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Biomedical subjects

A M Carr

Publications and source records attributed to A M Carr.

83 records · Page 5Linked to original sources
PubMed1991

Cloning and characterization of the rad4 gene of Schizosaccharomyces pombe; a gene showing short regions of sequence similarity to the human XRCC1 gene.

The rad4.116 mutant of the fission yeast Schizosaccharomyces pombe is temperature-sensitive for growth, as well as being sensitive to the killing actions of both ultraviolet light and ionizing radiation. We have cloned the rad4 gene by complementation of the temperature sensitive phenotype of the rad4.116 mutant with a S. pombe gene bank. The rad4 gene fully complemented the UV sensitivity of the rad4.116 mutant. The gene is predicted to encode a protein of 579 amino acids with a basic tail, a possible zinc finger and a nuclear location signal. The amino terminal part of the predicted rad4 ORF contains two short regions of similarity to the C-terminal part of the human XRCC1 gene. Codon usage suggests that the gene is very poorly expressed, and this was confirmed by RNA studies. Gene disruption showed that the rad4 gene was essential for the mitotic growth of S. pombe.

Base Sequence↗
PubMed1991

Cloning and characterisation of the rad9 DNA repair gene from Schizosaccharomyces pombe.

The rad9.192 DNA repair mutant from the fission yeast, Schizosaccharomyces pombe, is sensitive to both UV and ionising radiation. The rad9 gene has been cloned by complementation of the gamma-ray sensitivity of the mutant cell line. A 4.3 kb HindIII fragment was found to confer resistance to both types of radiation. The region of complementation was further localised to a 2.6 kb HindIII-EcoRV fragment, which, by DNA sequence analysis, was found to contain sequences capable of coding for a 427 amino acid protein, if three introns were postulated to remove stop codons. The introns were confirmed by sequence analysis of cDNA clones and PCR products derived from cDNA. The product of transcription is a 1.6 kb mRNA of low abundance. The putative rad9 protein shows no homology to any published sequence. A truncated protein is capable of complementing the radiation sensitivity of the rad9.192 mutant. Deletion of the gene is not lethal and the null allele has a similar phenotype to the rad9.192 mutant.

Amino Acid Sequence↗
PubMed1990

Metabolic effects of isoflurane on rat lungs perfused in situ.

1. The current experiments studied the effects of the inhalation anesthetic, isoflurane, on 5-hydroxytryptamine (5-HT) metabolism, protein synthesis, and angiotensin-converting enzyme activity in perfused rat lungs. 2. Under first order reaction conditions, isoflurane decreased the accumulation of tissue 5-hydroxyindoleacetic acid, the principle metabolite of 5-HT in a concentration-related, competitive, and reversible manner, indicating inhibition of endothelial 5-HT uptake. 3. In apparent contrast, isoflurane appeared to stimulate uptake of 5-HT by an imipramine-sensitive process, into a cell type unable to metabolize the parent amine. 4. Isoflurane increased absolute angiotensin-converting enzyme activity only at an inspired concentration of 5%. The anesthetic did not affect lung protein synthesis.

Animals↗
PubMed1989

A new device for balloon inflation during valvuloplasty: a preliminary report.

A new device using a lever concept has been designed to facilitate rapid inflation and deflation of balloons during valvuloplasty. This report summarizes and illustrates the design features of the balloon inflation device as well as in vitro results of testing of times for balloon inflation, deflation, and bursting.

Catheterization↗
PubMed1989

Molecular cloning and sequence analysis of mutant alleles of the fission yeast cdc2 protein kinase gene: implications for cdc2+ protein structure and function.

The cdc2+ gene function plays a central role in the control of the mitotic cell cycle of the fission yeast Schizosaccharomyces pombe. Recessive temperature-sensitive mutations in the cdc2 gene cause cell cycle arrest when shifted to the restrictive temperature, while a second class of mutations within the cdc2 gene causes a premature advancement into mitosis. Previously the cdc2+ gene has been cloned and has been shown to encode a 34 kDa phosphoprotein with in vitro protein kinase activity. Here we describe the cloning of 11 mutant alleles of the cdc2 gene using two simple methods, one of which is presented here for the first time. We have sequenced these alleles and find a variety of single amino acid substitutions mapping throughout the cdc2 protein. Analysis of these mutations has identified a number of regions within the cdc2 protein that are important for cdc2+ activity and regulation. These include regions which may be involved in the interaction of the cdc2+ gene product with the proteins encoded by the wee1+, cdc13+ and suc1+ genes.

Alleles↗
PubMed1989

Effects of ketamine and fentanyl on lung metabolism in perfused rat lungs.

The effects of ketamine and fentanyl on serotonin (5-hydroxytryptamine; 5-HT) metabolism, angiotensin-converting enzyme (ACE), and protein synthesis (PS) were investigated in an isolated lung model. Rat lungs were perfused in situ with a blood-free physiological salt solution. The pulmonary vasculature was exposed to ketamine (0.005-2.1 mM) or fentanyl (1.8-4.5 microM) for up to 2 h. After 1 h, accumulation of 5-[14C]hydroxyindoleacetic acid (5-HIAA) by the lung was monitored as an index of 5-HT metabolism. ACE activity was estimated from hydrolysis of [3H]benzoylphenylalanyl-alanyl-proline, a synthetic substrate for the enzyme. [3H]phenylalanine was added to the perfusate after 1 h, and its incorporation into acid-precipitable lung protein was measured over the subsequent hour. Ketamine inhibited 5-HT uptake in a concentration-related manner. The inhibition was characterized as competitive and reversible. Fentanyl had no effect on lung 5-HIAA accumulation. Neither drug altered ACE activity or protein synthesis over the concentration ranges tested. The results indicate an action by ketamine that inhibits the 5-HT membrane-transport process. The different effects observed by ketamine and fentanyl on this process could contribute to the diverse pharmacological properties of these two drugs.

Animals↗
PubMedDate not supplied

DNA repair in the fission yeast, Schizosaccharomyces pombe.

Mutants of the fission yeast Schizosaccharomyces pombe which are sensitive to UV and/or gamma-irradiation have been assigned to 23 complementation groups, which can be assigned to three phenotypic groups. We have cloned genes which correct the deficiency in mutants corresponding to 12 of the complementation groups. Three genes in the excision-repair pathway have a high degree of sequence conservation with excision-repair genes from the evolutionarily distant budding yeast Saccharomyces cerevisiae. In contrast, those genes in the recombination repair pathway which have been characterised so far, show little homology with any previously characterised genes.

Cloning, Molecular↗
PubMedDate not supplied

DNA structure checkpoint pathways in Schizosaccharomyces pombe.

The response to DNA damage includes a delay to progression through the cell cycle to aid DNA repair. Incorrectly replicated chromosomes (replication checkpoint) or DNA damage (DNA damage checkpoint) delay the onset of mitosis. These checkpoint pathways detect DNA perturbations and generate a signal. The signal is amplified and transmitted to the cell cycle machinery. Since the checkpoint pathways are essential for genome stability, the related proteins which are found in all eukaryotes (from yeast to mammals) are expected to have similar functions to the yeast progenitors. This review article focuses on the function of checkpoint proteins in the model system Schizosaccharomyces pombe. Checkpoint controls in Saccharomyces cerevisiae and mammalian cells are mentioned briefly to underscore common or diverse features.

DNA Replication↗