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PubMed1987

[Plasmid transformation of Bacillus cereus protoplasts].

The process of polyethyleneglycol-induced plasmid transformation of Bacillus cereus protoplasts was studied. Plasmid transfer into Bacillus cereus strains was demonstrated with the frequencies 1.3.10(1)-1.6.10(2) transformants per 1 mkg of plasmid DNA. The plasmids transferred are stably inherited by Bacillus cereus cells causing tetracycline resistance (pBC16) or kanamycin resistance (pUB110 and pBD64). The proposed method can be used for construction of Bacillus cereus strains having the plasmid determined characteristics.

Bacillus cereus↗
PubMed1988

[Hybridization of A-factor deficient mutants of Streptomyces griseus by means of fusion of protoplasts].

Characteristics of 6 A-factor deficient mutants of S. griseus are presented. The common feature of the mutants was impairment of sporulation, formation of aerial mycelium and streptomycin synthesis. Pair-by-pair hybridization of the mutants was performed with protoplast fusion followed by regeneration. 9 pair couplings of the mutants were performed. In 3 of them sporulating recombinants were detected. The antibiotic production level in 70 hybrids was different and ranged from 0 to 1700 micrograms/ml. The morphological features of the colonies and the number of the spores formed were also different. The common feature of all the 70 sporulating hybrid strains was recovery of synthesis of A-factor, an endogenic regulator of S. griseus development. Therefore, in the A-factor deficient mutants impairment of A-factor synthesis was induced not by the plasmid elimination, as was suggested, but by mutation of separate genes.

4-Butyrolactone↗
PubMed1988

[Identification of mutations in the asporogenic yeast Candida tropicalis using intrageneric fusion of protoplasts].

The possibility of genetic identification of mutations in asporogenic yeast by the technique of intrageneric fusion of yeast protoplasts of Candida tropicals and Saccharomyces cerevisiae has been demonstrated for Candida tropicals strains G5-9 (Ade- Leu-) and G32-4 (Leu-). The mutations to auxotrophy ade- in the strain G5-9 and leu- in G32-4 of Candida tropicals are allelic to ade2 and leu1 mutations in the genes of Saccharomyces cerevisiae yeast. The allelic character of adenine auxotrophy mutation in Candida tropicals and ade2 mutation in Saccharomyces cerevisiae is confirmed by the absence of AIR-carboxylase activity in cellular extract from the strain G5-9.

Alleles↗
PubMed1977

Antitumor activity of protoplast membrane from group A streptococcus.

Cytoplasmic membrane of Group A streptococcus has been obtained by treatment of the cells with a phage-associated lytic enzyme to dissolve the streptococcal cell wall, followed by shocking osmotically. The protoplast membrane fraction (PMF) remained as a distinct homogeneous structure in the electron micrograph and analysis showed a low rhamnose content. Febrile response produced by PMF was very slightly exhibited or not at all. PMF showed weak suppression against the growth of rat Yoshida sarcoma cells in culture and inhibition of [3H]-uridine incorporation into the sarcoma cells in vitro. In vivo antitumor experiments demonstrated that PMF has a mild inhibiting effect against mouse Ehrlich ascites carcinoma, though there was not observed a definite correlation between survival rate and dose level. Antitumor activity of PMF was thermo-labile and was strikingly abolished by treatment with a bacterial enzyme, Nagarse, but not so much by alpha-chymotrypsin.

Animals↗
PubMed1978

[Comparative study of the effect of ionic and non-ionic surface-active compounds on plasmic membrane of yeast protoplasts].

Lytic effect of some cationic surface-active compounds (SAC) on yeast protoplast plasmic membrane is studied. Comparative analysis of the lytic effect of anionic, cationic and non-ionic SAC is carried out, a correlation between key physico-chemical characteristics of the agents (critical concentration of micellization, hydrophyle-lipophyle balance) and their lytic activity is investigated. A proposition is made on the presence in all biphylic compounds of a hydrophyly gradient, which is due to the effect of hydrophylic group on lipophylic properties of hydrophobic part of the molecule, and possible role of this factor in thelytic effect of biphylic compounds on biological membranes is discussed.

Cell Membrane↗
PubMed1986

A nystatin-resistant mutant of Saccharomyces cerevisiae: isolation and characterization by electron microscopy and chemical analysis of whole cells, cell-walls and protoplasts.

