Radular myoglobin and protein variation within and among some littorinid species (Mollusca : Gastropoda)

The radular muscles of several littorinid species, including Littorina litt orea, L. saxatilis, L. obtusata, L. striata and Melaraphe neritoides, conta in myoglobin (Mb), Here we report on the presence of radular Mb in eight ot her littorinids: L, compressa, L, arcana, L. fabalis, Nodilittorina punctat a, N. trochoides, N. radiata, Littoraria undulata and Littoraria cingulifer a. Using native polyacrylamide gel electrophoresis (PAGE) and isoelectric f ocusing (IEF) we compared the Mb and soluble protein (SP) profiles of these species. This suggested that: (1) L. saxatilis and L. arcana may have spec ific Mb/SP profiles, (2) Littoraria spp., Nodilittorina spp. and L. striata share similar Mb patterns, (3) Mb is remarkably diverse in the genus Litto rina, (4) L. littorea shows intraspecific Mb/SP variation, (5) L saxatilis does not show geographic Mb/SP differences, and (6) IEF uncovers substantia l hidden Mb/SP heterogeneity not shown by PAGE (particularly for Melarhaphe neritoides). Hence, littorinid Mb/SP may be a useful taxonomic marker whos e ecophysiological significance deserves further study, even if its genetic basis remains unclear.