Search PubMed⌕ Search

Biomedical subjects

I Ferrero

Publications and source records attributed to I Ferrero.

52 records · Page 3Linked to original sources
PubMed1991

Catabolite repression by galactose in overexpressed GAL4 strains of Saccharomyces cerevisiae.

Catabolite repression by galactose was investigated in several strains of Saccharomyces cerevisiae grown on different carbon sources. Galactose repressed as much as glucose; raffinose was less effective. Full derepression was achieved with lactate. The functions tested were L-lactate ferricytochrome c oxidoreductase, NAD-glutamate dehydrogenase, and respiration. Galactose repression was observed only in the GAL4 but not in the gal4 strain. The presence of multiple copies of the GAL4 gene enhanced the repression by galactose. Different alleles of the GAL4 gene and the copy number did not affect glucose repression.

Alleles↗
PubMed1990

Isolation and characterization of carbon catabolite repression mutants in Saccharomyces cerevisiae.

Two carbon catabolite repression mutants of S. cerevisiae were isolated and characterized. In spite of the selection procedure (red colonies after tetrazolium overlay at high glucose concentration) the mutants exhibited a respiration which was as repressed as that of the parental strain or even more repressed. When grown at high glucose concentration the mutants display hyper-repression of cytochrome aa3 and of certain mitochondrial enzymes (L- and D-lactate dehydrogenases) but not of others (malate dehydrogenase, succinate dehydrogenase), indicating the existence of separate control sites for the different genes involved in the mitochondrial biogenesis. The data obtained pointed out that the same mutation affects both repression and derepression. In addition, the mutation(s) give rise to the complete derepression of the cytoplasmic enzyme NAD-glutamate dehydrogenase at 10% glucose whereas the enzyme is normally repressed at 3% glucose. The results of the genetic analysis indicate the mitochondrial nature of the mutation(s).

Carbon↗
PubMed1986

The respiratory activities of four Hansenula species.

The respiratory activities and the cytochrome spectra from four species belonging to the genus Hansenula have been analysed. The results obtained and described in this paper show that H. glucozyma possesses only the primary, antimycin A-sensitive respiration, H. anomala and H. californica possess primary and secondary (salicylhydroxamate-sensitive) respirations, whereas H. saturnus possesses three respiratory activities (AA-sensitive, SHAM-sensitive, and AA + SHAM-insensitive). The respiratory activity of H. glucozyma is glucose-repressible, whereas the activities of the other species are not. In addition, antimycin A (AA) and erythromycin (ERY) in the culture media differently inhibit the growth of the four species and regulate the respiratory pathways in the species analysed.

Antimycin A↗
PubMed1985

Antimycin A- and hydroxamate-insensitive respiration in yeasts.

In this paper evidence is presented for the mitochondrial localization of the antimycin A (AA) + salicylhydroxamate (SHAM)-insensitive respiration of the yeasts Kluyveromyces lactis, Endomycopsis capsularis and Hansenula saturnus. Such a respiration, which can be sustained by NADH and NADPH but not by succinate, is inhibited by high concentrations of azide. AA + SHAM-insensitive respiration is not phosphorylating and its postulated physiological role is to oxidize NADH.

Antifungal Agents↗
PubMed1984

Lymphocyte populations and T cell subpopulations in blood of patients with non-Hodgkin lymphomas.

Lymphocytic populations and T cell subsets were studied in the blood of patients with nonleukemic non-Hodgkin lymphoma. A statistically significant decrease of both the T lymphocytes and the OKT4-, OKT8-binding cells was detected in low-grade malignant lymphomas (LGML). A significant decrease of the T cell population and of the OKT4-binding cells was also found in high-grade malignant lymphomas (HGML); in these, the OKT8-binding cells were not lowered. The amount of the circulating B lymphocytes was not found to be altered both in HGML and in LGML.

Adult↗
PubMed1983

Respiratory pathways in Hansenula saturnus.

