The association between chloroplasts of Codium fragile and the mollusc Elysia viridis - III. Movement of photosynthetically fixed 14 C in tissues of intact living E. viridis and in Tridachia crispata

When Elysia viridis or Tridachia crispata were incubated in the light in solutions containing NaH 14 CO 3 and either glucose or galactose, fixed 14 C was released to the medium as glucose or galactose. The effect is selective for although, for example, mannose also causes 14 C release from E. viridis , none occurs if sorbose, fructose or maltose are present. The phenomenon has been reported in other associations between autotrophs and heterotrophs, where it has formed the basis of ‘inhibition techniques'. It is assumed that the external unlabelled compound can enter and exchange with the labelled form at some stage in its movement through the association. In E. viridis , the effect was also found with alanine. Various lines of evidence show that the ‘inhibiting’ compound traps the 14 C as it moves between animal cells. The total amount of fixed 14 C released by glucose ‘inhibition’ in Elysia was approximately 12%. ‘Inhibition techniques’ may be of considerable value in the study of intercellular transport of molecules.