Thalassiosiraceae is a family of

diatoms 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 ...

in the order

Thalassiosirales ''Thalassiosirales'' is an order of centric diatoms. As of 2015, the order contained 471 species. Species in the order Thalassiosirales are common in brackish, nearshore, and open-ocean habitats, with approximately the same number of freshwater a ...

. The family of Thalassiosiraceae have the unique quality of having a flat valve face. These diatoms are common in brackish, nearshore, and open-ocean habitats, with approximately the same number of freshwater and marine species.

Morphology and ultrastructure

Thalassiosiraceae include some of the smallest known diatoms, such as the genera '' Minidiscus'' and ''

Mediolabrus ''Mediolabrus'' is a genus of centric diatoms within the family Thalassiosiraceae. Known ''Mediolabrus'' species live planktonically in brackish and fresh water. This genus, together with the related '' Minidiscus'', includes some of the smalles ...

'' with diameters as small as 1.9 μm (in '' M. comicus''). Unlike

Naviculaceae Naviculaceae is a diatom family in the order Naviculales. Naviculaceae are typically composed of lineate areolae, one of the many forms of areolae. Some of the other areolae are punctate (''Gomphoneis'') and loculate (''Diploneis''). These can b ...

who are symmetrical in shape, some Thalassiosiraceae are tangentially undulate. Thalassiosiraceae are centric diatoms with fultoportulae (central tube passing through the valve and two or more satellite pores). These structures can often be mistaken for areolae present in many diatom families that can be found in different forms such as those in ''

Navicula ''Navicula'' is a genus of boat-shaped diatom (single-celled photosynthetic organisms), comprising over 1,200 species, though many ''Navicula'' species likely do not belong in the genus strictly speaking. ''Navicula'' is Latin for "small ship", ...

'' or ''

Gomphoneis ''Gomphoneis'' is a genus of diatoms in the family Gomphonemataceae. References * * ''Gomphoneis''
at WoRMS Cymbellales Diatom genera {{Diatom-stub ...

'' known as lineolate and punctate areolae''.''

Model organisms

The species ''

Thalassiosira pseudonana ''Thalassiosira pseudonana'' is a species of marine centric Bulka diatoms. It was chosen as the first eukaryotic marine phytoplankton for whole genome sequencing. ''T. pseudonana'' was selected for this study because it is a model for diatom ...

'' was chosen as the first

eukaryotic The eukaryotes ( ) constitute the Domain (biology), domain of Eukaryota or Eukarya, organisms whose Cell (biology), cells have a membrane-bound cell nucleus, nucleus. All animals, plants, Fungus, fungi, seaweeds, and many unicellular organisms ...

marine

phytoplankton Phytoplankton () are the autotrophic (self-feeding) components of the plankton community and a key part of ocean and freshwater Aquatic ecosystem, ecosystems. The name comes from the Greek language, Greek words (), meaning 'plant', and (), mea ...

for whole

genome sequencing Whole genome sequencing (WGS), also known as full genome sequencing or just genome sequencing, is the process of determining the entirety of the DNA sequence of an organism's genome at a single time. This entails sequencing all of an organism's ...

. ''T. pseudonana'' was selected for this study because it is a model for diatom physiology studies, belongs to a genus widely distributed throughout the world's oceans, and has a relatively small genome at 34 mega

base pair A base pair (bp) is a fundamental unit of double-stranded nucleic acids consisting of two nucleobases bound to each other by hydrogen bonds. They form the building blocks of the DNA double helix and contribute to the folded structure of both DNA ...

s. Scientists are researching diatom light absorption, using the marine genus ''

Thalassiosira ''Thalassiosira'' is a genus of centric diatoms, comprising over 100 marine and freshwater species. It is a diverse group of photosynthetic eukaryotes that make up a vital part of marine and freshwater ecosystems, in which they are key primary pr ...

''.

References

* * * * * Thalassiosirales Diatom families {{Diatom-stub