AN ECOPHYSIOLOGICAL INTERPRETATION OF HEMOGLOBIN MULTIPLICITY IN 3 HERBIVOROUS MARINE TELEOST SPECIES FROM NEW-ZEALAND

Hemoglobin components (isohemoglobins) and their isoelectric points (p I) were analysed for three herbivorous marine teleosts, and the functi onal properties of their unfractionated, stripped hemolysates were det ermined. Kyphosus sydneyanus and Girella tricuspidata possess six isoh emoglobins and share a dominant cathodic band (pI = 8.61). Odax pullus possesses four isohemoglobins characterised by two strongly anodic ba nds (pI = 5.80, 4.89). Equilibrium binding studies of the hemolysate c omplexes from K. sydneyanus and G. tricuspidata revealed high oxygen a ffinities which were relatively insensitive to pH, whereas oxygen affi nity was markedly lower and more pH sensitive in O. pullus. Moreover, hemoglobin-oxygen affinity was less temperature-sensitive in K. sydney anus than in O. pullus. These observations support the hypothesis that hemoglobin oxygen loading in the cool-temperate species (O. pullus) m ay be compromised in the most northerly (warm) limits of its distribut ion, and that ecologically equivalent species in warmer and thermally variable habitats (K. sydneyanus and G. tricuspidata) possess more cat hodic isohemoglobins which are less influenced by pH and temperature. (C) 1998 Elsevier Science Inc. All rights reserved.