Showing papers by "Wieland Meyer published in 1996"
TL;DR: Identical ITS sequences and the high similarity of PCR-fingerprinting patterns indicate a very close relationship between T. reesei/H.
Abstract: The relationship of the important cellulase producing asexual fungus Trichoderma reesei to its putative teleomorphic (sexual) ancestor Hypocrea jecorina and other species of the Trichoderma sect. Longibrachiatum was studied by PCR-fingerprinting and sequence analyses of the nuclear ribosomal DNA region containing the internal transcribed spacers (ITS-1 and ITS-2) and the 5.8S rRNA gene. The differences in the corresponding ITS sequences allowed a grouping of anamorphic (asexual) species of Trichoderma sect. Longibrachiatum into Trichoderma longibrachiatum, Trichoderma pseudokoningii, and Trichoderma reesei. The sexual species Hypocrea schweinitzii and H. jecorina were also clearly separated from each other. H. jecorina and T. reesei exhibited identical sequences, suggesting close relatedness or even species identity. Intraspecific and interspecific variation in the PCR-fingerprinting patterns supported the differentiation of species based on ITS sequences, the grouping of the strains, and the assignment of these strains to individual species. The variations between T. reesei and H. jecorina were at the same order of magnitude as found between all strains of H. jecorina, but much lower than the observed interspecific variations. Identical ITS sequences and the high similarity of PCR-fingerprinting patterns indicate a very close relationship between T. reesei and H. jecorina, whereas differences of the ITS sequences and the PCR-fingerprinting patterns show a clear phylogenetic distance between T. reesei/H. jecorina and T. longibrachiatum. T. reesei is considered to be an asexual, clonal line derived from a population of the tropical ascomycete H. jecorina.
239 citations
TL;DR: The results indicate that RAPD analysis is a sensitive and useful method for investigating environmental sources of human infection with this biotype and raises the possibility of an alternative and as yet unidentified natural habitat of C. neoformans var.
Abstract: Sixty-one clinical and forty-nine environmental isolates of Cryptococcus neoformans var. gattii from Australia and the United States were analyzed by random amplification of polymorphic DNA (RAPD), using 12- to 22-mer primers in pairs, and/or PCR fingerprinting with a single primer derived from the microsatellite core sequence of the wild-type phage M13 (5' GAGGGTGGCGGTTCT 3'). Three major genetic profiles were identified by both typing techniques. A single RAPD profile (VGI) predominated among clinical isolates (44 of 48, 92%) and isolates from host eucalypts (45 of 45, 100%) from Australia. Of the 94 Australian isolates, 4 (3 clinical and 1 environmental) were assigned to profile VGII; 2 of these were recovered from patients and one was recovered from plant debris from Western Australia. Only one Australian clinical isolate was assigned to profile VGIII. A different distribution of RAPD profiles (four VGIII, two VGII, and one VGI) was found among four clinical and three environmental isolates from the United States. RAPD profiles of 8 of the 101 isolates studied revealed minor genetic variants, 4 of profile VGI and 4 of profile VGII. Genetic concordance between the majority of clinical and environmental isolates in Australia is consistent with the hypothesis that human disease is acquired from exposure to host eucalypts. Profiles of clinical isolates were independent of body site of infection, and profiles of all isolates were stable over time. Analysis by PCR fingerprinting confirmed the RAPD results. A second RAPD profile (VGII) was associated with infection in southwest Western Australia, where the two host eucalypts do not occur naturally. This raises the possibility of an alternative and as yet unidentified natural habitat of C. neoformans var. gattii. Our results indicate that RAPD analysis is a sensitive and useful method for investigating environmental sources of human infection with this biotype.
140 citations
TL;DR: By comparing species-specific PCR fingerprints ofclinical isolates with those of reference strains, clinical isolates could be identified to the species level even if they could not be identified by routine biochemical methods.
Abstract: DNA polymorphisms in different species and strains of the genus Candida were assessed by amplifying genomic DNA with single nonspecific primers. This PCR method employed an arbitrary primer (the 10-mer AP3), a primer derived from the intergenic spacer regions (T3B), and the microsatellite primers (GTG)5 and (AC)10. Distinctive and reproducible sets of amplification products were observed for 26 different Candida and 8 other fungal species. The numbers and sizes of the amplification products were characteristic for each species. All yeast species tested could be clearly distinguished by their amplification patterns. With all primers, PCR fingerprints also displayed intraspecies variability. However, PCR profiles obtained from different strains of the same species were far more similar than those derived from different Candida species. By comparing species-specific PCR fingerprints of clinical isolates with those of reference strains, clinical isolates could be identified to the species level even if they could not be identified by routine biochemical methods.
96 citations