Press, New York, N.
Hardin, B. The competitive exclusion principle. Harris, G. Phytoplankton ecology: structure, function and fluctuation. Chapman and Hall, New York, N. Honjo, T. Overview on bloom dynamics and physiological ecology of Heterosigma akashiwo , p. Smayda and Y. Shimizu ed. Elsevier Science Publishers B. Hutchinson, G. The paradox of the plankton. Jochem, F. Probing the physiological state of phytoplankton at the single-cell level. Scientia Marina 64 : Lang, A. Culley, and C. Genome sequence and characterization of a virus HaRNAV related to picorna-like viruses that infects the marine toxic bloom-forming alga Heterosigma akashiwo.
Virology : Lawrence, J. Effect of viral infection on sinking rates of Heterosigma akashiwo and its implications for bloom termination.
Chan, and C. Viruses causing lysis of the toxic bloom forming alga Heterosigma akashiwo Raphidophyceae are widespread in coastal sediments of British Columbia, Canada. Marie, D. Partensky, D. Vaulot, and C. Enumeration of phytoplankton, bacteria, and viruses in marine samples, p.
Robinson ed. Murray, A. Viral dynamics: a model of the effects of size, shape, motion and abundance of single-celled planktonic organisms on other particles. Nagasaki, K. Isolation of a virus infectious to the harmful bloom causing microalga Heterosigma akashiwo Raphidophyceae. Ando, I. Imai, S. Itakura, and Y. Virus-like particles in Heterosigma akashiwo Raphidophyceae : a possible red tide disintegration mechanism.
Ando, S. Itakura, I. Imai, and Y. Viral mortality in the final stage of Heterosigma akashiwo Raphidophyceae red tide. Plankton Res.
Tarutani, and M. Thus, biotic factors such as host specificity and viral life cycle, and not just abiotic processes such as dispersal, affect marine RNA virus distribution. Sequence differences relative to reference genomes imply that virus quasispecies are under purifying selection, with synonymous single-nucleotide variations dominating in genomes from geographically distinct regions resulting in conservation of amino acid sequences.
Conversely, sequences from coastal South Africa that mapped to marine RNA virus JP-A exhibited more nonsynonymous mutations, probably representing amino acid changes that accumulated over a longer separation. This biogeographical analysis of marine RNA viruses demonstrates that purifying selection is occurring across oceanographic provinces.
These data add to the spectrum of known marine RNA virus genomes, show the importance of dispersal and purifying selection for these viruses, and indicate that closely related RNA viruses are pathogens of eukaryotic microbes across oceans.
This is the first study that analyzes marine environmental RNA viral assemblages in an evolutionary and broad geographical context. This study contributes the largest marine RNA virus metagenomic data set to date, substantially increasing the sequencing space for RNA viruses and also providing a baseline for comparisons of marine RNA virus diversity.
0コメント