Calcium, Copper Protein And Oxygen Affinity In Haemocyanins Of Aestivating And Nonaestivating Snails (Achatina achatina)
Under dry conditions, land snails withdraw into their shells closing the entrance with a calcified mucous membrane called epiphragm and become dormant (aestivate). In this state, the partial pressure of oxygen gradually falls to low levels whereas the partial pressure of carbon dioxide rises. We have investigated the effect of aestivation on the haemolymph inorganic ions, the oxygen affinity of haemocyanin in the giant African snail, Achatina achatina. After four months of aestivation, they were 46.35%, 4.19%, 44.60% decreases in haemolymph protein, pH and body weight respectively and significant increases in haemolymph Cu2+ and Ca2++, i.e is 161.16% and 75.09% respectively. The increases in divalent ions which may have resulted from the need to buffer the decrease in extracellular pH during aestivation is likely responsible for the high oxygen affinity of haemocyanin (43.0% increase) from aestivating snails through co-operative oxygen binding.
Key Words: Aestivation, snail, Achatina achatina, inorganic ions, haemocyanin, absorption spectra, oxygen affinity.
Bio-Research Vol.2(1) 2004: 115-123
CB Lukong, HA Onwubiko