PubMed Health⌕ Search

Biomedical subjects

M Polsinelli

Publications and source records attributed to M Polsinelli.

At least 37 records · Page 2Linked to original sources
PubMed1989

Isolation of Bacillus subtilis transformation-deficient mutants and mapping of competence genes.

We have isolated and characterized 48 Bacillus subtilis competence-deficient mutants. The mutants, obtained by nitrosoguanidine mutagenesis or by insertional mutagenesis with transposon Tn917, had a reduced transformation frequency and a wild-type transduction frequency. The com mutations were mapped by PBS1 transduction and at least four new com genes have been identified. The mutants were also characterized for their capacity to bind and take up the transforming DNA.

Bacillus subtilis↗
PubMed1989

Isolation and characterization of Saccharomyces cerevisiae mutants resistant to sulphite.

Several spontaneous and UV-induced sulphite resistant mutants of Saccharomyces cerevisiae have been isolated and characterized. Some of the UV-induced mutants appeared to be much more resistant than the spontaneous ones, as judged by their plating efficiency and cellular growth in the presence of increasing concentrations of sulphite. All the resistant mutants seemed to have an intracellular glutathione content and glutathione reductase activity higher than and an extracellular glutathione concentration lower than the parental strain.

Culture Media↗
PubMed1988

Glutathione and glutathione metabolizing enzymes in yeasts.

Total glutathione content, glutathione peroxidase, glutathione transferase and glutathione reductase activities have been measured in 12 species of yeasts. All the strains tested contained glutathione, though in different amounts, as well as the above mentioned enzymes. To discriminate between the selenium-dependent and the selenium-independent form, glutathione peroxidase activity has been measured with both H2O2 and cumene hydroperoxide. Rhodotorula glutinis appeared to be the only strain in which the selenium-dependent form was not found, but this yeast exhibited the highest level of selenium-independent glutathione peroxide activity as compared to the other strains.

Glutathione↗
PubMed1987

A spectroscopic investigation of cobalt(II) substituted alkaline phosphatase.

The electronic and 1H NMR spectra are reported for the cobalt(II) alkaline phosphatase (EC 3.1.3.1.) system at pH around 6 in the range 0-2 mol of cobalt per mol protein. It is shown that under the present experimental conditions cobalt(II) selectively populates the A sites. Three isotropically shifted NH signals have been detected in the A site that indicate the presence of three histidines in the coordination sphere of cobalt(II). The electronic spectra and the nuclear relaxation properties are consistent with pentacoordination of cobalt(II) in the A site. The finding of reproducible preparation routes for the derivatives, and of appropriate experimental conditions for the observation of their 1H NMR spectra, open new possibilities for the spectroscopic investigation of alkaline phosphatase.

Alkaline Phosphatase↗
PubMed1985

Competence proteins in Bacillus subtilis com mutants.

The synthesis of nucleases and proteins specific for competence development have been studied in four different Bacillus subtilis competence-deficient mutants. The nuclease analysis showed that two DNA-binding-deficient mutants were impaired in three nuclease activities involved in binding and entry of donor DNA. The other two strains did not show any reduction in nuclease activities. Two-dimensional gel electrophoresis of the proteins, synthesized during competence development, revealed that all four mutants are lacking several competence-specific polypeptides. Our data show that these com mutations have a strong pleiotropic effect, which could be due to a block in the metabolic pathway leading to competence development.

Bacillus subtilis↗
PubMed1984

Isolation and characterization of Bacillus subtilis mutants altered in competence.

