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E Bartnik

Publications and source records attributed to E Bartnik.

At least 37 records · Page 2Linked to original sources
PubMed1995

The S. cerevisiae nuclear gene SUV3 encoding a putative RNA helicase is necessary for the stability of mitochondrial transcripts containing multiple introns.

The product of the nuclear gene SUV3 is implicated in a variety of post-transcriptional processes in yeast mitochondria. We have analysed the effect of SUV3 gene-disruption on the expression of intron-containing alleles of the mitochondrial cytb and cox1 genes. We have constructed several strains with mitochondrial genomes containing different combinations of cytb and cox1 introns, and associated these genomes with the disruption of SUV3. The resulting strains were tested for their respiratory competence and spectral cytochrome content. All the strains containing only two or three introns showed normal expression of cytb and cox1, whereas the strains containing more introns were unable to express the appropriate gene. The analysis of mitochondrial RNAs by Northern hybridisation showed that the loss of respiratory competence in the strains containing more introns is due to the decrease of mRNA level with no over-accumulation of high-molecular-weight precursors. However, the transcription of the genes was not affected. These results led us to the notion that SUV3 is required for the stability of intron-containing cytb and cox1 transcripts in a cumulative way, not dependent on any particular intron.

Carbon↗
PubMed1995

The suv3 nuclear gene product is required for the in vivo processing of the yeast mitochondrial 21s rRNA transcripts containing the r1 intron.

We have constructed a yeast mitochondrial genome containing only one group-I intron, r1, from the 21s rRNA gene and introduced this genome into a strain bearing a disruption of the suv3 gene. The presence of the r1 intron alone causes a block in respiration, while the isogenic strain containing the intronless genome is respiratory competent. Northern analysis indicates that the functional suv3 protein is necessary for the yeast cell in order to process the r1-containing transcripts: in the absence of the suv3 protein the hybridization pattern of the excised r1 intron is altered and the amount of mature 21s rRNA is 50-fold lower. We suggest that the multifunctional suv3 protein, which displays motifs of ATP-dependent RNA helicases, is necessary for the in vivo pathway leading to formation of mature 21s rRNA from the transcripts containing the r1 intron in mitochondria of Saccharomyces cerevisiae.

Blotting, Northern↗
PubMed1994

How many 5S rRNA genes and pseudogenes are there in Aspergillus nidulans?

We have estimated the number of 5S rRNA genes in Aspergillus nidulans using two-dimensional agarose gel electrophoresis and hybridization to appropriate probes, representing the 5'-halves, the 3'-halves of the 5S rRNA sequence and a sequence found at the 3'-end of all known A. nidulans pseudogenes (block C). We have found 23 5S rRNA genes, 15 pseudogenes consisting of the 5'-half of the 5S rRNA sequence (of which 3 are flanked by block C) and 12 copies of block C which do not seem to be in the vicinity of 5S rRNA sequences. This number of genes is much lower than our earlier estimates, and makes our previously analyzed sample of 9 sequenced genes and 3 pseudogenes much more representative.

Aspergillus nidulans↗
PubMed1994

Evolutionary conservation of the transcribed spacer sequences of the rDNA repeat unit in three species of the genus Aspergillus.

We have cloned and sequenced the two intervening transcribed spacers in the rDNA repeat unit of three Aspergillus species--A. nidulans, A. awamori and A. wentii. The A. wentii and A. awamori spacers are almost identical and share a high degree of homology with the A. nidulans spacers. All spacers have a high G-C content (66%-76%) and the potential of forming complex secondary structures, which may indicate that they play a role in the maturation of pre-rRNA molecules.

Aspergillus↗
PubMed1993

Assembly of pericellular matrices by COS-7 cells transfected with CD44 lymphocyte-homing receptor genes.

