Structural and Immunological Studies on the Protoplast Membrane of the Yeast
            <i>Candida utilis</i>

Mendoza, Concepción García; Lopez, M. D. Garcia; Uruburu, F.; Villanueva, Julio R.

doi:10.1128/jb.95.6.2393-2398.1968

Cited by 13 publications

(2 citation statements)

References 14 publications

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“…A role for magnesium and calcium in the stabilization of membranes during the process of spheroplast formation is suggested. Similar functions have been attributed to these elements in yeasts (Lewis & Stephanopoulos 1967;Mendoza et al 1968).…”

Section: Spheroplasts Spheroplast Ly Sates and Aflatoxins 489supporting

confidence: 69%

Preparation and Properties of Spheroplasts from Aspergillus parasiticus with Special Reference to the de novo Synthesis of Aflatoxins

Tyagi

Venkitasubramanian

1981

Journal of Applied Bacteriology

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Spheroplasts were prepared from Aspergillusparasiticus NRRL 3240using~-glucuronidase from Helix pornaria. They were osmotically fragile spherical structures which lysed when suspended in hypotonic buffers. Purity of the preparation was confirmed by phase-contrast microscopy. Maximal conversion of mycelia to spheroplasts was achieved with 48 and 72 h old cultures. Spheroplasts were metabolically active as indicated by the incorporation of labelled thymidine, uridine and leucine into DNA, RNA and proteins, respectively. A significant incorporation of [meth~l-~H] thymidine into trichloroacltic acid-insoluble material suggested the presence of thymidine kinase in this organism. Spheroplasts and lysates demonstrated the ability to incorporate labelled acetate into aflatoxins. Maximum incorporation was observed in those prepared from 96 h old cultures. Lysates were more efficient in de n o w aflatoxin synthesis as compared to intact mycelia and spheroplasts.AFLATOXINS are secondary metabolites produced by certain strains of Aspergillus ~~Q V U S and A . parasiticus. Attempts to prepare cell-free extracts, active in de novo aflatoxin synthesis, from A . parasiticus cultures, by grinding with sea sand in the presence of sucrose/EDTA and mannitol /EDTA buffers proved unsuccessful, indicating that the enzymes involved in aflatoxin biosynthesis may be part ofa complex whose native conformation is altered by drastic treatments. The conversion of mycelia to spheroplasts followed by osmotic lysis to yield lysates might preserve the integrity of the enzyme complex. Hence a study was made of gentler methods of disrupting the mycelium. In this paper, we report the method used for studying the incorporation of [1-I4C] acetate into aflatoxins in spheroplasts and their lysates prepared from A . parasiticus. Materials and Methods ChemicalsAsparagine, Tris (hydroxymethyl) aminomethane, fl-mercaptoethanol, 2,5-diphenyloxazole, 1,4-bis[2-(5-phenyloxazolyl)] benzene, bovine serum albumin and pglucuronidase (from Helix pornaria) were purchased from Sigma Chemical Co., St.

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Section: Spheroplasts Spheroplast Ly Sates and Aflatoxins 489supporting

confidence: 69%

Preparation and Properties of Spheroplasts from Aspergillus parasiticus with Special Reference to the de novo Synthesis of Aflatoxins

Tyagi

Venkitasubramanian

1981

Journal of Applied Bacteriology

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“…to lysis by distilled water. No apparent new structure of a cell wall could Recently, the problem of whether yeast protobe detected on the surface of protoplasts in plasts are true protoplasts has been raised by ultrathin sections at the end of the logarithmic some workers (6,19,21). Ottolenghi (19) re-261 VOL.…”

Section: Discussionmentioning

confidence: 99%

Analytical Studies on Regeneration of Protoplasts of Geotrichum candidum by Quantitative Thin-Layer-Agar Plating

et al. 1969

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A preparation of pure protoplasts of Geotrichum candidum became osmotically stable and colonies developed when the protoplasts were embedded in stabilizing thin-layer-agar and incubated with stabilizing basal medium. When growing protoplasts were exposed to distilled water and then reincubated with basal medium, the process of regeneration of protoplasts could be quantitatively demonstrated by counting colonies. The process was divided into three phases, lag, logarithmic, and stationary. Furthermore, the state of regeneration of protoplasts at each phase could be seen in detail by microscopic studies of protoplasts under similar growth conditions. In the lag phase, which lasted for 2 hr after inoculation, protoplasts were completely destroyed when placed in distilled water. During the logarithmic phase, from 2 to 5 hr after inoculation, protoplasts rapidly became osmotically stable and about 18% of them were growing. In the stationary phase, most protoplasts developed germ tubes within 2 hr. These results suggested that there are two main phases, although individual cells passed through three different conditions, osmotically labile, osmotically stable, and growing. No apparent structure of cell wall material could be detected by electron microscopy on the surface of the membrane of these osmotically stable cells. This suspension was contaminated with a large amount of ghosts and partially digested cells (Fig.

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The Structure, Synthesis and Functions of the Yeast Cell Wall-a Review

MacWilliam¹

1970

Journal of the Institute of Brewing

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Glucan, mannan, chitin, protein, phosphate and lipid are found in the walls of all brewing yeasts so far examined although the contents and composition of each varies, as does the content of wall in the cell. Both glucan and mannan have branched structures and are linked to protein. Chitin is probably also bound to protein and phosphate to mannan. Some of the enzymic activities present in the wall are associated with the mannan‐protein fraction. This fraction is located on the outer surface of the wall and appears to play a part in the appearance of flocculence in brewing yeast during fermentation.

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Structural and Immunological Studies on the Protoplast Membrane of the Yeast Candida utilis

Cited by 13 publications

References 14 publications

Preparation and Properties of Spheroplasts from Aspergillus parasiticus with Special Reference to the de novo Synthesis of Aflatoxins

Preparation and Properties of Spheroplasts from Aspergillus parasiticus with Special Reference to the de novo Synthesis of Aflatoxins

Analytical Studies on Regeneration of Protoplasts of Geotrichum candidum by Quantitative Thin-Layer-Agar Plating

The Structure, Synthesis and Functions of the Yeast Cell Wall-a Review

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