| Budget Amount *help |
¥2,300,000 (Direct Cost: ¥2,300,000)
Fiscal Year 1996: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1995: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Research Abstract |
We have found two C-type lectins named BRA-2 ad BRA-3 in the hemolymph of the acorn barnacle Megabalanus rosa. Because of large amount of BRAs and also presence of seasonal variation of lectin content in the hemolymph, we postulate the contribution of lectin to biomineralization. We prepared the shell matrix proteins from well-washed and dried acorn barnacle shell. In gel filtration on Sephadex G-50 column, the matrix gel protein fraction gave two peaks which inhibited the calcium carbohydrate crystal. The larger molecular weight fraction contained a protein band (22k) which was stained by anti-BRA-2 antibody when checked by Western blotting after SDS-PAGE.Interestingly, no component positive to antibody to BRA-3 lectin, another lectin component in the hemolymph, was observed. When the acorn barnacle received a surgery to place a stainless ball in the mantle from the basal plate, the ball was fully covered by calcium carbonate. We, then, analyzed the presence of humoral lectins in the matrix protein fraction prepared from newly formed calcium carbonate layr by ELISA.We detected the presence of BRA-2 and also BRA-3. The basal plate of the acorn barnacle, on the other hand, contain BRA-2 and a trace of BRA-3. These results suggest that BRA-2 plays a certain role in the crystal formation of calcium carbonate in the acorn barnacle.
Balanus rostratus, a close related species to M.rosa, was found to contain a C-type lectin in the hemolymph, but the lectin did not show any inhibitory activity against crystal gtowth of calcium carbonate. The inhibitory activity was detected in the low molecular weight fraction. This suggest that the physiological function of humoral lectins is species-specific, even among the C-type lectins
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