The capacity to assemble and retain a pericellular matrix is correlated with the expression of the cell surface binding sites specific for the extracellular matrix macromolecule hyaluronan. These binding proteins have been termed hyaluronan receptors. The lymphocyte-homing receptor CD44 may have identity with these hyaluronan receptors. To determine whether hyaluronan receptors function independently in this capacity for matrix assembly, mammalian cells were transfected with cDNA encoding the putative hyaluronan receptor CD44. After transfection with CD44 cDNA, COS cells gained the capacity to assemble hyaluronan-dependent pericellular matrices in the presence of exogenously added hyaluronan and proteoglycan. Thus, CD44 receptors do function as matrix-organizing, matrix-anchoring hyaluronan-binding proteins. In addition, the expression of CD44/hyaluronan receptors alone is sufficient to direct this matrix assembly. If matrix assembly is a function of cells in vivo that express hyaluronan receptors, this raises interesting possibilities for the role of the receptors in cell migration, when new extracellular matrix environments are encountered.

Animals↗
PubMed1991

Structure and evolution of 5S rRNA genes and pseudogenes in the genus Aspergillus.

We have cloned and determined the nucleotide sequence of 18 DNA fragments hybridizing to 5S rRNA from two Aspergillus species--A. wentii and A. awamori. Four of the analyzed sequences were pseudogenes. The gene sequences of these two species were very similar and differed from Aspergillus nidulans at both constant and microheterogeneous sites.

Aspergillus nidulans↗
PubMed1990

The 210-kD nuclear envelope polypeptide recognized by human autoantibodies in primary biliary cirrhosis is the major glycoprotein of the nuclear pore.

We have recently reported a new family of nuclear autoantibodies in a subset of patients with primary biliary cirrhosis. These antibodies bind to a nuclear envelope polypeptide(s) of approximately 200 kD, the exact identity of which was not established. In this study, we show that all of these autoantibodies are directed against a 210-kD integral membrane glycoprotein of the nuclear pore.

Autoantigens↗
PubMed1989

Chromatin structure and levels of expression and DNA methylation in the E3 region of chromosomally integrated adenovirus type 12 DNA.

Integrated adenovirus type 12 (Ad12) genes in Ad12-transformed cell lines were investigated for chromatin structure, expression levels and states of DNA methylation. The E3 region in the Ad12-transformed cell line HA12/7 is hypermethylated and not expressed. The same region in the Ad12-transformed hamster cell lines T637 and A2497-3 is transcribed and undermethylated (Kruczek, I. and Doerfler, W. (1982) EMBO J. 1, 409-414). There was no significant difference in the DNase I sensitivity of the E3 region when nuclei of the aforementioned cell lines were incubated with this nuclease. In contrast, incubation of these nuclei with the restriction endonuclease PstI and subsequent cleavage of the DNA with BamHI generated an additional 0.9 kbp fragment in T637 and A2497-3 DNA which was not observed after treating HA12/7 nuclei and DNA in the same way. This finding was interpreted as indicative of differences in the chromatin structure of the E3 region depending on its state of transcriptional activity and its level of methylation. The E1 and major late promoter regions, which were transcriptionally active and inactive, respectively, in all three cell lines investigated, did not exhibit differences in sensitivity towards DNase I or PstI treatment of nuclei. More refined technology will be required to compare the chromatin structure of active versus inactive genes.

Adenovirus Early Proteins↗
PubMed1989

Primary structure analysis of an integral membrane glycoprotein of the nuclear pore.

The complete primary structure of an integral membrane glycoprotein of the nuclear pore was deduced from the cDNA sequence. The cDNA encodes a polypeptide of 204,205 D containing a 25-residue-long signal sequence, two hydrophobic segments that could function as transmembrane segments, and 13 potential N-linked oligosaccharide addition sites. Endoglycosidase H reduces the molecular mass by approximately 9 kD suggesting that not all of these 13 sites are used. We discuss possible models for the topology of this protein in the pore membrane as well as a possible role in the formation of pores and pore complexes.

