marine_viruses

marine_viruses - f o c u S o n M a R I n E M I c R o b IE...

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University of British Columbia, Departments of Earth and Ocean Sciences, Botany, and Microbiology and Immunology, 1461 BioSciences, 6270 University Boulevard, Vancouver, British Columbia V6T 1Z4, Canada. e-mail: csuttle@eos.ubc.ca doi:10.1038/nrmicro1750 Virosphere The portion of the Earth in which viruses occur or which is affected by viruses; sometimes called the viriosphere. Heterotrophic Describes an organism that uses organic compounds for both energy and growth. Autotrophic Describes an organism that uses inorganic compounds for both energy and growth. In the oceans phytoplankton are the most common autotrophs. Marine viruses — major players in the global ecosystem Curtis A. Suttle Abstract | Viruses are by far the most abundant ‘lifeforms’ in the oceans and are the reservoir of most of the genetic diversity in the sea. The estimated 10 30 viruses in the ocean, if stretched end to end, would span farther than the nearest 60 galaxies. Every second, approximately 10 23 viral infections occur in the ocean. These infections are a major source of mortality, and cause disease in a range of organisms, from shrimp to whales. As a result, viruses influence the composition of marine communities and are a major force behind biogeochemical cycles. Each infection has the potential to introduce new genetic information into an organism or progeny virus, thereby driving the evolution of both host and viral assemblages. Probing this vast reservoir of genetic and biological diversity continues to yield exciting discoveries. The oceans cover more than 70% of the Earth’s surface. They control the climate, provide a significant amount of the protein that is consumed globally and produce approximately half of the Earth’s oxygen. Microorganisms are a major force behind the nutrient and energy cycles in the world’s oceans and constitute more than 90% of the living biomass in the sea. It is estimated that viruses kill approximately 20% of this biomass per day. As well as being agents of mortality, viruses are one of the largest reservoirs of unexplored genetic diversity on the Earth. The virosphere is probably inclusive of every environ- ment on the Earth, from the atmosphere to the deep bio- sphere. However, nowhere is the importance of viruses more evident than in the world’s oceans. The observation that millions of virus-like particles are present in every millilitre of ocean water 1 , coupled with evidence that viruses are substantial agents of mortality in heterotrophic and autotrophic plankton 2,3 , has focused attention on the enormous underestimation of the effects of viral infec- tion in the sea. It has become apparent that viruses are major players in the mortality of marine microorganisms and, consequently, affect nutrient and energy cycles as well as the structure of microbial communities.
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This note was uploaded on 10/18/2010 for the course BIEB BIEB 132 taught by Professor Hastings during the Fall '09 term at UCSD.

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marine_viruses - f o c u S o n M a R I n E M I c R o b IE...

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