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N Marmiroli

Publications and source records attributed to N Marmiroli.

31 records · Page 2Linked to original sources
PubMed1984

Modification of nuclear gene expression by inhibition of mitochondrial translation during sporulation in MAT alpha/MATa diploids of Saccharomyces cerevisiae.

Sporulation of S. cerevisiae MAT alpha-/MATa was accompanied by a novel pattern of protein synthesis as shown by the disappearance of some "mitotic" polypeptides and by the appearance of a new set of "meiotic" polypeptides. Inhibition of mitochondrial protein synthesis by erythromycin within the 1st h caused the disappearance of several "meiotic" polypeptides. These meiotic polypeptides were also sensitive to cycloheximide and were localized in the cytosol, demonstrating that they were not mitochondrial translational products. Since erythromycin affected neither protein synthesis nor sporulation in a mitochondrially inherited eryr mutant, we conclude that mitochondrial protein synthesis is needed for the expression of some nuclear genes during sporulation.

Diploidy↗
PubMed1983

The role of the nuclear gene "mitochondrial mutability control" (MMC1) in the process of mutability of the mitochondrial genome by different mutagens in Saccharomyces cerevisiae.

The accumulation of respiratory deficient (RD) mutants in Saccharomyces cerevisiae depended upon the mutagens used and upon the presence of the nuclear gene previously identified as MMC1 (one) which we showed to control the spontaneous and the erythromycin-induced RD mutability. In this paper data are reported about the accumulation of RD mutants in the presence of manganous ions (Mn++) and UV which was higher in the mmc1 (one) than in MMC1 strains. We found that the characters 'low spontaneous' and 'low induced' RD mutability by erythromycin, manganous ions and UV, were controlled by the same genetic determinant. In the presence of manganous ions, also the frequency of antibiotic resistant mutants capR and eryR was higher in the mmc1 strains. Moreover, the accumulation of RD mutants in the presence of berenil, 5-fluorouracil and basic fuchsin was higher in the mmc1 than in MMC1 strains. In contrast, RD mutants accumulation by acriflavine and ethidium bromide treatments did not appear affected by the MMC1 genetic constitution.

Acriflavine↗
PubMed1983

Involvement of mitochondrial protein synthesis in sporulation: effects of erythromycin on macromolecular synthesis, meiosis, and ascospore formation in Saccharomyces cerevisiae.

Cells of strain Z270 (MAT alpha/MAT alpha) of Saccharomyces cerevisiae did not undergo ascospore formation in buffered or unbuffered acetate sporulation medium in the presence of erythromycin. The drug inhibited sporulation when added within the first 6 to 8 h and affected to different extents some of the metabolic and sporulation-specific events that normally occur during this period. In sporulation medium, protein synthesis was highly sensitive to erythromycin, whereas RNA synthesis was unaffected and premeiotic DNA synthesis was partially inhibited. Intragenic recombination occurred at normal rates for the various heteroallelic loci tested, but rates of intergenic recombination were markedly reduced, and commitment to haploidization did not occur; hence, development was evidently arrested between intragenic and intergenic recombination. Cells kept for 8 h in acetate sporulation medium that were ready for sporulation in water without erythromycin failed to sporulate in water containing the drug, indicating that erythromycin can inhibit sporulation independent of acetate utilization.

DNA, Fungal↗
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

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↗
PubMed1981

IMP1/imp1: a gene involved in the nucleo-mitochondrial control of galactose fermentation in Saccharomyces cerevisiae.

In some strains of Saccharomyces cerevisiae, the induction of enzymes of the Leloir pathway, galactose fermentation and growth on galactose depend on mitochondrial function; mitochondrial dependence is elicited through the recessive allele imp1 of the nuclear gene IMP1. The genetic element IMP1 is not allelic to any of the known GAL genes; IMP1 strains can grow on and ferment galactose in respiratory-deficient (RD) condition or in the presence of the mitochondrial inhibitors ethidium bromide and erythromycin; whereas, imp1 strains can grow on and ferment galactose only in respiratory-sufficient (RS) condition. The imp1 elicited mitochondrial dependence apparently involves regulation of the synthesis of the galactose catabolizing enzymes and synthesis of the galactose specific permease. IMP1 is not the only genetic determinant that elicits an interaction of the mitochondrion and the expression of the Gal system; the GAL3 gene, whose role in galactose utilization is demonstrated by the long-term adaptation phenotype of gal3 rS mutants, gives rise to a noninducible phenotype in RD condition or in the presence of mitochondrial inhibitors.