Amino Acid Sequence↗
PubMed1988

Intermediate filaments in the giant muscle cells of the nematode Ascaris lumbricoides; abundance and three-dimensional complexity of arrangements.

The body muscle cells of the nematode Ascaris lumbricoides are characterized by massive amounts of intermediate filaments (IF). These occur in all three regions of this giant cell type. They traverse the cytoplasm of the balloon-like belly, which houses the nucleus, and occur as bundles in the arm-like extensions to the nerve. The organization of IF in the third region, the contractile fiber, was analyzed further by serial sections and three-dimensional reconstruction. IF bundles traverse the glycogen-rich lumina of the fiber and reach as baskets around the sarcomeres. Together with numerous dense bodies they form the Z-band-like arrangements. IF bundles reach the plasma membrane at hemidesmosome-like specializations often situated at deep membrane invaginations filled with a fibrillar component of the extracellular matrix. The ultrastructural appearance of IF bundles is connected to the contractional state of the sarcomeres. They appear straight in extended muscle but coil up upon contraction. In the pharynx massive IF bundles are oriented longitudinally. A second type of IF bundles follows the radially oriented sarcomeres. These reveal pronounced Z-band type structures with massive disks. IF surround the sarcomeres and seem to terminate at these disks. We discuss possible functions of the complex IF organization in body muscle and pharynx.

Animals↗
PubMed1987

Microheterogeneity in Aspergillus nidulans 5S rRNA genes.

We have determined the sequence of 4 Aspergillus nidulans 5S rRNA genes and compared it with 4 previously established sequences. No extensive homologies are found in 5' flanking sequences, but in the 3' flanks of two genes and two pseudogenes similar sequences are observed. In the coding sequences differences occur in 7 positions. Two 5S rRNA genes which are found in one plasmid 1.1 kb apart are located in opposite orientations.

Aspergillus nidulans↗
PubMed1986

Aspergillus nidulans 5S rRNA genes and pseudogenes.

The sequence of four Aspergillus nidulans 5S rRNA genes and of two pseudogenes has been determined. A conserved sequence about 100 bp upstream of the 5S rRNA coding sequences has been found in three genes and one pseudogene. The two pseudogenes correspond to the 5' half of the 5S rRNA coding sequence and their 3' flanking sequences which are not homologous to 5S rRNA are strongly conserved.

Aspergillus nidulans↗
PubMed1986

Intermediate filaments in muscle and epithelial cells of nematodes.

Current concepts of the developmentally controlled multigene family of intermediate filament (IF) proteins expect the origin of their complexity in evolutionary precursors preceding all vertebrate classes. Among invertebrates, however, firm ultrastructural as well as molecular documentation of IFs is restricted to some giant axons and to epithelia of a few molluscs and annelids. As Ascaris lumbricoides is easily dissected into clean tissues, IF expression in this large nematode was analyzed by electron microscopic and biochemical procedures and a monoclonal antibody reacting with all mammalian IF proteins. We document for the first time the presence of IFs in muscle cells of an invertebrate. They occur in three muscle types (irregular striated pharynx muscle, obliquely striated body muscle, uterus smooth muscle). IFs are also found in the epithelia studied (syncytial epidermis, intestine, ovary, testis). Immunoblots on muscles, pharynx, intestine, uterus, and epidermis identify a pair of polypeptides (with apparent molecular masses of 71 and 63 kD) as IF constituents. In vitro reconstitution of filaments was obtained with the proteins purified from body muscle. In the small nematode Caenorhabditis elegans IF proteins are so far found only in the massive desmosome-anchored tonofilament bundles which traverse a special epithelial cell type, the marginal cells of the pharynx. We speculate that IFs may occur in most but perhaps not all invertebrates and that they may not occur in all cells in large amounts. As electron micrographs of the epidermis of a planarian--a member of the Platyhelminthes--reveal IFs, the evolutionary origin of this cytoplasmic structure can be expected either among the lowest metazoa or already in some unicellular eukaryotes.

Animals↗