The pyrenoid ultrastructure in Oocystis lacustris Chodat (Chlorophyta, Trebouxiophyceae) (original) (raw)
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The pyrenoid ultrastructure in Oocystis lacustris
Fottea, 2009
The fine structure of vegetative cells of Oocystis lacustris has been studied with special attention to the ultrastructure of the pyrenoid and its starch sheath. The TEM-investigation showed that the pyrenoid matrix is homogenous, not traversed by thylakoids and the surrounding starch sheath is continuous, horseshoe-shaped or fragmented in 2 starch plates. This starch sheath structure is regarded as a common feature within Oocystis and closely related genera Eremosphaera and Neglectella.
An Ultrastructural Study of the Pyrenoid of Schizochlamys (Chlorophyceae: Tetrasporales)
Transactions of the American Microscopical Society, 1977
JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org. An ultrastructural study of the pyrenoid of Schizochlamys (Chlorophyceae: Tetrasporales). Trans. Amer. Micros. Soc., 96: 398-402. Electron microscopy of field-collected vegetative cells of Schizochlamys gelatinosa revealed a pyrenoid extending from the inner surface of the chloroplast. The entire structure is enclosed by a cap, differing completely from the types of pyrenoids previously described for the green algae. Schizochlamys is placed in the family Schizochlamidaceae n. fam., distinct from the Tetrasporaceae, on the basis of its pyrenoid ultrastructure, zoospore flagellation, and pseudocilia configuration.
THE CELL ULTRASTRUCTURE OF LOBOCHLAMYS CULLEUS (CHLAMYDOMONADACEAE, CHLOROPHYTA) - in Russian
The structure of five strains of volvocophycean alga Lobochlamys culleus was studied by light and transmission electron microscopies. The cells are sunounded by a thin wall and a large portion of fibrillar material. The cell wall consists of two layers: outer (middle), very thin, with cristallic structure and inner fibrillar one. Plasmalemma is usually rough. The chloroplast has thylakoids usually combined in 3 to 5, and its stroma has numerous ribosomes, some osmiophilic globules and starch grains; there are some places or zones free from thylakoids and starch. Such zones have equal density with the chloroplast stroma. Pyrenoid is usually sunounded by a sheath of 3--4 starch grains and has an electron-dense stroma, traversed by the pair of straight thylakoids (pyrenoid type III). The place of contacting thylakoid pairs is unusually wide, so that it may be more than two, or two very modified. Stigma is formed by a single row of pigment globules, and discovered only in strain SAG 19. 72. The nucleus is of the complex chromocentric type. It forms characteristic long lobes in large cells. The fine structure of L. culleus is similar to that of L. segnis, but differs at least in mitochondrium localities and the absence of crystalloids/ presence of free zones in the chloroplast. Despite the different mating behaviour, the ultrastructural features of the cells in all five studied strains have the same peculiarities. Therefore all of the strains undoubtedly belong to one species L. culleus.
Algological Studies/Archiv für Hydrobiologie, Supplement Volumes, 2000
Ultrastructural examination of three glucosamine-type Chlorella species (C. vulgaris var. vulgaris, C. kessleri, C. sorokiniana), forming a related group in phylogenetic trees inferred from 18S rRNA gene sequences (FRIEDL 1995, Huss et al. 1999), revealed a similar cell ultrastructure but some differences in early and later stages of the cell wall development. All species mentioned above contain the monosaccharide glucosamine as the main constituent of the rigid cell wall (TAKEDA 1991, 1993a, 1993b). A thin electrondense layer is the first visible' structure covering the young daughter protoplasts of C. vulgaris and C. sorokiniana. Layered microfibrils can be observed in cross-sections of adult cell walls. Remnants of the broken maternal cell walls (MCW) persist in a culture medium. In C. kessleri the initial electrondense layer was not found. The cell wall is hardly visible, no rrricrofibrillar structure was detected. No MCW remnants were found in the medium. Negatively stained microfibrils of all the three species obtained by IN NaOH and 2M TFAA treatment are straight or slightly bent. The pyrenoid is transversed by two thylakoids. The rigid cell wall of C. luteoviridis is composed of glucose and mannose (TAKEDA 1991, 1993a, 1993b). However some ultrastructural features of C. luteoviridis resemble that of glucosamine-type cWorellas (the thin electrondense layer covering the young daughter protoplasts, microfibrillar structure of the adult cell wall visible on cross-sections, MCW remnants persisting in a medium). Microfibrils do not form a net, they are kinked and flexuous. C. luteoviridis differs from glucosamine-type species in the pyrenoid structure (the pyrenoid is bisected by four or two thylakoids). Thickness of microfibrils in all studied species is about 5 nm.
