Book of Abstracts (PDF) - International Mycological Association

IMC7 Main Congress Theme V: CELL BIOLOGY AND PHYSIOLOGY Posters
intercellular hyphae and plant cortical cells were imaged
using laser scanning confocal microscopy (LSCM). Using
the optical xy confocal slices, a 3D reconstruction of a twin
structure was produced and the surface area of each
arbuscule was measured. The measurement of surface area
together with logistic regression calculated over the time
course study indicated that there was a delay in
development of the second arbuscule. Intercellular spaces
within the root cortex appear responsible for determining
the structural type of colonization. Crooks (1933) described
the unusual cell divisons (and hence intercellular spaces) in
L. usitatissimum roots which is used to produce a
conceptual model of this Arum-type mycorrhiza. Crooks
DM. 1933. Botanical Gazette 95: 209-239.
1093 - In vitro retention of 137 Cs and potassium by the
mycelium of mycorrhizal and saprotrophic
basidiomycete fungi
I. Druzhinina 1* , V. Karg 2 & M. Berreck 3
1 Institute of Botany, University of Vienna, Rennweg 14, A-
1090, Vienna, Austria. - 2 Institute of Microbiology,
University of Innsbruck, Innsbruck, Austria. - 3 Federal
Institute for Agricultural Research, Vienna, Austria. - Email:
druzhini@mail.zserv.tuwien.ac.at
After Chernobyl disaster it has become apparent that
natural losses of 137 Cs from the European forest soils are
proceeding extremely slowly due to the ability of various
fungi to accumulate this radionuclide. Large differences
were observed in 137 Cs levels in fruit bodies of various
edible fungal species often independent from the site and
time of sampling. This phenomenon has led a number of
radioecological modelers to conclude that radionuclides
contamination in fungi is very difficult to predict. This
paper presents results of the experimental investigation of
137 Cs uptake by fungal mycelium versus undisturbed
potassium metabolism. A special methodology was
employed to study the ability of mycelium of mycorrhizal
species - Suillus variegatus, S. grevillei - and saprotrophic -
Pleurotus ostreatus, Stropharia rugosoannulata - to retain
137 Cs and potassium dependent on: (i) genomic factor
(strain and species), (ii) cultivation conditions (composition
of the medium and the growth rate), (iii) metabolism
activity and (iv) in a stream of time. Since high
radiocaesium/potassium ratios were demonstrated for
ectomycorrhizal fungi only, we postulate the existence of a
high-affinity potassium efflux system in cells of
mycorrhizal fungi; it is likely that this system promotes the
retention of accumulated radiocaesium inside the cell,
while potassium can be released back to the medium.
1094 - Mapping of psychro- and/or halotolerance of
Penicillium spp. and Aspergillus spp. and correlations of
enzyme profile and habitat
M.J. Due * , K. Karlshøj & J.C. Frisvad
BioCentrum-DTU, Technical University of Denmark,
Søltofts Plads, Building 221, DK-2800, Kgs. Lyngby,
Denmark. - E-mail: c958218@student.dtu.dk
The extracellular enzymatic activity of psychro- and/or
halotolerant Penicillium spp. and Aspergillus spp. were
studied and the correlations to habitat investigated. 170
isolates were screened. As expected, the results showed
that the Penicillia tend to be more psychrotolerant and the
Aspergilli have better halotolerance. Except for the
halophiles, it was observed that the higher the incubation
temp., the better the halotolerance. Only mild halophiles
were found. Of these many tended to stay halophile at
lower temp. Among the Aspergilli only psychrotolerant
isolates were found. The Penicillia yielded some
psychrofilic isolates. The fastest growing isolates were
selected for semi-quantitative enzyme screening. These
were inoculated on triglyceride, casein and lignocellulosic
liquid media with various amounts of NaCl added. The
enzyme activities in the media were tested after 10 to 14
days of growth. Assays were performed for proteinases,
hemi- and cellulases and lipases on assay plates. It is
expected that the isolates will exhibit habitat specific
enzyme profiles, with the enzyme activity dependant on
temperature and A w of the habitat. This hypothesis
originates from the fact, that most fungi are highly habitat
specific and not metropolitan. It is also expected, that while
all (or most of) the isolates will have activity for the
substrates screened against, there will be a difference in
activity correlated to their habitat.
1095 - A MAT-2 mating-type gene in the homothallic
fungus Aspergillus nidulans
P.S. Dyer
School of Life and Environmental Sciences, University of
Nottingham, University Park, Nottingham, NG7 2RD, U.K.
- E-mail: Paul.Dyer@Nottingham.ac.uk
Mating-type (MAT) genes have been identified from the
pyrenomycete, loculoascomycete and discomycete classes
of ascomycete fungi. By using hot-start PCR with
degenerate primers, together with thermal asymmetric
interlaced (TAIL)-PCR, it has been possible to identify a
characteristic MAT-2gene from the plectomycete fungus
Aspergillus nidulans. It includes a conserved high mobility
group (HMG)-domain. RACE-PCR analysis has confirmed
transcription of the gene during sexual reproduction and
the presence of an intron in a conserved position within
MAT-2 genes. Further analysis of the flanking regions of
the MAT-2 gene revealed the presence of a 5S ribosomal-
DNA sequence, a putative gene with homology to an
element of the anaphase-promoting complex (APC) of
Schizosaccharomyces pombe, and a putative gene with
homology to the transmembrane receptor SYG1 from
Saccharomyces cerevisiae. The presence of an APC
homologue provided evidence of microsyteny around the
MAT locus. However, no MAT-1 alpha-domain gene could
be detected. This suggests either that a MAT-1 homologue
may be present elsewhere in the genome, not directly
adjacent to the MAT-2 locus, or that A. nidulans may
contain only a MAT-2 mating-type gene. This would be a
Book of Abstracts 331