Cell Nucleus↗
PubMed1981

Computer-assisted karyotyping system of banded chromosomes.

The banding automatic system (BAS) we describe in this paper is a computer-assisted karyotyping system suitable for the analysis of both normal and abnormal karyotypes in banded chromosome specimens. In the BAS system recognition of the various features and constituents of the chromosomes is performed by an operator, whereas chromosome identification and classification are entrusted to a computer. The connection between operator and computer is the CYGEN1 program, which is tailored to distinguish chromosome morphology on the basis of the operator input band patterns alone. The karyotyping operation is therefore significantly speeded up: the operator simply has to read through a certain number of banded metaphases, encoding band-pattern data to the computer. The machine signals when the operation has gone through the whole karyotype or, for instance, when chromosomes are missing or present in extra number above the significance level from the analyzed metaphases. Chromosome identification and classification are then carried out by the computer, which performs as a real-time recognizing key. Moreover, the data being accumulated in the computer will provide a file of cytogenetic records accessible to the operator, as well as to the computer, for further diagnostic operations. The efficacy of the BAS system is demonstrated for the diagnosis of various structural aberrations, including a complex translocation. The processing of 20 metaphases by the method described takes 40-45 min, and a cytogenetic technician can make effective use of the system after 25-30 h of intensive training.

Chromosome Aberrations↗
PubMed1980

Analysis of rho mutability in Saccharomyces cerevisiae. I. Effects of mmc and pet-ts alleles.

Two additional types of nuclear determinants involved in the control of spontaneous mutability of rho in S. cerevisiae have been identified: mmc and the pet-ts 1, 2, 10, 52 and 53 genes. These genes in their mutated recessive form increase at various extents the number of respiratory deficient cytoplasmic "petite" mutants accumulated. The gene mmc does not affect the respiratory activity and is not temperature-dependent whereas the pet-ts genes determine at the non permissive temperature a respiratory deficient phenotypes even if they affect the mutability of rho at the permissive and at the non permissive temperature. The data here reported suggest that a "replicative complex" exists for the mitochondrial DNA. It is in the purpose of this paper to deal with the relative contribution that mmc and pet-ts gene products have in ensuring the fidelity of this "replicative complex".

Alleles↗
PubMed1977

Dependence of cytoplasmic on mitochondrial protein synthesis in K. lactis CBS 2360. II. Genetic studies.

A few eryR mutants independently isolated from K. lactis CBS 2360 display a conditional lethal phenotype at the temperature of 36 degrees C. In addition to drug resistance, also conditional lethality shows a non-Mendelian pattern of inheritance and is affected by exposure of the cells to Ethidium Bromide, indicating that in this yeast mitochondrial DNA controls cell viability. The results obtained from biochemical analysis suggest that the cellular functions in which are involved the gene products of the mitochondrial mutants analized are cytoplasmic protein and RNA syntheses.

Cytoplasm↗
PubMed1975

In vivo and in vitro effects of rifampicin and streptolydigin on transcription of Kluyveromyces lactis in the presence of nystatin.

Rifampicin and streptolydigin, if used in conjunction with nystatin, depress the growth of Kluyveromyces lactis. The incorporation of labeled leucine into protein is inhibited by nystatin whereas the incorporation of labeled uracil into RNA is inhibited by rifampicin in nystatin-treated cells. In order to study the mechanism of inhibition of RNA synthesis we purified by DEAE-Sephadex column chromatography four forms of RNA polymerase from K.lactis cells. The general properties of these enyzmes are similar to those of Saccharomyces cerevisiae and of other eukaryotic RNA polymerases. In particular, enzymes IA, IB and III are more active with poly[d(A-T)] template and Mn-2+ than with native or denatured calf thymus DNA. Enzyme II shows optimal activity with denatured calf thymus DNA and Mn2+. When challenged with native calf thymus DNA all enzymes prefer Mg-2+ as a divalent cation whereas with denatured calf thymus DNA all enzymes are more active with Mn-2+. Enzyme II is inhibited by lambda-amanitin but no enzyme is sensitive to rifampicin and streptolydigin. The inhibition of growth and uracil uptake observed when rifampicin is added to nystatin treated cells is probably not caused by a specific inhibition of transcription.

Anti-Bacterial Agents↗