Identification of two storage hexamers in the ant, Camponotus festinatus: accumulation in adult queenless workers.
Two electrophoretically and immunologically distinct storage hexamers (Hex 1 and Hex 2) have been identified in Camponotus festinatus workers. The molecular weights of the native molecules were estimated to be 460,000 (Hex 1) and 580,000 (Hex 2) by pore limiting gradient electrophoresis. Hex 1 partially dissociates with moderate alkaline pH. Both proteins are composed of a single type of apoprotein of approx. 73 (Hex 1) and 80 kDa (Hex 2). While most of Hex 2 is sequestered by the fat body before pupation, Hex 1 remains largely in the hemolymph during the last larval and pupal stages. Both proteins were detected only in low concentrations in the hemolymph of newly emerged adults, and they gradually disappear from adult workers maintained in the colonies. In queenless workers, however, Hex 1 and Hex 2 accumulate in the hemolymph and fat body, constituting the most abundant proteins together with vitellogenin. Camponotus festinatus storage hexamers bear some homologies in their N-terminal sequence with the arylphorins of Diptera and Lepidoptera, as well as with a crab hemocyanin. However, with respect to their amino acid composition, they can not be classified as arylphorins.