To determine whether amino-acid-induced inward currents of ciliated olfactory receptor neurons (ORNs) in rainbow trout (Oncorhynchus mykiss) include a Ca(2+)-activated Cl(−) conductance, we first studied changes in reversal potential and the current/voltage relationships of the responses of ORNs to an amino acid mixture (l-alanine, l-arginine, l-glutamate and l-norvaline; all 10 mmol l(−)(1)) with different concentrations of Na(+) and Cl(−) in the perfusion and recording pipette solutions. We also examined the effects of six different Cl(−) channel blockers on the responses of ORNs using a conventional whole-cell voltage-clamp technique. The amino acid mixture and one blocker were applied focally to the cilia of ORNs using a double-barrelled micropipette and a pressure ejection system. The expected shifts in reversal potential, indicating the contribution of the Ca(2+)-activated Cl(−) conductance, occurred in both positive and negative directions depending on the external and internal Na(+) and Cl(−) concentrations. Niflumic acid, flufenamic acid, NPPB [5-nitro-2-(3-phenylpropylamino)-benzonate] and DCDPC (3′, 5-dichlorodiphenylamine-2-carboxylate), at 0.5 mmol l(−)(1), reversibly blocked both the amino-acid-induced inward currents and the background activity in most ORNs. The effectiveness of these blocking agents varied from 77 to 91 % for ORNs perfused externally with standard Ringer's solution. SITS (4-acetamido-4′-isothiocyanatostilbene-2,2′-disulphonate), at 5.0 mmol l(−)(1), irreversibly inhibited the physiological response (100 % inhibition), whereas DIDS (4,4′-diisothiocyanatostilbene-2, 2′-disulphonate), at 5.0 mmol l(−)(1), had the smallest effect (45 %) of the inhibitors tested. The dose of niflumic acid inducing 50 % inhibition (IC(50)), determined specifically for the current component of the Ca(2+)-activated Cl(−) channels, was 70 μmol l(−)(1). Our results suggest that these blockers are not specific for Ca(2+)-activated Cl(−) channels and that the density of these channels varies between individual ORNs. Our results also show that the Ca(2+)-activated Cl(−) conductance plays an important role in olfactory transduction and allows fishes to adapt to various ionic environments.
New funding schemes for junior faculty staff
In celebration of our 100th anniversary, JEB has launched two new grants to support junior faculty staff working in animal comparative physiology and biomechanics who are within five years of setting up their first lab/research group. Check out our ECR Visiting Fellowships and Research Partnership Kickstart Travel Grants.
JEB@100: an interview with Monitoring Editor Stuart Egginton
Stuart Egginton reveals how he overcame the challenges of being a comparative physiologist in a medical school and how he would tell his younger self to trust his instincts when pursuing new ideas.
Travelling Fellowships from JEB
Our Travelling Fellowships offer up to £3,000 to graduate students and post-doctoral researchers wishing to make collaborative visits to other laboratories. Next deadline to apply is 27 October 2023
Feedforward and feedback control in the neuromechanics of vertebrate locomotion
Auke J. Ijspeert and Monica A. Daley provide an overview of key knowledge on feedback and feedforward control gained from comparative vertebrate experiments obtained from neuromechanical simulations and robotic approaches. Read the full Centenary Review Article here.
Light fine-tunes electric fish pulses to keep them in the shade
Weakly electric fish perceive their surroundings through electric chirrups and now Ana Camargo & colleagues have revealed that light fine-tunes the fish's electric pulses to ensure that they remain scheduled beneath the mats of vegetation they use for shelter, avoiding penetrating beams of light that could give them away.
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