Description
Members of this family (presently 3, including Prasinoderma co/onia/e Hasegawa and Chihara , a recently described colony-forming species from the Western Pacific (Hasegawa et al. , 1996) a II belong in the marine picoplankton . Species are unicellular (rarely colonial), surrounded by a wall , and lack flagella. A channel in the pyrenoid contains a protrusion from the mitochondrion , a very unusual character shared with the flagellated prasinophyte Pseudoscourfieldia. Studies on the Rubisco-gene have confirmed phylogenetic relationship between these coccoid species and Pseudoscourfieldia (Daugbjerg et al. , 1995), but a relationship to the Mamieliales, as originally perceived , has not been confirmed. Like members of the Mamiellales , species of the Pycnococcaceae are probably secondarily reduced rather than primitive forms . The recently described Ostreococcus tauri Courties and Chretiennot-Dinet (Chretiennot-Dinet et al. , 1995) differs in pyrenoid structure and its phylogenetic position is presently unknown. member of the Prasinophyceae that lacks scales . The cell Fig . 21 A) is surrounded by a wall , which at one point possesses an operculum-lik e structure (enlarged as Fig . 21. B). C, chloroplast ; 0 ,. dictyosome M , mitochondrion ; P, pyrenoid. Fig . 21 A=28 ,000x. Fig . 21 B=48 ,000x . (From Guillard et al , 1991 ). bLM TEM 1. Cells with circular ring projecting slightly from one side, surrounded by circle of holes (visible only in EM) .. .... ........ ... ... .. .... .... Prasinoco HYCEAE 1. Cells with an operculum ..... . ... .. . Pycnococcus
Type species
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Raw text
Members of this family (presently 3, including Prasinoderma co/onia/e Hasegawa and Chihara , a recently described colony-forming species from the Western Pacific (Hasegawa et al. , 1996) a II belong in the marine picoplankton . Species are unicellular (rarely colonial), surrounded by a wall , and lack flagella. A channel in the pyrenoid contains a protrusion from the mitochondrion , a very unusual character shared with the flagellated prasinophyte Pseudoscourfieldia. Studies on the Rubisco-gene have confirmed phylogenetic relationship between these coccoid species and Pseudoscourfieldia (Daugbjerg et al. , 1995), but a relationship to the Mamieliales, as originally perceived , has not been confirmed. Like members of the Mamiellales , species of the Pycnococcaceae are probably secondarily reduced rather than primitive forms . The recently described Ostreococcus tauri Courties and Chretiennot-Dinet (Chretiennot-Dinet et al. , 1995) differs in pyrenoid structure and its phylogenetic position is presently unknown. member of the Prasinophyceae that lacks scales . The cell Fig . 21 A) is surrounded by a wall , which at one point possesses an operculum-lik e structure (enlarged as Fig . 21. B). C, chloroplast ; 0 ,. dictyosome M , mitochondrion ; P, pyrenoid. Fig . 21 A=28 ,000x. Fig . 21 B=48 ,000x . (From Guillard et al , 1991 ). bLM TEM 1. Cells with circular ring projecting slightly from one side, surrounded by circle of holes (visible only in EM) .. .... ........ ... ... .. .... .... Prasinoco HYCEAE 1. Cells with an operculum ..... . ... .. . Pycnococcus