SS2.03 Phytoplankton Ecology Using Molecular Approach
Date: Thursday, June 13, 2002
Location: Poster Session - VCC
 
Bruhn, A, , University of Aarhus, Aarhus, Denmark, Annette.Bruhn@biology.au.dk
Buch-Illing, H, , University of Aarhus, Aarhus, Denmark, Heiko.Illing@biology.au.dk
LaRoche, J, , Institut für Meereskunde, Kiel, Germany, jlaroche@ifm.uni-kiel.de
RichardsonK, University of Aarhus, Aarhus, Denmark, Richardson@biology.au.dk
 
IDENTIFICATION OF TWO FUNCTIONAL GENES INVOLVED IN PHYTOPLANKTON METABOLISMS OF DISSOLVED ORGANIC NITROGEN: THE UREASE- AND THE FORMAMIDASE-GENE
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With the intention of identifying functional genes for enzymes involved in specific nitrogen metabolisms of eucaryotic phytoplankton, genes coding for urease and formamidase have been identified. This has only been achieved earlier for prokaryotic phytoplankton. Degenerate primers were designed for conserved regions of the genes. A 321 bp fragment of the urease gene has been identified in five species of eucaryotic phytoplankton: Chaetoceros sp., Amphora coffeaeformis, Emiliania huxleyi, Aureococcus anophagefferens and Amphidinium operculata, representing the Bacillariophyceae, the Prymnesiophycea, the Pelagophyceae and the Dinophyceae. The fragments have been sequenced and confirmed to be urease. In two species of eucaryotic phytoplankton, Emiliania huxleyi and Amphora coffeaeformis, a 495 bp fragment of the formamidase gene has been identified, sequenced and confirmed to be formamidase. In all cases, the sequences show greater homology with eucaryotic genes than with procaryotic genes indicating an evolutionary relationship to the eucaryotic enzymes. Axenic cultures of the studied species grew well in artificial seawater media containing only urea or formamide as a sole nitrogen source, confirming their ability to utilize simple organic nitrogen compounds to support their growth.