1. The mode of action of the pyrethroid insecticide deltamethrin on inexcitable embryonic cultured cockroach neurones has been investigated using the patch-clamp technique. 2. Whole-cell recordings of the current induced by step depolarizations of the cell membrane showed that concentrations of deltamethrin ranging from 10(−8) to 5 × 10(−6) mol l-1 induced a small tetrodotoxin (TTX)-sensitive inward current that peaked at around +10 mV and reversed at around +60 mV. The activation and inactivation kinetics of this current were much slower than those of the axonal sodium current in this same species and were relatively insensitive to membrane potential. Steady-state inactivation was almost absent. 3. Single-channel activity associated with the action of the insecticide was analyzed using the cell-attached configuration. Three distinct patterns of activity were found: (1) discrete single-channel events of relatively short duration, (2) long events of comparatively small amplitude and (3) complex bursts made up of a succession of openings and closings to several levels. These three patterns were analyzed quantitatively using specially designed programs. 4. The first pattern of activity could be seen in most patches. It consisted of short (1–10 ms) rectangular events of comparatively small amplitude (1.5 pA at rest) and very low open time probability (around 0.001). The current-voltage relationship of these small events was linear over the voltage range studied and the (extrapolated) reversal potential approximated ENa. 5. The second pattern of activity was observed less frequently. The channels could stay open for very long periods (up to several seconds) and occasionally flickered between two or more levels. 6. The third pattern of activity was observed in many patches. During the burst, which could last from a few milliseconds to a few hundred milliseconds, the single-channel current jumped almost continuously between several levels (up to 7 or 8).
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.
An accelerometer-derived ballistocardiogram method for detecting heart rate in free-ranging marine mammals
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Max Czapanskiy and co show how the resting heart rates of blue whales are immortalized in the accelerometry traces collected by motion sensing data tags.
Global change and physiological challenges for Amazonian fish
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In their Review, Adalberto Luis Val and Chris Wood discuss the physiological threats to the unique and diverse fish fauna of Amazonia.
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