Fig. 8. Specificity of endocytosis of ¹²⁵I-fluorescein–pDNA in cultured cod atrial endocardial endothelial cells. Monolayer cultures were incubated for 2 h at 12°C with trace amounts of labelled ligand (approximately 2x10⁴ c.p.m.; 20 ng) alone (control) or together with excess amounts of unlabelled macromolecules (100 µg ml^–1). The following macromolecules were used: plasmid DNA (pDNA), thymus DNA (ThDNA), formaldehyde-treated serum albumin (FSA), fucoidan and mannan. The results are presented as a percentage of the control value and are mean + s.e.m. of three independent experiments.