Intercellular assimilate translocation in Gracilaria cornea (Gracilariaceae, Rhodophyta)

Assimilate translocation has been identified and characterized in Gracilaria cornea under different conditions. Carbon fixation and translocation were carried out by inserting the base part of the thallus into a bicarbonate labeled solution in seawater and exposing its upper part to the air (open system) or to a non-labeled solution above a rubber septum (closed system). After a pulse-chase treatment in the light, three separate sections of each thallus were extracted by DMF (high molecular weight photosynthates) or by ethanol (low molecular weight). The results indicate a high rate of active photosynthate translocation which is directly related to inorganic carbon gradients in the thallus, and probably also to sugar gradients in the thallus. Translocation parameters of Gracilaria cornea are lower than of brown algae, as Gracilaria does not contain specific translocation tissues.