Immunolocalization Of A Voltage-Gated Calcium Channel Beta Subunit In The Tentacles And Cnidocytes Of The Portuguese Man-Of-War, Physalia Physalis

This study investigated the localization of a voltage-gated calcium channel (VGCC) beta subunit in the tentacles and cnidocytes of the Portuguese man-of-war using confocal immunocytochemistry. An antibody specific to the Ca2+ channel beta subunit of the Portuguese-man-of-war (PpCa(V)beta) was generated, and characterized by Western immunoblotting. The antibody labeling was widespread in the ectoderm of cnidosacs of the tentacles. The binding of the antibody on isolated cnidocytes was distributed at the base of the cell and appeared as multiple strong fluorescent plaques located around the basal hemisphere of the cell. The distribution of PpCa(V)beta in the cnidocyte is consistent with previous studies on other hydrozoans that demonstrated that cnidocytes convey sensory information to other cnidocytes through chemical synapses in which the cnidocyte is presynaptic to elements of the animal's nervous system. Importantly and surprisingly, PpCa(V)beta did not localize to the apical surface of the cnidocyte where the exocytotic events involved in cnidocyst discharge are thought to take place.