|Vacuolar-type ATPase in the accessory boring organ of Nucella lamellosa (Gmelin) (Mollusca: Gastropoda): role in shell penetration|
Clelland, E.S.; Saleuddin, A.S.M. (2000). Vacuolar-type ATPase in the accessory boring organ of Nucella lamellosa (Gmelin) (Mollusca: Gastropoda): role in shell penetration. Biol. Bull. 198: 272-283
In: Biological Bulletin. Marine Biological Laboratory: Lancaster, Pa. etc.. ISSN 0006-3185, more
|Authors|| || Top |
- Clelland, E.S.
- Saleuddin, A.S.M.
The structure and function of the accessory boring organ (ABO) of muricid gastropods has been de-scribed in numerous studies, and the ABO of Nucella la-mellosa was found to be similar to those of other muricid species. The active cap region of the ABO is composed of tall, mitochondria-rich cells with distinct brush borders at their apicies, surrounding a hemolymph-containing central sinus. Using antibodies specific for vacuolar-type ATPase (V-ATPase), enzyme immunoreactivity was found to be limited to the brush border of the epithelial cells. Electron immunohistochemistry revealed that V-ATPase immunore-activity resides in the plasma membranes of the microvilli. Immunodot blotting using yeast V-ATPase as a positive control confirmed the specificity of the reactions. SDS-PAGE of membrane suspensions from the ABO revealed protein bands of the requisite molecular weight for V-ATPase subunits. Western blots suggest that antibodies raised against mammalian V-ATPase subunits recognize subunits of the molluscan V-ATPase. The molecular weights of these identified subunits are similar to those in mammals. The V-ATPase-specific inhibitor bafilomycin A 1 inhibited ATPase activity in samples of ABO homogenate by about 10% relative to control, providing further evidence for the presence of V-ATPase. Specific V-ATPase activity was about 67 picomoles of inorganic phosphate per micro-gram of protein per minute in the homogenate. Collectively this evidence strongly suggests that a vacuolar-type proton transporting ATPase is present in the brush border of the accessory boring organ of Nucella lamellose, and is responsible for acidifying secretions from this gland. Similarities between the ABO, osteoclasts, and the mantle of freshwater bivalves also suggest that the mechanism for decalcification of calcareous substrates is conserved.