The fate of sperm specific non-histone chromosomal proteins after fertilization in sea urchins.

To determine the transitions of sea urchin sperm specific non-histone chromosomal proteins (Sp NHCP) following fertilization, their presence in zygotes during and after male pronuclear formation was investigated by comparing the electrophoretic patterns of NHCP obtained from gametes with those isolated from zygotes. Polyclonal antibodies directed against whole Sp NHCP were used to detect, by Western immunoblots, the Sp NHCP among the NHCP present in zygotes at different times post-insemination. The results obtained from immunological and electrophoretic studies indicate that shortly after fertilization the majority of Sp NHCP are lost. The electrophoretic patterns of NHCP obtained from unfertilized eggs were almost identical with those observed for NHCP isolated from zygotes. This similarity strongly suggests that the NHCP of unfertilized eggs are conserved after fertilization.