Sallie Watson "Penny" Chisholm is an American biological oceanographer at the Massachusetts Institute of Technology. She is an expert in the ecology and evolution of ocean microbes. Her research focuses particularly on the most abundant marine phytoplankton, Prochlorococcus, that she discovered in the 1980s with Rob Olson and other collaborators. She has a TED talk about their discovery and importance called "The tiny creature that secretly powers the planet".
Phycodnaviridae is a family of large (100–560 kb) double-stranded DNA viruses that infect marine or freshwater eukaryotic algae. Viruses within this family have a similar morphology, with an icosahedral capsid. As of 2014, there were 33 species in this family, divided among 6 genera. This family belongs to a super-group of large viruses known as nucleocytoplasmic large DNA viruses. Evidence was published in 2014 suggesting that specific strains of Phycodnaviridae might infect humans rather than just algal species, as was previously believed. Most genera under this family enter the host cell by cell receptor endocytosis and replicate in the nucleus. Phycodnaviridae play important ecological roles by regulating the growth and productivity of their algal hosts. Algal species such Heterosigma akashiwo and the genus Chrysochromulina can form dense blooms which can be damaging to fisheries, resulting in losses in the aquaculture industry. Heterosigma akashiwo virus (HaV) has been suggested for use as a microbial agent to prevent the recurrence of toxic red tides produced by this algal species. Phycodnaviridae cause death and lysis of freshwater and marine algal species, liberating organic carbon, nitrogen and phosphorus into the water, providing nutrients for the microbial loop.
The microbial loop describes a trophic pathway where, in aquatic systems, dissolved organic carbon (DOC) is returned to higher trophic levels via its incorporation into bacterial biomass, and then coupled with the classic food chain formed by phytoplankton-zooplankton-nekton. In soil systems, the microbial loop refers to soil carbon. The term microbial loop was coined by Farooq Azam, Tom Fenchel et al. in 1983 to include the role played by bacteria in the carbon and nutrient cycles of the marine environment.
The microbial food web refers to the combined trophic interactions among microbes in aquatic environments. These microbes include viruses, bacteria, algae, heterotrophic protists. In aquatic ecosystems, microbial food webs are essential because they form the basis for the cycling of nutrients and energy. These webs are vital to the stability and production of ecosystems in a variety of aquatic environments, including lakes, rivers, and oceans. By converting dissolved organic carbon (DOC) and other nutrients into biomass that larger organisms may eat, microbial food webs maintain higher trophic levels. Thus, these webs are crucial for energy flow and nutrient cycling in both freshwater and marine ecosystems.
The Institute for Biodiversity and Ecosystem Dynamics (IBED) is one of the ten research institutes of the Faculty of Science of the Universiteit van Amsterdam. IBED employs more than 100 researchers, with PhD students and Postdocs forming a majority, and 30 supporting staff. The total annual budget is around 10 m€, of which more than 40 per cent comes from external grants and contracts. The main output consist of publications in peer reviewed journals and books. Each year around 15 PhD students defend their thesis and obtain their degree from the Universiteit van Amsterdam. The institute is managed by a general director appointed by the Dean of the Faculty for a period of five years, assisted by a business manager.
The sea surface microlayer (SML) is the boundary interface between the atmosphere and ocean, covering about 70% of Earth's surface. With an operationally defined thickness between 1 and 1,000 μm (1.0 mm), the SML has physicochemical and biological properties that are measurably distinct from underlying waters. Recent studies now indicate that the SML covers the ocean to a significant extent, and evidence shows that it is an aggregate-enriched biofilm environment with distinct microbial communities. Because of its unique position at the air-sea interface, the SML is central to a range of global marine biogeochemical and climate-related processes.
The prasinophytes are a group of unicellular green algae. Prasinophytes mainly include marine planktonic species, as well as some freshwater representatives. The prasinophytes are morphologically diverse, including flagellates with one to eight flagella and non-motile (coccoid) unicells. The cells of many species are covered with organic body scales; others are naked. Well studied genera include Ostreococcus, considered to be the smallest free-living eukaryote, and Micromonas, both of which are found in marine waters worldwide. Prasinophytes have simple cellular structures, containing a single chloroplast and a single mitochondrion. The genomes are relatively small compared to other eukaryotes . At least one species, the Antarctic form Pyramimonas gelidicola, is capable of phagocytosis and is therefore a mixotrophic algae.
Micromonas is a genus of green algae in the family Mamiellaceae.
Marnaviridae is a family of positive-stranded RNA viruses in the order Picornavirales that infect various photosynthetic marine protists. Members of the family have non-enveloped, icosahedral capsids. Replication occurs in the cytoplasm and causes lysis of the host cell. The first species of this family that was isolated is Heterosigma akashiwo RNA virus (HaRNAV) in the genus Marnavirus, which infects the toxic bloom-forming Raphidophyte alga, Heterosigma akashiwo. As of 2021, there are twenty species across seven genera in this family, as well as many other related virus sequences discovered through metagenomic sequencing that are currently unclassified.
