Glycerol 3-Phosphate Dehydrogenases in Social Bees

Abstract

Electrophoretic analysis of extracts of 12 bumblebee species revealed complex patterns of extramitochondrial diphosphopyridine nucleotide-dependent glycerol 3-phosphate dehydrogenase (EC 1.1.1.8) variants. Most Bombus species show one pattern, while Bombus nevadensis has a second and Bombus occidentalis a third pattern. All three Psithyrus (i.e. parasitic bumblebee) species tested have a fourth pattern. All patterns share one feature, i.e. there is both a slow and fast migrating set of two to four bands each. The slow set, as a whole, stains more intensely than the fast set in flight muscle extracts, whereas the opposite is true for extracts of heads and abdomens. The slow sets have been termed alar-muscular, the fast sets omniregional. The major alar-muscular isozyme has been crystallized from thoraces of B. nevadensis. The omniregional isozymes of most, but not all, bumblebees utilize triphosphopyridine nucleotide, whereas none of the alarmuscular variants utilize this nucleotide. Electrophoretic experiments indicate that most, if not all, the variants differ in primary structure. In contrast to bumblebees, honeybees have only one form of glycerol 3-phosphate dehydrogenase. Rabbit antibodies directed against glycerol 3-phosphate dehydrogenase of honeybees and of B. nevadensis were prepared. Each of these antisera precipitated the honeybee enzyme and all of the bumblebee isozymes. Immunological experiments using the micro-complement fixation technique with anti-B. nevadensis glycerol 3-phosphate dehydrogenase reveal that thoracic extracts of all other bumblebees tested cross-reacted very strongly, with Bombus bifarius and B. occidentalis extracts showing slightly less reactivity than that of the other Bombus and Psithyrus species. Honeybee extracts cross-reacted much more weakly. Micro-complement fixation studies with anti-honeybee glycerol 3-phosphate dehydrogenase suggest that extracts of different bumblebee species are immunochemically indistinguishable from one another.