Species-specific oocyte proteins as molecular markers for Lineus taxonomy

The yolk proteins from the eggs of five species of thenemertean genus Lineus were analysed and theresulting data were used to define L. longissimus, L. sanguineus, L. lacteus, L. ruber, and L. viridis as distinct taxa (species to date). All fivespecies have at least one large (80–60 kDa) and onemedium sized (45–30 kDa) vitellin subunit, but thereare significant differences in the number and sizes ofthe molecular subunits. The large and medium sizedvitellin components of all the species areglycosylated, except for the 145 kDa protein of L. sanguineus. Rabbit antibodies to the L. lacteus vitellin subunits cross-reacted withthe vitellin subunits in the eggs of the otherspecies. The vitellin components of these five speciesof nemertean are very similar. Two species, L.ruber and L. viridis, lay their eggsin gelatinous masses, and the electrophoretic patternsof the jelly proteins show that the physicalconsistency of the jelly depends on molecular weightsof the components. The egg mass of L. viridis contains smaller proteins than the egg massof L. ruber. The repeatablespecies-specific patterns of vitellin componentsprovide a useful complement to the usual taxonomiccriteria.