Purification and chemical characterization of caudodorsal cell hormone-II from the egg-laying controlling caudodorsal cells of Lymnaea stagnalis

Abstract Caudodorsal cell hormone-I (CDCH-I), a 36 amino acid peptide synthesized by the caudodorsal cells (CDCs), is one of the major neuropeptides present in the cerebral ganglia of the freshwater snail, Lymnaea stagnalis . This peptide induces ovulation and egg-mass formation, and, in addition, acts on neuronal circuits involved in the control of overt egg-laying behavior. cDNA cloning studies revealed that there is a CDCH gene family comprising two genes coding for CDCH-I and the related yet distinct CDCH-II, respectively. In the present study, using sequential high performance gel permeation and reversed phase high performance liquid chromatography, we have isolated and sequenced the peptide CDCH-II. This neuropeptide has the following sequence: Ser-Ile-Thr-Asn-Asp-Leu- Arg-Ala-Ile-Ala-Asp-Ser-Tyr-Leu-Tyr-Asp-Gln-His-Lys-Leu-Arg-Glu-Gln-Gln-Glu-Glu-Asn-Leu-Arg-Arg-Arg-Phe-Tyr-Glu-Leu- Ser-Leu-Arg-Pro-Tyr-Pro-Asp-Asn-Leu. The sequence differs from those predicted by the cDNA sequence encoding preproCDCH-II at two positions, suggesting the polymorphism of CDCH-II exists in L. stagnalis .