Assimilate translocation has been identified and characterized in Grac
ilaria cornea under different conditions. Carbon fixation and transloc
ation 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, th
ree separate sections of each thallus were extracted by DMF (high mole
uclar weight photosynthates) or by ethanol (low molecular weight). The
results indicate a high rate of active photosynthate translocation wh
ich is directly related to inorganic carbon gradients in the thallus,
and probably also to sugar gradients in the thallus. Translocation par
ameters of Gracilaria cornea are lower than of brown algae, as Gracila
ria does not contain specific translocation tissues.