Molecular cloning of a cDNA encoding the neuropeptides APGWamide and cerebral peptide 1: Localization of APGWamide-like immunoreactivity in the central nervous system and male reproductive organs ofAplysia

Abstract

While much is known about the neural and endocrine mechanisms that control egg laying in the gastropod mollusk Aplysia, relatively little is known about the regulation of male reproductive activity in this simultaneous hermaphrodite. In the present study, we have cloned and sequenced a cDNA that encodes a precursor protein, the predicted posttranslational processing of which presumably generates nine copies of the neuropeptide Ala-Pro-Gly-Trp-NH2 (APGWamide), five connecting peptide sequences, and a C-terminal peptide. The sequence of one connecting peptide is identical to the previously characterized cerebral peptide 1. Northern blot analysis identified two major APGWamide mRNA transcripts (approximately 1.3 kb, approximately 2.4 kb), which were present in central nervous system ganglia, but were most abundant in the right cerebral and right pedal ganglia. Immunohistochemical studies using sexually mature Aplysia demonstrated that the vast majority of APGWamide-like immunoreactivity was localized in 30-40 neurons along the anterior and medial margins of the right cerebral ganglion and in a cluster of 15-20 neurons in the right pedal ganglion. A total of only about ten immunoreactive neurons were located in other ganglia. Immunohistochemistry also demonstrated that APGWamide was present in the reproductive organs that participate in the storage or transport of sperm, including the small hermaphroditic duct (site of sperm storage before mating), the white hemiduct (also known as the copulatory duct), and penial complex. As a group, these data suggest that APGWamide may play a role in regulating male reproductive function in Aplysia, as it does in other gastropods.

Histochemical survey of transmitters in the central ganglia of the gastropod mollusc Phestilla sibogae

“…Although other species have anteriomedial 5-HT-immunoreactive cells, P. sibogae is the first species reported to have asymmetrically positioned 5-HT-immunoreactive cells on the right side. Bilaterally asymmetric populations of cells containing other transmitters have been reported in other gastropods and such cells have been shown or assumed to be involved in the control of male reproductive organs found on the right side only (Croll and Van Minnen 1992;Fan et al 1997;Li and Chase 1995;. Consistent with these findings, 5-HT-immunoreactive fibres have also been found in the penial complex of P. sibogae (D. M. Boudko and R. P. Croll, unpublished observations).…”

Identification and Characterization of the Feeding Circuit-Activating Peptides, a Novel Neuropeptide Family ofAplysia

“…At present we do not know which part of the FCAP peptide is responsible for its bioactivity. The FCAP precursor predicts a number of acidic peptides, but such peptides are often, although not always (Fan et al, 1997;Brezden et al, 1999), degraded and may function to compensate for the basic nature of the processing sites.…”

Environmental-endocrine control of reproductive maturation in gastropods: implications for the mechanism of tributyltin-induced imposex in prosobranchs

“…The neuropeptide APGWamide is secreted by the anteromedial region of the right cerebral ganglion, the right pedal ganglion, the copulatory duct, and penial complex of males (de Lange and van Minnen 1998;Fan et al 1997). APGWamide contributes to male mating behavior (Koene et al 2000) as well as the activity of the penis retractor muscle and muscles involved in ejaculation (Li et al 1992;Vangolen et al 1995).…”