Expression of OrcoScer\UAS.T:Avic\GFP in one olfactory sensory neuron, under the control of Scer\GAL4Or42b.PF and in an Orco1/Orco2, reduces the strength of 'weathervaning' in chemotaxis, compared to wild-type larvae with bilateral function. These larvae exhibit the reorientation bais observed in wild-type.
Larvae with olfactory input restricted to a single unilateral Or42a-expressing olfactory receptor neuron (expressing OrcoScer\UAS.T:Avic\GFP under the control of Scer\GAL4Or42a.PF in a single olfactory receptor neuron in a Orco1/Orco2 background) navigate poorly and show tortuous paths in an assay to study the response to a stable gradient of the odour ethyl butyrate, failing to robustly orient towards the gradient.
Orco1/Orco2 larvae expressing OrcoScer\UAS.T:Avic\GFP under the control of Scer\GAL4Or42a.PF unilaterally in single olfactory sensory neuron on one side of the head are able to navigate up an exponential gradient of the odorant isoamyl acetate, although their paths meander more than Orco1/Orco2 larvae expressing OrcoScer\UAS.T:Avic\GFP under the control of Scer\GAL4Or42a.PF bilaterally in both Or42a-expressing olfactory sensory neurons. Unilaterally rescued animals in which the right olfactory sensory neuron is functional perform better than unilaterally rescued animals in which the left olfactory sensory neuron is functional.
Orco1/Orco2 larvae expressing OrcoScer\UAS.T:Avic\GFP under the control of Scer\GAL4Or1a.PF bilaterally in both Or1a-expressing olfactory sensory neurons detect an exponential methyl benzoate odorant gradient with sufficient accuracy to reach the peak zone of the gradient field in 60% of cases. Orco1/Orco2 larvae expressing OrcoScer\UAS.T:Avic\GFP under the control of Scer\GAL4Or1a.PF unilaterally in single olfactory sensory neuron on one side of the head have a low chemotaxis score in this assay and while larvae in which the right olfactory sensory neuron is functional show some rescue of chemotaxis compared to Orco1/Orco2 larvae, larvae in which the left olfactory sensory neuron is functional show no rescue of chemotactic behaviour.