Marine microorganisms are defined by their habitat as microorganisms living in a marine environment, that is, in the saltwater of a sea or ocean or the brackish water of a coastal estuary. A microorganism is any microscopic living organism or virus, which is invisibly small to the unaided human eye without magnification. Microorganisms are very diverse. They can be single-celled or multicellular and include bacteria, archaea, viruses, and most protozoa, as well as some fungi, algae, and animals, such as rotifers and copepods. Many macroscopic animals and plants have microscopic juvenile stages. Some microbiologists also classify viruses as microorganisms, but others consider these as non-living.
Prasinovirus is a genus of large double-stranded DNA viruses, in the family Phycodnaviridae that infect phytoplankton in the Prasinophyceae. There are three groups in this genus, including Micromonas pusilla virus SP1, which infects the cosmopolitan photosynthetic flagellate Micromonas pusilla.
Phaeocystis is a genus of algae belonging to the Prymnesiophyte class and to the larger division of Haptophyta. It is a widespread marine phytoplankton and can function at a wide range of temperatures (eurythermal) and salinities (euryhaline). Members of this genus live in the open ocean, as well as in sea ice. It has a polymorphic life cycle, ranging from free-living cells to large colonies.
The viral shunt is a mechanism that prevents marine microbial particulate organic matter (POM) from migrating up trophic levels by recycling them into dissolved organic matter (DOM), which can be readily taken up by microorganisms. The DOM recycled by the viral shunt pathway is comparable to the amount generated by the other main sources of marine DOM.
A marine food web is a food web of marine life. At the base of the ocean food web are single-celled algae and other plant-like organisms known as phytoplankton. The second trophic level is occupied by zooplankton which feed off the phytoplankton. Higher order consumers complete the web. There has been increasing recognition in recent years that marine microorganisms.
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. They can infect all types of life forms, from animals and plants to microorganisms, including bacteria and archaea.
Algal viruses are the viruses infecting algae, which are photosynthetic single-celled eukaryotes. As of 2020, there were 61 viruses known to infect algae. Algae are integral components of aquatic food webs and drive nutrient cycling, so the viruses infecting algal populations also impacts the organisms and nutrient cycling systems that depend on them. Thus, these viruses can have significant, worldwide economic and ecological effects. Their genomes varied between 4.4 to 560 kilobase pairs (kbp) long and used double-stranded Deoxyribonucleic Acid (dsDNA), double-stranded Ribonucleic Acid (dsRNA), single-stranded Deoxyribonucleic Acid (ssDNA), and single-stranded Ribonucleic Acid (ssRNA). The viruses ranged between 20 and 210 nm in diameter. Since the discovery of the first algae-infecting virus in 1979, several different techniques have been used to find new viruses infecting algae and it seems that there are many algae-infecting viruses left to be discovered
Virivore comes from the English prefix viro- meaning virus, derived from the Latin word for poison, and the suffix -vore from the Latin word vorare, meaning to eat, or to devour; therefore, a virivore is an organism that consumes viruses. Virivory is a well-described process in which organisms, primarily heterotrophic protists, but also some metazoans consume viruses.
Alison Buchan is the Carolyn Fite Professor at the University of Tennessee. She is known for her work on bacteria in natural environments, especially bacteria within the Roseobacter group. In 2022 she was named as a fellow of the American Academy of Microbiology.
Phaeocystis globosa virus virophage, or PgVV, or Preplasmiviricota sp. Gezel-14T, is a polinton-like virus, which are small DNA viruses that are found integrated in protist genomes. Similar to virophages, PgVV requires a helper virus to replicate. Phaeocystis globosa virus virophage has a parasitic relationship with its helper virus species Phaeocystis globosa virus (PgV). They are a species of giant virus that infect algae of the genus Phaeocystis.
Phytoplankton are characterized as organisms which are unable to swim against a current and produce their own organic carbon via photosynthesis. They are responsible for producing approximately 50 percent of the Earth’s primary productivity and are therefore crucial in maintaining both marine ecosystems and adding a significant amount of oxygen to the atmosphere. However, as with other organisms, phytoplankton are hosts to many diverse forms of parasites, including, but not limited to, fungal- and non-fungal zoosporic parasites, Dinoflagellates, Cercozoans, and viruses. Parasites use nutrients from their hosts, at that organisms expense, and display diverse methods of infection. Parasites can play integral roles in the dynamics and interactions between phytoplankton and their communities, such as controlling population abundance, distribution and biodiversity.
