Hemocyanins of the genus Uca: structural polymorphisms and native oligomers

Abstract The monomeric subunit composition of fiddler crab hemocyanins was examined in four species, using native polyacrylamide gel electrophoresis. The intraspecific variation was limited in Ucaprinceps monilifera and spinicarpa , but neither species was monomorphic. The variation was also smaller in U. crenulata coloradensis than found previously in U. pugilator . In U. musica musica , however, the variation was greater than in any other species examined thus far, regardless of family. In U. princeps monilifera and musica musica particular bands were invariably found together. In U. musica musica , the linked bands occupied very similar positions on the gels; they may represent similar polypeptides. In both species, the linked bands belonged to two mutually exclusive sets, one of which occurred more frequently than the alternative. In part because an intermediate condition was never observed, these phenotypes cannot be interpreted as products of different alleles encoded at the same locus. As in other crustaceans, the electrophoretic banding patterns were highly species specific and intraspecific variation did not produce phenotypes that could be confused with those of another species. The oligomer composition of the hemocyanins of five species was examined by size-exclusion HPLC. In contrast to a previous report on a different member of the genus, the hemocyanins of all five assemble primarily to the 2 × 6-meric level, with the 1 × 6-meric fraction being minor.