Search PubMed⌕ Search

Biomedical subjects

A Galizzi

Publications and source records attributed to A Galizzi.

At least 55 records · Page 3Linked to original sources
PubMed1985

Amplification of a chromosomal region in Bacillus subtilis.

We report on the amplification in Bacillus subtilis of a defined DNA sequence after exposure of the bacteria to increasing levels of antibiotic. The experimental system consisted of transformation of competent cells with a plasmid (pRHA39) unable to replicate in the host and carrying the alpha-amylase gene derived from B. subtilis. Selection of transformants resistant to 5 micrograms of chloramphenicol per ml resulted in the isolation of strains with the plasmid integrated into the chromosome at the site of homology, by a Campbell type mechanism. Starting from such a nontandem duplication, amplification was achieved by growing the bacteria in increasing concentrations of chloramphenicol. By dilution, Southern blotting, and hybridization to a radioactive probe, we estimated a copy number of about 10 for the amplified sequence of samples grown in the presence of 50 micrograms of chloramphenicol per ml. No free plasmid could be detected in the amplified strains. The extent of the amplified region was the same for all transformants, and the endpoints appeared to be the same in all isolates. As a consequence of the amplification, there was a noticeable increase in amylase production, and the amount of enzyme produced correlated with gene dosage. The amplification did not occur in a recE genetic background.

Alleles↗
PubMed1985

[Not Available].

Explore the source record for details and available documents.

History, Modern 1601-↗
PubMed1983

Nucleotide sequence of the amylase gene from Bacillus subtilis.

The gene coding for amylase (EC.3.2.1.1) has been isolated and sequenced from Bacillus subtilis by cloning in lambda Charon4A and pBR322. The entire coding sequence and large preceding and following regions, comprising the presumed transcriptional and translational regulatory regions, were sequenced. The coding sequence shows a large open reading frame with a translated molecular weight of 72,800 and a presumed signal sequence of approximately thirty-two amino acids. When the intact gene is present in Escherichia coli, it confers the ability to degrade starch, indicating that the gene is expressed in a functional state.

Amino Acid Sequence↗
PubMed1982

Pattern of RNA transcription during Bacillus subtilis spore outgrowth.

During the outgrowth of Bacillus subtilis spores, there is a period of RNA and protein synthesis in the absence of DNA replication. Two mutants of B. subtilis, PB2442 (gsp-4) and PB2452 (gsp-81), were used to study the pattern of RNA synthesis during this period. The two mutants are temperature-sensitive in the outgrowth phase, and show a limited amount of incorporation of (3H)uridine at 47 degrees C. The RNAs synthesized during a 2 min pulse with (3H)uridine were hybridized to EcoRI-digested DNA, after agarose gel electrophoresis and transfer to nitrocellulose paper (Southern technique). For both mutants the transcripts synthesized at 35 degrees C at different times were different. Differences were also observed in the transcripts made at 47 degrees C. For both mutants, in the presence of chloramphenicol, the same hybridization pattern was obtained for RNAs pulse-labelled at different periods during outgrowth.

Bacillus subtilis↗
PubMed1981

Integration and excision of a plasmid in Bacillus subtilis.

We have studied the behaviour in Bacillus subtilis of a plasmid (pPV21) carrying the thymidylate synthetase gene of phage phi3T (thyP3). The plasmid can transform efficiently the competent cells of all the strains tested. Polyethylene glycol (PEG)-mediated protoplast transformation is efficient only for recE, recD or recF mutants. When present in recombination proficient strains, the plasmid can be integrated into the chromosome, primarily at the thyA locus. This has been shown by genetic mapping and by blot-hybridization. A second less efficient site is at (or near to) the attachment site of phage phi3T. Excision of the plasmid restores the EcoRI restriction pattern of the parental DNA, although with the loss of the defective thyA endogenotic allele and the retention of the thyP exogenotic gene.

Bacillus subtilis↗
PubMed1980

A bacterial test in liquid culture for the detection of mutagenic activity of antibacterial compounds: studies with cephalosporine HR 756.

A detailed procedure for the short term evaluation of mutagenic activity in the Salmonella assay in liquid cultures is given for Cephalosporine HR 756. The essential steps of the test are: a) determination of absence of interference of the pKM101 plasmid present in the bacterial tester strains, b) determination of the doses of the antibiotic required to obtain a limited killing, c) introduction of appropriate controls with known mutagenic compounds active in the presence and in the absence of metabolic activation, d) segregation of mutants. Following this procedure we have determined the absence of any mutagenic activity in the liquid assay of Cephalosporine HR 756.

Animals↗
PubMed1979

Mutants of Bacillus subtilis affected in spore outgrowth.

Six mutants of Bacillus subtilis 168 that are temperature-sensitive in spore outgrowth were isolated. The outgrowth process proceeds normally at 35 degrees C, but at the non-permissive temperature (47 degrees C) it is arrested at a specific stage characteristic for each mutant strain. The mutants are not altered in vegetative growth whether at 35 degrees C or at 47 degrees C. They were characterized for their ability to synthesize RNA, proteins and DNA during outgrowth. A mutant defective in spore germination was also isolated; less than 5% of its spores can germinate at any of the temperatures tested. The mutations were mapped by means of transduction and transformation. The isolation of a number of outgrowth mutants which map at different loci and which affect outgrowth at different times is discussed in relation to the regulation of this process.

Bacillus subtilis↗
PubMed1978

Studies on transduction process by SPP1 phage.

