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