Book of Abstracts (PDF) - International Mycological Association

IMC7 Main Congress Theme V: CELL BIOLOGY AND PHYSIOLOGY Posters
channels have been cloned from filamentous fungi and
only a few recordings of ion channel activity have been
made from hyphal cells. In an attempt to gain an insight
into the role of ion channels in fungal hyphal physiology,
NcTOKA was cloned from the filamentous fungus,
Neurospora crassa. Hydropathy analysis showed NcTOKA
to be a member of the two-pore domain K+ channel family.
The patch clamp technique was used to investigate the
biophysical properties of NcTOKA after heterologously
expression of NcTOKA in yeast. NcTOKA mediated
mainly time-dependent outward whole cell currents which
represented K+ efflux. However, expression of NcTOKA
was able to overcome the K+ auxotrophy of a yeast mutant
missing the K+ uptake transporters, TRK1 and TRK2,
suggesting that NcTOKA mediated K+ influx. Consistent
with this, close inspection of NcTOKA-mediated currents
revealed small inward K+ currents at potentials negative of
EK. NcTOKA single channel activity was characterised by
rapid flicking between the open and closed states with a
unitary conductance of 14 pS. NcTOKA was effectively
blocked by extracellular Ca2+, verapamil, quinine and
TEA but insensitive to Cs+, 4-aminopyridine and
glibenclamide. The physiological significance of NcTOKA
is discussed in the context of its biophysical properties.
1167 - Identification of fungal enzymes in faecal
droplets from leaf-cutter ants
S. Rønhede * & S. Rosendahl
Department of Mycology, Institute of Botany, University of
Copenhagen, O.Farimagsgade 2D, DK 1353, Copenhagen
K, Denmark. - E-mail: stigr@bot.ku.dk
The enzymatic capability of the symbiotic fungus is crucial
for the ability of leaf-cutter ants to use fresh leaves as a
substrate. The ants place their faeces as droplets on the
plant material before it is incorporated into the fungusgarden,
and these faecal droplets contain enzymes of which
some are of fungal origin. The aim of the present study was
to identify specific fungal enzymes in faecal droplets from
the leaf-cutter ants Acromyrmex echinatior and Atta
colombica to clarify the role of these enzymes in
degradation of leaves in the fungus-garden. CMCases,
laccase, proteases and pectinases were identified in faecal
droplets by isoelectric focusing and staining in overlays.
The amount of fungal pectin esterase in faecal droplets was
comparable to that in pure mycelium indicating that the
enzymes pass the ant-gut without loosing activity. The
importance of the fungal enzymes for the evolutionary
transition of the ants from feeding on dead organic material
to be able to exploit fresh leaves is discussed.
1168 - ABC transporters in Trichoderma harzianum
M. Ruocco 1* , V. Scala 2 , S. Woo 2 , S. Lanzuise 2 , G. Del
Sorbo 2 , F. Scala 2 & M. Lorito 2
1 Istituto CNR per la Protezione delle Piante IPP, Via
Università, 100, 80055 Portici (NA), Italy. - 2 Dept.
354
Book of Abstracts
ARBOPAVE- Plant Pathology, University of Naples, Via
Università, 100, 80055 Portici (NA), Italy. - E-mail:
miruocco@unina.it
ATP-binding cassette (ABC) transporters are membrane
glycoproteins that utilize the energy derived from the
hydrolysis of ATP to drive transport of endogenous
metabolites and toxic xenobiotics through biological
membranes. Overexpression of some ABC's determines
simultaneous resistance to many chemically unrelated
compounds whereas disruption of genes encoding ABC
transporters is associated with increased sensitivity to the
same compounds. We hypothesize that ABC transporters
of Trichoderma harzianum have an important role in a
number of processes such as resistance to environmental
toxicants produced either by soil microflora or introduced
by human activity (e.g. fungicides, heavy metal pollutants),
secretion of factors (mycotoxins and cell wall degrading
enzymes) necessary for the establishment of a compatible
interaction with a host fungus. Several oligonucleotides
were designed from conserved regions of the sequences of
many ABC transporters from different filamentous fungi,
and used to clone and partially sequence several genes
encoding putative ABC transporters from genomic DNA of
Trichoderma harzianum P1. Functional analysis to
investigate their role during mycoparasitic events are in
progress. We are using gene disruption and overexpression
in Trichoderma to determine the involvement of these
transporters in biocontrol and fitness.
1169 - Influences of temperature and light on
morphological changes during fruit body formation in
Flammulina velutipes
Y. Sakamoto 1* & Y. Tamai 2
1 Ibaraki Prefectural Forestry Research Insutitute,
Nakamachi To 4692, Nakagun, Ibaraki 311-0122, Japan. -
2 Division of Environmental Resources, Graduate School of
Agriculture, Hokkaido University, North 9, West 9, Kitaku,
Sapporo, 060-8589, Japan. - E-mail:
yuichisakamoto@hotmail.com
Influences of light and temperature on morphological
changes during fruit body formation in Flammulina
velutipes were investigated. Fruit bodies of F. velutipes
were induced after temperature reduction in complete
darkness. However, fruit bodies formed in complete
darkness had a long stipe with undeveloped pileus on the
top (pinhead fruit body), thinner and whiter than normal
fruit bodies formed under light illumination. This suggests
that F. velutipes can be induced fruit bodies, but cannot
mature in complete darkness. We subsequently irradiated
light to pinhead fruit bodies formed in complete darkness.
It is revealed that pinhead fruit bodies formed in complete
darkness can be induced pileus after light stimulation. We
could observe hymenium formation immediately after light
stimulation. We also observed thickening and pigmentation
after light stimulation, suggesting that light can directly
induce fruit body maturation in F. velutipes. Protein
expression patterns were investigated by two-dimensional
electrophoresis, and 22 protein spots were newly expressed
in the mycelia and fruit bodies after temperature reduction