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G Lucchini

Publications and source records attributed to G Lucchini.

72 records · Page 4Linked to original sources
PubMed1983

Disomic and diploid meiotic products in Saccharomyces cerevisiae. Effect of vincristine, vinblastine, adriamycin, bleomycin, mitomycin C and cyclophosphamide.

The effect of some antineoplastic drugs on the induction of disomic and diploid meiotic products in Saccharomyces cerevisiae was evaluated. Vincristine and vinblastine turned out not to be effective on any of the four genetic phenomena studied (sporulation, recombination, disomic induction and diploid induction). Adriamycin showed only slight activity in inducing diploids, particularly during the first meiotic division. Cyclophosphamide was active on both phenomena leading to the formation of disomic and diploid spores. Mitomycin C and bleomycin were effective on the induction of diploids. In all of these inductions, the origin of diploids was due to failure of the second meiotic division. No significant effects were found on recombination frequency. As a general conclusion, one may assume that formation of aneuploid and diploid gametes are two distinct phenomena, not necessarily correlated from the point of view of the mechanism and of the specificity of induction.

Antineoplastic Agents↗
PubMed1983

A short nucleotide sequence required for regulation of HIS4 by the general control system of yeast.

We have made deletions of the HIS4 5' noncoding region in vitro and inserted these deletions into the yeast genome by transformation. Deletions that extend from -588 to -235 have no detectable effects on either promoter or regulatory functions. Deletions that extend to -138 affect promoter function, but are still regulated by the general control of amino acid biosynthesis. A deletion that extends to -136 cannot derepress HIS4 mRNA in response to the general control. This deletion removes all copies of the sequence 5'-TGACTC-3', which appears at positions -194, -182 and -138 in strains without the deletion. The importance of at least one copy of this repeat for regulation of HIS4 is shown by the reappearance of this sequence in revertants of the -136 deletion that have regained the regulatory response. The fact that deletion of this sequence leads to the inability to derepress suggests that HIS4 is under positive control.

Base Sequence↗
PubMed1980

Initiation of protein synthesis in isolated mitochondria and chloroplasts.

N5-Formyltetrahydrofolate, a competitive inhibitor of the formylation of the initiator Met-tRNAfMet in an in vitro assay, is a powerful inhibitor of amino acid incorporation in isolated Saccharomyces cerevisiae mitochondria and in Euglena gracilis chloroplasts. Thus, a large part of the incorporation is dependent upon new initiation acts. On the contrary, the rate of incorporation can be largely increased by addition of the specific formyl group donor, N10-formyltetrahydrofolate. Experiments are also reported strongly suggesting that the formylation of Met-tRNAfMet is an absolute requirement in order to initiate protein synthesis in chloroplasts, as has been shown in mitochondria.

Chloroplasts↗
PubMed1980

Hycanthone as a specific frameshift mutagen in Saccharomyces cerevisiae.

Reversion of mutations of different molecular nature was studied after treatment with hycanthone in mild conditions (0.05--0.4 mM, 4 h in the dark, pH 7.2). The mutagen had a very low reversion activity on 3 missense and 4 nonsense mutations (2 UAA and 2 UAG), although it was very active on 3 frameshift mutations. Our data on intragenic reversion and frameshift suppressors indicate that hycanthone can induce both insertions and deletions.

Dose-Response Relationship, Drug↗
PubMed1979

Nuclear inheritance of resistance to antimycin A in Saccharomyces cerevisiae.

A group of 30 independent mutants of Saccharomyces cerevisiae, resistant to the respiratory inhibitor antimycin A, was investigated from a genetical and biochemical point of view. All the mutants can be grouped into two nuclear loci: AMY1 maps on the VII chromosome, between leu 1 and trp 5; AMY2 is close to its centromere on either chromosome XVIII or XIX. Both genes do not affect mitochondrial structures or functions.

Antimycin A↗
PubMed1978

Effect of mutation in the aromatic amino acid pathway on sporulation of Saccharomyces cerevisiae.

Mutations in ARO1 and ARO2 genes coding for enzymes involved in the common part of the aromatic amino acid pathway completely block the sporulation of Saccharomyces cerevisiae when in a homozygous state, whereas mutations in all the other genes of the same pathway do not. This effect is not due to the lack of any intermediate metabolite but rather to the accumulation of a metabolite preceding chorismic acid. Shikimic acid or one of its precursors was identified as the possible inhibitor. The presence of the three aromatic amino acids in the sporulation medium restores the ability to undergo meiosis. This seems not to be due to a feedback inhibition of the first enzymes of the pathway but rather to a competition between aromatic amino acids and the inhibitor on a site specific for the meiotic process. The inhibition of sporulation seems to occur at a very early step in meiosis, as indicated by the lack of premeiotic DNA synthesis in aro1 and aro2 mutants.

DNA↗
PubMed1977

Dependence of mitochondrial protein synthesis initiation on formylation of the initiator methionyl-tRNAf.

The effect of N10-formyl-H4folate on mitochondrial peptide chain initiation has been studied in isolated mitochondria of Saccharomyces cerevisiae. The addition of N10-formyl-H4-folate strongly stimulates the incorporation of amino acids into mitochondrial protein at both 6 and 15 mm Mg2+. Still higher stimulation (up to 10-fold) has been obtained in the production of de novo synthesized initial peptides, measured as peptidyl puromycin derivatives. The maximum effect is observed at 0.1 mM N10-formyl-H4folate. At 5 mM puromycin, the ratio formylated/unformylated peptides is 3, as shown by electrophoretic analysis. At 10 mM puromycin, the ratio is increased to more than 6. This is due to the presence of deformylase and amidohydrolase activities, which are more effective the longer the initial peptide is synthesized; at increasing puromycin concentrations, progressively shorter peptide chains are formed. Chemically synthesized fMet-puromycin and Met-puromycin are virtually stable when incubated with intact or frozen and thawed mitochondria. More careful kinetic analysis shows an early cessation of the initial peptide formation in the samples without N10-formyl-H4-folate. This indicates that the formylation of methionyl-tRNA formylatable species is an absolute requirement for mitochondrial peptide chain initiation.

Drug Stability↗
PubMedDate not supplied

Placental transfer of theophylline in an in vitro closed perfusion system of human placenta isolated lobule.

Theophylline (TH) is a methylated xanthine widely used in the treatment of asthmatic pregnant women. Because of the scant available information on the transplacental profile, the time course of TH transfer was studied by an in vitro human placental perfusion. 6 placentas were perfused with Earle's enriched bicarbonate buffer for 180 min using recirculating maternal and fetal circuits. The physiological and biochemical properties of the tissue were well maintained. TH data were compared to those of antipyrine (AP), an usual marker in placental perfusions. The disappearance of TH from the maternal circuit was studied after administration of 15 mg/l in maternal perfusate. TH appeared in the fetal circuit within 5 min. Equilibrium was achieved in both circuits. TH fetomaternal mass ratio became constant (FMM = 0.45 +/- 0.01) after 80 min of perfusion and maternal to fetal clearance was 2.59 +/- 0.24 ml/min. About 16% of TH maternal dose was recovered in the tissue, while 18% appeared in fetal circulation. TH recovery was 89 +/- 9%. On the basis of our results, similar concentrations could be predicted in mother and fetus after maternal TH intake. The TH transfer profile is consistent with in vivo values reported in humans and animals at delivery.

Antipyrine↗