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G Hausner

Publications and source records attributed to G Hausner.

10 recordsLinked to original sources
PubMed2002

Phylogenetic relationships among strains of the entomopathogenic fungus, Nomuraea rileyi, as revealed by partial beta-tubulin sequences and inter-simple sequence repeat (ISSR) analysis.

AIMS: To elucidate the phyletic relationships among three members of the entomogenous fungal genus, Nomuraea, with an emphasis on N. rileyi. METHODS AND RESULTS: Relationships were evaluated by analysis of the beta-tubulin gene and of inter-simple sequence repeats (ISSR). The amplification product of the partial beta-tubulin gene was larger for N. atypicola than for N. rileyi, and sequencing of this gene fragment confirmed that N. atypicola possesses approximately 25 more nucleotides than N. rileyi and N. anemonoides. Based on neighbor joining and bootstrap analysis of the partial beta-tubulin gene, N. atypicola failed to form a monophyletic grouping with the other two species of Nomuraea. In contrast, the single isolate of N. anemonoides clustered with the N. rileyi isolates, and both taxa grouped with Epichloe typhina (Hypocreales: Clavicipitaceae). Results from this study suggested that N. rileyi and N. anemonoides are closely related to the Clavicipitaceae. In contrast, evidence indicated that N. atypicola is not closely related to this family, and that this taxon is not a Nomuraea. Based on the 83 polymorphic loci of ISSR, it was observed that isolates of N. rileyi from diverse geographical origins were distinctly different from both N. atypicola and N. anemonoides. Considerable heterogeneity was observed in the 18 isolates of N. rileyi tested, and several clusters contained isolates from disparate geographical locations and hosts. However, three isolates from the Philippines (three host species) and three strains isolated from velvetbean caterpillar (Anticarsia gemmatalis) larvae in South America did cluster together. Two other strains from Brazil (isolated from Spodoptera spp.) were distinct from the velvetbean caterpillar isolates from South America. CONCLUSIONS, SIGNIFICANCE AND IMPACT OF THE STUDY: The beta-tubulin gene was generally too conserved to resolve intraspecies variability. However, ISSR did identify polymorphisms among the isolates of N. rileyi tested. The results of this study indicate that ISSR may be used as robust molecular markers for studying the population genetics of this entomopathogenic fungus.

Mitosporic Fungi↗
PubMed2001

Phylogenetic relationships among group II intron ORFs.

Group II introns are widely believed to have been ancestors of spliceosomal introns, yet little is known about their own evolutionary history. In order to address the evolution of mobile group II introns, we have compiled 71 open reading frames (ORFs) related to group II intron reverse transcriptases and subjected their derived amino acid sequences to phylogenetic analysis. The phylogenetic tree was rooted with reverse transcriptases (RTs) of non-long terminal repeat retroelements, and the inferred phylogeny reveals two major clusters which we term the mitochondrial and chloroplast-like lineages. Bacterial ORFs are mainly positioned at the bases of the two lineages but with weak bootstrap support. The data give an overview of an apparently high degree of horizontal transfer of group II intron ORFs, mostly among related organisms but also between organelles and bacteria. The Zn domain (nuclease) and YADD motif (RT active site) were lost multiple times during evolution. Differences in domain structures suggest that the oldest ORFs were concise, while the ORF in the mitochondrial lineage subsequently expanded in three locations. The data are consistent with a bacterial origin for mobile group II introns.

Amino Acid Sequence↗
PubMed2001

Coevolution of group II intron RNA structures with their intron-encoded reverse transcriptases.

Catalytic RNAs are often regarded as molecular fossils from the RNA World, yet it is usually difficult to get more specific information about their evolution. Here we have investigated the coevolution of group II intron RNA structures with their intron-encoded reverse transcriptases (RTs). Unlike group I introns, there has been no obvious reshuffling between intron RNA structures and ORFs. Of the six classes of intron structures that encode ORFs, three are conventional forms of group II A1, B1, and B2 secondary structures, whereas the remaining classes are bacterial, are possibly associated with the most primitive ORFs, and have unusual features and hybrid features of group IIA and group IIB intron structures. Based on these data, we propose a new model for the evolution of group II introns, designated the retroelement ancestor hypothesis, which predicts that the major RNA structural forms of group II introns developed through coevolution with the intron-encoded protein rather than as independent catalytic RNAs, and that most ORF-less introns are derivatives of ORF-containing introns. The model is supported by the distribution of ORF-containing and ORF-less introns, and by numerous examples of ORF-less introns that contain ORF remnants.

Chloroplasts↗
PubMed2000

The small sodium-channel blocking factor in the cerebrospinal fluid of multiple sclerosis patients is probably an oligopeptide.

An endogenous factor that is able to reduce the fast transient sodium current of excitable cells has been reported to exist in the cerebrospinal fluid (CSF) of multiple sclerosis (MS) patients. This was confirmed with nine clinically definite MS patients in the acute relapse. In order to purify and chemically identify the factor, microconcentration and gel filtration high-performance liquid chromatography (HPLC) were applied. After each purification step the activity-containing fraction was determined using a biological assay. With all CSFs the activity was contained in the fraction corresponding to 600-800 Da molecular weight, indicating that the factor is chemically homogeneous. The biological activity of the CSF specimens was not correlated to the laboratory CSF data; however, it was correlated to the area under the 210 nm UV light absorption peak in the corresponding chromatogram, i.e. the 600-800 Da MW fraction. As the factor was degradable by acid hydrolysis and a carboxypeptidase, it is suggested that it might be a small peptide.