Phycologia, 1997
S. LIN & E. J. CARPENTER. 1997. Pyrenoid localization of Rubisco in relation to the cell cycle and growth phase of Dunaliella tertiolecta (Chlorophyceae) Phycologia 36: 24-31. Localization of ribulose I,S-bisphosphate carboxylase/oxygenase in pyrenoids of the chlorophyte Dunaliella tertiolecta Butcher was analyzed using immunofluorescence. Some cells displayed distinct pyrenoid-Rubisco staining (i.e. Rubisco was highly concentrated in the pyrenoid), whereas others displayed weak staining throughout the chloroplast stroma. Paired pyrenoid-Rubisco units were observed, suggesting that pyrenoid division had occurred. The percentage of cells having distinct pyrenoid-Rubisco staining (PR-index) was depressed drastically by darkness, but the cell cycle, which was monitored by immunofluorescence of the proliferating cell nuclear antigen (PCNA), was not affected. Inversely, neither the cell cycle inhibitors hydroxyurea and colchicine nor short-term nutrient depletion affected the PR-index. These results, along with the observation that cells with or without distinct pyrenoid-Rubisco staining had similar DNA contents, suggest that variation in pyrenoid localization of Rubisco was not cell cycle dependent. In addition, the PR-index increased along with growth rates in the early exponential growth phase and decreased to zero in the late stationary phase. After a stationary culture was diluted by fresh medium, the PR-index increased from 0 to high levels within 24 hours. These results suggest that pyrenoid localization of Rubisco is associated with the active growth phase.
The crystal lattice of the pyrenoid matrix of Prorocentrum Micans
Journal of Cell Science, 1969
The pyrenoid matrix of the marine dinoflagellate Prorocentrum micans is shown to consist of regular close-packed units, which form a cubic face-centred lattice. Numerous lamellae usually consisting of two apposed thylakoids traverse the pyrenoid matrix. They normally run strikingly parallel to each other, with an average distance of 139 nm between each stack. The three-layered unit membrane of the thylakoids penetrating the pyrenoid is 70Å thick, the same as the unit membrane of the chloroplast thylakoids. The total thickness of one thylakoid measures 190–220 Å. The globular units of the pyrenoid matrix have a calculated mean diameter of 232 Å, forming different line and dot patterns (hexagonal and cubic arrays) due to different section angles. Hexagonal patterns on prints result from projections of superimposed close-packed layers; they do not belong to one close-packing. Line patterns parallel to the thylakoid direction are composed without exception of 11 contrasted lines (6 and ...
PHYLOGENETIC POSITION OF THE OOCYSTACEAE (CHLOROPHYTA)
Journal of Phycology, 2000
The complete 18S rRNA gene sequences of three Oocystis A. Braun species (Oocystaceae) and three other chlorococcal algae, Tetrachlorella alternans (G. M. Smith) Kor . (Scenedesmaceae), Makinoella tosaensis Okada (Scenedesmaceae), and Amphikrikos cf. nanus (Fott & Heynig) Hind. (Chlorellaceae) were determined and subjected to four different phylogenetic analysis algorithms. Independent of the reconstruction method, these taxa clustered together as a monophyletic group (Oocystaceae) within the Trebouxiophyceae. This result was supported by high bootstrap values. A comparison of morphological data with the phylogenetic reconstructions indicated that the evolution of Oocystaceae was accompanied by a reduction in the number of plastids. This study fully supports the taxonomic assignment of the Oocystaceae as a distinct family. The diacritic criterion that the cell walls are composed of several cellulose layers with perpendicular fibril orientations is in accordance with the molecular data.
2016
Abstract: Confocal laser scanning microscopy was utilized to compare the chloroplast morphology and ontogeny among five strains of the green alga Asterochloris. Parsimony analysis inferred from the rDNA ITS sequences confirmed their placement in three distinct lineages: Asterochloris phycobiontica, Trebouxia pyriformis and Asterochloris sp. Examination by confocal microscopy revealed the existence of interspecific differences in the chloroplast ontogeny of Asterochloris; this was based upon either specific chloroplast structures observed in a single species, or on the differential timing of particular ontogenetic sequences. The occurrence of flat parietal chloroplasts prior to cell division, considered as a basic morphological discriminative character of Asterochloris, was clearly associated with the process of aplanosporogenesis. By contrast, chloroplast transformation prior to the formation of autospores proceeded simply by the multiple fission of the chloroplast matrix in the cel...