Expression of the egg-laying hormone gene family in the head ganglia of Aplysia.

RNA blotting and cDNA cloning techniques were used to study expression of the egg-laying hormone (ELH) gene family in the head ganglia of Aplysia californica. All head ganglia were found to express a 1800 nucleotide (nt) mRNA homologous to the ELH gene family. The nucleotide sequence of a clone isolated from a ring ganglia cDNA library demonstrates that this message encodes the ELH precursor. Further studies demonstrate the presence of a smaller, 1500 nt, transcript which encodes the peptide A precursor. However, the level of this mRNA is at least 10-fold lower than the ELH encoding message.