Hemoglobin polymorphism in the Atlantic croaker, Micropogon undulatus

Abstract

Ten hemoglobins from the teleost Micropogon undulatus were separated in native polyacrylamide gel electrophoresis. In a large sample taken from a tributary of the Chesapeake Bay in Virginia, the distribution of these hemoglobins confirmed a polymorphic condition, which was previously known in North Carolina animals. The intraspecific variation was unrelated to body length, indicating that it is an adult phenomenon. The 10 hemoglobins were expressed in seven different phenotypic banding patterns. Although several morphs were infrequent, no single phenotype comprised a majority of the sample, indicating that the variation is quite great. Several phenotypes differed from those in North Carolina animals and, conversely, several North Carolina phenotypes were not recovered from the Chesapeake Bay sample. This finding suggests that the polymorphism is more complex than observed in either investigation alone. The O₂ binding of hemolysates stripped of co-factors by dialysis revealed functional differences between some, but not all, Chesapeake Bay morphs. The most variable property was O₂ affinity, although a few differences in pH dependence and cooperativity were also observed. The O₂ binding of red blood cell preparations also differed. These differences were not identical to those between dialyzed hemolysates, suggesting that organic PO₄ co-factors may be involved as well.