Search PubMed⌕ Search

Biomedical subjects

K Wolf

Publications and source records attributed to K Wolf.

At least 127 records · Page 7Linked to original sources
PubMed1994

A mitochondrial group-I intron in fission yeast encodes a maturase and is mobile in crosses.

The open reading frame in the first intron of the mitochondrial gene encoding subunit I of cytochrome c oxidase encodes a maturase and stimulates homologous recombination in Escherichia coli. In this paper, we demonstrate that this intron is mobile in crosses, indicating that it also encodes an endonuclease. This is the first report on an intron which possesses mobility and acts as a maturase.

Cloning, Molecular↗
PubMed1994

Complete absence of mitochondrial DNA in the petite-negative yeast Schizosaccharomyces pombe leads to resistance towards the alkaloid lycorine.

The petite-positive yeast Saccharomyces cerevisiae can be efficiently and completely converted to respiratory-deficient cytoplasmic petite mutants by intercalating drugs. Rho0 petites from Schizosaccharomyces pombe could only be obtained in strains carrying a nuclear mutation. In this paper we report the efficient isolation of rho0 mutants in a Sch. pombe strain containing a mitochondrial mutator mutation. We also show that the alkaloid lycorine is able to differentiate between cells containing defective mitochondrial DNA (mit-) and those lacking mitochondrial DNA completely (rho0). Rho0 cells are resistant to the alkaloid whereas mit- and wild-type cells show the same sensitivity.

Amaryllidaceae Alkaloids↗
PubMed1994

The role of glutathione biosynthesis in heavy metal resistance in the fission yeast Schizosaccharomyces pombe.

Plants and the fission yeast Schizosaccharomyces pombe synthesize small cadmium-binding peptides, called phytochelatins, in response to cadmium. Derived from glutathione (GSH: gamma-Glu-Cys-Gly), they have the general structure (gamma-Glu-Cys)nGly, where n is 2-11. In order to study the biosynthesis of phytochelatins, we used the mutagen N-methyl-N'-nitro-N nitrosoguanidine (MNNG) to select mutants with a lowered GSH content. GSH-deficient mutants show a Cd-sensitive phenotype, whereas resistance to Cu is only slightly influenced. These Cd-sensitive mutants contain 2-15% of the wild-type GSH level. For three mutants a lowered activity of gamma-glutamylcysteine synthetase was measured. One of the mutants was transformed to Cd-resistance and the complementing fragment was analyzed further. The complementing fragment hybridized with chromosome III. In the transformants, GSH content was restored up to wild-type levels, whereas the activity of gamma-glutamylcysteine synthetase was significantly increased compared with the wild-type. Possible mechanisms for Cd-resistance in the transformants are discussed.

Cadmium↗
PubMed1994

[Clinical aspects of pulmonary tuberculosis].

The low incidence of pulmonary tuberculosis has led to a decrease of doctors expertise in this field. This review deals with clinical aspects of the disease. This article does not refer to the problem of simultaneous infection with tuberculosis and HIV. Pathogenesis, symptoms and diagnosis are discussed. A classification of intrathoracal manifestations of the disease with respect to clinical, radiologic and pathogenetic criteria is raised. To facilitate dealing with a certain case, a couple of questions are formulated and pragmatic answers are given. Risk-groups are specially emphasized to attract attention to the possibility of specific disease.

Bacteriological Techniques↗
PubMed1994

[Lateral urethrocystography in digital subtraction technique].

The first application of the digital subtraction technique to lateral urethrocystography is described. This methodology facilitates gynecological-urological operations by providing reliable investigation results and an unambiguous image interpretation. Methods and first experiences with the digital subtraction technique in gynecological-urological diagnosis are reported.

Female↗
PubMed1992

The adenylate kinase family in yeast: identification of URA6 as a multicopy suppressor of deficiency in major AMP kinase.

The gene URA6 encoding uridylate kinase (UK) from Saccharomyces cerevisiae was isolated as a multicopy suppressor of the respiratory-deficient phenotype of an S. cerevisiae mutant defective in the gene AKY2 encoding AMP kinase (AK). The URA6 gene also restored temperature resistance to two different temperature-sensitive mutations in the gene encoding Escherichia coli AK. By contrast, the gene encoding UK of Dictyostelium discoideum on a multicopy yeast shuttle plasmid, expressed under control of the constitutive yeast AKY2 promoter, failed to complement the deficiency in yeast, although such transformants expressed high UK activity. We show that yeast UK exerts significant AK activity which is responsible for the complementation and is absent in the analogous enzyme from D. discoideum. Since UK also significantly phosphorylates CMP (but not GMP), it must be considered an unspecific short-form nucleoside monophosphate kinase. Wild-type mitochondria lack UK activity, but import AKY2. Since multicopy transformation with URA6 heals the Pet- phenotype of AKY2 disruption mutants, the presence of AKY2 in the mitochondrial intermembrane space is not required to maintain respiratory competence. However, furnishing UK with the bipartite intermembrane space-targeting presequence of cytochrome c1 improves the growth rates of AKY2 mutants with nonfermentable substrates, suggesting that AK activity in mitochondria is helpful, though not essential for oxidative growth.