We isolated and characterized four Bacillus subtilis competence-deficient mutants. The mutants were obtained by nitrosoguanidine mutagenesis and by screening for mutants unable to be transformed both on solid and in liquid medium. Most of the mutants obtained in this way were tested for their sensitivity to the DNA-damaging agents methyl methanesulfonate, mitomycin C, and UV light. Among the mutants which did not show an increased sensitivity to these agents, four were chosen for further characterization. Data were obtained which indicate that the mutants are reduced in chromosomal and plasmid transformation and in transfection, whereas they are not altered in transduction and in protoplast transformation. Transformation experiments carried out by mixing a culture of a mutant with a culture of a wild-type strain gave some complementation for competence with one of the strains. The mutants were also characterized for their capacity to bind, take up, and break down transforming DNA; furthermore, the four competence mutations were mapped, and the results indicate that they belong to four different genes.

Bacillus subtilis↗
PubMed1981

Effect of a new pyrimidine analog on Bacillus subtilis growth.

2-Amino-5-ethoxycarbonylpyrimidine-4(3H)-one, a pyrimidine analog, inhibited growth of Bacillus subtilis. Data were obtained which suggested that the analog interfered with the methylation process. A mutant resistant to the inhibitor was isolated, and the mutation was mapped.

Bacillus subtilis↗
PubMed1980

Transfer of plasmid pRD1 from Escherichia coli to Azospirillum brasilense.

Data are presented which indicate that plasmid pRD1 can be transferred from Escherichia coli to strains of Azospirillum brasilense with a frequency of about 10(-7). The reverse was also possible; in this case the frequency of transfer appeared to be much higher, about 5 x 10(-1). Transfer of the plasmid was also obtained between strains of A. brasilense; in this cross the transfer frequency was very high (about 10(-1)). Moreover the pRD1 plasmid seems very stable in A. brasilense cells.

Azotobacter↗
PubMed1976

New purine markers in Bacillus subtilis.

Four new genetic markers involved in purine biosynthesis in Bacillus subtilis are clustered and lie between purE and tre. An additional new pur marker is located near purA.

Bacillus subtilis↗
PubMed1975

Genetic and enzymic studies on the recombination process in Bacillus subtilis.

We have isolated recombination deficient mutants of Bacillus subtilis on the basis of their sensitivity to methyl-methane-sulfonate or ultraviolet light, or of their inability to be transformed on solid medium. We have analyzed the mutants for several recombination and repair properties; we have grouped them in 5 classes on the basis of their phenotype and tested them for the activity of several enzymes acting on DNA, ie. DNA polymerase, polynucleotide ligase, ATP dependent DNase, and a DNase acting on single-stranded DNA. One mutant was found reduced in the latter DNase. Some of the mutants have been mapped, and they correspond to three different genes denominated rec D, rec F and rec G. All the recombination deficient mutants of B. subtilis described in the literature have been grouped in 7 classes; the mutations belong to 13 (and possibly 15) different genes distributed along the map. A coherent nomenclature and the criteria for a standard study of the rec mutants are proposed.

Bacillus subtilis↗
PubMed1975

A new mutant of Bacillus subtilis altered in the initiation of chromosome replication.

We have isolated a new mutant of Bacillus subtilis temperature sensitive in DNA replication; its properties are those of an initiation mutant. When liquid cultures are shifted to 48 degrees DNA replication is the first macromolecular synthesis that stops, but only after synthesis of the amount of DNA predicted for the completion of one replication round. When spores of the mutant are germinated and shifted to 48 degrees at subsequent times, one round of DNA replication is observed only when the shift occurs between 60 and 100 min; earlier shifts do not allow replication to start, later shifts allow more than one replication. The DNA replicated after a shift to high temperature is enriched in markers close to the terminus. The reinitiation of DNA replication stopped by the high temperature, takes place following a shift to a permissive temperature only if protein synthesis is allowed. Examination of DNA replication following toluene treatment shows that the elongation of DNA chains is not affected at the non-permissive temperature. This mutant is shown by PBS-1 mapping to correspond to a new gene denominated dna P, which is located between the thy A and fur A genes and is distinct from all the mapped dna and rec genes of Bacillus subtilis. The mutation confers to the cells also a deficiency in the ability to be transformed, to be transfected with SPP1 phage DNA, and to survive treatment with methyl-methane sulfonate. These deficiencies, observed at the permissive temperature, are no more temperature dependent than in the parental strain. The ability to perform homologous and heterologous transduction with PBS-1 phage and the sensitivity to ultraviolet radiation or mitomycin C are normal.

