Marine surfaces and the expression of specific byssal adhesive protein variants in Mytilus

Mytilus foot protein-3 (Mfp-3) is a highly polymorphic protein family locat ed in the byssal adhesive plaques of blue mussels. Previous evidence sugges ted that the deposition of selected Mfp-3 variants might be influenced by t he type of surface to which the mussel attaches; therefore, we undertook to rigorously investigate whether a correlation exists between surface type a nd Mfp-3 variants. Two hypotheses were tested in M. galloprovincialis and M edulis. One hypothesis was that individual mussels deposit specific Mfp-3 variants on different surfaces. Laser desorption-ionization mass spectromet ry was used to detect Mfp-3 variants on the underside of byssal adhesive pl aques. The other hypothesis was that the transcription of specific Mfp-3s i s induced by different surfaces. This was measured by using denaturing grad ient gel electrophoresis to separate closely related amplified complementar y DNAs among individual mussels attached to stainless steel, glass, or poly ethylene surfaces. Band stabs of several Mfp-3 cDNAs were sequenced. The re sults clearly showed that individual mussels secreted a similar suite of Mf p-3 variants onto glass, plastic, and steel. Likewise, the expression of Mf p-3 cDNA transcripts in individual mussels revealed no clear correlation be tween messenger RNA expression and the type of surface. Thus, the expressio n and secretion of specific Mfp-3 variants do not appear to be surface-indu ced. These results underscore the importance of following individual mussel s rather than populations in surface studies.