Book of Abstracts (PDF) - International Mycological Association

IMC7 Main Congress Theme V: CELL BIOLOGY AND PHYSIOLOGY Posters
Extracts from the fungus strain P0297 showed strong
activities in two concurrent screenings of natural extracts
for new antiviral compounds active against Herpes Simplex
Virus 1 (HSV1) and for novel antiparasitic agents active
against the protozoan pest Eimeria tenella, respectively.
Strain P0297 was identified as Pochonia chlamydosporia
var. catenulata sensu Zare et al. [Nova Hedwigia 73 (1-2)
51-86, 2001] by morphological studies and comparison of
DNA sequences with data from type strains. Fermentation
of the fungus in 10 litre scale and bioassay-guided
preparative HPLC of the crude extracts yielded several
biologically active metabolites, which were identified by
NMR spectroscopy and mass spectrometry. Besides
Monorden (Radicicol), several structurally related
resorcylic acid lactones, for which the trivial names
Pochonins are proposed, were obtained as congeners. In
addition, the spiro-alkaloid Pseurotin A was isolated. Upon
modification of fermentation conditions, a drastic shift in
the secondary metabolite profiles of strain P0297 occurred
when bromide salts were added to the medium.
Interestingly, the fungus now produced the monocillins,
which constitute non-halogenated analogues of monorden
and pochonins. All compounds were studied on their
antiviral and anticoccidial properties in cellular replication
assays. Furthermore, their activities against estrogenic
receptors were evaluated. Their isolation, structure
elucidation and biological activities are discussed.
1119 - Heterologous expression of Phanerochaete
manganese peroxidases in Pleurotus ostreatus
Y. Honda 1* , C. Imamura 2 , H. Takahashi 2 , T. Watanabe 1 &
M. Kuwahara 3
1 Wood Res Inst., Kyoto Univ., Gokasho, Uji 611-0011,
Japan. - 2 Toyota Central R&D labs., Yokomichi, Nagakute,
Aichi 480-1192, Japan. - 3 Inst. Wood Technol., Akita Prif.
Univ., kaieizaka, Noshiro, Akita 016-0876, Japan. - Email:
yhonda@kuwri.kyoto-u.ac.jp
Manganese peroxidases catalyze oxidation of Mn(II) to
Mn(III) in the presence of hydrogen peroxide and form a
class of extracellular peroxidases of white rot
basidiomycetes. The enzymes have been focus of research
interests because of their importance in lignin
biodegradation and potential for utilization in many
industrial processes. Genomic and cDNA sequences
encoding manganese peroxidase have been cloned and
characterized from variety of white rot basidiomycetes,
including Ceriporiopsis subvermispora, Phanerochaete
chrysosporium, Pleurotus ostreatus and Pleurotus eringii.
However, overexpression of active ligninolytic peroxidases
is difficult with non-basidiomycetous host systems such as
Escherichia coli, Saccharomyces cerevisiae and
Aspergillus spp. We have developed a recombinant gene
expression system in P. ostreatus, using promoter and
terminator sequences of sdi1 which encodes iron-sulfur
subunit of succinate dehydrogenase. The system was
successfully used to overexpress one of its manganese
peroxidase genes, mnp3 under the control of homologous
sdi1 expression signals. Here we report heterologous
expression of wild-type and artificially mutagenized
manganese peroxidases from P. chrysosporium using the
gene expression system in P. ostreatus.
1120 - Antifreeze proteins from snow mold fungi
T. Hoshino * , M. Kiriaki, I. Yumoto & S. Tsuda
National Institiute of Advanced Industrial Science and
Technology (AIST), 2-17-2-1, Tsukisamu-Higashi,
Toyohira-ku, Sapporo 062-8517, Japan. - E-mail:
tamotsu.hoshino@aist.go.jp
Many living organisms have biochemical strategies to
protect themselves against freezing. Antifreeze protein
(AFP) are one of biochemical defense mechanisms by
which intracellualr ice formation is inhibited. Typhula
ishikariensis, one of snow molds secreted a 22kDa protein
that only accumulated in culture at a subzero temperature.
Reported fish AFPs bound to prism faces of ice crystals
that were formed hexagonal bipyramid. The short axes (aaxes)
of ice crystals of fish AFPs were limited by the size
of the initial ice. However, fungal AFP-bound ice could
grow not only in the c-axis direction but also in the a-axis
direction. Therefore, fungal AFP formed ice that was 10fold
larger than that of fish AFP-bound ice and became a
distorted hexagonal bipyramid shape resembling Stone Age
knives. Fish AFPs can cover all ice-growth sites of prism
faces and those AFP-bound ice crystals can grow only in
the direction of basal faces (c-axis). Our results showed
that fungal AFP-bound ice could grow not only in the caxis
direction but also in the a-axis direction. Therefore, it
is assumed fungal AFP-bound ice has extra space for
crystal growth in prism faces. It is thought that the number
of binding fungal AFPs per area of prism face is less than
those of fish or plant AFPs. However, the highest
measurable value of antifreeze activity of fungal AFPs is
higher than average values reported for fish AFPs. It is
therefore thought that fungal AFPs inhibit ice growth by
another mechanism.
1121 - Repression of chsB expression reveals the
functional importance of class IV chitin synthase gene
chsD in Aspergillus nidulans
M. Ichinomiya * , H. Horiuchi & A. Ohta
Department of Biotechnology, The University of Tokyo, 1-
1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan. - E-mail:
aa07117@mail.ecc.u-tokyo.ac.jp
Chitin is one of the major constituents of the cell wall of
Aspergillus nidulans. To date, five chitin synthase genes
(chsA-D, and csmA) in this fungus have been isolated and
characterized in our laboratory. We have reported
previously that a chsB single disruptant exhibits severe
growth defects, whereas chsA, chsC, and chsD single
mutants do not show any obvious growth defects. Here, we
constructed conditional chsB mutants in which chsB
expression was controlled under the repressible alcA
Book of Abstracts 339