''Braarudosphaera bigelowii'' is a coastal

coccolithophore Coccolithophores, or coccolithophorids, are single-celled organisms which are part of the phytoplankton, the autotrophic (self-feeding) component of the plankton community. They form a group of about 200 species, and belong either to the kingdom ...

in the fossil record going back 100 million years to the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the more recent of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''cre ...

Coccolithophore

The

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Braarudosphaeraceae consist of single-celled coastal phytoplanktonic algae with

calcareous Calcareous () is an adjective meaning "mostly or partly composed of calcium carbonate", in other words, containing lime (mineral), lime or being chalky. The term is used in a wide variety of Science, scientific disciplines. In zoology ''Calcare ...

scales with five-fold symmetry, called pentaliths. With 12 sides, it has a regular dodecahedral structure, approximately 10 micrometers across.

Nitroplast

''B. bigelowii'' has a

nitroplast A nitroplast is an organelle found in certain species of algae, particularly in the marine algae ''Braarudosphaera bigelowii''. It plays a crucial role in nitrogen fixation, a process previously thought to be exclusive to bacteria and archaea. Th ...

organelle, originated some 100 million years ago from a cyanobacterial

endosymbiont An endosymbiont or endobiont is an organism that lives within the body or cells of another organism. Typically the two organisms are in a mutualism (biology), mutualistic relationship. Examples are nitrogen-fixing bacteria (called rhizobia), whi ...

called UCYN-A2, which allows ''B. bigelowii to'' fix nitrogen and convert it into compounds useful for cell growth. This phenomenon is previously known from

diatom A diatom (Neo-Latin ''diatoma'') is any member of a large group comprising several Genus, genera of algae, specifically microalgae, found in the oceans, waterways and soils of the world. Living diatoms make up a significant portion of Earth's B ...

s in the family ''Rhopalodiaceae'', where a nitrogen fixing and non-photosynthetic

cyanobacteria Cyanobacteria ( ) are a group of autotrophic gram-negative bacteria that can obtain biological energy via oxygenic photosynthesis. The name "cyanobacteria" () refers to their bluish green (cyan) color, which forms the basis of cyanobacteri ...

, a diazoplast, provides the photosynthetic host cell with nitrogen.

Name

The genus name ''Braarudosphaera'' is in honour of Norwegian botanist

Trygve Braarud Trygve Braarud (15 September 1903 – 9 July 1985) was a Norwegian botanist. He specialized in marine biology, and was affiliated with the University of Oslo for most of his career. Career He was born in Verdal Municipality, and had ten older si ...

(1903–1985). He specialized in marine biology, and was affiliated with the

University of Oslo The University of Oslo (; ) is a public university, public research university located in Oslo, Norway. It is the List of oldest universities in continuous operation#Europe, oldest university in Norway. Originally named the Royal Frederick Univ ...

References

External links

Haptophyte species Nitrogen compounds Tilings in biology {{Taxonbar, from=Q23056336