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Biomedical subjects

R Cortese

Publications and source records attributed to R Cortese.

174 records · Page 10Linked to original sources
PubMed1977

Biosynthesis of tRNA in histidine regulatory mutants of Salmonella typhimurium.

HisU mutants of Salmonella typhimurium are depressed in the histidine operon since they have lower intracellular concentration of histidyl-tRNAHis. In this paper we present evidences showing that a strain carrying a hisU mutation (hisUl206) is altered in a nucleolytic enzyme involved in tRNA maturation process. The analysis of several hisU mutants indicates that hisU region of bacterial genome may account for more than one function involved in tRNA biosynthesis.

Histidine↗
PubMed1977

Biochemical and regulatory properties of Escherichia coli K-12 hisT mutants.

Escherichia coli K-12 hisT mutants were isolated, and their properties were studied. These mutants are derepressed for the histidine operon, map close to the purF locus at about 49.5 min on the E. coli linkage map, and lack pseudouridylate synthetase activity. The defect in this enzyme leads to the absence of pseudouridines in the anticodon loop of several transfer ribonucleic acid species, as evidenced by the altered elution profile on reversed-phase chromatography and resistance to amino acid analogues. Finally, the hisT mutants studied have a reduced growth rate that appears to be linked to hisT, although it is not known whether it is due to the same mutation. The normal generation time can be restored by supplementing the medium with adenine, uracil, and isoleucine.

Adenine↗
PubMed1977

Relationship between juxtaglomerular apparatus and plasma renin activity in human reno-vascular hypertension.

Juxtaglomerular cell count (JGCC) and juxtaglomerular activity (JA) on the fragments of the ischemic kidney and plasma renin activity (PRA) in peripheral venous blood were studied in 26 renovascular patients. In 11 cases PRA was also measured in renal venous blood. JGCC and JA values were always above normal range and both were significantly related to the PRA values in peripheral venous blood, while only JA was related to the PRA values in renal venous blood. These data indicate that in human renovascular hypertension the juxtaglomerular apparatus is hyperplastic and hypergranulated: the correlation between its morphological appearance and PRA seems to indicate that the renin-angiotensin system may be in some way involved in the genesis of hypertension.

Adolescent↗
PubMed1977

Mutagenicity of pesticides containing 1,3-dichloropropene.

In a systematic study of the mutagenic effect of chemical compounds used as pesticides, we found that D. D. soil fumigant and Telone are mutagenic. The test was performed using the bacterial tester strains following the procedure developed by Ames. The active principle of D. D. soil fumigant and Telone is a mixture of the cis and trans isomers of 1,3-dichloropropene. Both isomers are mutagenic in Salmonella strains TA 1535 and TA 100. 2,3-Dichloro-1-propene, a minor component (5%) of the commercial preparation Telone, was also found to be mutagenic in strains TA 1535 and TA 100. Mutagenesis of these tester strains is an indication of a base-pair substitution event causing a missense mutation. 1,3-Dichloropropene is widely used in agriculture all over the world. In Italy 2,187,100 kg were produced in 1972. In California over 1,000,000 kg of 1,3-dichloropropene-containing pesticides were used in 1971.

Allyl Compounds↗
PubMed1974

Pleiotropy of hisT mutants blocked in pseudouridine synthesis in tRNA: leucine and isoleucine-valine operons.

The hisT gene codes for an enzyme responsible for the conversion of uridine to pseudouridine (Psi) in the anticodon region of many tRNA species in Salmonella typhimurium. We have previously shown that a hisT mutant has tRNA(His) which lacks pseudouridine in this region and as a consequence has an altered chromatographic behavior. We show here a similar alteration in chromatographic behavior of all tRNA(Leu) and one tRNA(Ile) species from a hisT mutant. By contrast, tRNA(Val), which contains no pseudouridine except for the one in the TPsiCG sequence, is chromatographically unaltered in a hisT mutant. The absence of pseudouridine in the anticodon region of tRNA in hisT mutants has been previously shown to cause derepression of the histidine operon. We show here that in hisT mutants the regulation of the leucine and the isoleucine and valine operons is also affected: the enzymes of these operons are refractory to repression by the branched chain amino acids. However, there is no difference between hisT and wild type in the pattern of derepression caused by isoleucine or valine limitation and only a slight difference in the enzyme levels in cells grown on minimal medium. The alteration in the regulation of branched chain amino acid operons may also explain why hisT mutants are resistant to inhibition of growth by the amino acid analogues 5,5,5-trifluoroleucine, beta-hydroxyleucine, and norleucine and by the oligopeptides glycylglycylnorleucine and norleucylnorleucine.

Acids↗