The egg-laying hormone (ELH) is a peptide hormone that controls a series of complex but stereotyped egg-laying behaviors of the sea slug Aplysia californica. In the ELH precursor, several bioactive peptides are also found, which work together to induce egg laying.
The ELH of Aplysia californica consists of 36 aa, and the C-terminal Lys is amidated. The structures of ELH-related peptides are relatively conserved among the genus Aplysia. However, the structure of ELH-related peptides is diverse among the different orders in mollusks, except for the C-terminal amide.
The egg-laying hormone (ELH) was purified from the bag cells, a pair of clusters of neurosecretory cells located on the rostral side of the abdominal ganglion of Aplysia californica. The peptide triggers a series of egg-laying behaviors in this animal.
ELH induces egg laying when it is injected into Aplysia and other gastropods.It also induces ovulation from the isolated ovotestis of Aplysia. However, the coordination of multiple peptides encoded on the ELH precursor is essential for egg-laying behavior.
