Organotypic cultures of the avian salt gland: biosynthesis of membrane proteins.

The salt glands of control and salt-stressed ducklings were dissociated with collagenase to produce cell aggregates or 'minilobules' which were cultured. The fine-structural organization of freshly isolated and cultured (up to 72 h) aggregates were examined and showed surprisingly intact fine-structural organization with minimal changes from untreated glands. Incorporation of [3H]leucine into total protein, membrane protein and immunoprecipitable Na,K ATPase was determined in cultures at various time points, by pulse or pulse-chase experiments. Incorporation of label was linear for 4 h in protein, but higher in cultures of salt-stressed glands than in controls. Na,K ATPase was synthesized throughout the time of the experiment, the rate being highest during the first 4 h, reaching a plateau by 24 h. Up to 10% of the total label was present in Na,K ATPase. These results are discussed with reference to the use of minilobule culture to analyse further synthesis and assembly during biogenesis and control of these processes.