SICKLING OF ANOXIC RED-BLOOD-CELLS IN FISH

The occurrence of the mutant hemoglobin Hb S in human red blood cells results in sickle cell anemia. This disease, including its genetic and molecular bases, has been extensively investigated and is well unders tood (1,2). The presence of deoxy-induced sickling of animal erythrocy tes is largely unknown, however. We examined red blood cells (RBCs)fro m several fish species in vitro under aerated and anoxic conditions. O ur polarized light microscopic techniques were aimed at establishing c orrelations between erythrocyte morphology, state of oxygenation, spec tral absorbance, linear dichroism, and linear birefringence. We found no fish with intracellular HbO(2) polymerization; but there were intra erythrocytic aggregations of deoxy Hb with a high degree of either mol ecular order or disorder. The ordered aggregates in the RBCs of Atlant ic cod, haddock, and toadfish were remarkably similar in dichroic rati o magnitudes and birefringence to those in human RBCs that contain HbS . Therefore, fish hemoglobins appear to be good models of sickling dis orders and polymerization-related phenomena. The consequences of sickl ing on animal health and fish aquaculture remain to be studied.