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K Wolf

Publications and source records attributed to K Wolf.

At least 109 records · Page 6Linked to original sources
PubMed1995

Gcs1, a gene encoding gamma-glutamylcysteine synthetase in the fission yeast Schizosaccharomyces pombe.

By complementation of a mutant resistant to N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) we have identified the gcs1 gene, encoding a putative gamma-glutamylcysteine synthetase. The gene is possibly interrupted by two introns and has 49% identical and 80% similar amino acids compared with the homologous protein from rat. In comparison with the Saccharomyces cerevisiae homologue it possesses 41% identical and 74% similar amino acids.

Amino Acid Sequence↗
PubMed1995

Histomorphometric examinations of free revascularised iliac crest bone after transplantation for mandibular reconstruction.

At the present time the vascularised bone graft is the best procedure for reconstruction of mandibular defects in poor recipient tissues. We obtained 23 drill biopsies from different regions of vascularised bone transplants during the removal of the osteosynthesis plates from 14 patients who had poor recipient tissues. For comparison, we took five biopsies from the native iliac crest and eight biopsies from six patients with avascular bone transfer into unimpaired surrounding tissues. Microradiographs of the bone preparations were used for a computerised semi-automatic morphometric analysis. We evaluated the volumetric density (VV, %) and the mean trabecular diameter (D-TRAB, micron). In the central regions, the revascularised transplants decreased in volumetric density and in mean trabecular diameter. Compared with the average values of iliac crest bone, the avascular grafts increased in both parameters. The revascularised grafts showed significantly lower volumetric density and significantly lower mean trabecular diameters in the central regions than in the regions near to the mandibular stump. The avascular grafts actually showed the reverse effect. The results are discussed with particular reference to the quality of the recipient tissues, to the maintenance of graft viability, to functional stress, and to the design of the transplant.

Adult↗
PubMed1995

Nucleotide sequence of the Schizosaccharomyces japonicus var. versatilis ribosomal RNA gene cluster and its phylogenetic implications.

Fission yeasts form a small but heterogeneous group of ascomycetes and it is still unclear whether they should be subdivided into three genera (Schizosaccharomyces, Octosporomyces, Hasegawaea) or remain a single genus (Schizosaccharomyces). In order to decide whether a new genus Hasegawaea should be established for the species Schizosaccharomyces japonicus and Schizosaccharomyces versatilis, we have characterized the entire rDNA cluster in Schizosaccharomyces japonicus var. versatilis and compared it with the homologous region from Schizosaccharomyces pombe and with complete rRNA gene sequences from other yeast genera. From a phage genomic library a recombinant lambda phage containing the entire rDNA repeat unit was isolated. In this paper we report the primary sequence of the 18s, 5.8s and 25s rRNA coding regions. The S. japonicus var. versatilis rRNA genes are 1823 (18s), 158 (5.8s) and 3422 (25s) nucleotides long. The two sequences of the larger rRNA genes exhibit 95.7% (18s) and 93% (25s) similarity with the homologous genes from S. pombe. The differences between the rRNA genes of S. japonicus and S. pombe, however, are much smaller than the intrageneric differences within the rDNA sequences of other yeast genera. Therefore, subdivision of fission yeasts into the genera Schizosaccharomyces and Hasegawaea does not to seem to be justified.

Base Sequence↗
PubMed1995

Physiological characterization of a cadmium-resistant mutant in the fission yeast Schizosaccharomyces pombe.

After treatment of the wild-type strain 975 h+ with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) mutants able to grow on YEP-medium containing 15 mM CdCl2 were isolated. Mutant R17 showed a specific resistance to Cd, but no increased tolerance to Pb(NO3)2, CuSO4 or ZnCl2. No higher content of Cd-binding phytochelatins could be detected, but the mutant accumulated lower levels of Cd than the corresponding wild-type. No change, however, was observed in the accumulation of Cu. Under the influence of Cd, the respiratory activity of mutant R 17 is reduced less than in the wild-type. The mechanism of resistance could be an increased secretion or a decreased uptake of Cd.

Cadmium↗
PubMed1995

Subcellular localization of the inducible Chlorella HUP1 monosaccharide-H+ symporter and cloning of a Co-induced galactose-H+ symporter.

The unicellular green alga Chlorella kessleri can induce monosaccharide-H+ symport catalyzing the energy-dependent transport of D-glucose (D-Glc) and several other pentoses and hexoses across the plasmalemma. The gene coding for the inducible HUP1 monosaccharide-H+ symporter has been cloned and the protein has been characterized previously. The data presented in this paper demonstrate that the presence of the HUP1 gene product alone is not sufficient to cover the broad substrate specificity of monosaccharide transport in induced Chlorella cells. Two other HUP genes are shown to be co-induced in Chlorella in response to D-Glc in the medium. The cloning of HUP2 and HUP3 cDNA and genomic sequences is described, both being very homologous to HUP1. Modification of the 5' untranslated sequences of full-length cDNA clones of HUP2 and HUP3 allowed the functional expression of both transporters in Schizosaccharomyces pombe. HUP2 was shown to be a galactose-H+ symporter, whereas the substrate specificity of the HUP3 gene product is very similar to that of the HUP1 protein. However, HUP3 does not seem to be induced to high levels in Glc-treated Chlorella cells. Results are also presented proving that the product of the HUP1 gene is localized in the plasmalemma of D-Glc-induced Chlorella cells and is absent in plasma membranes of noninduced cells. Incubation of thin sections of Chlorella cells with anti-HUP1 antibodies and a fluorescence-labeled, second antibody yielded a ring of fluorescence on the surface of Glc-induced Chlorella cells.

Base Sequence↗
PubMed1995

Renal artery stenosis rapidly enhances atrial natriuretic peptide gene expression.

