Book of Abstracts (PDF) - International Mycological Association

IMC7 Main Congress Theme V: CELL BIOLOGY AND PHYSIOLOGY Posters
The effects of the metal ions (Zn+2, Cu+2 and Fe+2 ), as
single or in mixed treatments were observed through
changes in A. flavus RNA, RT-PCR levels, and by
differential genetic expression using microarray analysis,
and also assessed by fungal dry weight accumulation,
aflatoxin and OMST production. The interaction between
the metal ions and the aflatoxin and/or its precursor OMST
was determined by electrospray ionization mass
spectrometer. The direct effects of metal ions on fungal
growth, aflatoxin, and OMST synthesis, varied according
the type of metal ion and expressed to either single ion or
amendment of ion mixture. All ion treatments induced
changes of fungal total RNA and mRNA levels and
associate fungal growth, biosynthesis of aflatoxin and its
precursor OMST. All mixed metal ions treatments boosted
total RNA synthesis and enhanced expression of fungal
RNA and the RT-PCR, as well as fungal biomass and
synthesis of aflatoxin and OMST. These treatments thus
induce changes in pattern of gene expression of A. flavus
related to fungal growth and synthesis of aflatoxin and its
precursor OMST. The differential genetic effects of these
treatments were also clearly expressed by the microarray
results. The electrospray ionization mass spectrometer
analysis showed distinct differential binding of the metal
ions to OMST.
1086 - Carbon and nitrogen allocation patterns in the
two green algal lichens Hypogymnia physodes and
Platismatia glauca in relation to nutrient supply
L. Dahlman 1* , J. Persson 2 , T. Näsholm 2 & K. Palmqvist 1
1 Ecology and Environmental Science, Umeå University SE-
901 87 Umeå, Sweden. - 2 Forest Genetics and Plant
Physiology, Umeå Plant Science Center SE-901 83 Umeå,
Sweden. - E-mail: Lena.Dahlman@eg.umu.se
We investigated resource investments in lichens, by
quantifying major carbon and nitrogen pools in two green
algal lichens in nutrient enriched and poor habitats.
Investments between the symbionts were determined by
quantifying ribitol and chlorophyll a for the photobiont,
and mannitol, ergosterol and chitin for the mycobiont. Two
soluble carbohydrates, arabitol and glucose, as well as
amino acids and proteins were also quantified. The soluble
carbohydrate concentrations were twice as high, c. 4% of
thallus dry weight, and thallus N concentrations were 2-4
times higher in thalli from the nutrient enriched compared
to the nutrient poor habitat. The proportion of thallus N
invested in proteins was similar in the two habitats, while
the amino acid pool was doubled in the fertilized thalli.
This increase could be attributed to the N- rich amino acid
arginine. Both lichens displayed an increased proportion of
photobiont cells in relation to mycobiont hyphae in the
nutrient enriched habitat. Resulting in a significantly higher
ribitol to mannitol ratio, and a higher Chl a to ergosterol
ratio, in thalli from the nutrient enriched habitat.
Suggesting that the photobiont had benefited more than the
mycobiont from the fertilization, and the increased arginine
concentration suggests that the mycobiont may suffer from
a relative carbon shortage. Both lichens were still healthy
and alive, so the altered balance between the bionts might
be an adaptation to handle the fertilization stress.
1087 - Proteinases involved in skin degradation by the
oomycete pathogen Pythium insidiosum
D.J. Davis 1* , C. Bonati 1 , K. Lanter 1 , S.D. Makselan 1 &
N.P. Money 2
1 College of Mount St. Joseph, Department of Chemistry,
Cincinnati, Ohio, 45233, U.S.A. - 2 Miami University,
Department of Botany, Oxford, Ohio, 45056, U.S.A. - Email:
diana_davis@mail.msj.edu
The oomycete Pythium insidiosum is the only stramenopile
pathogen of humans and other mammals. In essence, the
mechanism of tissue invasion utilized by this
microorganism is identical to the process employed by
every other filamentous fungus that colonizes animal or
plant tissues: invasive growth depends upon the exertion of
force by the hyphal apex, and the degree to which the
substrate is degraded by secreted enzymes. Biomechanical
experiments prove that Pythium insidiosum achieves a 100fold
reduction in the strength of cutaneous and subcutaneous
tissue through proteinase secretion. In an attempt
to identify the enzymes that play a primary role in tissue
degradation, we have isolated and characterized a number
of unique serine- and metallo-proteinases. By analyzing the
effectiveness of each protein at facilitating hyphal
penetration of collagen-rich membranes it is possible to
distinguish between their nutritional and 'barrier-dissolving'
roles.
1088 - Lichens as a model-system for symbiotic
organisms under most extreme conditions
J.-P. de Vera & S. Ott *
Botanical Institute, University of Duesseldorf,
Universitätsstr.1, D-40225 Duesseldorf, Germany. - Email:
otts@uniduesseldorf.de
As a consequence of the symbiotic state of lichens both the
bionts are able to colonize habitats where the separate
bionts would not be able to survive. The symbiosis of
lichens reflects a high degree of complexity and plasticity.
The combination of both enables these organisms to
colonize most extreme habitats. Besides the already well
investigated microorganisms lichens are good modelsystems
to examine adaptation strategies to most extreme
environments. Because of the symbiotic nature of the
lichens a 3-component-system can be used for
investigations: the mycobiont, the photobiont and the
lichen itself. Our investigations are based on such a system.
The influence of different doses of UV A, B, C on the
vitality of fungal (mycobiont) spores and the germination
process has been investigated. The spores are cultivated on
a variety of different subtrates to testing the influence of
the UV radiation. The influence of vacuum conditions has
been investigated. The aim of this research is to test the
reaction of a symbiotic organism and its respective bionts
to highly extreme conditions. For interpretation of results
Book of Abstracts 329