Picobiliphyte
Encyclopedia
Picobiliphytes or Picobiliphyta are a group of eukaryotic
algae
, discovered in 2007, which are found among the smallest members of photosynthetic picoplankton
.
They are sometimes called "biliphytes".
s occur in picoplankton
. In addition, for a period of two years, samples were taken in the Atlantic, in the Mediterranean, before the coast of Scotland, Alaska and Norway. Picobiliphyta were found particularly within the nutrient-poor ranges from cold coastal seas, where they can constitute up to 50 percent of the biomass
.
ers investigated gene sequences of the 18S gene
, common to all cells
. The identity of new organisms can be deduced from a comparison of familiar and unfamiliar gene sequences. “The gene sequences found in these algae could not be associated with any previously known group of organisms”, explain Dr Klaus Valentin and Dr. Linda Medlin, co-authors of the study and molecular biologists
at the Alfred Wegener Institute for Polar and Marine Research
in Bremerhaven
. The algae in this study were found in plankton samples originating from various regions of the North Atlantic and the Mediterranean. The scientists have discovered a group of organisms which, despite being completely new to science, have a wide distribution. “This is a good indication for how much there is still to discover in the oceans, especially using molecular tools”, says Valentin.
Apart from the unfamiliar gene sequences, the researchers also detected phycobiliprotein
s. In red algae
, for example, these proteins occur as pigments. But in this newly discovered group of algae, the phycobiliproteins appear to be contained inside the plastid
s, where the photosynthesis
occurs. Hence, it provides a clear indication that the researchers are dealing with previously unidentified group of algae. Referring to their small size and the presence of phycobiliproteins, the researchers named the new group "Picobiliphyta". A 2011 study conducted by researchers at Rutgers University
and Bigelow Oceanographic Labs used whole genome shotgun sequence data from three individual Picobiliphyte cells to show absence of plastid-targeted or photosystem proteins within their nuclear genomes. This suggests that Picobiliphytes are in fact heterotrophs.
Some sources group picobiliphytes within the cryptomonads-haptophytes assemblage.
Eukaryote
A eukaryote is an organism whose cells contain complex structures enclosed within membranes. Eukaryotes may more formally be referred to as the taxon Eukarya or Eukaryota. The defining membrane-bound structure that sets eukaryotic cells apart from prokaryotic cells is the nucleus, or nuclear...
algae
Algae
Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...
, discovered in 2007, which are found among the smallest members of photosynthetic picoplankton
Photosynthetic picoplankton
Photosynthetic picoplankton is the fraction of the plankton performing photosynthesis composed by cells between 0.2 and 2 µm . It is especially important in the central oligotrophic regions of the world oceans that have very low concentration of nutrients.- History :* 1952: Description of the...
.
They are sometimes called "biliphytes".
Discovery
At the end of the 1990s with the European project "Picodiv" it would be clarified which organismOrganism
In biology, an organism is any contiguous living system . In at least some form, all organisms are capable of response to stimuli, reproduction, growth and development, and maintenance of homoeostasis as a stable whole.An organism may either be unicellular or, as in the case of humans, comprise...
s occur in picoplankton
Picoplankton
Picoplankton is the fraction of plankton composed by cells between 0.2 and 2 μm that can be either :* photosynthetic * heterotrophic Some species can also be mixotrophic....
. In addition, for a period of two years, samples were taken in the Atlantic, in the Mediterranean, before the coast of Scotland, Alaska and Norway. Picobiliphyta were found particularly within the nutrient-poor ranges from cold coastal seas, where they can constitute up to 50 percent of the biomass
Biomass (ecology)
Biomass, in ecology, is the mass of living biological organisms in a given area or ecosystem at a given time. Biomass can refer to species biomass, which is the mass of one or more species, or to community biomass, which is the mass of all species in the community. It can include microorganisms,...
.
Affinities to other organisms
ResearchResearch
Research can be defined as the scientific search for knowledge, or as any systematic investigation, to establish novel facts, solve new or existing problems, prove new ideas, or develop new theories, usually using a scientific method...
ers investigated gene sequences of the 18S gene
Gene
A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...
, common to all cells
Cell (biology)
The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos....
. The identity of new organisms can be deduced from a comparison of familiar and unfamiliar gene sequences. “The gene sequences found in these algae could not be associated with any previously known group of organisms”, explain Dr Klaus Valentin and Dr. Linda Medlin, co-authors of the study and molecular biologists
Molecular biology
Molecular biology is the branch of biology that deals with the molecular basis of biological activity. This field overlaps with other areas of biology and chemistry, particularly genetics and biochemistry...
at the Alfred Wegener Institute for Polar and Marine Research
Alfred Wegener Institute for Polar and Marine Research
The Alfred Wegener Institute of Polar and Marine Research is a scientific organization located in Bremerhaven, Germany. The institute was founded in 1980 and is named after revolutionary meteorologist climatologist, and geologist Alfred Wegener...
in Bremerhaven
Bremerhaven
Bremerhaven is a city at the seaport of the free city-state of Bremen, a state of the Federal Republic of Germany. It forms an enclave in the state of Lower Saxony and is located at the mouth of the River Weser on its eastern bank, opposite the town of Nordenham...
. The algae in this study were found in plankton samples originating from various regions of the North Atlantic and the Mediterranean. The scientists have discovered a group of organisms which, despite being completely new to science, have a wide distribution. “This is a good indication for how much there is still to discover in the oceans, especially using molecular tools”, says Valentin.
Apart from the unfamiliar gene sequences, the researchers also detected phycobiliprotein
Phycobiliprotein
Phycobiliproteins are water-soluble proteins present in cyanobacteria and certain algae that capture light energy, which is then passed on to chlorophylls during photosynthesis. Phycobiliproteins are formed of a complex between proteins and covalently bound phycobilins that act as chromophores...
s. In red algae
Red algae
The red algae are one of the oldest groups of eukaryotic algae, and also one of the largest, with about 5,000–6,000 species of mostly multicellular, marine algae, including many notable seaweeds...
, for example, these proteins occur as pigments. But in this newly discovered group of algae, the phycobiliproteins appear to be contained inside the plastid
Plastid
Plastids are major organelles found in the cells of plants and algae. Plastids are the site of manufacture and storage of important chemical compounds used by the cell...
s, where the photosynthesis
Photosynthesis
Photosynthesis is a chemical process that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight. Photosynthesis occurs in plants, algae, and many species of bacteria, but not in archaea. Photosynthetic organisms are called photoautotrophs, since they can...
occurs. Hence, it provides a clear indication that the researchers are dealing with previously unidentified group of algae. Referring to their small size and the presence of phycobiliproteins, the researchers named the new group "Picobiliphyta". A 2011 study conducted by researchers at Rutgers University
Rutgers University
Rutgers, The State University of New Jersey , is the largest institution for higher education in New Jersey, United States. It was originally chartered as Queen's College in 1766. It is the eighth-oldest college in the United States and one of the nine Colonial colleges founded before the American...
and Bigelow Oceanographic Labs used whole genome shotgun sequence data from three individual Picobiliphyte cells to show absence of plastid-targeted or photosystem proteins within their nuclear genomes. This suggests that Picobiliphytes are in fact heterotrophs.
Some sources group picobiliphytes within the cryptomonads-haptophytes assemblage.