Biochemical sex dimorphism in Lineus lacteus

Egg-specific and sperm-specific proteins fromLineus lacteus females and males were investigated byanalytical electrophoreses. These major sex-specificproteins define the sexual dimorphism of biochemicalmetabolism and are useful for studying vitellogenesisand spermatogenesis. The major yolk proteins in theeggs of the nemertean, Lineus lacteus, wereidentified by gradient gel electrophoresis. The 2vitellin proteins were designated vitellin V1 (460 kDa) andvitellin V2 (260 kDa). The vitellins wereidentified as lipoglycoproteins by selective staining.Three major vitellin subunits (75, 41 and 40 kDa) werefound in oocytes of L. lacteus byelectrophoresis under denaturing conditions(SDS-PAGE). Polyclonal antibodies were raised to eachvitellin subunit. The binding of these rabbitantibodies to vitellins V1 and V2 showed that vitellinV1 contained a single major 75 kDa polypeptide, whilevitellin V2 had two major polypeptides (41 and 40 kDa).Five male-specific proteins (52, 50, 41, 35 and 32 kDa) wereidentified in the sperm of Lineuslacteus by gradient gel electrophoresis. Four lowmolecular weight proteins (18–13 kDa) can also be usedas molecular markers of male sexual maturation. Theseproteins were nucleosomal core histones. The chromatinof L. lacteus sperm contained onlyhistones as no protamines or protamine-like proteinswere detected. But the sperm nucleosomal protein maynot be entirely somatic-histones, as a sperm-specifichistone (Sp H) was also found.