p. 279 - 288 BIOCHEMICAL AND CELLULAR RESPONSES OF MYTILUS GALLOPROVINCIALIS LMK. TO TEMPERATURE STRESS Maria Mirza 1) and C. Craciun 2) 1) Institute Roumain de Recherches Marines Constanta 2) Cluj-Napoca University, Dept. of Experimental Biology Abstract Mytilus galloprovincialis at temperature shocks from 4 degree C to 30 degree C and 9 degree C to 30 degree C, survives 50 and 140 hours respectively. In the first hours of the exposure the males die faster than the females and the resistance of the young is greater than that of the old. When the temperature gap is longer the survival period is shorter. The shock between 21.5 degree C to 30 degree C after 30 hours induces a significant increase of the hepatopancreas catalase activity, and a diminution of this activity in the adductor muscle. After 60 hours the activity diminish but Lowry's protein from tested organs and the hemolymph lactic acid increase. The intensity of the transformations varies in accordance with the tissue and sex. The electron-microscopic study shows the increased distructive effects of temperature stress on mantle tissue cells.