Bacillus subtilis↗
PubMed1975

Genetic and biochemical characterization of a ribosomal mutant of Bacillus subtilis resistant to sporangiomycin.

The antibiotic sporangiomycin affects the growth of Bacillus subtilis by inhibiting protein synthesis. Mutants of B. subtilis resistant to sporangiomycin have been isolated. One of these, PB 1690, has been further studied. The analysis of subcellular fractions from the mutant has shown that the biochemical effect of the mutation is an alteration of a site on the 50S ribosomal subunit responsible for the binding of the antibiotic: the mutant ribosomes do not bind sporangiomycin and are capable of carrying out phenylalanine polymerization in the presence of sporangiomycin. The resistance mutation maps on the chromosomal region where the ribosomal markers map. The mutant strain is also resistant to the action of the chemically related antibiotic thiostrepton. Treatment of B. subtilis ribosomes with LiCl results in the detachment of a group of proteins including the one responsible for sporangiomycin resistance. Active ribosomes can be reconstructed by mixing "split proteins" and "core particles" of either parental or mutant origin. The fate of the mutant protein can now be followed by assaying reconstructed ribosomes for capacity to bind sporangiomycin and for resistance to the action of the antibiotic in the reactions for phenylalanine polymerization.

Anti-Bacterial Agents↗
PubMed1975

Properties of Bacillus subtilis mutants temperature sensitive in germination.

A new mutant of Bacillus subtilis defective in the outgrowth phase of spore germination has been isolated. When incubated at 46 C, the spores of the mutant gave rise to abnormally large swollen cells. Genetic crosses show that the mutant is different from the three previously described. The genetic analysis indicates two regions of the B. subtilis chromosome involved in the control of the spore outgrowth.

Bacillus subtilis↗
PubMed1974

Properties of a Bacillus subtilis strain lacking DNA polymerase I.

We have isolated a mutant of Bacillussubtilis deficient in DNA polymerase I, denominated polA42, which shows a reduced ability to repair the damage to DNA by UV radiation, MMS and mitomycin C;the ability to perform recombination is not appreciably impaired.DEAE cellulose chromatography allows the separation of polymerases I and II from the parental strain;a simple procedure is also described which allows to separate rapidly the polymerases II and III of the mutant strain. The three separated polymerases have similar catalytic properties but they can be distinguished for their sensitivity to inhibitors: PCMB inhibits polymerases II and III but not polymerase I; HPUra inhibits only polymerase III. All three enzymes are unaffected by nalidixate. The DNA synthesis occurring in cells of the polA42 strain permeabilized with toluene is inhibited by nalidixate, whereas the synthesis occurring in polA(+) toluenized cells is unaffected by the drug. The polA gene has been mapped by transduction and localized between the phe(12) and argA(3) genes.

Bacillus subtilis↗
PubMed1973

Mutants of Bacillus subtilis temperature sensitive in the outgrowth phase of spore germination.

Thirteen thermosensitive mutants of Bacillus subtilis defective in the outgrowth phase of spore germination were isolated. The spores of the mutants grow into vegetative cells at 35 C but not at 47 C, whereas the vegetative cells grow equally well at both temperatures. At 47 C all the mutant spores are able to initiate germination, but the process stops at an early phase of outgrowth in one strain and in a late phase in the other 12 strains. The spore of the latter gives rise to a swollen cell unable to divide. In all mutants, the normal phenotype is restored when the spores are grown in the presence of 20% sucrose or 2% NaCl. The synthesis of deoxyribonucleic acid and proteins does not seem to be altered in the mutants giving swollen cells. The mutants were grouped into three distinct genetic classes by transformation.

Amino Acids↗