Absorption of immunomodulating β(1,3)-glucan in yolk sac larvae of Atlantic halibut, Hippoglossus hippoglossus (L.)

A soluble immunomodulating β(1,3)‐glucan, laminaran, was given in drinking water to yolk‐sac larvae of Atlantic halibut, Hippoglossus hippoglossus L. The larvae absorbed laminaran when the concentration was 25 mg l–1. After 5 days exposure to laminaran, each larva contained 2.3 ng and 46 ng of 3H‐ and 125I‐labelled laminaran, respectively. After 10 days exposure, each larva contained 4.5 ng and 47 ng of 3H‐ and 125I‐laminaran, respectively. The absorption was confirmed by fluorescence microscopy of larvae exposed to fluorescein‐labelled laminaran (FITC‐laminaran). The fluorescence was localized to cells in the intestinal epithelial layer and the skin epithelial layer.