THE ORIGIN OF ECHINOID HATCHING ENZYME MESSENGER RNA*

Abstract

To determine if echinoid hatching enzyme mRNA is newly synthesized from embryonic chromatin or is a maternal mRNA stored in the unfertilized egg, hybrid adromerogones were constructed containing a sea urchin (Strongylocentrotus purpuratus) genome in sand dollar (Dendraster excentricus) cytoplasm. Such hybrid andromerogones developed at a normal rate to the blastula stage but failed to hatch. Diploid hybrids or merogones containing at least 1 complement of sand dollar genome hatched on the normal maternal schedule. Since the sea urchin hatching enzyme is not able to digest the sand dollar fertilization membrane, this failure to hatch is evidence that new mRNA synthesis from embryonic chromatin is required before hatching enzyme can be synthesized.