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Ilona Pfeiffer

Publications and source records attributed to Ilona Pfeiffer.

10 recordsLinked to original sources
PubMed2006

Interpretation of mtDNA RFLP variability among Aspergillus tubingensis isolates.

Aspergillus tubingensis isolates collected from distant geographic areas were earlier classified into six groups on the basis of the mtDNA RFLP variability they exhibited (mtDNA types 2a-2f). In the present work, we investigated the reason for the intraspecific mtDNA variability and we describe here how this fungus, with a relatively small mitochondrial genome, can display intraspecific polymorphism due to intron acquisition and also sporadic point mutations affecting the recognition motifs of the restriction enzymes employed in the RFLP analysis. Three different LAGLI-DADG type group I introns were identified in the cox1 gene amongst the six mtDNA RFLP types. MtDNAs of types 2b and 2d contain all of the three introns, mtDNA of type 2f carries only one, and the other mtDNA types contain two introns each. Comparative analysis showed that the first and second introns of mtDNAs of types 2b and 2d are well distributed among fungi, indicating their active horizontal transfer capacity. The third intron occurs rarely among fungi and is restricted to a limited number of fungal species, namely to A. tubingensis and the yeast Candida stellata. It is interesting that this intron is present in a small mitochondrial genome such as that of A. tubingensis and, considering its rarity, its presence amongst black Aspergillus isolates is recommended to be considered as a tool to establish taxonomical unit(s) or to track down evolutionary divergence of closely related taxonomical units.

Aspergillus↗
PubMed2006

Mycocin production in Pseudozyma tsukubaensis.

Killer activity expressed at pH values ranging from 3.5 to 6.0 was found in the ustilaginaceous yeast-like species, Pseudozyma tsukubaensis. Its killer phenotype was incurable, and extrachromosomal genetic elements were not detected. The toxin excreted with a molecular mass above 15 kDa is fungicidal, resistant to proteolytic cleavage, thermolabile and active only against fungi within the Ustilaginomycetes (the orders Microstromatales and Ustilaginales).

Mycotoxins↗
PubMed2004

Mitochondrial DNA organisation of the mtDNA type 2b of Aspergillus tubingensis compared to the Aspergillus niger mtDNA type 1a.

A physical and functional map of Aspergillus tubingensis mtDNA type 2b was constructed and compared to Aspergillus niger typeI a mtDNA. The gene content and order, as well as the patterns of restriction sites, were similar. Two unidentified ORFs and several repeat elements were found in the region between the ndhl and ndh4 genes on both mtDNAs. The sizes of the A. niger and A. tubingensis mtDNAs were 31.23 and 33.06 kb. respectively, the difference was principally attributed to the altered intron content of their coxl genes.

Aspergillus↗
PubMed2004

Mycocin production in Cryptococcus aquaticus.

Double-stranded RNA viruses of about 35 nm in diameter were isolated from a mycocin-secreting strain of Cryptococcus aquaticus. A derivative of this strain, lacking small dsRNA, was non-mycocinogenic and sensitive to its own toxin. The killing pattern of this mycocin was restricted to some species of the Cystofilobasidiales clade. Despite the differences in genome size of dsRNA viruses in mycocinogenic strains of Cryptococcus aquaticus, Cystofilobasidium sp. CBS 6569, Cystofilobasidium bisporidii, Cystofilobasidium infirmominiatum, Trichosporon pullulans and Xanthophyllomyces dendrorhous and killing patterns of their mycocins, the viral genomes showed homology in hybridisation experiments.

Cryptococcus↗
PubMed2003

Interpretation of intraspecific variability in mtDNAs of Aspergillus niger strains and rearrangement of their mtDNAs following mitochondrial transmissions.

