Regeneration and maturation of daughter cell walls in the autospore-forming green alga Chlorella vulgaris (Chlorophyta, Trebouxiophyceae)

Yamamoto, Maki; Fujishita, Mariko; Hirata, Aiko; Kawano, Shigeyuki

doi:10.1007/s10265-004-0154-6

Cited by 81 publications

(59 citation statements)

References 16 publications

(19 reference statements)

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“…This type of internal body is extremely rarely preserved in acritarchs as a consequence of the extremely thin (2 to 59 nm) [39,40,41] cell walls of autospores and aplanospores in many modern chlorococcalean algae that are only rarely strengthened by more resistant biomacromolecules like sporopollenin and algaenan [11] making them resistant to decomposition processes. [42,43] Thus, a purely diagenetic (i.e., abiotic) origin of the acritarch internal bodies can be excluded.…”

Section: Discussionmentioning

confidence: 99%

Laser‐Raman and atomic force microscopy assessment of the chlorococcalean affinity of problematic microfossils

Kremer

Bauer

Stark

et al. 2011

J Raman Spectroscopy

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Organic-walled microfossils of uncertain origin, classified to an informal group named acritarchs, are most commonly interpreted as the resting cysts of marine eukaryotic phytoplankton. Some acritarchs have recently been interpreted as vegetative cells of chlorococcalean green algae, based on internal bodies that have been interpreted as their asexual reproductive structures (spores). To verify this interpretation, we applied confocal Raman spectroscopy and atomic force microscopy (AFM) to study the ultrastructure and nanostructure of exceptionally preserved acritarchs with internal bodies from the early Silurian cherts (c. 430 Ma-old) of Frankenwald (Germany). Three-dimensional Raman mapping showed the spatial distribution of carbonaceous material and other minerals in the walls of the analysed internal bodies and confirmed that these structures are comparable with spores of chlorococcalean microalgae. Our findings document therefore the oldest thus far known vegetative cells of sporulating green algae. The combination of confocal Raman and AFM techniques yielded detailed information about the nanostructure and fossilisation mode of the mineralised organic walls of both the central vesicles and the enclosed spore-like bodies.Keywords: acritarch microfossils, mineralization, Silurian, Raman, AFM 2 IntroductionThe informal taxonomic category of organic-walled microfossils named acritarchs [1] has an unclear systematic affiliation. They are traditionally interpreted as the cysts of unicellular organisms. [1,2] During the Proterozoic and Paleozoic, acritarchs formed the basis of the marine food chain and played an important role in the evolution of the global ecosystem. Acritarchs were therefore the main primary producers in the ocean for a long time and, as oxygenic microorganisms, they must have not only controlled the evolution of the marine ecosystem but also influenced planetary biochemical cycles. Acritarch-like fossils are among the oldest morphological traces of life [3] , and the elucidation of their biological relationships sheds new light on the evolution of the early biosphere. It has recently been suggested that at least some acritarchs are the sporulating vegetative stages of unicellular green microalgae because they show internal bodies that can be interpreted as spores. [4] The classification of acritarchs as green algae therefore has an important bearing on the overall understanding of basic processes in the evolution of Earth's biosphere. A precise morphological and chemical characterisation of acritarch internal bodies and of their threedimensional arrangement is difficult because they are typically studied either in thin sections or after extraction from fossil-bearing rock. A detailed chemical or morphological study of microfossils usually requires physical or chemical preparation to extract the microfossils from the rock matrix, which can cause their partial or even total destruction. However, even the maceration process does not allow for extraction and study of these microfossils and their f...

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Section: Discussionmentioning

confidence: 99%

Laser‐Raman and atomic force microscopy assessment of the chlorococcalean affinity of problematic microfossils

Kremer

Bauer

Stark

et al. 2011

J Raman Spectroscopy

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“…Thus, C. sorokiniana and C. lobophora were observed to have almost the same cell wall structure as C. vulgaris. In C. vulgaris, the daughter cell wall, which unites with the outer surface of the plasma membrane, increases in thickness as the cell grows (Yamamoto et al 2004). In C. sorokiniana and C. lobophora, we also observed that the outer surface of the plasma membrane (O) increased its thickness as the cell grew during the cell-growth phase.…”

Section: Electron Microscopic Observation Of Cell Wall Structure In Fmentioning

confidence: 97%

“…This technique preserves cells in a form close to that of living cells and consequently allows the observation of fine cell structures. Using this technique, Yamamoto et al (2004) examined the structural changes that occurred with growth in premature thin electrondense daughter cell walls during the cell-growth and cell-division phases in C. vulgaris. The cell began to synthesize a new daughter cell wall shortly after its release from the autosporangium.…”

