Licht‐ und elektronenmikroskopische Untersuchungen an regenerierenden Protoplasten von <i>Polystictus versicolor</i>

Strunk, Christa

doi:10.1002/jobm.19690090306

Cited by 6 publications

(2 citation statements)

References 19 publications

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“…Granules, often connected to short microfibrils, have also been found at the plasmalemma/wall interphase in yeast cells (2,16,17). In the early stages of wall regeneration by protoplasts of Polystictus versicolor, Strunk (18) found globular particles (about 400 A) associated with the incipient microfibrillar network.…”

Section: Discussionmentioning

confidence: 99%

Microfibril assembly by granules of chitin synthetase.

Ruíz-Herrera¹,

Sing²,

Woude³

et al. 1975

Proc. Natl. Acad. Sci. U.S.A.

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Purified preparations of chitin synthetase (EC 2.4.1.16; UDP-2-acetamido2-eoxy--glucose:chitin 4-flacetamidodeoxyglucosyltransferase), capable of forming microfibrils in vitro, were isolated from yeast cells of Mucor rouxii. Chitin synthetase was obtained either by substrateinduced liberation of bound enzyme (54,000 X g pellet) or by isolation of unbound enzyme present in the 54,000 X g su ernatant of a cell-free extract. Both preparations contained ellipsoidal granules from about 350 to 1000 A diameter. Many granules exhibited a marked depression. No typical unit membrane profiles appeared in thin sections of glutaraldehyde/Os04-fixed samples. Upon incubation with substrate and activators, chitin microfibrils were produced. The microfibrils were often found intimately associated with granules. The most common configurations were: a microfibril with a granule at one end, or two microfibrils "arising" from the same granule. These findings lend support to the granule hypothesis for the elaboration of cell wall microfibrils by endsynthesis.The mechanism of formation of microfibrillar cell walls of plants and fungi has been the subject of various investigations. This topic has been recently reviewed (1, 2). Most studies have been concerned with the formation of cellulose and chitin. It is generally agreed that the nonfibrillar, amorphous components of the wall pose fewer spatial problems of biosynthesis. As to microfibrils, their shape, size, and orientation present a number of spatial demands for their elaboration. Among the organelles commonly suggested as the site of elaboration of microfibrillar polysaccharides are: plasmalemma (3, 4), Golgi apparatus (5, 6), and granules present between wall and plasmalemma (1, 2, 7). We have recently shown (8) that chitin microfibrils can be assembled in vitro by a "solubilized" form of chitin synthetase (EC 2.4.1.16; UDP-2-acetamido-2-deoxy-D-glucose:chitin 4-,B-acetamidodeoxyglucosyltransferase) prepared from yeast cells of Mucor rouxii. The enzyme was "solubilized" from a crude membrane-rich preparation (35,000 X g pellet) by incubation with the enzyme substrate, uridine diphosphate N-acetyl-D-glucosamine (UDP-GlcNAc), and activator, N-acetyl-D-glucosamine (GlcNAc), at 0°C. The present communication examines the electron microscopic morphology of chitin synthetase isolated by this technique and also of unbound enzyme separated from a crude cellfree extract of the yeast form of M. rouxii. MATERIALS AND METHODSCultivation Techniques. Spores (1.5 X 108) of Mucor rouxii, IM-80, were inoculated into 0.5 liter of liquid YPG (yeast extract/peptone/glucose) medium (9) in 2-liter Erlenmeyer flasks and incubated in a reciprocating shaker at 280C for 12 hr. A mixed gas stream (30% CO2 + 70% N2) was bubbled through the medium during the entire incubation period.Cell-Free Extract-Preparation. Yeast cells from 1.5 liters of medium were harvested on sintered-glass filters, washed twice with 200 ml of ice-cold 0.05 M phosphate buffer, pH 6.0, containing 10 mM MgCl2, resuspended in ...

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Section: Discussionmentioning

confidence: 99%

Microfibril assembly by granules of chitin synthetase.

Ruíz-Herrera¹,

Sing²,

Woude³

et al. 1975

Proc. Natl. Acad. Sci. U.S.A.

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“…Nevertheless, the presence of microfibrils of skeletal wall polysaccharides can almost invariably be demonstrated in cell walls formed de novo on the surfaces of regenerating fungal protoplasts (e.g., 2,88,96,197,247,265). Also, refined cytological and biochemical methods, such as partial enzymatic digestion of the walls followed by electron microscopy, reveal the fibrous nature of certain wall components (118,119,121,135; Kopecka et al, Proc.…”

Section: Wall Architecturementioning

confidence: 99%

Biosynthesis of cell walls of fungi.

Farkas¹

1979

Microbiological Reviews

196

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FORMATION OF CELL WALLS .120 General .120 Biosynthesis of Individual Wall Components .121 Chitin .121 Glucans .124 ten on this subject in the last years (e.g., 5, 9, 10, 15, 16, 205). However, some general explanations are necessary to serve as an introduction to the problem of fungal cell walls. Chemical Structure The remarkable properties of fungal walls, such as their mechanical strength, morphological features, and biological activity, are undoubtedly based on their particular chemical composition. Bartnicki-Garcia (15) pointed out that a close correlation exists between taxonomic classification and cell wall composition among fungi. Polysaccharides, which represent about 80 to 117

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Licht‐ und elektronenmikroskopische Untersuchungen an regenerierenden Protoplasten von Polystictus versicolor

Cited by 6 publications

References 19 publications

Microfibril assembly by granules of chitin synthetase.

Microfibril assembly by granules of chitin synthetase.

Biosynthesis of cell walls of fungi.

Licht‐ und elektronenmikroskopische Untersuchungen an jungen Protoplasten von Polystictus versicolor

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