Structure of a typical virus, in this case a phage.[1] The appearance of these viruses has been likened to a miniature lunar lander.[2] Marine viruses are essential to the regulation of marine ecosystems.[3]
Marine viruses are defined by their habitat as viruses that are found in marine environments, that is, in the saltwater of seas or oceans or the brackish water of coastal estuaries. Viruses are small infectious agents that can only replicate inside the living cells of a host organism, because they need the replication machinery of the host to do so.[4] They can infect all types of life forms, from animals and plants to microorganisms, including bacteria and archaea.[5]
When not inside a cell or in the process of infecting a cell, viruses exist in the form of independent particles called virions. A virion contains a genome (a long molecule that carries genetic information in the form of either DNA or RNA) surrounded by a capsid (a protein coat protecting the genetic material). The shapes of these virus particles range from simple helical and icosahedral forms for some virus species to more complex structures for others. Most virus species have virions that are too small to be seen with an optical microscope. The average virion is about one one-hundredth the linear size of the average bacterium.
A teaspoon of seawater typically contains about fifty million viruses.[6] Most of these viruses are bacteriophages which infect and destroy marine bacteria and control the growth of phytoplankton at the base of the marine food web. Bacteriophages are harmless to plants and animals but are essential to the regulation of marine ecosystems. They supply key mechanisms for recycling ocean carbon and nutrients. In a process known as the viral shunt, organic molecules released from dead bacterial cells stimulate fresh bacterial and algal growth. In particular, the breaking down of bacteria by viruses (lysis) has been shown to enhance nitrogen cycling and stimulate phytoplankton growth. Viral activity also affects the biological pump, the process which sequesters carbon in the deep ocean. By increasing the amount of respiration in the oceans, viruses are indirectly responsible for reducing the amount of carbon dioxide in the atmosphere by approximately 3 gigatonnes of carbon per year.
Marine microorganisms make up about 70% of the total marine biomass. It is estimated marine viruses kill 20% of the microorganism biomass every day. Viruses are the main agents responsible for the rapid destruction of harmful algal blooms which often kill other marine life. The number of viruses in the oceans decreases further offshore and deeper into the water, where there are fewer host organisms. Viruses are an important natural means of transferring genes between different species, which increases genetic diversity and drives evolution. It is thought viruses played a central role in early evolution before the diversification of bacteria, archaea and eukaryotes, at the time of the last universal common ancestor of life on Earth. Viruses are still one of the largest areas of unexplored genetic diversity on Earth.
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^Bonnain C, Breitbart M, Buck K (2016). "The ferrojan horse hypothesis: iron-virus interactions in the ocean". Frontiers in Marine Science. 3: 82. doi:10.3389/fmars.2016.00082. S2CID 2917222.
^These Tiny Organisms Have Some Really Weird Shapes, National Geographic, 12 November 2016.
^Cite error: The named reference Shors2008 was invoked but never defined (see the help page).
^Brussaard CP, Baudoux AC, Rodríguez-Valera F (2016). Stal LJ, Cretoiu MS (eds.). Marine Viruses. Springer International Publishing. pp. 155–183. doi:10.1007/978-3-319-33000-6_5. ISBN 9783319329987. {{cite book}}: |work= ignored (help)
^Koonin EV, Senkevich TG, Dolja VV (2006). "The ancient Virus World and evolution of cells". Biology Direct. 1: 29. doi:10.1186/1745-6150-1-29. PMC 1594570. PMID 16984643.{{cite journal}}: CS1 maint: multiple names: authors list (link) Modified text was copied from this source, which is available under a Creative Commons Attribution 2.0 International License.
^Suttle C (2005). "Viruses in the sea". Nature. 437 (7057): 356–361. Bibcode:2005Natur.437..356S. doi:10.1038/nature04160. PMID 16163346. S2CID 4370363.
Marineviruses are defined by their habitat as viruses that are found in marine environments, that is, in the saltwater of seas or oceans or the brackish...
still poorly understood, such as for the role of viruses in marine ecosystems. Most marineviruses are bacteriophages, which are harmless to plants and...
double-stranded DNA (dsDNA) viruses, and those that have one strand of DNA in their genome, called single-stranded DNA (ssDNA) viruses. dsDNA viruses primarily belong...
still poorly understood, such as for the role of viruses in marine ecosystems. Most marineviruses are bacteriophages, which are harmless to plants and...
A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals...
reproduces until the cell bursts, releasing viruses. Viruses can also enter a lysogenic cycle, in which the virus writes its DNA into the host genome. When...
prokaryotic phytoplankton are also bacterioplankton). Virioplankton are viruses. Viruses are more abundant in the plankton than bacteria and archaea, though...
community structure, genetic diversity and ecological roles of viruses in mangrove ecosystems. Viruses are the most abundant biological entities on earth, present...
with host-specific viruses (also known as phages) increases, making them more susceptible to viral infection and lysis. Thus, viruses moderate the population...
Hepatitis D virus, which requires Hepatitis B virus to coinfect cells in order to replicate. Helper viruses are also commonly used to replicate and spread...
criteria as defined in the scientific literature vary, giant viruses are generally described as viruses having large, pseudo-icosahedral capsids (200 to 400 nanometers...
proportion of lysogenic viruses, this indicates that viruses are selected to be integrated pro-viruses rather than free floating viruses and that the auxiliary...
member viruses based on their genome type, host range, and genetic similarity. Viruses with three genome types are included: positive-strand RNA viruses, negative-strand...
identical copies of the original virus. Unlike most living things, viruses do not have cells that divide; new viruses assemble in the infected host cell...
becoming available to higher trophic levels. DOM, POM and the viral shunt VirusesViruses are the "most abundant biological entities on the planet", particularly...
prokaryotes, fungi, other unicellular eukaryotes), and viruses. Although initially driven by studies of marine organisms, much of the research on the emerging...
Varidnaviria is a realm of viruses that includes all DNA viruses that encode major capsid proteins that contain a vertical jelly roll fold. The major...
tb01592.x. Brusca, R. C.; Gilligan, M. R. (1983). "Tongue replacement in a marine fish (Lutjanus guttatus) by a parasitic isopod (Crustacea: Isopoda)" (PDF)...
comparable to the amount generated by the other main sources of marine DOM. Viruses can easily infect microorganisms in the microbial loop due to their...
Animal viruses are viruses that infect animals. Viruses infect all cellular life and although viruses infect every animal, plant, fungus and protist species...
members of the Nucleocytoplasmic large DNA viruses group. CroV has one of the largest genomes of all marineviruses known, consisting of ~730,000 base pairs...
that all require the presence of another virus to replicate. Many of these are plant viruses, but animal viruses can be seen in the case of dependoviruses...
single-cell organisms including bacteria, Archaea, Protista, and associated viruses, exploring and discovering unknown microbial diversity, and placing that...
be considered as members of the microbiome. The integration of phages, viruses, plasmids, and mobile genetic elements is more controversial. Whipps's...
dynamics. Phytoplankton viruses are a type of marinevirus. There is substantial genetic variation in phytoplankton viruses, just as there is substantial...
rarely longer than about 2 cm. A few species infecting certain marine fish are larger, and marine forms are generally larger than those found on freshwater...
the naked eye. They are phytoplankton typically found in freshwater and marine systems, living in both the water column and sediment. They are unicellular...
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Modified text was copied from this source, which is available under a Creative Commons Attribution 2.0 International License.