Hansenula saturnus is a petite-negative yeast species which displays a different pattern of respiration depending on the age of the cultures. The respiration is sensitive to antimycin A (AA) in the early exponential phase, is sensitive to the simultaneous addition of AA and salicylhydroxamic acid (SHAM) in the middle exponential phase and is sensitive to SHAM in the late exponential and stationary phase. The three respiratory activities are all associated to the mitochondrial fraction. The presence of AA in the growth medium determines the induction of the AA + SHAM-insensitive respiration which is 50% inhibited by 5 mM azide. On the contrary, the presence of erythromycin in the growth medium, which inhibits mitochondrial protein synthesis in this yeast species and the synthesis of cytochromes aa3 and b, totally prevents the appearance of AA + SHAM-insensitive respiration. Moreover, the antibiotic affects cell viability, suggesting a role of the mitochondrial protein synthesis in the cell cycle of H. saturnus.

Antimycin A↗
PubMed1983

Mitochondrial NAD, L-lactate dehydrogenase and NAD, D-lactate dehydrogenase in the yeast Saccharomyces cerevisiae.

Mitochondrial NAD-linked L- and D-lactate dehydrogenase activities have been found in the yeast Saccharomyces cerevisiae grown at high (3%) but were absent at low (0.6%) glucose concentrations. The inhibition of mitochondrial protein synthesis by chloramphenicol and of primary respiration by antimycin A determines the appearance of the two activities even at low (0.6%) glucose concentration. Two respiratory deficient strains belonging respectively to the mit- class (which maintains mitochondrial protein synthesis) and to the rho- class (which loses mitochondrial protein synthesis) display the activities even at low (0.6%) glucose concentration. L- and D-lactate have been detected in the growth medium when the cultures had been undertaken at high glucose concentrations, but were absent at low glucose concentrations.

Anaerobiosis↗
PubMed1983

The role of glucose and aminoacid starvation in the sensitivity of protein and RNA synthesis to cycloheximide and erythromycin in the yeast Saccharomyces cerevisiae.

In Saccharomyces cerevisiae dependence of ribonucleic acid synthesis on protein synthesis occurring during nutritional shift down conditions was evidenced. The results obtained indicated that yeast had "stringent control" of ribonucleic acid synthesis and that this control was reversed by cycloheximide only under glucose starvation or ammonia starvation in the presence of acetate as carbon source (phenotypic relaxation). Therefore, it appeared that the "phenotypic relaxation" of RNA synthesis depended on the carbon source present in the medium suggesting that the process could be negatively controlled by glucose or by some glucose catabolite(s). Such a phenotypic relaxation was sensitive to erythromycin treatment. On the other hand, total protein synthesis carried out during amino-acid starvation in the presence of glucose or ammonia starvation in the presence of acetate was 30%-40% inhibited by erythromycin, showing that in these conditions sensitivity to a non legitimate inhibitor could be triggered off in an haploid strain, and that such sensitivity did not depend on the presence of glucose in the medium.

Amino Acids↗
PubMed1981

Induction by glucose of an antimycin-insensitive, azide-sensitive respiration in the yeast Kluyveromyces lactis.

Increasing the glucose concentration from 0.1 to 10% in exponentially growing cultures of Kluyveromyces lactis CBS 2359 does not repress the antimycin-sensitive respiration (QO2 of 80 microliter O2 . h-1 . mg-1 dry weight) but raises the antimycin-insensitive respiration from 3 to 12 microliter O2 . h-2 . mg-1 dry weight. Antimycin A inhibits the growth of K. lactis on a variety of substrates with the exception of glucose at concentrations equal to or higher than 1% where substantial antimycin-insensitive respiratory rates are induced. It can be concluded that a minimal antimycin-insensitive QO2 is necessary for cellular growth when the normal respiratory pathway is not functional. The antimycin-insensitive respiration elicited by growth in high glucose concentrations is poorly inhibited by hydroxamate and is inhibited by 50% by 90 microM azide or 1 mM cyanide. These concentrations are much higher than those necessary to inhibit cytochrome c oxidase which is not involved in the antimycin-insensitive respiration as was demonstrated by spectral measurements. A pigment absorbing at 555 nm is specifically reduced after addition of glucose to antimycin-inhibited cells. The same pigment is reoxidized by further addition of high concentrations of sodium azide indicating its participation in the antimycin-insensitive, azide-sensitive respiration.