A mutant of Saccharomyces cerevisiae NCYC 239 with a high minimum inhibitory concentration (35 micrograms ml-1) for nystatin, compared to that of the parent strain (2 micrograms ml-1), was derived by a series of subcultures in media containing increasing antibiotic concentrations. In the absence of nystatin, the growth rate of the mutant was significantly lower than the parent strain, although mean cell-size and size-distribution were similar. No differences between strains were detectable by electron microscopy. Analysis of whole cells showed the total sterol present and the ratio of ergosterol:24(28)dehydroergosterol was similar. However, there were marked differences in amino acid content and chain-length of fatty acids in the cell wall, and protoplasts from resistant cells had decreased amounts of unsaturated fatty acids. It is suggested that alterations in cell wall components in the mutant may be directly linked to the mechanism of nystatin resistance.

Amino Acids↗
PubMed1982

Effect of alpha-amanitin and actinomycin D on RNA synthesis in the protoplasts of Aspergillus nidulans.

RNA synthesis was studied in protoplasts from Aspergillus nidulans, which remained metabolically active for several days under the appropriate conditions. It is concluded, that at certain actinomycin D concentrations the ribosomal RNA synthesis can be selectively inhibited. However, alpha-amanitin at concentrations up to 400 micrograms/ml neither influenced the total nor the RNA polymerase II directed RNA synthesis. It was possible to discriminate between the RNA polymerase I or II directed RNA synthesis due to the presence of poly(A) tails attached to at least part of the RNA, presumably messenger RNAs, or their precursors.

Amanitins↗
PubMedDate not supplied

[Hybridization of asporogenic strains of Hansenula polymorpha yeasts by protoplast fusion].

Intrastrain and interstrain hybrids of different ploidy were produced by the fusion of protoplasts of Hansenula polymorpha haploid and diploid strains. The diploid hybrids were found to be stable in contrast to the triploid and tetraploid hybrids. The instability of the triploid and tetraploid states in Hansenula polymorpha was expressed in the elevated frequency of spontaneous formation of auxotrophic markers and in the decreased content of DNA per cell in the course of storage.

Ascomycota↗
PubMed1984

5'-dephosphorylated 2',5'-adenylate trimer and its analogs. Inhibition of tobacco mosaic virus replication in tobacco mosaic virus-infected leaf discs, protoplasts, and intact tobacco plants.

The effect of the 5'-dephosphorylated 2',5'-adenylate trimer and its 2',5'-trimer core analogs on the inhibition of tobacco mosaic virus (TMV) replication was determined in tobacco leaf discs, protoplasts, and whole tobacco plants, using infectivity tests and enzyme-linked immunosorbent assays. A structure-activity-metabolic stability-toxicity analysis of the 2',5'-adenylate trimer core molecule in TMV-infected Nicotiana glutinosa was determined. Modification at either the 6-amino position of the adenylate residues (i.e. inosinate trimer core) or at the 2' terminus (i.e. A-A-ara-A or A-A-Tu) inhibited replication of TMV. Modification of the 3'-hydroxyl group of the adenylate residues to 3-deoxyribose (i.e. the 2',5'-cordycepin trimer core) inhibited TMV replication better than the 2',5'-adenylate trimer core molecule. With enzyme-linked immunosorbent assays, there was complete inhibition of TMV replication by 200 nM 2',5'-adenylate trimer core for 60 h and by 200 nM 2',5'-cordycepin trimer core for 96 h. The amount of 2',5'-oligonucleotides associated with the leaves was determined using 2',5'-[3H]cordycepin trimer core; 1 X 10(-12) mol/cm2 of plant leaves inhibited TMV replication by 99%. No 2',5'-phosphodiesterase activity was detected in TMV-infected and noninfected leaf extracts. Therefore, the 2',5'-trimer cores were potent inhibitors of TMV replication at nanomolar concentrations, i.e. at 1000-fold lower concentration than that required in mammalian systems.

Adenosine↗
PubMed1980

[Formation of stable diploid bacteria by fusion of protoplasts of Bacillus subtilis and the effect of rec- mutations on the fusion products formed].

