Reversed bohr and root shifts in hemocyanin of the marine prosobranch,Buccinum undatum: Adaptations to a periodically hypoxic habitat

Summary Oxygen binding properties of the hemocyanin-containing blood ofBuccinum undatum were examined in vitro and in vivo under normoxic (150 mmHg) and hypoxic (50 mmHg) conditions at 10°C. Blood pH and showed a decrease in vivo under hypoxic conditions. Oxygen uptake at high water, was about 18 ml O₂/kg·h (wet weight) and the critical oxygen tension between 25 and 50 mm Hg. In vitro the O₂ binding to hemocyanin showedn-values independent of pH, while both O₂ affinity and oxygen carrying capacity were strongly pH dependent. Oxygen affinity increased below pH=8.1 and thus showed a pronounced reversed Bohr shift in the physiological pH range (7.550 mm Hg). The role of hemocyanin in the transport of oxygen in relation to ambient O₂ availability is discussed.