Section: Introductionmentioning

confidence: 99%

Late type of daughter cell wall synthesis in one of the Chlorellaceae, Parachlorella kessleri (Chlorophyta, Trebouxiophyceae)

Yamamoto

Kurihara

Kawano

2005

Planta

Self Cite

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Autosporulation is a common mode of propagation for unicellular algae. Autospore-forming species of Chlorellaceae, Chlorella vulgaris Beijerinck, C. sorokiniana Shihira et Krauss, C. lobophora Andreyeva, and Parachlorella kessleri (Fott et Nováková) Krienitz et al. have glucosamine as the main constituent of their rigid cell wall. Recent phylogenetic analyses have showed that the Chlorellaceae divided into two sister groups: the Chlorella-clade and the Parachlorella-clade. We compared the cell wall structure and synthesis of the daughter cell wall in the four species by electron microscopy using rapid freezing and freeze substitution methods. The cell wall of C. vulgaris, C. sorokiniana, and C. lobophora consisted of an electron-dense thin layer with an average thickness of 17-20, 22, and 19 nm, respectively. In these three species, daughter cell wall synthesis occurred on the outer surface of the plasma membrane in the early cell-growth phase. The cell wall of P. kessleri, however, was electron-transparent and 54-59 nm in thickness. Ruthenium red staining of P. kessleri indicated that ruthenium-red-specific polysaccharides accumulated over the outer surface of the plasma membrane. Immunoelectron microscopic observation with an anti-beta-1, 3-glucan antibody and staining with wheat germ agglutinin (WGA) indicated that the cell wall contained beta-1, 3-glucan and WGA specific N-acetyl-beta-D-glucosamine. In P. kessleri, daughter cell wall synthesis began after successive protoplast division. The daughter cell wall synthesis during autosporulation in the four species of Chlorellaceae can be classified into two types-the early and the late types.

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“…Cell wall synthesis in regenerating protoplasts was observed using a cell wall-specific fluorescent dye [Maeda and Ishida, 1967;Nishiyama et al, 1995;Yamamoto et al, 2004]. Cultured regenerating protoplasts were exposed to the magnetic field for varying durations (t ¼ 0, 1, 2, 3 h), stained with a fluorescent dye (Fluorescent Brightener 28, Sigma) at a final concentration of 10 mg/ml, and observed under an inverted microscope (IX70-FLA) operating in epifluorescence mode (filter: BA475; diachronic mirror: DM455).…”

Section: Measurement Of Cell Wall Synthesismentioning

confidence: 99%

Magnetic field exposure stiffens regenerating plant protoplast cell walls

Haneda

Fujimura

Iino

2006

Bioelectromagnetics

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Single suspension-cultured plant cells (Catharanthus roseus) and their protoplasts were anchored to a glass plate and exposed to a magnetic field of 302 +/- 8 mT for several hours. Compression forces required to produce constant cell deformation were measured parallel to the magnetic field by means of a cantilever-type force sensor. Exposure of intact cells to the magnetic field did not result in any changes within experimental error, while exposure of regenerating protoplasts significantly increased the measured forces and stiffened regenerating protoplasts. The diameters of intact cells or regenerating protoplasts were not changed after exposure to the magnetic field. Measured forces for regenerating protoplasts with and without exposure to the magnetic field increased linearly with incubation time, with these forces being divided into components based on the elasticity of synthesized cell walls and cytoplasm. Cell wall synthesis was also measured using a cell wall-specific fluorescent dye, and no changes were noted after exposure to the magnetic field. Analysis suggested that exposure to the magnetic field roughly tripled the Young's modulus of the newly synthesized cell wall without any lag.

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Regeneration and maturation of daughter cell walls in the autospore-forming green alga Chlorella vulgaris (Chlorophyta, Trebouxiophyceae)

Cited by 81 publications

References 16 publications

Laser‐Raman and atomic force microscopy assessment of the chlorococcalean affinity of problematic microfossils

Laser‐Raman and atomic force microscopy assessment of the chlorococcalean affinity of problematic microfossils

Late type of daughter cell wall synthesis in one of the Chlorellaceae, Parachlorella kessleri (Chlorophyta, Trebouxiophyceae)

Magnetic field exposure stiffens regenerating plant protoplast cell walls

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