Paulinella
Encyclopedia
Paulinella is a genus of about nine species of freshwater amoeboid
s.
Its most famous member is the photosynthetic P. chromatophora which has recently (evolutionarily speaking) taken on a cyanobacterium as an endosymbiont
. This is striking because the chloroplast
s of all other known photosynthetic eukaryote
s derive ultimately from a single cyanobacterium endosymbiont which was taken in probably over a billion years ago in plants (and subsequently adopted into other eukaryote
groups, by further endosymbiosis events). The P. chromatophora symbiont was related to the Prochlorococcus
and Synechococcus
cyanobacteria (sister to the group consisting of the living members of those two genera). Other than the symbiont, P. chromatophora is closely related to the heterotrophic P. ovalis.
Amoeboid
Amoeboids are single-celled life-forms characterized by an irregular shape."Amoeboid" and "amœba" are often used interchangeably even by biologists, and especially refer to a creature moving by using pseudopodia. Most references to "amoebas" or "amoebae" are to amoeboids in general rather than to...
s.
Its most famous member is the photosynthetic P. chromatophora which has recently (evolutionarily speaking) taken on a cyanobacterium as an endosymbiont
Endosymbiont
An endosymbiont is any organism that lives within the body or cells of another organism, i.e. forming an endosymbiosis...
. This is striking because the chloroplast
Chloroplast
Chloroplasts are organelles found in plant cells and other eukaryotic organisms that conduct photosynthesis. Chloroplasts capture light energy to conserve free energy in the form of ATP and reduce NADP to NADPH through a complex set of processes called photosynthesis.Chloroplasts are green...
s of all other known photosynthetic eukaryote
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...
s derive ultimately from a single cyanobacterium endosymbiont which was taken in probably over a billion years ago in plants (and subsequently adopted into other eukaryote
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...
groups, by further endosymbiosis events). The P. chromatophora symbiont was related to the Prochlorococcus
Prochlorococcus
Prochlorococcus is a genus of very small marine cyanobacteria with an unusual pigmentation . These bacteria belong to the photosynthetic picoplankton and are probably the most abundant photosynthetic organism on Earth....
and Synechococcus
Synechococcus
Synechococcus is a unicellular cyanobacterium that is very widespread in the marine environment. Its size varies from 0.8 µm to 1.5 µm...
cyanobacteria (sister to the group consisting of the living members of those two genera). Other than the symbiont, P. chromatophora is closely related to the heterotrophic P. ovalis.