Book of Abstracts (PDF) - International Mycological Association

IMC7 Main Congress Theme V: CELL BIOLOGY AND PHYSIOLOGY Posters
1076 - Weathering in a saxicolous lichen community: A
geobiological research project
T. Bjelland
Department of Botany, University of Bergen, Allégaten 41,
N-5007 Bergen, Norway. - E-mail:
torbjorg.bjelland@bot.uib.no
The weathering in a saxicolous lichen community growing
on sandstone has been studied. Lichen and rock samples
have been analysed by high performance thin-layer
chromatography/thin-layer chromatography, scanning
electron microscopy, and X-ray diffraction analysis, and
rock samples also by X-ray fluorescence spectroscopy
analysis. The study clearly indicates that lichen mediated
weathering leads to fragmentation and chemical dissolution
of the rock and its component minerals. Despite the
heterogeneity of the rock, and the fact that the studied
weathering rinds are the result of complex interactions of
physical, chemical, and biological weathering processes
during the postglacial period, the results show that some
crustose lichen taxa are clearly more aggressive in aiding
weathering than other taxa in a lichen community. There is
a positive correlation between the degree of weathering and
species with high amounts of hyphae within the rock.
Differences in content of lichen compounds seem to be a
more likely explanation for the variations in chemical
weathering, than differences in oxalic acid production. The
results further imply that there is an indirect relationship
between weathering effect and ecology in saxicolous
lichens, but whether this is a specific strategy for nutrient
requirements remains unclear. It is also suggested that
lichens generally increase the weathering processes, except
at locations with extremely high abrasion, where they may
protect the surface.
1077 - Biochemical pathway studies on the loline
alkaloids of the grass endophyte, Neotyphodium
uncinatum
J.D. Blankenship 1 , M.J. Spiering 1 , L.P. Bush 2 , R.B.
Grossman 3 & C.L. Schardl 1*
1 University of Kentucky, Dept. of Plant Pathology,
Lexington, KY 40546, U.S.A. - 2 University of Kentucky,
Dept. of Agronomy, Lexington, KY 40546, U.S.A. -
3 University of Kentucky, Dept. of Chemistry, Lexington, KY
40546, U.S.A. - E-mail: schardl@uky.edu
The insecticidal loline alkaloids (1-aminopyrrolizidines)
are produced in mutualistic associations of Festuca and
Lolium species with their respective fungal endophytes.
Reliable production of N -formylloline (NFL) and N -
acetylnorloline (up to a total of 1000 µg/ml) in cultures of
the meadow fescue endophyte, Neotyphodium uncinatum,
has facilitated studies on the loline alkaloid biosynthetic
pathway. Based on loline alkaloid structures, it was
previously suggested that lolines are polyamine products.
However, our precursor feeding experiments, employing
GC-MS and NMR analyses, indicated that lolines share
common precursors with, but are not derived from,
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Book of Abstracts
polyamines. Labels from 5-[ 13 C]-ornithine and 1,2-[ 13 C]ornithine
were incorporated into specific positions of the
B-ring in the pyrrolizidine-ring structure of NFL, but the
pattern of incorporation differed from what would be
expected if a polyamine intermediate was involved.
Feeding studies with 4-[ 13 C] and [ 15 N]-aspartic acid gave
enrichment in the expected position of the pyrrolizidine Aring
(at C-3) and the 1-amine, respectively. Universally
[ 13 C]-labeled methionine did not incorporate in the
pyrrolizidine ring system, but labeled the 1-amino methyl
and 1-amino formyl groups. These studies demonstrated
the origins of the carbon atoms in NFL: the B ring is
derived from ornithine, the A ring is from aspartic acid,
and the N-methyl and N-formyl carbons are from the Smethyl
carbon of methionine.
1078 - Cell state dynamics and pattern formation in
polymorphic fungi
E.V. Bogomolova
St.Petersburg State University, Dept. of Botany,
Universitetskaya emb. 7/9, 199034 St.Petersburg, Russia. -
E-mail: evgenia@EB6711.spb.edu
One of the most topical problems of cell and complex
systems biophysics is elucidation of driving forces,
mechanisms and dynamics of pattern formation and
growth. Modern molecular genetics do not allow to
understand fully fundamental principles of morphological
plasticity. The main idea of our work is to reveal and
describe the generic principles of regulation of cell states
dynamics in polymorphic fungi, of morphogenesis and
differentiation from the point of view of self-organization
theory. Experimental study of cell state dynamics in some
strains of polymorphic fungi (black yeasts) has shown cell
state transitions (spontaneous or induced by various culture
conditions). The main morphogenetic factors (governing
parameters) were revealed on the basis of experimental
analysis of the data obtained for several black yeast strains.
In preliminary surveys we have found that regulation of
cell state switch exhibits some dynamic properties. Such
properties include: 1) all-or-none transitions between
discrete states (with a stochastic component); 2)
reversibility vs. irreversibility of such state transitions
(asymmetry of transition probabilities); 3) hysteresis (in
response to transition-triggering agents); 4) autocatalysis or
autoinhibition of cell state transitions; 5) symmetry
breaking events. Cell state transitions (in particular,
mycelial/yeast) result in changes of colony form, and
consequently, in diverse development strategies and
substrate colonisation patterns of fungi.