Biomedical subjects

G Müller-Starck

Publications and source records attributed to G Müller-Starck.

4 recordsLinked to original sources

PubMed2005

Beech leaf colonization by the endophyte Apiognomonia errabunda dramatically depends on light exposure and climatic conditions.

Ozone and light effects on endophytic colonization by Apiognomonia errabunda of adult beech trees (Fagus sylvatica) and their putative mediation by internal defence compounds were studied at the Kranzberg Forest free-air ozone fumigation site. A. errabunda colonization was quantified by "real-time PCR" (QPCR). A. errabunda-specific primers allowed detection without interference by DNA from European beech and several species of common genera of plant pathogenic fungi, such as Mycosphaerella, Alternaria, Botrytis, and Fusarium. Colonization levels of sun and shade leaves of European beech trees exposed either to ambient or twice ambient ozone regimes were determined. Colonization was significantly higher in shade compared to sun leaves. Ozone exhibited a marginally inhibitory effect on fungal colonization only in young leaves in 2002. The hot and dry summer of 2003 reduced fungal colonization dramatically, being more pronounced than ozone treatment or sun exposure. Levels of soluble and cell wall-bound phenolic compounds were approximately twice as high in sun than in shade leaves. Acylated flavonol 3- O-glycosides with putatively high UV-B shielding effect were very low in shade canopy leaves. Ozone had only a minor influence on secondary metabolites in sun leaves. It slightly increased kaempferol 3- O-glucoside levels exclusively in shade leaves. The frequently prominent hydroxycinnamic acid derivative, chlorogenic acid, was tested for its growth inhibiting activity against Apiognomonia and showed an IC50 of approximately 8 mM. Appearance of Apiognomonia-related necroses strongly correlated with the occurrence of the stress metabolite, 3,3',4,4'-tetramethoxybiphenyl. Infection success of Apiognomonia was highly dependent on light exposure, presumably affected by the endogenous levels of constitutive phenolic compounds. Ozone exerted only minor modulating effects, whereas climatic factors, such as pronounced heat periods and drought, were dramatically overriding.

Ascomycota↗

PubMed2003

A cyclophilin gene marker confirming geographical differentiation of Norway spruce populations and indicating viability response on excess soil-born salinity.

A newly identified cyclophilin-encoding cDNA clone was used to design a codominant inherited EST-PCR marker in Norway spruce. The study of the current minor polymorphism revealed a geographically structured differentiation pattern across 17 test populations, showing a slight clinal variation south-north through Europe. Based on the frequency of alleles, isolation-by-distance analysis and the Ewens-Watterson test, we conclude that a selectively neutral random-drift mutation recently occurred within the Alpine population group, thus being responsible for the genetic variation detected. Analysis of tolerant and susceptible subsets of two adjacent Bavarian spruce populations affected by soil-born NaCl pollution, revealed that the cyclophilin marker locus also confirms biased genotype frequencies. Considering an unlinked PCR marker of a ribosomal protein-encoding EST clone, deviations between pooled tolerant subsets and pooled sensitive subsets were proven to be more significant for two-locus homozygous genotypes than for each locus alone. We suggest that both loci are linked to adaptive genomic regions. Their potential to test the feasibility of marker-assisted selection of both NaCl-tolerant and drought resistant tree populations is discussed.

Adaptation, Physiological↗

PubMed2001

Selection effects of air pollution on gene pools of Norway spruce, European silver fir and European beech.

The effects of industrial pollution on allelic and genotypic structures of Norway spruce. European silver fir and European beech were investigated by means of isozyme analysis. In a mixed Norway spruce-silver fir forest stand in an area heavily polluted by sulphur dioxide and heavy metals in the region of Spis (eastern Slovakia), pairs of neighbouring damaged and apparently healthy trees were selected in two replicates (44 and 69 pairs in a heavily and moderately damaged stand, respectively). Pairwise sampling of trees with contrasting vitality was applied to reduce potential effects of site heterogeneity on the vitality of sampled trees. No significant differences in allelic and genotypic frequencies were found between sets of healthy and declining trees. There were differences in the single-locus heterozygosities, but these were not consistent between the replicates. However, the set of damaged trees exhibited higher levels of genetic multiplicity and diversity, possibly due to the deleterious effect of rare alleles under the conditions of air pollution. Consequently. following the decline of pollutant-sensitive trees, the remaining stand will be depleted of a part of alleles with unknown adaptive value to future selection pressures.

Abies↗

PubMed1981

Aminopeptidases in seeds of picea abies (L.) Karst.: characterization of leucine aminopeptidase by molecular properties and inhibitors.

By either acrylamide or starch gel electrophoresis of Norway spruce (Picea abies) seed extracts, two prominent isoenzyme bands were obtained after staining for leucine aminopeptidase (LAP). These bands were proved to correspond to each other by reelectrophoresis in both gel media. Single endosperm studies with acrylamide gels showed clearly that, in addition to LAP, two bands are expressed after staining for alanine aminopeptidase (AAP) as well. Both the LAP and the AAP activities appeared together as a single peak between catalase and ferritin after gel chromatograhy on Sepharose. Isoelectric focusing in sucrose gradients proved the two LAP activities to have identical isoelectric points revealed that LAP, but not AAP, is detectable by standard starch gel electrophoretic procedures. The two LAP bands refer to approximate molecular weights of 71,000 and 131,000, respectively. Disaggregation studies did not conclusively determine whether these two bands represent different enzymes or not. only inhibitors succeeded in producing a definite differentiation by selective inhibition of one of the two bands. It is concluded that in both gel media the isoenzyme bands reflect the activity of two distinct leucine aminopeptidases.

Aminopeptidases↗