Veliger 23:155–158Ĭurtis LA, Hurd LE (1981a) Crystalline style cycling in Ilyanassa obsoleta (Say) (Mollusca: Neogastropoda): further studies. Science 235:1509–1511Ĭurtis LA, Hurd LE (1980) The effect of salinity on crystalline style occurrence in the estuarine snail, Ilyanassa obsoleta (Say), and its possible significance with respect to local distribution. Biol Bull Mar Biol Lab Woods Hole 169:377–390Ĭurtis LA (1987) Vertical distribution of an estuarine snail altered by a parasite. Mar Biol 59:137–140Ĭurtis LA (1985) The influence of sex and trematode parasites on carrion response of the estuarine snail Ilyanassa obsoleta. American Elsevier, New YorkĬurtis LA (1980) Daily cycling of the crystalline style in the omnivorous, deposit-feeding estuarine snail Ilyanassa obsoleta. Mar Poll Bull 20:458–462Ĭlarke GM (1969) Statistics and Experimental Design. J Mar Biol Assoc UK 66:611–640īryan GW, Gibbs PE, Huggett RJ, Curtis LA, Baily DS, Dauer DM (1989) Effects of tributyltin pollution on the mud snail, Ilyanassa obsoleta, from the York River and Sarah Creek, Chesapeake Bay. Mar Poll Bull 20:22–26īryan GW, Gibbs PE, Hummerstone LG, Burt GR (1986) The decline of the gastropod Nucella lapillus around south-west England: evidence for the effect of tributyltin from antifouling paints. This must be recognized when studying organisms exposed to these conditions.Īlzieu C, Sanjuan J, Michel P, Borel M, Dreno JP (1989) Monitoring and assessment of butyltins in Atlantic coastal waters. The altered biology associated with imposexinducing environments extends beyond female I. Two lines of evidence indicate that conditions which generated female imposex (organotin molecules in the water) also affected male sexuality: 1) healthy males normally lose the penis following reproduction but they tended to retain it where imposex-inducing conditions were strong and 2) males parasitized by trematodes usually lose the penis but tended not to under strong imposex-inducing conditions. Imposex was most frequent among females in a segment of the Lewes and Rehoboth Canal (68%, n=376) and there was significant spatial heterogeneity of imposex frequencies (range=43–98%) even within this habitat. Our data therefore indicate that the preproGFAD gene encodes the precursor of a neuropeptide that participates in the regulation of male mating behavior.The spatial distribution of the “imposex” phenomenon (the imposition of male characters on females) among populations of Ilyanassa obsoleta in southern Delaware, USA estuaries was studied. D-GFAD also suppressed activity of neurons modulating feeding behavior. Intracellular activation of individual neurons expressing the preproGFAD gene also elicited penis movements. In preparations containing CNS with intact innervation of reproductive organs, bath application of D-GFAD caused extensive movements of the penis but not of other reproductive organs. Injection of synthetic D-GFAD in nanomolar concentrations into intact animals caused an increase of the heartbeat rate and opening of the genital atrium. The first of them (achatin-I) contains D-Phe the second (achatin-II) is its L-Phe-containing stereoisomer. This peptide has the same sequence as two previously isolated peptides from a related snail, Achatina fulica. The post-translational processing of the prohormone may lead to the generation of seven tetrapeptides, Gly-Phe-Ala-Asp-COOH (GFAD). The preprohormone is 108 amino acids long and contains a hydrophobic leader peptide and eight Lys-Arg recognition sites for endoproteolysis. The expression in this particular region is observed in adult animals but not in juvenile ones. Most notable is the expression of preproGFAD gene in the right mesocerebrum, where the neurons controlling mating behavior are located. Analysis of the expression of this gene shows that it is neurospecific and expressed in several groups of CNS neurons. We report the isolation of a cDNA clone encoding a neuropeptide precursor named preproGFAD from the central nervous system (CNS) of the snail Helix lucorum.
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