EFFECT OF OXYGEN AND SALT ON HEMOLYMPH OXYGEN-BINDING IN THE BRINE SHRIMP ARTEMIA-FRANCISCANA

The oxygen-binding properties of haemolymph from laboratory-reared Art emia franciscana were investigated in vitro. Adult female brine shrimp without eggs were acclimated to seven different combinations of salin ity and oxygen. The oxygen affinity (P-50) of unprocessed haemolymph r ises with acclimation oxygen partial pressure (PO2) up to normoxic val ues, after which no influence of oxygen occurs. The increase in P-50 w ith acclimation PO2 can be explained by the change in proportion of ea ch of three different haemoglobins in the haemolymph. Salinity acclima tion has no effect on haemolymph P-50. The effects of the different ma jor salts [NaNO3, NaCl, Ca(NO3)(2), Mg(NO3)(2)], pH, and the metal-bin ding ligand EGTA on the oxygen-binding properties of buffered haemolym ph (of shrimp acclimated to 10 parts per thousand salinity) were also studied. Little or no effect of these salts could be found. A small Bo hr effect (pH 6.5 to 9.1, phi = - 0.11) was noted. Addition of EGTA ca used a significant decrease of the oxygen affinity at concentrations u p to 50 mmoll(-l).