TNRNFLRFamide was isolated and sequenced from the stomatogastric nervous system of the crab Cancer borealis by reverse-phase high performance liquid chromatography followed by automated Edman degradation. An SDRNFLRFamide-like peptide that exactly co-migrated with SDRNFLRFamide was also observed. The effects of TNRNFLRFamide and SDRNFLRFamide on the gastric and pyloric rhythms of the stomatogastric nervous system of the crab Cancer borealis were studied. Both peptides activated pyloric rhythms in quiescent preparations in a dose-dependent manner with a threshold between 10(−11) and 10(−10) mol l-1. Both peptides increased the pyloric rhythm frequency of preparations showing moderate activity levels and had relatively little effect on preparations that showed strong pyloric rhythms prior to peptide application. Both peptides evoked gastric mill activity in preparations without existing gastric rhythms. The activation of the gastric rhythm is associated with activation of oscillatory properties in the dorsal gastric neurone. The induction of gastric rhythms by these peptides was accompanied by switches from pyloric-timed activity to gastric-timed activity by several stomatogastric ganglion neurones. Application of these peptides provides direct experimental control of circuit modification in the stomatogastric nervous system.
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.
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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