Isolation and characterization of six cDNAs involved in carbon metabolism in Laminaria digitata (Phaeophyceae)

An expressed sequence tag (EST) approach was used to retrieve cDNA clones i nvolved in carbon metabolism in Laminaria digitata Lamouroux. Six partial o pen reading frames were identified, respectively encoding an alpha-type car bonic anhydrase (CA), glucose-6-phosphate dehydrogenase (G6PDH), 6-phosphog luconate dehydrogenase (6PGDH), phosphoglycerate kinase (PGK), glycolate ox idase (GLO), and GDP-4-keto-6-D-mannose-3,5-epimerase-4-reductase, also kno wn as fucose synthase (FS), These enzymes were further characterized throug h Southern blot analyses, amino acid sequence comparisons, and patterns of expression. In contrast to the other genes, which are expressed in both the gametophytic and sporophytic generations of L. digitata, the alpha-type ca rbonic anhydrase messenger RNA was shown by RTPCR and northern blot analyse s to be present in the gametophytes only. The evolutionary relationships of these genes and their interest as molecular tools for investigating carbon fluxes in brown algae are discussed.