Adenylate Kinase↗
PubMed1992

[Color-coded duplex ultrasonography compared to phlebography in deep leg and pelvic vein thrombosis].

Between March 1990 and March 1991, in a prospective study, 100 patients (53 men, 47 women, median age 61.5 years) with suspected deep venous thrombosis of the lower extremities, colour duplex ultrasonography (CDU) (Ultramark 9, ATL) were investigated using the slow-flow technique. The CDU findings obtained for the external iliac vein (distal segment), the common femoral, the superficial femoral and popliteal veins, together with those of the veins of the lower extremity, were compared with the results of phlebography, which is considered to be the gold standard for this type of investigation. The sensitivity/specificity of CDU in diagnosing deep venous thrombosis was, from proximal to distal: 95.4%/100%, 100%/99%, 96.8%/97.1%, 98.5%/95.5% and 96.3%/98%. Fibrinolytic therapy (ultra high-dose short-term therapy: n = 16 patients; conventional fibrinolytic therapy: n = 4 patients) was indicated in 20 patients. In this group of patients identical results were obtained with CDU and ascending phlebography. Our experience shows CDU to be a supplementary diagnostic procedure to real-time B mode ultrasonic imaging in the establishment of the primary diagnosis, and to be superior to it in the follow-up evaluation of the results of fibrinolytic treatment. Both in the establishment of the primary diagnosis and follow-up of thrombosis of the deep leg and pelvic veins, CDU is the equal of phlebography. The advantage of the latter is in the documentation of the entire venous system and staging of post-thrombotic syndrome.

Adult↗
PubMed1992

[Isolation of H. pylori proteins and support for their suitability in serologic diagnoses].

H.pylori-proteins were separated using gel chromatographic methods. These antigens were tested for their suitability to detect H.pylori-specific antibodies. A complex of two proteins (62 kDa and 30 kDa) was a strong and specific antigen. A third protein (13 kDa) was a good but nonspecific antigen. Concerning these facts we compared two often used antigen preparations for serodiagnosing H.pylori-specific antibodies (acid-glycine preparation and sarcosyl-insoluble outer membrane proteins). The sarcosyl-insoluble material contains more specific antigens and lower levels of nonspecific proteins compared to the acid-glycine preparation. Based on these results we conclude that the outer membrane preparation seems to be more suitable for the serodiagnosing of H.pylori-specific antibodies.

Antibodies, Bacterial↗
PubMed1991

The mitochondrial genome of fission yeast: inability of all introns to splice autocatalytically, and construction and characterization of an intronless genome.

In this paper we report the inability of four group I introns in the gene encoding subunit I of cytochrome c oxidase (cox1) and the group II intron in the apocytochrome b gene (cob) to splice autocatalytically. Furthermore we present the characterization of the first cox1 intron in the mutator strain anar-14 and the construction and characterization of strains with intronless mitochondrial genomes. We provide evidence that removal of introns at the DNA level (termed DNA splicing) is dependent on an active RNA maturase. Finally we demonstrate that the absence of introns does not abolish homologous mitochondrial recombination.

Amino Acid Sequence↗
PubMed1991

Characterization of a novel open reading frame, urf a, in the mitochondrial genome of fission yeast: correlation of urf a mutations with a mitochondrial mutator phenotype and a possible role of frameshifting in urf a expression.

Between the genes for tRNA(gin) and tRNA(ile) an open reading frame of 227 amino acids has been identified which is unique among known mitochondrial genomes and which has been termed urf a (Lang et al. 1983; Kornrumpf et al. 1984). It uses the "mitochondrial" genetic code, i.e., it contains a TGA codon, whereas all other protein-encoding genes, and all but one intronic open reading frame, use the "standard" genetic code (UGG for tryptophan). A previous paper has demonstrated that "mutator" strains show an increased formation of mitochondrial drug-resistant and respiration-deficient mutants (including deletions). In this paper we show that the mutator activity is correlated with mutations in urf a. A detailed analysis of one urf a mutant is presented (anar-6), where the deletion of an A residue leads to a frameshift mutation and consequently to premature termination of the putative protein. The phenotype of colonies originating from a single mutant clone varies from no growth up to full growth on non-fermentable substrate. This phenomenon of phenotypic segregation can be explained by the ability of the cell to perform translational frameshifting. A detailed analysis of the DNA sequence and the putative urf a protein will be presented and a possible function of the protein will be discussed.

Amino Acid Sequence↗
PubMed1991

The Chlorella H+/hexose cotransporter gene.

The complete genomic sequence of the inducible Chlorella kessleri H+/hexose cotransporter (HUP1) has been obtained from two overlapping clones isolated from a lambda gt10 library. The HUP1 gene is interrupted by 14 introns with the first intron being located in the 5'-untranslated part of the gene. The average intron length is 220 bp, yielding a very regular intron/exon pattern in the gene. The codon usage in this gene is strongly biased with a clear preference for C and a strong suppression of A. A consensus sequence for a putative algal polyadenylation sequence is shown and compared with other algal cDNA sequences.

Base Sequence↗