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1.
Gian Maria Rossolini Patrizia Muscas Alessandra Chiesurin Giuseppe Satta 《FEMS microbiology letters》1994,119(3):321-328
Abstract Analysis of the Salmonella chromosomal region located upstream of the fimA gene (coding for the major type 1 fimbrial subunit) showed a close linkage of this gene to the folD gene (coding for the enzyme 5,10-methylenetetrahydrofolate dehydrogenase/5, 10-methenyltetrahydrofolate cyclohydrolase), indicating that the fim gene cluster of Salmonella , unlike that of Escherichia coli , has no regulatory genes located upstream of fimA and apparently terminates with this gene. The respective locations of the fim and folD genes in the E. coli and Salmonella genetic maps suggests that the fimA-folD intergenic region of Salmonella encompasses a junctional site of a genetic rearrangement that probably originated from the different chromosomal location of the fim genes in these species. 相似文献
2.
S Papa S Capitani A Matteucci M Vitale P Santi A M Martelli N M Maraldi F A Manzoli 《Cytometry》1987,8(6):595-601
The development of hepatocyte polyploidy in rats aged up to 4 months was analyzed by flow cytometry using both scatter and fluorescent parameters to distinguish DNA diploid and DNA tetraploid populations and to discriminate between parenchymal and non-parenchymal compartments. The precise origin of each class of nuclei was assessed in whole liver homogenate using purified hepatocytes, obtained by liver perfusion followed by separation on Percoll gradient, and identifying the peaks corresponding to parenchymal nuclei. The results indicate that preparative procedures involving homogenization of the rat liver tissue caused loss of the DNA octaploid population. Data on the relative proportion of the different DNA ploidy elements during rat liver development, which are in good agreement with those observed by cell analysis by means of microspectrophotometry, indicate the usefulness of flow cytometry as a choice method for the analysis of ploidy distribution. 相似文献
3.
Mario Marini Gianna Roscetti Lucilla Bongiorno Alessandra Urbani L. Giorgio Roda 《Neurochemical research》1990,15(1):61-67
Seven groups of enkephalin-degrading enzymes and three groups of inhibitors active on these enzymes were separated from human plasma. The activity of the enzymes in hydrolyzing enkephalins and of the inhibitors in protecting enkephalins from proteolysis was measured. Results obtained with the endogenous inhibitors were compared to those relative to synthetic inhibitors. Data obtained indicate that all enkephalin-degrading enzymes found in plasma are significantly inhibited by the endogenous substances present in this tissue. The inhibition of the different classes of plasma enzymes by two of the three groups of endogenous substances is quite uniform, while one group of inhibitors appears specific to dipeptidylpeptidases. Results obtained are discussed in terms of the functional role of the inhibitory substances and of the possible pharmacological implication of their presence in human plasma. 相似文献
4.
Alessandra Faraoni Roberto Santucci Luigi Campanella Gloria Tranchida Maurizio Brunori 《Biometals》1990,3(2):122-124
Summary The electrochemical behaviour of Fe(III)-protoporphyrin IX entrapped into a cellulose triacetate membrane has been investigated by cyclic voltammetry. The physical entrapment into a solid matrix does not modify the redox properties of the entrapped berries, which also act as efficient promoters in the electrochemistry of cytochromec. Such a system represents a promising example of a simple solid-state promoter, and stimulates further investigations in order to obtain more complex systems that may be of significance for basic and applied bioelectrochemistry. 相似文献
5.
The susceptibility or resistance to 26 antimicrobial agents was determined for 64 strains of Listeria monocytogenes and 102 strains of L. innocua isolated from Italian meat products. Some strains of L. monocytogenes were found to be resistant to tetracycline, erythromycin, co-trimoxazole and clindamycin. No plasmids were found in any L. monocytogenes strain. Five strains of L. innocua contained a 7.9 kbp plasmid, but these isolates were not resistant to any antibiotic in common and treatment with curing agents could not eliminate resistance to antibiotics. These results suggest that antibiotic resistance was not likely to be plasmid mediated in our strains. 相似文献
6.
