Showing papers on "Protoplast published in 1971"
TL;DR: Passive permeabilities of the cell wall and protoplast of Bacillus megaterium strain KM were characterized by use of 50 hydrophilic probing molecules (tritiated water, sugars, dextrans, glycols, and polyglycols) which varied widely in size.
Abstract: Passive permeabilities of the cell wall and protoplast of Bacillus megaterium strain KM were characterized by use of 50 hydrophilic probing molecules (tritiated water, sugars, dextrans, glycols, and polyglycols) which varied widely in size. Weight per cent uptake values (R(w)) were measured at diffusional equilibrium under conditions that negated the influences of adsorption or active transport. Plots of R(w) for intact cells as a function of number-average molecular weight ( M(n)) or Einstein-Stokes hydrodynamic radius ( r(ES)) of the solutes showed three phases: a protoplast uptake phase with a polydisperse exclusion threshold of M(n) = 0.6 x 10(3) to 1.1 x 10(3), r(ES) = 0.6 to 1.1 nm; a cell wall uptake phase with a polydisperse exclusion threshold of M(n) = 0.7 x 10(5) to 1.2 x 10(5), r(ES) congruent with 8.3 nm; and a total exclusion phase. Isolated cell walls showed only the latter two phases. However, it became evident that the cell wall selectively passed only the smallest molecules in a heterodisperse polymer sample. When the molecular-weight distributions of polyglycol samples ( M(n) = 1,000, 1,450, and 3,350) were determined by analytical gel chromatography before and after uptake by intact cells or isolated cell walls, a quasi-monodisperse exclusion threshold was obtained corresponding to M(n) = 1,200, r(ES) = 1.1 nm. The permeability of isolated protoplasts was assessed by the relative ability of solutes to effect osmotic stabilization. An indefinite exclusion threshold, evident even with monodisperse sugars, was attributed to lengthwise orientation of the penetrating rod-shaped molecules. Altogether, the best estimate of the limiting equivalent porosity of the protoplast was 0.4 to 0.6 nm in radius and of the cell wall, 1.1 nm.
422 citations
TL;DR: Protoplasts were produced from a soybean cell culture by enzymatic removal of the cell wall and there was a large amount of protoplast fusion during formation.
Abstract: Protoplasts were produced from a soybean cell culture by enzymatic removal of the cell wall. The protoplasts were fixed after various periods of culture. There was a large amount of protoplast fusion during formation. The nuclear behaviour during division was observed. Nuclear fusion prior to nuclear division was common. Almost complete synchronization of multinucleates was found. Various abnormalities were present in nuclear and cellular division which could have led to aneuploid production.
73 citations
TL;DR: There have been several reports of plant cell wall regeneration1–4 and two reports of division following protoplast formation3, 4 but only one of sustained cell division3.
Abstract: THERE have been several reports of plant cell wall regeneration1–4 and two reports of division following protoplast formation3, 4 but only one of sustained cell division3.
66 citations
TL;DR: In a variety of experiments, turbidity and the net content of protein, ribonucleic acid (RNA) and deoxyribon nucleic acid increase at the same rate, indicating balanced macromolecular biosynthesis.
Abstract: Osmotically fragile forms of Streptococcus faecalis 9790 were grown in 0.5 m sucrose- or 0.5 m NH4Cl-stabilized medium. The “protoplast” cultures exhibit an average growth rate constant of 0.66 to 0.94 mass doublings/hr. In a variety of experiments, turbidity and the net content of protein, ribonucleic acid (RNA) and deoxyribonucleic acid increase at the same rate, indicating balanced macromolecular biosynthesis. A total of two to three mass doublings was obtained, with no evidence of cell division. After osmotic shock, “protoplast” cultures released 93 to 94% of their RNA content in a form not sedimentable at 12,800 × g for 15 min, in contrast to streptococci, which released 7% of their RNA content after the same treatment.
57 citations
TL;DR: The mechanism of regeneration of mycelial protoplasts from Aspergillus nidulans wild-type and strain p76 has been investigated and it is suggested that the mechanism reflects the site of origin of the protoplast from the parent hypha.
Abstract: SUMMARY: The process of regeneration of mycelial protoplasts from Aspergillus nidulans wild-type and strain p76 has been investigated. In liquid media two patterns of regeneration were observed. In the first, the protoplasts produced chains of yeast-like cells and eventually the terminal cell produced a hypha. In the second wall ‘shells’ were formed into which the cytoplasm migrated. It is suggested that the mechanism of regeneration reflects the site of origin of the protoplast from the parent hypha.
