Book of Abstracts (PDF) - International Mycological Association

IMC7 Main Congress Theme V: CELL BIOLOGY AND PHYSIOLOGY Posters
Guinberteau). Nuclear number in vegetative mycelium
varied from 1 to 8 per cell and most of the cells contained 4
nuclei. We observed amitotic nuclear divisions and nuclear
migration through dolipore septum. Morphometric
measuring of basidia and nuclear apparatus were made.
Some preliminary results were obtained for ploidy level
and place of meiosis in examined strains. We have
described in details basidium morphogenesis in all the
strains by using light and electron microscopy. We've
observed: asynchronous 2-nd meiotic division;
asynchronous migration of postmeiotic nuclei into
sterigmata; postmeiotic mitosis in basidium. Electron
microscopy of basidial nuclei showed the presence of
synaptonemal complexes (SC) in all the strains; in
heterothallic and primary homothallic ones we revealed SC
for the first time. This fact confirms the processing of
meiotic division in basidia of all the strains. We've
reconstructed life cycles of all investigated strains.
1200 - Biochemical and molecular characterization of
arginase from Agaricus bisporus: Expression study in
sporophore formation and postharvest development
M.J.M. Wagemaker 1* , C. van der Drift 1 , M.S.M. Jetten 1 ,
L.J.L.D. Van Griensven 2 & H.J.M. Op den Camp 1
1 Department of Microbiology, University of Nijmegen,
Toernooiveld 1, 6525 ED, The Netherlands. - 2 Wageningen
UR, Plant Research International B.V., P.O. Box 16, 6700
AA Wageningen, The Netherlands. - E-mail:
matthe@sci.kun.nl
An extensive survey of higher fungi reveals that members
of the family Agaricaceae, including Agaricus bisporus,
accumulate substantial amounts of urea in their fruit
bodies. During postharvest storage the amount of urea even
increases substantially. Such a large increase in urea
content may affect the quality of the stored mushroom, e.g.
by the formation of ammonia from urea through urease
action. Production of urea is not limited to fruit bodies, but
also occurs in the mycelium. Despite the abundance of urea
in the edible mushroom A. bisporus little is known about its
physiological role, although it was proposed that in fruit
bodies urea is an end product of catabolic pathways. Two
major mechanisms for urea formation can be envisaged:
the ornithine cycle and nucleic acid degradation. Arginase
is the ornithine cycle enzyme that catalyzes the hydrolysis
of arginine to urea and ornithine. In the scope of the study
on urea metabolism, the work on arginase was initiated
with the isolation of the arginase cDNA, gDNA and
promoter region. Sequence analysis revealed the cDNA
encodes a 311 aa protein which is probably expressed in
the cytosol. Expression of the cDNA in E. coli has been
established as a His-tagged protein. The purified
recombinant protein was used to determine enzyme
kinetics. The characterized gene and enzyme are used as
molecular markers to study expression and regulation
during sporophore formation and postharvest development.
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Book of Abstracts
1201 - Effect of Glomus intraradices inoculation on
phosphate uptake in lettuce with two different P
sources
Y.H. Wong * & W.K. Chan
Department of Applied Biology and Chemical Technology,
The Hong Kong Polytechnic University, Hung Hom,
Kowloon, Hong Kong, China. - E-mail:
00900991r@polyu.edu.hk
The effect of Glomus intraradices inoculation on
phosphate uptake in Lactuca sativa L. (lettuce) cultivated
in sand was examined. Soluble KH2PO 4 (SP) and sparingly
soluble Ca5(PO 4) 3OH (RP) were applied to the potting
medium at the rates of 0, 25, 125 mgP/kg sand. The harvest
at week 6 shown that among all the treatments, the nonmycorrhizal
(NM) plants with 25 mg SP/kg sand had the
highest yield in dry matter. However, within the RP
treatments, the dry matter for the mycorrhizal (M) plants
with 25 mg and 125 mg RP/kg sand were significantly
higher (P