Adolescent↗
PubMed2000

A circular mitochondrial plasmid incites hypovirulence in some strains of Cryphonectria parasitica.

In the chestnut-blight fungus Cryphonectria parasitica, a plasmid, pCRY1, occurs in the mitochondria of several strains isolated at various locations in the northeastern United States and Canada. The monomer of this plasmid is a 4.2-kb circular double-stranded DNA that has no detectable sequence homology with the 160-kb mitochondrial DNA of Ep155, a standard virulent laboratory strain of C. parasitica. The circular nature and oligomeric characteristics of the plasmid were deduced from the heterogeneous size of plasmid DNA molecules as detected by one- and two-dimensional gel-electrophoresis, the nature and alignment of restriction fragments, and the lack of detectable termini in the nucleotide sequence. The cytoplasmic location of the plasmid was deduced from its co-purification with mitochondria, uniparental (maternal) transmission in sexual crosses, dissociation from the nuclei of the donor strain during its horizontal transfer between vegetatively compatible strains through hyphal anastomoses, and mitochondrial codon usage (UGA = Try). The pCRY1 plasmid contains a long open reading frame that is transcribed and potentially encodes a unique 1214 amino-acid, B-family DNA polymerase similar to those encoded by the LaBelle and Fiji circular mitochondrial plasmids of Neurospora. In this subgroup of proteins, the DTD motif characteristic of B-family DNA polymerases is replaced by TTD. Amino-acid motifs related to those that are characteristic of the 3'-->5' exonuclease domains of B-family DNA polymerases have been located in the amino-terminal portion of the proteins. A comparison of isogenic plasmid-free and plasmid-containing cultures indicates that pCRY1 is an infectious agent that effects a reduction in the pathogenicity of some, but not all, strains of C. parasitica.

Amino Acid Sequence↗
PubMed1999

A long open reading frame in the mitochondrial LSU rRNA group-I intron of Cryphonectria parasitica encodes a putative S5 ribosomal protein fused to a maturase.

A 4238-bp intervening sequence within the highly conserved U11 region of the mitochondrial large subunit ribosomal RNA gene of the fungus Cryphonectria parasitica Ep155 has been sequenced and identified to be a group-I intron. This is the largest group-I intron reported to-date for fungal mitochondrial genomes. The intron contains an 851-codon open reading frame encoding a putative, but complete, small-subunit ribosomal protein of 510 amino acids which is fused at its carboxyl terminus to a 311 amino-acid polypeptide representing a typical maturase-like protein. A short open reading frame of 83 amino acids with some similarity to maturases, but lacking a translation-initiation codon, was also noted at the 3' end of the intron. The unusual size of the intron and the arrangement of the open and truncated reading frames suggest that this segment of the mtDNA of C. parasitica has arisen by a fusion of components from two or more different introns, possibly involving the re-location of intronic genes.

Amino Acid Sequence↗
PubMed1996

Physical and genetic map of the mitochondrial genome of Cryphonectria parasitica Ep155.

In the chestnut-blight fungus, Cryphonectria parasitica, a cytoplasmically transmissible (infectious) form of hypovirulence is associated with mitochondrial DNA (mtDNA) mutations that cause respiratory deficiencies. To facilitate the characterization of such mutations, a restriction map including the probable location of 13 genes was constructed for a relatively well-characterized virulent strain of the fungus, Ep155. The physical map is based on the order of all fragments generated by cleavage of the mtDNA by the PstI restriction endonuclease and includes some of the cleavage sites for HindIII, EcoRI, and XbaI. It was constructed from hybridization patterns of cloned mtDNA fragments with Southern blots of mtDNA digested with the four restriction enzymes. On this map, the probable locations of genes commonly found in the mitochondrial genomes of ascomycetes were determined by low-stringency hybridization of cloned Neurospora crassa mitochondrial gene probes to Southern blots of C. parasitica mtDNA. The data indicate that the mtDNA of strain Ep155 is a circular molecule of approximately 157 kbp and ranks among the largest mitochondrial chromosomes observed so far in fungi. The mtDNAs of 11 different C. parasitica isolates range in size from 135 to 157 kbp and in relatedness from 68 to 100 percent, as estimated from restriction-fragment polymorphisms. In addition to the typical mtDNA, the mitochondria of some isolates of the fungus contain double-stranded DNA plasmids consisting of nucleotide sequences not represented in the mtDNA of Ep155.

Ascomycota↗
PubMed1993

Molecular evolutionary analysis based on the amino acid sequence of catalase.

Heme-containing catalase sequences from 20 different organisms representing prokaryotes, fungi, animals, and plants have been compiled for phylogenetic reconstruction. Phylogenies based on distance and parsimony analysis show that fungal and animal catalases can be derived from one ancestor, whereas bacterial catalases fail to form a monophyletic group. Plant catalases appear to form a second class of catalases that arose independently from a possible prokaryotic ancestor.

Amino Acid Sequence↗
PubMed1993

Unusually compact ribosomal RNA gene cluster in Sphaeronaemella fimicola.

The ribosomal DNA repeat unit of Sphaeronaemella fimicola was found to be a 13.7-kb tandem repeat with a relatively long nontranscribed spacer (NTS) and an unusually compact ribosomal RNA gene cluster. The DNA sequence of an 850-bp PCR amplification product containing the 3' end of the small subunit rRNA (SSrRNA) gene, the 5.8s gene, and the 5' end of the large subunit rRNA (LSrRNA) gene was determined. The putative internal spacers flanking the 5.8s RNA gene could be the shortest yet noted for any fungus, totaling only 102 bases.

Ascomycota↗