55 citations
TL;DR: About 50% of the total protoplasts enzymatically isolated from callus cells of maize endosperm were multinucleate, suggesting that fusion of single protoplast occurred during the protoplast isolation process.
46 citations
TL;DR: According to this work, hexachlorophene is physically disruptive at intermediate or high relative concentrations but acts in a more subtle fashion at the minimal lethal concentration.
Abstract: Hexachlorophene is a soap-compatible bisphenol that has been widely used as an antiseptic, yet its mechanism of action is undefined The relative threshold concentration for bactericidal effect on a susceptible test organism, Bacillus megaterium, was established to be about 10 μg/mg of cell dry weight At this or at high (≥100 μg/mg) concentration, adsorptive uptake by cells displayed saturation kinetics At about 30 μg/mg, the time course of adsorption occurred in three distinct stages The triphasic pattern was interpreted to represent successive penetration of and adsorption by the cell wall, the protoplast membrane, and the cytoplasm This interpretation was substantiated by determinations of hexachlorophene adsorption by isolated cell components Electron microscopy disclosed cytopathology, evidenced as gaps or discontinuities, in the protoplast membrane (but not in the cell wall or cytoplasm) at > 30 μg of hexachlorophene per mg of cell dry weight Similarly, treatment with > 30 μg/mg allowed a fluorescigenic dye (tolyl-peri acid) to penetrate into the protoplast However, no detectable cytological manifestations were discerned at the minimum lethal concentration of 10 μg/mg Apparently, hexachlorophene is physically disruptive at intermediate or high relative concentrations but acts in a more subtle fashion at the minimal lethal concentration
40 citations
TL;DR: Very slow rates of uptake were observed with intact organisms but protoplast preparations assimilated the nucleic acid precursors much more readily.
Abstract: The entry of both nucleotides and base precursors into whole cells and the nucleic acid fraction of the blue-green alga Anacystis nidulans has been examined. Very slow rates of uptake were observed with intact organisms but protoplast preparations assimilated the nucleic acid precursors much more readily.
31 citations
TL;DR: The ability of protoplast membranes to catalyse peptidoglycan synthesis has been investigated and appears to be an all-or-none process, is not prevented by chloramphenicol and is maximal within 30 min at 37°.
30 citations
TL;DR: Preliminary tests suggest that it may be possible to infect using purified virus or even virus RNA, and the method of protoplast preparation and regeneration was essentially that devised by C. F. Roberts & R. Rosenberger for producing protoplasts from Aspergillus.
Abstract: Virus infection through hyphal anastomoses, the only method reported so far for infecting moulds with double-stranded RNA viruses (Lhoas, 1971) is dependent on the compatibility between the donor strain and the strain to be infected, and is therefore of rather limited use. The new technique described here allows infection with extracellular virus and, although it has been developed with crude virus preparations, preliminary tests suggest that it may be possible to infect using purified virus or even virus RNA.
Protoplasts were prepared from virus-free and morphologically distinct Penicillium stoloniferum strains susceptible to viruses (Lhoas, 1971): strain 1, obtained from strain atcc 10111, produces white conidia, and strain 2, obtained from strain cmi 91966, produces fawn conidia. The method of protoplast preparation and regeneration was essentially that devised by C. F. Roberts & R. F. Rosenberger (personal communication) for producing protoplasts from Aspergillus.
28 citations
TL;DR: An inducible lytic enzyme complex from Streptomyces satsumaensis was capable of releasing spherical protoplast-like bodies from the mycelium of Geotrichum candidum and showed the presence of chitinase, mannanase and laminaranase.
Abstract: An inducible lytic enzyme complex from Streptomyces satsumaensis was capable of releasing spherical protoplast-like bodies from the mycelium of Geotrichum candidum. An analysis of this enzyme complex revealed the presence of chitinase, mannanase and laminaranase. Also a combination of chitinase and exolaminaranse from other sources could produce the “protoplasts” under standard conditions.
TL;DR: The location of oxido-reduction sites detectable by means of potassium tellurite has been studied in Bacillus subtilis indicates that the methods used in protoplast formation which lead to the separation of mesosomes and cytoplasmic membranes do not produce important changes in the location of respiratory enzymes.
TL;DR: It has now been shown that the biological activity depends upon the integrity of the lactone bond and that hydrolysis or reversion to the closed ring form can be simply attained by treatment with alkaline or acidic conditions.
TL;DR: Phase contrast optics reveal cytoplasmic granules, the size of mitochondria, which serve to indicate such dynamic processes as cyclosis in Lycopersicum pimpinellifolium berries.