1. Monosynaptic connections between a giant serotonin-containing neurone and its serotonin-containing followers in the snail Helix pomatia were studied in isolated preparations of the central nervous system. The presynaptic cell was the LP3 cell in the left pedal ganglion and the followers were the RPas cells in the right parietal ganglion. 2. The light microscopical morphology of the pre- and postsynaptic cells was investigated in whole-mount preparations following intracellular injection with a nickel-lysine complex. Axons from LP3 project towards the cerebral and suboesophageal ganglia or run in peripheral nerves which innervate feeding muscles and the foot. The follower neurones (RPas) project into nerves which innervate the heart and other visceral organs. The axons of LP3 and the RPas cells run in close proximity in the visceral ganglia. 3. Ionophoretic application of serotonin onto the membrane of the postsynaptic RPas neurones mimicked the excitatory effect of the stimulation of the presynaptic LP3. Both the synaptic transmission between LP3 and its followers and the excitatory effect of exogenously applied serotonin on the RPas neurones decreased or were blocked in the presence of serotonin or the serotonin antagonists tryptamine, bufotenine, 7- methyltryptamine and MDL 72222-EFO2 in the bath. From this, we conclude that the excitatory neurotransmitter between LP3 and followers is serotonin and not some other neurotransmitter which might coexist with serotonin in LP3. 4. The serotonergic monosynaptic connections between LP3 and its right parietal followers may play a role in a variety of serotonin-mediated physiological and behavioural responses, forming a link between feeding, locomotion and visceral functions.
In the field: an interview with Martha Muñoz
Martha Muñoz is an Assistant Professor at Yale University, investigating the evolutionary biology of anole lizards and lungless salamanders. In our new Conversation, she talks about her fieldwork in Indonesia, Costa Rica, the Dominican Republic and the Appalachian Mountains, including a death-defying dash to the top of a mountain through an approaching hurricane.
Call for new preLighters
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preLights is the preprint highlighting community supported by The Company of Biologists. At the heart of preLights are our preLighters: early-career researchers who select and write about interesting new preprints for the research community. We are currently looking for new preLighters to join our team. Find out more and apply here.
Graham Scott in conversation with Big Biology
Graham Scott talks to Big Biology about the oxygen cascade in mice living on mountaintops, extreme environments for such small organisms. In this JEB-sponsored episode, they discuss the concept of symmorphosis and the evolution of the oxygen cascade.
Trap-jaw ants coordinate tendon and exoskeleton for perfect mandible arc
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Trap-jaw ants run the risk of tearing themselves apart when they fire off their mandibles, but Greg Sutton & co have discovered that the ants simultaneously push and pull the mandibles using energy stored in a head tendon and their exoskeleton to drive the jaws in a perfect arc.
Hearing without a tympanic ear
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In their Review, Grace Capshaw, Jakob Christensen-Dalsgaard and Catherine Carr explore the mechanisms of hearing in extant atympanate vertebrates and the implications for the early evolution of tympanate hearing.
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