CRYOPROTECTIVE PROPERTIES OF ANTIFREEZE G LYCOPROTEINS UPON FREEZING OF FISH SPERM

Cryoconseruation of sperm of various fish species (rainbow trout, stee lhead salmon, and carp) has shown cryoprotective properties of antifre eze glycoproteins: the activity and fertilizing capacity of spermatozo a increased after thawing in the presence of antifreeze glycoproteins. Their effect depended on the protein concentration and degree of puri fication: in case of insufficient purification the cryoprotective effe ct of antifreeze proteins was suppressed at increasing concentration b y an inhibitory influence of foreign proteins present in the preparati on, especially in a cryoconserving medium containing 10% DMSO. A highl y purified preparation of antifreeze glycoproteins has shown a <<dose- response>> activation to a protein concentration of 20 mg/ml. Large (< <1-4>>) and small (<<6-7>>) molecules of antifreeze glycoproteins adde d separately in the equilibrium medium did not show cryoprotective pro perties but their joint presence in the medium produced cooperative po tentiation. Chemically modified molecules of antifreeze proteins (oxid ation of galactose of cleavage off disaccharide) fully lost their cryo protective capacity.