Haemocyanin oxygen binding and the physiological ecology of a range of talitroidean amphipods (Crustacea) II. Effect of freezing, inorganic ions, and urate on O2 binding in vitro

Abstract

The effect of variations in [K], [Ca], [Mg], [NaCl], and [urate] on the in vitro O2 binding properties of haemocyanin (Hc) from three talitroidean species, viz. the aquatic Apohyale pugettensis, the semi-terrestrial Megalorchestia californiana, and the semi-/euterrestrial Traskorchestia traskiana were studied. Freezing altered the cooperativity of Hc from A. pugettensis and M. californiana but not T. traskiana. Variations in [NaCl], [K], and [Mg] had no effect on cither O2 affinity or cooperativity of the Hc except for A. pugettensis Hc where an increase in [Mg] resulted in an increase in both O2 affinity and cooperativity. Increasing [Ca] or [urate] increased O2 affinity of both A. pugettensis and M. californiana but not T. traskiana Hc. These effects were most marked in A. pugettensis. The results suggest a negative correlation between sensitivity to Hc effectors and the degree of terrestrial adaptation of a particular amphipod species.