Physical and functional maps of mitochondrial DNAs of Aspergillus niger strains representing different mitochondrial DNA RFLP patterns were constructed and compared. In spite of the high similarity in the organisation of mitochondrial DNAs among examined strains, differences could be easily recognised by applying molecular markers, such as the different intron content of the cox1 genes, the sequence of the intergenic regions between the Met- and His-tRNA genes and downstream of the tRNA-Gly gene. Intraspecific mitochondrial transfers between the heterokaryon incompatible mitochondrial oligomycin-resistant A. niger strain, as the donor, and other A. niger-sensitive strains bearing different RFLP patterns resulted in oligomycin-resistant progeny possessing either rearranged or unchanged donor mitochondrial DNA and recipient nuclei. Since the intergenic marker sequences of mitochondrial DNAs turned out to be identical in the donor and the progeny, it can be assumed that the oligomycin-resistant progeny inherit the mitochondrial DNA of the donor strain; this may either remain unchanged or may be modified by a mobile intron of the cox1 gene of the recipient mitochondria.

Aspergillus niger↗
PubMed2003

Double-stranded RNA viruses in a mycocinogenic strain of Cystofilobasidium infirmominiatum.

The viral particles (about 30 nm in diameter) that contain dsRNAs (2.0 and 6.3 kbp) encapsidated by a coat of protein were detected in a mycocin-secreting strain of Cystofilobasidium infirmominiatum isolated from plants in an oak forest (Moscow region). The mycocin with a molecular mass above 15 kDa is fungicidal (maximum activity at pH 4.5) and active mainly against some species of the Cystofilobasidiales and Filobasidiales ('Cryptococcus aerius' clade). Curing by incubation at elevated temperature resulted in the concomitant loss of dsRNAs and mycocinogenic activity, and cured derivatives became sensitive to the mycocin produced by the parent strain.

Basidiomycota↗
PubMed2002

Organization of mitochondrial DNA in the basidiomycetous Dioszegia hungarica (Cryptococcus hungaricus) species.

The organization of mitochondrial DNA was investigated in the six collection strains of the basidiomycetous yeast Dioszegia hungarica (Cryptococcus hungaricus) isolated so far. Physical and partial functional maps were constructed. Two strains (CBS 6324 and 6576) were identical while three others (CBS 4214, 5124, 6953) differed not only in the distribution of restriction sites but in gene order as well. Results confirm the hypothesis that these five strains are representatives of different closely related species. The sixth strain CBS 6569 revealed a unique mitochondrial genome organization. Its mtDNA separated into eight bands on agarose gel without enzymatic digestion. These molecules carried mitochondrial genes, and RFLP analysis of the four largest molecules using frequently-cutting restriction enzymes (KpnI and SmaI) showed them to have strongly homologous sequences. This unique mtDNA organization was also observed in a strain of Cystofilobasidium capitatum, providing evidence that CBS 6569 belongs to the Cystofilobasidium clade.

Cryptococcus↗
PubMedDate not supplied

Differences in mitochondrial genome organization of Cryptococcus neoformans strains.

The organization of the mitochondrial genomes in two strains belonging in different varieties of Cryptococcus neoformans was analysed. Physical maps of the mtDNA of the IFM5844 (var. neoformans) and IFO410 (var. grubii) strains were constructed by using EcoRI and EcoRV restriction enzymes; functional maps were constructed by hybridization, cloning and sequencing. Most of the genes important in the mitochondrial function (ND1, ND2, ND3, ND4, ND4L, ND5, ND6, ATP6, ATP9, COX1, COX2 and COB) and protein synthesis (SsrRNA and LsrRNA) were localized. We did not find any differences between the strains in the order of these genes. However, they differed significantly in the sizes of the mtDNAs: 32.6 kb for IFM5844, and 24.1 kb for IFO410. This can be attributed to two large regions of the mtDNA. In these regions, differences were found in the numbers of introns in COX1 (no intron in var. grubii, 5 introns in var. neoformans), COB (1 intron in var. grubii, 2 introns in var. neoformans), LsrRNA (no intron in var. grubii, 2 introns in var. neoformans), and ND5 (no intron in var. grubii, 1 intron in var. neoformans) genes. In several introns of the COB and COX1 genes LAGLIDADG motifs were found. Differences were also observed in the nucleotide sequences of some genes and in the sizes and sequences of intergenic regions. The nucleotide sequences of the genes of the IFM and IFO strains were compared with those of the H-99 and JEC 21 strains from the database. Surprisingly high similarities were found between the strains belonging in var. grubii (IFO 410 and H-99) and var. neoformans (IFM 5844 and JEC 21).

Cloning, Molecular↗