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Biomedical subjects

E Gallori

Publications and source records attributed to E Gallori.

17 recordsLinked to original sources
PubMed2000

DNA as a possible target for antitumor ruthenium(III) complexes.

The interaction of two experimental ruthenium(III)-containing antitumor complexes-Na[trans-RuCl(4)(DMSO)(Im)] (NAMI) and dichloro(1,2-propylendiaminetetraacetate)ruthenium(III) (RAP)-with DNA was investigated through a number of spectroscopic and molecular biology techniques, including spectrophotometry, circular dichroism, gel shift analysis, and restriction enzyme inhibition. It was found that both complexes slightly alter DNA conformation, modify its electrophoretic mobility, and inhibit DNA recognition and cleavage by some restriction enzymes, though they were less effective than cisplatin in producing such effects. Notably, the effects produced by NAMI on DNA were much larger than those induced by RAP. Implications of these results for the mechanism of action of ruthenium(III) antitumor complexes are discussed.

Animals↗
PubMed2000

Clay minerals protect bacteriophage PBS1 of Bacillus subtilis against inactivation and loss of transducing ability by UV radiation.

The effect of UV radiation on the survival of and transduction by phage PBS1 of Bacillus subtilis, free or adsorbed on the clay minerals montmorillonite (M) and kaolinite (K), was studied. After free or clay-associated phage (approximately 10(7) PFU.mL-1) was irradiated with UV light (254 nm) for 0, 1, 2, 5, 10, and 30 min and then allowed to infect B. subtilis FB300 (thiB4 metA29 argF4 Rfmr), the phage was titered, and Met+ transductants were enumerated on selective media. After 1 min of irradiation, the titer of free and clay-associated phage decreased significantly (approximately 1.6 times for free phage, and approximately 4.9 and 6.8 times for M and K, respectively), whereas the transduction frequency increased significantly (approximately 3 times for free phage and approximately 1.4 and 2.2 times for M and K, respectively). The titer and transduction frequency of clay-associated phage remain essentially constant between 1 and 10 min of irradiation, whereas the titer of free phage decreased by approximately 1 order of magnitude after 5 min of irradiation. When free phage was irradiated for 10 min, the titer and transduction frequency decreased by approximately 2 and 0.5 orders of magnitude, respectively, whereas 30 min of irradiation was necessary to obtain comparable decreases with clay-associated phage. These results indicated that phages are protected to some extent from UV radiation when adsorbed on clay minerals.

Aluminum Silicates↗
PubMed1999

Clay-nucleic acid complexes: characteristics and implications for the preservation of genetic material in primeval habitats.

The equilibrium adsorption of three nucleic acids: chromosomal DNA, supercoiled plasmid DNA, and 25S rRNA, on the clay minerals, montmorillonite (M) and kaolinite (K), were studied. Adsorption of the nucleic acid on the clays was rapid and maximal after 90 min of contact time. Chromosomal DNA was adsorbed to a greater extent than plasmid DNA and RNA, and the adsorption was also greater on M than on K. Adsorption isotherms were of the L type, and a plateau was reached with all the complexes, with the exception of chromosomal DNA adsorbed on M. To deterine where nucleic acids are adsorbed on clay minerals and the nature of the interaction, complexes were studied by X-ray diffraction (X-RD), electron microscopy, and Fourier transform infrared (FT-IR) spectroscopy. X-RD showed that nucleic acids did not penetrate the clay, indicating that the adsorption occurred primarily on the external surfaces of clay particles, as also suggested by electron microscopy observations. FT-IR spectra of clay-tightly bound nucleic acid complexes showed adsorption bands that indicate a variation of the nucleic acids status as a consequence of their adsorption on clay. Data obtained suggested that the formation of clay-nucleic acid complex could have an important role in the preservation of genetic material in primeval habitats.

Adsorption↗
PubMed1999

Interaction between bacteriophage PBS1 and clay minerals and transduction of Bacillus subtilis by clay-phage complexes.