The conditions for optimal transduction efficiency of the Bacillus subtilis phage SPP1 have been investigated. By irradiating transducing lysates with u.v. light we have been able to obtain a fivefold increase in the number of transductants and to reduce strongly the interference caused by infective particles. Any dependence of SPP1 transduction on PBSX induction has been ruled out by the use of xin mutants, which are unable to induce the defective phage. SPP1 mediated transduction is susceptible to the restriction and modification system of B. subtilis. The rec functions involved in the recombination of the SPP1 transduced DNA fragment are probably identical to those required in DNA transformation and heterologous PBS1 transduction.

Bacillus subtilis↗
PubMed1977

RNA polymerase from Bacillus subtilis: isolation of core and holo enzyme by DNA-cellulose chromatography.

A new procedure for the purification of B. subtilis RNA polymerase, based on mild lysis of cells, low speed centrifugation, gel filtration, DEAE-Sephadex chromatography and affinity chromatography on DNA-cellulose, yields three forms of enzyme referred here as enzyme A, B and C. As revealed by SDS gel electrophoresis, enzyme A has the subunit structure of core polymerase plus some small polypeptides. Its catalytic properties are similar to those of core polymerase. Enzyme B has the composition of core polymerase. Both enzymes A and B can be stimulated by the addition of beta factor. Enzyme C has the holo-enzyme composition. The pattern of sensitivity of the three forms of enzyme towards KCl are very different: enzymes A and B, even at low concentration of salt, are inhibited with all the DNA templates tested, whereas enzyme C shows a pattern of stimulation specific for each DNA tested. The transcripts of the three enzymes on phage SPP1 DNA template have been analyzed by hybridization to the separated strands. Only enzyme C selectively transcribed the H strands.

Bacillus subtilis↗
PubMed1977

Host cell reactivation of Bacillus subtilis bacteriophages.

Host cell reactivation of ultraviolet-irradiated phage can be used as a probe of the bacterial repair system and to determine phage and cellular contributions to the repair process. Using the Bacillus subtilis phages SPP1, SP01, phie, and phi29, we found that the uvr-1 and polA functions are involved in the host cell reactivation of the four phages. SPP1 was the only phage whose reactivation was also decreased in recA, recD, and recF mutant cells. We studied variations of host cell reactivation for SPP1 during spore outgrowth; at high ultraviolet doses the activity of a spore repair system requiring deoxyribonucleic acid polymerase I became evident. The spore repair system was completely replaced by the vegetative one by 120 min of outgrowth.

Bacillus subtilis↗
PubMed1976

Synthesis of RNA and protein in a mutant of Bacillus subtilis temperature sensitive during spore germination.

Bacillus subtilis strain PB 2427 temperature sensitive in the synthesis of RNA during spore germination and outgrowth has been characterized to some extent. At non permissive temperature (46 degrees C) strain PB 2427 synthesizes stable and unstable RNA for 50 min from the beginning of germination and then stops. Most of the stable RNA is degraded to shorter molecules but can be identified as ribosomal RNA by hybridization-competition experiments. At non permissive temperature, in the presence of chloramphenicol, synthesis of RNA proceeds, though at a reduced rate, for at least 90 min. By hybridization-competition experiments it can also be shown that the RNA synthesized at 46 degrees C in the presence of chloramphenicol includes transcripts that are absent, from the RNA synthesized at 46 degrees C in the absence of drug. The RNA polymerase (holo and core) purified from vegatative cells of the mutant strain does not appear to have a greater heat-lability as compared with the enzyme purified from the parental strain. At non permissive temperature only six polypeptide chains with MW ranging from 47,000 to 78,000 daltons are synthesized by the germinating spores of the mutant.

Bacillus subtilis↗
PubMed1975

Mode of action of polymyxin B: physiological studies with Bacillus subtilis-resistant mutant.

Polymyxin B resistance in Bacillus subtilis can be suppressed by the synergistic action of lysozyme or of an analogous cell wall lytic activity released by B. subtilis spores during germination. Such a synergistic effect is probably due to partial cell-wall digestion by lysozyme that allows polymyxin to reach its site of action and is therefore distinct from the analogous synergistic effect described by other authors in Escherichia coli. In the latter case polymyxin B probably damaged the outer membrane, allowing lysozyme to reach and digest the cell wall.

Bacillus subtilis↗
PubMed1975

Genetic and physiological studies on the site of action of distamycin A.

Two new genetic loci of Bacillus subtilis are identified by mutations that confer resistance to distamycin A and to other antibacterial agents. The chromosomal region where they map probably contains a cluster of genes whose products are related to membrane structure and function. Some of the biological effects of distamycin A are still in evidence in the resistant mutants indicating that the drug possibly acts at multiple sites. Most biological effects of the drug (including the phenotypic correction of a morphopoietic mutation) are likely to be due to the interaction of distamycin A with membrane (or surface) structures.

Bacillus subtilis↗
PubMed1975

Synchronous germination and outgrowth of fractionated Bacillus subtilis spores: tool for the analysis of differentiation and division of bacterial cells.

A fraction of Bacillus subtilis 168 spores, purified by Urografin isopycnic density centrifugation, heat activated, and inoculated in nutrient broth plus glucose, germinated and outgrew very synchronously. Synchrony was documented by nuclear staining and fluorescence microscopy, and by determining the variation of the buoyant density of the cells during outgrowth. Cell mass increased at constant rates and the passage from one rate to the next was dependent upon deoxyribonucleic acid (DNA) synthesis. DNA synthesis inhibitors induced the formation of anucleated sister cells in a vast majority of the population, indicating that septation was programmed and became independent from DNA synthesis very early in the cell cycle.

Azo Compounds↗
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↗