1. The central ganglia of a number of gastropod molluscs (including the marine snail Aplysia californica and the terrestrial snail Helix pomatia) contain neurones which exhibit endogenous patterns of oscillatory activity. 2. This oscillatory activity can be modulated for long periods of time by synaptic and hormonal stimulation. 3. Stimulation of appropriate pre-synaptic nerves causes long-lasting hyperpolarization in these neurones, with complete abolition of oscillatory activity. This synaptic response is mediated by an increase in K+ conductance, together with a decrease in inward (Na+/Ca2+) conductance. The ionic conductances affected by synaptic stimulation are those responsible for producing the rhythmic oscillations. 4. The oscillatory activity can also be modulated by the vertebrate neurohyophyseal peptides, vasopressin and oxytocin, and by an endogenous peptide-containing extract of molluscan ganglia. In contrast to synaptic stimulation, these agents cause an increase in oscillatory activity. 5. The endogenous molluscan factor which produces an increase in oscillatory activity can be purified by affinity chromatography on bovine neurophysin linked to Sepharose. This indicates that the molluscan nervous system may contain a neurohypophyseal-like peptide. 6. Oscillatory activity can be modulated by manipulation of cyclic nucleotide metabolism in these neurones. Increases in cAMP alone are associated with abolition of oscillatory activity; this mimics long-lasting synaptic hyperpolarization. Increases in cAMP and cGMP together are associated with an increase in oscillatory activity and mimic the effects of the vertebrate and molluscan peptides. Thus, it is possible that cyclic nucleotides play a role in these physiological responses.
In the field: an interview with Harald Wolf
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In our new Conversation, Harald Wolf talks about his fieldwork experiences working with desert ants in Tunisia to understand their navigation.
Propose a new Workshop
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Our Workshops bring together leading experts and early-career researchers from a range of scientific backgrounds. Applications are now open to propose Workshops for 2024, one of which will be held in a Global South country.
Julian Dow steps down and John Terblanche joins the JEB team
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After 15 years with the journal, Julian Dow from University of Glasgow, UK, is stepping down as a Monitoring Editor. We wish Julian all the best for the future and welcome John Terblanche, Stellenbosch University, South Africa, who is joining the team. Julian talks about his long association with The Company of Biologists and the journal and John tells us about his life and career in this News article.
The capture of crude oil droplets by filter feeders at high and low Reynolds numbers
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Researchers from the University of Montreal, Canada, reveal how tiny filter feeding barnacles and Daphnia entrap and consume minute droplets of crude oil, introducing the pollutant at the bottom of the food chain.
Patterns and processes in amphibious fish
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In their Review, Keegan Lutek, Cassandra Donatelli and Emily Standen discuss the biomechanics and neural control of terrestrial locomotion in amphibious fish. They explore how locomotor mode depends on body shape, physical constraints and phylogeny.
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