Bacteriophage PBS1 of Bacillus subtilis was rapidly adsorbed on montmorillonite (M) and kaolinite (K), and adsorption was maximal after 30min on both clays. There was no correlation between adsorption and the cation exchange capacity of the clays. Studies with sodium metaphosphate (a polyanion that interacts with positively charged sites on clay) indicated that positively charged sites on K were primarily responsible for the adsorption of the phage, whereas other mechanisms appeared to be involved in adsorption of the phage on M. X-ray diffraction and electron microscopic analyses showed that the phage partially intercalated M. Survival of the phage was increased by adsorption on the clays, and adsorbed phage maintained its ability to transduce bacterial cells for at least 30 days (the longest time studied) after the preparation of the clay-phage complexes. Electron microscopic observations indicated that transduction by the clay-phage complexes was primarily the result of the phage detaching from the clays in the presence of host cells.

Adsorption↗
PubMed1998

Stability of water-soluble and lipid-soluble paramagnetic probes in Bacillus subtilis.

Batch cultures of the Gram-positive bacterium Bacillus subtilis PB19 have been investigated for their metabolic action to electron spin resonance (ESR) probes. Five- and six-membered water-soluble and lipid-soluble nitroxides have been used, which were reduced most probably to the corresponding hydroxylamine derivatives. The reduction was followed by the ESR signal intensity and found to be dependent on chemical structure and stability, lipophilic/hydrophilic character, charge, concentration, and temperature. Water-soluble nitroxides did not show apparent toxicity towards B. subtilis, in contrast with n-DXSA (n=5, 12, 16) which were found to be strongly cytotoxic. The cytotoxicity depended on the position of the doxyl unit along the hydrocarbon chain. The hydrophilic nitroxides were reduced at a much slower rate relative to the lipophilic ones. Membrane diffusion was suggested to be a slower process relative to chemical reduction for water-soluble nitroxides. The lipophilic nitroxides were solubilized into the membrane where they were rapidly reduced with a reduction maximum at 303-310 K, which is the optimal growth temperature of B. subtilis, while an inactivation at higher temperatures was observed. Both toxicity and reduction rates of nitroxides strongly indicated that the reduction was an enzyme-mediated process taking place near the outer surface of the periplasmic membrane.

Bacillus subtilis↗
PubMed1995

Phylogeny of the genus Azospirillum based on 16S rDNA sequence.

The 16S rDNA of 17 strains of Azospirillum, 14 assigned to one of the known species A. amazonense, A. brasilense, A. halopraeferens, A. irakense and A. lipoferum, and the other three of uncertain taxonomic position, was sequenced after polymerase chain reaction amplification and analysed in order to investigate the phylogenetic relationships at the intra-generic and super-generic level. The phylogenetic analysis confirms that the genus Azospirillum constitutes a phylogenetically separate entity within the alpha subclass of Proteobacteria and that the five species are well defined. A. brasilense and A. lipoferum are closely related species and form one cluster together with A. halopraeferens; the pair of species A. amazonense and A. irakense forms a second cluster in which Rhodospirillum centenum is also placed.

Azospirillum↗
PubMed1993

Use of random amplified polymorphic DNA (RAPD) for generating specific DNA probes for microorganisms.

We report the rapid generation of DNA probes for several Azospirillum strains. This method does not require any knowledge of the genetics and/or the molecular biology of the organism (genome) to be investigated. The procedure is based on the generation of random amplified polymorphic DNA (RAPD) fingerprints using primers with an embedded restriction site. The amplification product(s) peculiar to one strain or common to two or more strains can be purified, cloned, sequenced and used as molecular probes in hybridization experiments for the detection and identification of microorganisms. We have tested this methodology in the nitrogen-fixing bacterium Azospirillum by amplyfing the total DNA extracted from several Azospirillum strains. We have used amplification bands with different specificity as molecular probes in hybridization experiments performed on amplified DNA. Results obtained have demonstrated the usefulness of this methodology for Azospirillum. Its use in microbial ecology studies as a general strategy to generate specific DNA probes is also discussed.

