Biochemical studies on haemoglobin variants of the irus macaque.

Haemolysates from 202 M. irus, imported mainly from Thailand and Vietnam, were examined by starch-gel electrophoresis. In addition to the normal haemoglobin, Hb-Ami, two major haemoglobin variants designated as Hb-Pmi and Hb-Qmi and two minor com­ ponents were found. Hb-Pmi, which occurred in 12 % of the sample, forms molecular aggre­ gates, especially when released from the red cell. Peptide analysis showed th a t it differs from Hb-Ami in the absence of peptides a-TP I I I and a-Tp IV. Sera from animals with this haemoglobin in their red cells show two haeme-positive bands in addition to the usual single haptoglobin b an d ; this pattern can be produced in the sera of some animals which do not possess it, by addition of H b-Pmi. Hb-Qmi, which occurred in 24 % of the animals, migrates anodally to Hb-Ami a t alkaline pH and does not form aggregates. I t is found in two ranges of concentration when present with Hb-Ami. I t was shown by recombination experiments to have normal /?Ami-chains. The sample was polymorphic for a minor com­ ponent which was shown to have normal /?Ami chains. Some animals have two major haemoglobins and also this minor component and therefore possesses three different non/?-chains. I t is suggested th a t the minor component is the product of a m utated duplicate of the a-locus. The population genetics of these variant haemoglobins and the possible selective role of simian malaria are discussed.