MONTHLY VARIATIONS OF 5'NUCLEOTIDASE IN LOPHOPUS-CRYSTALLINUS, A FRESH-WATER BRYOZOAN

Specimens of Lophopus crystallinus, a freshwater bryozoan, were collec ted from the Lake of Piediluco (Umbria, Italy) at monthly intervals an d studied for their protein content and 5'nucleotidase activity. They showed considerable differences in protein content, ranging from 0.2 t o 2.5 mg/ml. The activity of non-specific phosphatase and 5'-nucleotid ase showed a regular decrease which followed in reverse order the incr ease of protein content. Specimens, collected in December showed the h ighest protein content and the lowest activities. Furthermore, 5'nucle otidase activity was largely coincident with that of non-specific phos phatase. In each preparation, alkaline phosphatase activity was higher than acid phosphatase, and the activity of these enzymes decreased in parallel with an increase of protein content. A correlation of 5'nucl eotidase activity of Lophopus crystallinus with its environment was te ntatively proposed.