Species specificity of barnacle settlement-inducing proteins

We previously isolated a larval settlement-inducing protein complex (SIPC) from adult extracts of the barnacle, Balanus amphitrite using a nitrocellul ose membrane settlement assay. In the present study, we found that the extr acts of other adult barnacles. Megabalanus rosa and Balanus eburneus, also induced the settlement of B. amphitrite cyprids although the inductive acti vity was slightly lower than that of conspecific extracts. Furthermore, we examined reactivity to anti-SIPC antibody in adult extracts from six specie s of Japanese barnacles other than B. amphitrite, brine shrimp and eight ma rine sessile organisms besides barnacles. The results showed that all barna cles examined contained SIPC-like proteins with slightly different molecula r weight, while the other animals did not react to the antibody by immunobl ot analysis. These findings suggest that species specificity in settlement- inducing proteins of barnacles is not so strict, but these proteins are cha racteristic to barnacle species. (C) 2000 Elsevier Science Inc. All rights reserved.