Book of Abstracts (PDF) - International Mycological Association

IMC7 Main Congress Theme V: CELL BIOLOGY AND PHYSIOLOGY Posters
mainly responsible for facilitating water uptake via fine
roots of spruce, and that the down-regulation of gene
expression is an adaptation to the improved water supply
mediated by the symbiotic fungus.
1144 - Characterisation of a phosphate transporter in
Candida albicans
P. Martineau * , T.-L. Tremblay & L. Giasson
Laval University, School of Dentistry, GREB, Quebec, Qc,
G1K 7P4, Canada. - E-mail:
philippemartineau@videotron.ca
The human pathogen Candida albicans is a dimorphic
fungus that can reversibly alter its mode of growth from
yeast-like cells to mycelial cells, depending upon its
environment. As the mycelial form is usually associated
with candidiasis, genes involved in the control of
dimorphism represent potential targets for the development
of antifungal drugs. Using the differential display
technique, we have identified a gene preferentially
expressed in the mycelial cells. We have cloned and
sequenced that gene. Sequence analysis revealed that this
gene displays 70% homology with the Saccharomyces
cerevisiae Pho89 gene, encoding a phosphate transporter.
The C. albicans CaPho89 gene was cloned into a S.
cerevisiae expression vector and transformed into a S.
cerevisiae pho89 null mutant strain. Phosphate transport in
the transformants was evaluated using [ 32 P]orthophosphate.
The results obtained showed that CaPho89
could complement the S. cerevisiae pho89 mutation,
suggesting that CaPho89 encodes a functionnal phosphate
transporter.
1145 - Mitochondrial group-I intron in a higher
basidiomycete, Pleurotus ostreatus, is mobile in sexual
crosses
T. Matsumoto * & Y. Fukumasa-Nakai
Tottori Mycological Institute, Kokoge-211, Tottori-shi,
Tottori, Japan. - E-mail: kin-matu@infosakyu.ne.jp
Inter-parental recombination between mitochondrial (mt)
genomes of Pleurotus ostreatus occurred at high frequency
in sexual crosses. To reveal the process leading to this
recombination, we estimated a certain recombination site in
each parental mitochondrial genome contributing to the
generation of the new restriction fragments which
characterized a RFLP pattern of recombinant mtDNA, and
determined their nucleotide sequences. It was found that
the regions of recombination within parental mtDNAs
possessed consensus sequences in common, which were
divided by some regions of non-consensus sequences.
Meanwhile, the nucleotide sequences in the new restriction
fragments and their surrounding regions in recombinant
mtDNA were harbored all consensus and non-consensus
sequences recognized in both parental mtDNA, suggesting
that this structure was caused by the integration of regions
with non-consensus sequences that exist in only one
parental mtDNA to the other. All non-consensus sequences
were homologous to the sequences of the group I intron
reported in fungi. They also included the ORF sequences
that encode the LAGLIDADG motif, a characteristic of
endonuclease involved in intron mobility. These results
indicate that the manner of recombination for generating
the new restriction fragment is elucidated by gene
conversion, achieved by the mobility of the introns. This
suggests that, in P. ostreatus, intron mobility is playing a
large role for the increase of diversity of mtDNA.
1146 - Effect of carminic acid and other mediators on
lignosulfonates degradation by extracellular enzymes of
Trametes versicolor
A. Matuszewska * , G. Nowak & A. Leonowicz
M. Curie-Sklodowska University, Departament of
Biochemistry, Pl. M. Curie-Sklodowskiej 3, 20-031 Lublin,
Poland. - E-mail: amatusze@hermes.umcs.lublin.pl
Many low-molecular mass compounds have been
suggested as possibly mediating mobile factors during
biodegradation of lignin. Degradation of lignosulfonates by
ligninolytic enzymes produced by the white-rot fungus
Trametes versicolor was studied. The 29,6 kDa fraction of
Peritan Na obtained by a gel filtration method using a
Sephadex G-100 column was used as a substrate. The
substrate was incubated with extracellular idiophasic
enzymes of Trametes versicolor and with mediators. HBT
(1-hydroxybenzotriazole), ABTS (2,2'azinobis-(3ethylbenzenthiazoline-6-sulfonic
acid) and carminic acid
were used as mediators. Following the incubation products
were separated using gel filtration on a Sephadex G-50
column and capillary electrophoresis. When the mediators
were added to the incubation mixture, depolymerization
was more extensive than in the experiment with no
mediators. In the presence of carminic acid the
depolymerization was the most extensive and as it's result a
fraction of about 2 kDa appeared. Similar results were
observed when HBT or ABTS were used. However,
products of higher molecular weight besides the 2 kDa
fraction were also obtained. Experiments with the reaction
mixtures supplemented with H2O 2 were also performed.
The above experiments revealed that only in the case of
HBT used as a mediator H 2O 2 addition resulted in the
increased depolymerization of lignosulfonates. Supported
by the EC Contract ICA 2-CT-2000-10050, and by KBN
grant 139/E-SPUB-M-5PR-UE/DZ 280/2000.
Book of Abstracts 347