The aim of this study was to examine the influence of the systemic renin-angiotensin system on the gene expression of atrial natriuretic peptide in rat hearts. The renin-angiotensin system was stimulated (1) by unilateral renal artery clipping (0.2-mm clip, 2 days), producing a fourfold increase of circulating plasma renin activity and increasing blood pressure; (2) by furosemide infusion with simultaneous salt substitution, increasing plasma renin activity values to 45 ng angiotensin I/h per milliliter without changing blood pressure; or (3) by administration of the calcium antagonist amlodipine, which increased plasma renin activity values to 42 ng angiotensin I/h per milliliter and lowered blood pressure. Unilateral renal artery clipping increased atrial natriuretic peptide mRNA levels approximately 20-fold in the left ventricles and approximately twofold in the right ventricles and atria. Furosemide infusion had no effect on cardiac atrial natriuretic peptide mRNA levels, and in amlodipine-treated rats, cardiac atrial natriuretic peptide mRNA levels decreased to 30% of control values. The increase of atrial natriuretic peptide mRNA in the ventricles during renal artery clipping was blunted by the administration of the angiotensin-converting enzyme inhibitor ramipril, which also attenuated the blood pressure rise. In clipped rats amlodipine did not change elevated plasma renin activity values but abolished the rise of blood pressure and also attenuated the rise of atrial natriuretic peptide mRNA in the hearts. These findings indicate that an increase of the activity of the systemic renin-angiotensin system does not result in an obligatory change in cardiac atrial natriuretic peptide gene expression.(ABSTRACT TRUNCATED AT 250 WORDS)

Aldosterone↗
PubMed1994

Transposable group II introns in fission and budding yeast. Site-specific genomic instabilities and formation of group II IVS plDNAs.

The recent report on RNA-mediated group II intron (IVS, intervening sequence) transposition in mitochondria (mt) of Saccharomyces cerevisiae and Podospora anserina and the demonstration of reverse transcriptase (RT) activity encoded by the mobile S. cerevisiae intron cox1-aI1 suggests that group II introns constitute a new class of site-specific retro-like (retroid) elements. This is supported by the finding that the mitochondrial cob1-bI1 intron from the fission yeast Schizosaccharomyces pombe, encoding an RT-like open reading frame, is transposed in mtDNA populations. In agreement with the involvement of an RNA-intermediate in IVS transposition: First, the insertion sites were preceded by at least an IBS1-like (intron binding site) motif, which corresponds to the upstream exon and suffices to form the IBS1/EBS1 (EBS: exon binding site) base-pairing interactions. Second, intron transposition was conservative with respect to sequences flanking the insertion sites. We formulated the hypothesis that transient IVS insertion at non-allelic sites followed by recombination can be viewed as a general molecular mechanism, applicable equally well to site-specific genomic instabilities involving splice-site borders of group II introns and to the formation of extra-genomic IVS plasmid DNAs (plDNAs). We used polymerase chain reaction (PCR) techniques to detect infrequent rearrangements in mtDNA and report here on duplicative IVS transposition, twintron formation (e.g. bI1 insertion into another bI1 intron), and IVS insertions at canonical 5' exon-intron borders in S. pombe (cob1-bI1) and in S. cerevisiae (cox1-aI1). These data substantiate the concept that group II intron homing, IVS transposition and circular IVS plDNA formation involve a common RNA-mediated mechanism. Finally, the findings suggest that extra-genomic group II IVS copies are not restricted to senescence mycelia of P. anserina, but constitute natural components of group II IVS-containing genomes.

Apoproteins↗
PubMed1994

A tRNA gene mapping within the chloroplast rDNA cluster is differentially expressed during the development of Daucus carota.

In vivo analysis of expression of the chloroplast rDNA cluster during somatic embryogenesis of Daucus carota (D.carota) was performed by Northern-blot analysis with different DNA probes, spanning both the 16S rRNA gene, the 16S-23S rRNA spacer, which contains the two mosaic tRNA genes tRNA(Ile) and tRNA(Ala), and the region upstream of the 16S rRNA gene, where a tRNA(Val) maps. We show that expression both of the spacer tRNAs tRNA(Ile) and tRNA(Ala) is not significantly regulated during development whereas the amount of the transcript corresponding to tRNA(Val) is not detectable during early embryonic stages and progressively accumulates during late phases. Multiple transcription start sites have been identified upstream of the tRNA(Val) gene by S1 mapping analysis, which are activated late during the embryogenesis. These data indicate that developmental control mechanisms act on plastid gene expression during embryogenesis in carrot.

Base Sequence↗
PubMed1994

NADH: ubiquinone oxidoreductase in obligate aerobic yeasts.

The strictly aerobic yeasts Candida pinus, Cryptococcus albidus, Rhodotorula minuta, Rhodotorula mucilaginosa and Trichosporon beigelii possess mitochondrial NADH dehydrogenases with significant features of the NADH:ubiquinone oxidoreductase (complex I). These species show in all growth phases and under standard cultivation conditions, NADH dehydrogenases of approximately 700 kDa, which are sensitive to rotenone, a specific inhibitor of this complex. Identical results were obtained with the weakly fermenting C. pinus. The facultatively fermenting yeasts Saccharomyces cerevisiae and Kluyveromyces marxianus do not possess the 700 kDa-complex and are insensitive to rotenone. In S. cerevisiae, a rotenone-insensitive NADH dehydrogenase of about 500-600 kDa is detected only in stationary phase cells. As in Neurospora crassa, upon incubation of the obligately aerobic yeast R. mucilaginosa with chloramphenicol, an intermediate NADH dehydrogenase of approximately 350 kDa was formed, which was insensitive to rotenone.

Aerobiosis↗