STUDIES ON TISSUE ARGINASE AND UREOGENESIS IN FRESH-WATER TELEOSTS

1. 1. Arginase activity was assayed in liver tissue homogenates of nineteen species of fresh-water teleosts. Liver arginase activity ranged from 0.58 units/mg of protein in the northern redhorse (Moxostoma macrolepidotum) to 42.66 units/mg of protein in the tullibee (Coregonis artedi). 2. 2. Arginase levels were highest in liver tissue followed by kidney and heart tissue. Activity was also assayed in spleen, gills, ovaries, testes, muscle and brain tissue in representative species. 3. 3. Findings suggest diet may play an important role in the level of liver arginase activity and that degradation of dietary arginine may contribute substantially to urea production in teleosts. © 1969.