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P Tudzynski

Publications and source records attributed to P Tudzynski.

25 records · Page 2Linked to original sources
PubMed1988

Structural and functional analysis of mitochondrial plasmids in Claviceps purpurea.

Several strains of Claviceps purpurea, a phytopathogenic Ascomycete, contain mitochondrial (mt) plasmids in high molar excess relative to mtDNA. Comparative analysis of plasmids of four strains of different geographic origin revealed that all the plasmids are structurally related (size; linearity; restriction map; probably 5'-linked terminal protein; terminal inverted repeats, TIRs); two of them are even identical, indicating a possible mobility of these genetic entities. In strain K it was shown that plasmid titres are comparably high in axenic cultures and in parasitic structures (sclerotia). Detailed analysis of plasmid pClK1 proved the existence of a perfect TIR of 327 bp; the plasmid's structure and details of its nucleotide sequence indicate a replication modus comparable to that of adenoviruses. pClK1 is almost completely transcribed resulting in two major transcripts of 3.5 and 3.15 kb, respectively. In plasmid-free strains (cured by ethidium bromide treatment) these mRNAs are not detectable; nevertheless they show no significant difference in phenotype. As judged from their structural properties they could be derived from viral ancestors. In this context the plasmids' close relationship to mt plasmids of higher plants may be of special interest.

Adenoviridae↗
PubMed1982

Replication and expression of a bacterial--mitochondrial hybrid plasmid in the fungus Podospora anserina.

Hybrid plasmids consisting of the bacterial plasmid pBR322 and plasmid-like DNA (pl DNA) sequences from the fungus Podospora anserina are not only able to replicate in Escherichia coli but also in the fungus. This was proved by both biophysical and biological evidence involving buoyant density profiles, DNA.DNA hybridization, and restriction analysis--all confirming that pl DNA behaves as a true plasmid. During its amplification in P. anserina, the hybrid plasmid does not lose its prokaryotic coding capacity as shown after retransfer and subsequent cloning in E. coli. P. anserina is able to express both the eukaryotic and the prokaryotic genetic information of the hybrid plasmid because the occurrence of senescence and the production of beta-lactamase could be shown in experiments involving specific hybrid plasmids. In the same systems, it was possible to demonstrate that a hybrid plasmid containing, instead of pl DNA, a pl DNA homologous region of native mtDNA also could function as a true plasmid. This hybrid plasmid contained about 25% of the genetic information pl DNA, which corresponds to about 6% of the genetic information of mtDNA. Thus, the data show that hybrid plasmids may be used to shuttle genetic information between P. anserina and E. coli. hence, through the use of a mtDNA replicon, as evidenced by the pl DNA of P. anserina, another pathway in genetic engineering is established.

DNA Replication↗
PubMed1980

Characterization and cloning of plasmid like DNA of the ascomycete Podospora anserina.

The previously reported existence of plasmid-like (pl) DNA in senescent mycelia of Podospora anserina was confirmed using new methodology. Detailed anaysis of bulk DNA has further shown a possible relationship between pl DNA and mt DNA. According to biophysical and electron microscopic experiments the pl DNA was found to consist of oligomeres having a basic unit with a contour length of 0.75 micrometer corresponding to 2.4 kb. To overcome the handicap that pl DNA is only produced in rather small amounts in the aging mycelia, this DNA was cloned in E. coli after insertion into a bacterial plasmid vector, pBR 322. It was possible to isolate a stable hybrid plasmid consisting of the vector and only one integrated monomere of pl DNA. The composition of this hybrid plasmid was confirmed by restriction endonuclease analysis and heteroduplex formation. A restriction map of the pl DNA is presented and its insertion site onto pBR 322 indicated.

Ascomycota↗
PubMed1979

Chromosomal and extrachromosomal control of senescence in the ascomycete Podospora anserina.

In Podospora anserina senescence leading to cellular death occurs regularly after prolonged vegetative propagation. However, the life span of this ascomycete may be extended by various means: 1. Mutations in a least 8 morphogenetic genes belonging to 4 linkage groups postpone drastically or even prevent in certain pairwise combinations (e.g. i viv) the onset of senescence. 2. Inhibitors of mt DNA and of mitochondrial protein synthesis show a life prolonging effect when added in low concentrations to the growth medium. 3. A similar effect was found when mycelia were fed exclusively on non repressive carbon sources. Whereas the anti-aging effect of specific mutated genes is rather permanent, the life prolonging action of the inhibitors and carbon sources is restricted and temporary. These substances have no long lasting effect, since after their removal from the medium aging proceeds. Physiological experiments have further shown the existence of three phases in the life span of Podospora anserina. During the juvenile phase aging is prevented by all of these compounds; during the presenescent phase aging is prevented by inhibitors of mt DNA only, and during the senescent phase aging is irreversible. Senescence may be induced in juvenile protoplasts by DNA extracted from senescent mycelia. This, together with the well known fact that senescence is extrachromosomically inherited, points to extrachromosomal DNA as the causative agent of senescence. This kind of DNA may be connected with or perhaps located in the mitochondria. Collectively, the data are consistent in showing that the syndrome of senescence in Podospora anserina is controlled by a chromosomal-extrachromosomal interaction. In this system, extrachromosomal DNA, perhaps a mt DNA, is identical with the infectious principle initiating the decay of the cell, and nuclear genes supervise its expression.

Aging↗
PubMed1977

Inhibitors of mitochondrial function prevent senescence in the ascomycete Podosprora anserina.

The onset of senescence, i.e. decrease of growth rate followed by cellular death, is prevented when inhibitors of mitochondrial function (ethidium-bromide, streptomycin, tiamulin) are present in the culture medium. If mycelia are transferred to a medium not containing one of these substances, senescence occurs after the usual time interval (30 d at 26 degrees C). Inhibitors of cytoplasmic protein synthesis such as emetine and cycloheximide have no effect in preventing senescence.

Ascomycota↗