A minority among the prototrophic clones formed when protoplasts from two polyauxotrophic strains of B. subtilis are fused has been shown to be diploid, carrying the parental deficient alleles in their DNA, and generally segregating auxotrophs when grown in nutrient medium. This is true whether the strains being fused are Rec+ or Rec-, since the rec- mutations used hardly affect recombinations occurring between chromosomes in diploid Bacteria.

Alleles↗
PubMed1981

Plasma membrane particles in yeast protoplasts.

Investigations of plasma membrane particles in Saccharomyces cerevisiae protoplasts are shortly reviewed. Particle arrangement into a hexagonal patterns is considered to reflect some minute changes in the biomembrane organization rather than functional differentiation. Plasma membrane invaginations are proved to be rigid structures capable of migrating in the fluid domain of the membrane. Density of the particles per unit area is related to the degree of membrane stretching which suggest that upon membrane extension new protein molecules are shifted towards the hydrophobic layer of the membrane.

Cell Membrane↗
PubMedDate not supplied

[Ultrastructural and cytochemical aspects of regenerating "Candida albicans" sphero-protoplasts (author's transl)].

Subcellular modifications associated with sphero-protoplast regeneration of Candida albicans were followed with the electron microscope. After 30 min of regeneration the ultrastructural study revealed a considerable proliferation of plasmalemma invaginations and an abundant synthesis of glycogen in association with an extension of the Golgi apparatus/endoplasmic reticulum system. Later, the inflection of these invaginations and their fusion with the plasmalemma lead to a rejection of cytoplasmic areas in the cell wall. Glycogen-like particles so released in the wall were distributed in clearly delineated layers. The incorporation of cytoplasmic material through the intermediary of the plasmalemma constituted a mechanism believed to mediate the reconstitution and thus the integrity of the newly-forming cell wall.

Candida albicans↗
PubMed1981

Protoplast fusion in the yeast Candida utilis.

Protoplasts obtained by snail enzyme treatment from two stable auxotrophic mutants of the yeast Candida utilis were induced to fuse by the use of polyethylene glycol. The hybrids formed from the auxotrophic parental strains were selected by complementation on stabilized minimal medium. Many of the hybrids were unstable and readily dissociated into their parental strains. Others, in which parental nuclei had fused, gave stable hybrid progeny. cytological and genetic evidence of these processes is presented.

Candida↗
PubMed1993

Hybrid construction by fusion of protoplasts of Endomycopsis fibuligera and Saccharomyces cerevisiae.

Protoplasts of an ethanol-producing strain of Saccharomyces cerevisiae (rho-, Cyc R, Ket R) and amylase-producing yeast Endomycopsis fibuligera (rho+, Cyc S, Ket S) were fused, which resulted in starch fermenting hybrids. The fusion frequency was 2 x 10(-7). The morphological appearance of the hybrids was similar to the petite parent S. cerevisiae strain. The amount of DNA in the hybrid was found to be slightly higher when compared with the individual parental strain.

Amylases↗
PubMed1976

[Biology of spheroplast- and protoplast-like types of L-forms of Escherichia coli K12 converted with penicillin].

A total of 21 strains of stable L-forms were obtained under the action of penicillin on various Hfr and F- strains of E. coli K12. Three morphological types of the L-forms obtained differed by the character of the cell elements, sensitivity to chemical agents, antibiotics and to T4 and T6 phages. Cell wall was revealed in one type of the L-forms, but the rest L-form types were devoid of the cell walls. Reference of the L-forms which preserved the cell wall to the spheroplastic type, and the L-forms devoid of the cell wall to the protoplastic type is suggested. A possibility of L-forms of spheroplastic type obtained from the Hfr strains to retain the sensitivity to f2 phage and to transmit their chromosomes to bacterial recipients in conjugation was demonstrated. The results obtained are discussed.

Anti-Bacterial Agents↗
PubMed1993

Transformation of wheat protoplasts mediated by cationic liposome and regeneration of transgenic plantlets.

E. coli plasmid pCGN1055 containing the hygromycin phosphotransferase (Hpt) gene under the control of the plant promoter was introduced into wheat protoplasts by cationic liposome (lipofectin)-mediated transformation, and transgenic albino plantlets were obtained. The transformation frequencies were 6.0% and 8.8% according to hygromycin resistance and DNA molecular hybridization. The assay of Hpt enzyme activity and Southern blot indicated the foreign gene existed and expressed in transgenic plantlets.

Cations↗