14C-Assimilate pattern and kinetics of photosynthetic14CO2-assimilation of the marine red algaBostrychia scorpioides

✍ Scribed by B. P. Kremer

• Publisher: Springer-Verlag
• Year: 1976
• Tongue: English
• Weight: 573 KB
• Volume: 129
• Category: Article
• ISSN: 0032-0935
• DOI: 10.1007/bf00390915

✦ Synopsis

Occurrence and metabolism of dulcitol and sorbitol in the marine red alga Bostrychia scorpioides (Huds.) Mont. (Ceramiales : Rhodomelaceae) were investigated. Both hexitols are rapidly 14C-labelled during photosynthesis in a HlaCO3-seawater medium and are accumulated at comparable rates. The absolute quantity amounts to about 3.2% on a dry weight basis; the percentage of 14C-labelling after 60rain is 30% for dulcitol and 40% for sorbitol. Additionally small amounts of free [14C] glucose were found. Pulse labelling experiments and changes in specific activity provide evidence that both hexitols are rapidly available respiratory substrates, which, however, are probably not interconvertible with polymeric compounds. Some chemotaxonomic aspects are discussed. 1958; Yamaguchi etal., 1966;Kremer and Willenbrink, 1972), as well as further alditols (hexitols) generally do not occur in Rhodophyceae, at least not as accumulated photosynthates (Kremer and Vogl, 1975). However, there are some reports in the earlier literature on the occurrence of dulcitol (= galactitol) and sorbitol (= glucitol) in the marine red alga Bostrachia scorpioides (Haas and Hill, 1931, 1932; Augier and Du M~rac, 1954;Quillet, 1965).

The present investigation was initiated to reexamine the occurrence of dulcitol and sorbitol in Bostrychia, to characterize their biosynthesis in relation to photosynthetic CO/-fixation, and to compare their specific metabolic function with the metabolism of mannitol in brown algae (Kremer, 1975a).