Ampicillin Resistance↗
PubMed1992

Mechanism of resistance to sulphite in Saccharomyces cerevisiae.

Growth inhibition and cell killing caused by sulphite were reduced in seven Saccharomyces cerevisiae sulphite-resistant independent mutants, compared to their parental strains. Genetic analysis showed that in the seven mutants resistance was inherited as a single-gene dominant mutation and that all the analyzed mutations were allelic, thus identifying a major gene responsible for sulphite resistance in S. cerevisiae. Two of the mutants, MBS20-9 and MBS30, were further characterized. 35S-sulphite uptake experiments showed that the ability to accumulate sulphite was markedly reduced in the two resistant strains. No difference between resistant and sensitive strains with respect to glyceraldehyde-3-phosphate dehydrogenase sensitivity to sulphite, or to intracellular glutathione content, were revealed. In contrast, the extracellular acetaldehyde concentration was higher in the resistant mutants, both in the presence and in the absence of sulphite.

Drug Resistance, Microbial↗
PubMed1991

Monitoring a genetically engineered bacterium in a freshwater environment by rapid enzymatic amplification of a synthetic DNA "number-plate".

In order to set up a sensitive and reliable detection method to monitor environmentally released genetically engineered microorganisms (GEMs) a 72-bp, double-stranded DNA fragment has been built by annealing and ligating four synthetic oligonucleotides. Binding sites for two 20-mer oligonucleotides are situated inside the DNA fragment, flanking the centre. Into the central part of the construction a 30-nucleotide identification sequence has been fitted. Thanks to the presence of the two oligonucleotide binding sites, the synthetic construction ("number-plate") can be submitted to enzymatic amplification using the polymerase chain reaction (PCR), thus enabling the identification system to take advantage of the outstanding sensitivity of this technique. When released into a freshwater microcosm, cells of Pseudomonas putida carrying a "number-plated" chromosome could be easily and rapidly detected merely by submitting boiled cell sediments to PCR amplification.

Base Sequence↗
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

[Not Available].

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History, Modern 1601-↗
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↗
PubMedDate not supplied

1,8-Naphthalic anhydride antidote enhances the toxic effects of captan and thiram fungicides on Azospirillum brasilense cells.

The effects of ten fungicides, six herbicides and four insecticides on the nitrogen-fixing bacterium Azospirillum brasilense were examined. The fungicides captan and thiram were the most toxic among the compounds tested. Cell growth and nitrogenase activity of the bacterium were markedly inhibited by low concentrations of the two fungicides. Antidote 1,8-naphthalic anhydride increased by a factor of 2 the cellular level of glutathione. The addition of the antidote in the presence of captan or thiram caused a similar increase in the glutathione content, but at the same time enhanced the toxicity of the two fungicides.

Azospirillum brasilense↗
PubMedDate not supplied

The histidine operon of Azospirillum brasilense: organization, nucleotide sequence and functional analysis.

A 3457-base pair fragment of Azospirillum brasilense DNA which complemented mutations in the hisA and hisF genes of Escherichia coli was sequenced. The sequence analysis revealed the presence of six major contiguous open reading frames (ORF). The comparison of the predicted amino acid sequence of these ORF with those encoded by the eubacterial, archaebacterial and eukaryotic his genes sequenced thus far revealed that four of them have a significant degree of homology with the E. coli hisH, hisA, hisF and the C-terminal domain of the hisI gene products. S1 mapping experiments indicated that the putative transcription start site coincided with the AUG translational initiation codon of the hisBd gene, the first gene of the A. brasilense his operon. Downstream from the last ORF, a sequence was identified which functions as a Rho-independent transcription terminator. Comparison of amino acid sequences, gene order and organization and evolutionary aspects of the A. brasilense his cluster are discussed.

Amino Acid Sequence↗