Meeting Abstract

P2.86  Tuesday, Jan. 5  Ultrastructure and immunocytochemistry of the apodemes and associated tissue in the chelae of the blue crab, Callinectes sapidus LEASER, Anne/E*; CRAWFORD, Emily/A; GAY, Daniel/M; DILLAMAN, Richard/M; University of North Carolina at Wilmington ael5075@uncw.edu

In the chelae of the blue crab, are two invaginations of the cuticle (apodemes) providing attachment sites for muscle. The morphology and composition of intermolt, premolt, and postmolt apodemes and associated tissue was revealed using light microscopy, immunocytochemistry, and transmission electron microscopy (TEM). Three polyclonal antibodies to C. sapidus cuticle proteins were used to determine the nature of the apodeme. Two of the antibodies are associated with calcified cuticle (CsCP8.5 and CsCp14.1) and one (CsAMP8.1) with uncalcified cuticle (arthrodial membrane). All 3 bound to the medial layer of the apodeme. Acridine orange (AO) staining of the apodeme differentiated the medial and lateral layers, with the fused epicuticular regions staining red and the adjacent cuticle staining green. AO staining of the epithelium showed a patchy distribution of red fluorescence indicating enhanced ribosomal activity in the portions of the cells during premolt and postmolt. A β-tubulin antibody and TEM confirmed the presence of bundles of microtubules interspersed with the secretory regions of the cells. TEM also revealed that these microtubules were attached to tonofibrils, which anchor the cuticle to the epithelium. The other end of the microtubule bundles forms a terminal z-band with the myofibrils of the muscle. The pattern of AO staining, the affinity for cuticle protein antibodies, as well as other ultrastructural features indicate that the apodemes are a unique cuticle type, with affinities to both calcified and uncalcified cuticle. Clues as to how muscle maintains function until very late in premolt is also revealed by examination of the cuticle-epithelial boundary over the molt cycle.