Reproduction-associated immunoreactive peptides in the nervous systems of prosobranch gastropods

Antibodies against reproductive peptides of Aplysia and Lymnaea were used to localize homologous immunoreactive peptides in the nervous systems of three prosobranch species: Busycon canaliculatum, Concholepas concholepas, and Tegula atra. Positive control experiments in L. stagnalis demonstrated the broad species range of the anti-egg-laying hormone (anti-ELH) antibody used in this study, and showed binding of anti-α-caudodorsal-cell peptide (anti-α-CDCP) to the same cells in cerebral and buccal ganglia. Dot immunoassays with synthetic ELH confirmed the reactivity and sensitivity (<0.1 μg) of the anti-ELH antibody. Experiments with preadsorbed antibody or no primary antibody confirmed its specificity. In B. canaliculatum, clusters of more than 300 neuronal cell bodies immunoreactive to both anti-ELH and anti-α-CDCP were observed along the medial margins of left and right cerebral ganglia. Anti-α-CDCP reacted with additional small populations of cerebral ganglion neurons not stained by anti-ELH. Anti-ELH and anti-α-CDCP also reacted with overlapping but different small populations of neurons in buccal ganglia. In C. concholepas and T. atra, ELH-like immunoreactivity was found in cerebral ganglia, and in T. atra in fibers in the cerebral ganglia and cerebral-pedal connectives. Thus, cerebral ganglia are the major locus of the ELH-like immunoreactivity in prosobranchs.