Scavenger-receptor-mediated endocytosis of lipopolysaccharide in Atlantic cod (Gadus morhua L.)
Tore Seternes1,*,
Roy A. Dalmo2,
James Hoffman2,
Jarl Bøgwald2,
Svetlana Zykova1 and
Bård Smedsrød1
1 Department of Experimental Pathology, Institute of Medical Biology, University of Tromsø, N-9037 Tromsø, Norway and
2 Institute of Marine Biotechnology, The Norwegian College of Fishery Science, University of Tromsø, N-9037 Tromsø, Norway

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Fig. 2. Time course of the appearance of radioactivity in tissues of the Atlantic cod (Gadus morhua L.) after intravenous administration of trace amounts of 125I-labelled lipopolysaccharide (0.51 µg kg1 body mass). The results are expressed as means + S.E.M. of three fish per time point.
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Fig. 3. Immunohistochemistry on (A) a section of atrium, (B) a section of ventricle and (C) a section of anterior kidney 48 h after intravenous administration of unlabelled lipopolysaccharide. Reaction product (arrows) was observed within endocardial endothelial cells (A,B) and probably in macrophages (C). Scale bars, 10 µm.
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Fig. 4. Fluorescence micrograph of atrial endocardial endothelial cells cultured on a glass coverslip (pooled cells from three fish) and incubated with fluorescein-labelled lipopolysaccharide for 1 h at 12°C. All endocardial cells in the monolayer cultures accumulated the probe. Note that fluorescence is confined to discrete vesicles probably representing endocytic vesicles. Scale bar, 10 µm.
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Fig. 5. Specificity of endocytosis of 125I-labelled lipopolysaccharide in cultured cod atrial endocardial endothelial cells (aEECs). Monolayer cultures of aEECs in 2 cm2 wells were incubated for 2 h at 12°C with trace amounts of labelled ligand (approximately 2x104 cts min1; 3 ng) alone (Control) or together with excess amounts of unlabelled macromolecules (100 µg ml1). The results are presented as a percentage of the control value and are means + S.E.M. of three independent experiments. F-LPS, fluorescein-labelled lipopolysaccharide; FSA, formaldehyde-treated serum albumin.
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Fig. 6. Kinetics of endocytosis of 125I-labelled lipopolysaccharide ([125I]LPS) in cultured cod atrial endocardial cells (aEECs). Monolayer cultures of aEECs in 2 cm2 wells were incubated with trace amounts of [125I]LPS (approximately 2x104 cts min1; 3 ng) at 12°C. The results are presented as the cell-associated percentage of the total added radioactivity and are the results from two independent experiments.
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Fig. 7. Intracellular degradation of endocytosed 125I-labelled lipopolysaccharide ([125I]LPS). Monolayer cultures of cod atrial endocardial cells in 2 cm2 wells were incubated for 48 h with [125I]LPS (approximately 2x104 cts min1; 3 ng). Solubilised cultures were analysed by gel filtration on a PD-10 column. The ordinate indicates the percentage of total eluted radioactivity. The results are mean of six wells ± S.E.M. Vt, total volume.
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© The Company of Biologists Ltd 2001