Antimycin A↗
PubMed1981

Effect of chloramphenicol, antimycin A and hydroxamate on the morphogenetic development of the dimorphic ascomycete Endomycopsis capsularis.

Mitochondrial protein synthesis, primary (antimycin-sensitive) respiration and secondary (antimycin-insensitive, salicyl-hydroxamate-sensitive) respiration, have been characterized in the dimorphic yeast Endomycopsis capsularis. The inhibition by chloramphenicol (CAP) of the morphogenetic development from the yeast-like form to the mycelial structure in this yeast could represent the intervention in the morphogenetic process of mitochondrial protein synthesis, since chloramphenicol blocks in vivo and in vitro mitochondrial protein synthesis. In fact, other functions such as primary and secondary respiration, do not seem to play a role in the morphogenetic development since their inhibition by antimycin A (AA) or by salicyl-hydroxamic acid (SHAM) does not affect the process. In addition, mitochondrial protein synthesis has been shown to be uninhibited by the two respiratory inhibitors.

Antimycin A↗
PubMed1978

Different phenotypes for the lactose utilization system in Kluyveromyces and Saccharomyces species.

Analysis of the system for the utilization of lactose in some strains of yeasts belonging to the genera Kluyveromyces and Saccharomyces revealed the occurrence of several genetic variants, corresponding to mutants expected on the basis of the model of Jacob and Monod for the lac system in E. coli. These results could be useful in the taxonomic analysis and in the phylogenetic evaluation of the Saccharomycetaceae.

Ascomycota↗
PubMedDate not supplied

RAG1 and RAG2: nuclear genes involved in the dependence/independence on mitochondrial respiratory function for growth on sugars.

The analysis of five independent isolates of Kluyveromyces lactis shows that CBS 2359, CBS 683 and CBS 4574 could grow in the presence of mitochondrial inhibitors (antimycin A, oligomycin or erythromycin) and that CBS 2360 and CBS 141 were unable to grow in the presence of drugs. The resistant growth was observed only on glucose and not on other fermentable carbon sources (galactose, lactose). The phenotype 'growth on glucose in the presence of mitochondrial inhibitors' was called Rag+. This phenotype was found to be controlled by two unlinked nuclear genes: RAG1 and RAG2. Either of their recessive alleles, rag1 and rag2, led to the Rag- phenotype (i.e. the failure of growth on glucose in the presence of antimitochondrial drugs). Rag- strains represent the case in which fermentative growth becomes absolutely dependent on the functioning of the normal respiratory chain.

Alleles↗
PubMedDate not supplied

Histochemical study of cardiac mast cells degranulation and collagen deposition: interaction with the cathecolaminergic system in the rat.

Although their role in the cardiovascular system is still largely unknown, mast cells are present in the myocardium of both experimental animals and humans. Interestingly, cathecolaminergic nerve fibres and mast cells are often described in close morphological and functional interactions in various organs. In the present study we investigated the effects of chronic interference with beta-adrenergic receptors (via either sympathectomy or beta-blockade) on cardiac mast cell morphology/activation and on interstitial collagen deposition. In rats subjected to chemical sympathectomizy with the neurotoxin 6-hydroxydopamine (6-OHDA) we observed a significant increase of mast cell density, and in particular of degranulating mast cells, suggesting a close relationship between the cardiac catecholaminergic system and mast cell activation. In parallel, chronic 6-OHDA treatment was associated with increased collagen deposition. The influence of the beta-adrenergic receptor component was investigated in rats subjected to chronic propranolol administration, that caused a further significant increase in mast cell activation associated with a lower extent of collagen deposition when compared to chemical sympathectomy. These data are the first demonstration of a close relationship between rat cardiac mast cell activation and the catecholaminergic system, with a complex interplay with cardiac collagen deposition. Specifically, abrogation of the cardiac sympathetic efferent drive by chemical sympathectomy causes mast cell activation and interstitial fibrosis, possibly due to the local effects of the neurotoxin 6-hydroxydopamine. In contrast, beta-adrenergic blockade is associated with enhanced mast cell degranulation and a lower extent of collagen deposition in the normal myocardium. In conclusion, cardiac mast cell activation is influenced by beta-adrenergic influences.

Animals↗