Amine oxidases have been purified to homogeneity from Pisum sativum, Lens esculenta, Lathyrus sativus and Cicer arietinum. The enzymes have a Mr. of 150 000 and are composed of two identical subunits of 72 000. The amine oxidases showed an isoelectrophoretic heterogeneity. 相似文献
7.
N M Maraldi F Marinelli A Galanzi N Zini A Ognibene R Del Coco A Matteucci S Papa 《Biology of the cell / under the auspices of the European Cell Biology Organization》1986,56(1):31-39
The morphology of intact or membrane-deprived interphase nuclei has been analysed by freeze-fracture electron microscopy. This method appears particularly useful for providing information on the distribution and organisation of chromatin and ribonucleoproteins in the absence of dehydration and embedding artifacts of conventional electron microscope techniques which, among other effects, appear to affect heterochromatin distribution, inducing its aggregation along the nuclear envelope. The main levels of chromatin superstructure, from nucleosome to solenoid fibres, are detectable in the replicas of freeze-fractured nuclei on the basis of the size of their shadow, a parameter particularly suitable for automated image analyses. 相似文献
8.
Monolayer black membranes from bipolar lipids of archaebacteria and their temperature-induced structural changes 总被引:1,自引:0,他引:1
Alessandra Gliozzi Ranieri Rolandi Mario De Rosa Agata Gambacorta 《The Journal of membrane biology》1983,75(1):45-56
The membrane of Caldariella acidophila, an extreme thermophilic archaebacterium, is characterized by unusual bipolar complex lipids. They consist of two nonequivalent polar heads, linked by a C40 alkylic component. The molecular organization of these lipids in the plasma membrane is still a matter of study. In this paper, we present current-voltage measurements on artificial bipolar lipid membranes, indicating that molecules are indeed organized as a covalently bound bilayer, in which each molecule is completely stretched and spans its entire thickness. Furthermore, conformational transitions of these artificial membranes (which could be formed only above 70 degrees C from a lipid/squalene dispersion) are analyzed in the 80 to 15 degrees C temperature range. Abrupt variations in capacitance and valinomycin-induced conductance seem to indicate the occurrence of at least two structural changes. Measurements are also extended to different solvent systems. Results are consistent with the picture of a monolayer bipolar lipid membrane in which few solvent molecules align themselves parallel to the lipophilic chains. The amount of solvent as well as the temperature at which conformational transitions occur, depend on the solvent system in which the lipid is dispersed. 相似文献
9.
The existence of chaotic attractors for discrete time series, derived from the occurrences of spikes during electrophysiological recordings, was investigated. The time series included between 800 and 5200 points per analyzed record. The spike trains were recorded in the substantia nigra pars reticulata (n=13) and in the auditory thalamus (n=14). The experiments were performed on anesthetized rats during spontaneous activity and during auditory stimulation. According to standard methods of dynamical systems theory, an embedding space was constructed using delay coordinates. The embedding and correlation dimensions were computed by means of the correlation integrals. For 7 of 27 samples, a deterministic structure with a low embedding dimension (ranging between 2 and 6) and a correlation dimension between 0.14 and 3.3 could be determined. Evidence was found that the sensory stimulation may affect the chaotic behavior. Single units recorded simultaneously from the same electrode tip may display different chaotic dynamics, even with a similar time-locked response to the stimulus onset. 相似文献
10.
Lino Piccinini Paola Borella Annalisa Bargellini Cristina Incerti Medici Alessandra Zoboli 《Biological trace element research》1996,51(1):23-30
The purpose of our study was to investigate the relationship between plasma and hair levels of Se, Zn, and Cu, and cancer.
We selected a total of 66 patients affected by either breast (38) or lung (28) cancer. They entered into the study at the
onset of disease, and before any chemical or radiotherapy. Controls were randomly selected among healthy people and were matched
for sex, age, smoking habits, and residence. In the group of breast cancer, a significant decrease in hair Se was found compared
to controls (p<0.01), whereas plasma Se was only slightly decreased. No difference between cases and controls was detected in both hair
and plasma levels of Zn and Cu. Subjects who developed lung cancer were significantly lower in hair Zn (p<0.05) and Cu (p<0.01) than controls, whereas there was no difference with regard to Se. In addition, plasma Cu of these patients was increased
as compared to controls. 相似文献