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General Information
Symbol
Dmel\Orco1
Species
D. melanogaster
Name
FlyBase ID
FBal0189833
Feature type
allele
Associated gene
Associated Insertion(s)
Carried in Construct
Also Known As
or83b1, Or83b-
Key Links
Nature of the Allele
Mutations Mapped to the Genome
 
Type
Location
Additional Notes
References
Associated Sequence Data
DNA sequence
Protein sequence
 
 
Progenitor genotype
Cytology
Nature of the lesion
Statement
Reference

Genomic sequence encoding the putative transcription start site and the first five transmembrane domains of Orco has been deleted and replaced by a w+* marker.

Insertion components
TI{TI}Orco1
Expression Data
Reporter Expression
Additional Information
Statement
Reference
 
Marker for
Reflects expression of
Reporter construct used in assay
Human Disease Associations
Disease Ontology (DO) Annotations
Models Based on Experimental Evidence ( 1 )
Disease
Evidence
References
Modifiers Based on Experimental Evidence ( 0 )
Disease
Interaction
References
Comments on Models/Modifiers Based on Experimental Evidence ( 0 )
 
Disease-implicated variant(s)
 
Phenotypic Data
Phenotypic Class
Phenotype Manifest In
Detailed Description
Statement
Reference

Orco1 homozygous adults exhibit a significantly decreased preference for apple juice in olfactory trap assays, as compared to controls.

The adult olfactory receptor neurons of Orco1 homozygotes are electrophysiologically silent; neurons additionally expressing OrcoUAS.mCherry, OrcoCBSΔ.UAS.mCherry, OrcoW341Δ.UAS.mCherry or OrcoRH344EE.UAS.mCherry under the control of Scer\GAL4Orco.2.642.Hsim\VP22 show an apparently normal dendritic morphology, as compared to controls.

In olfactory preference assays for polyamines, Orco1/Orco1 flies do not show any significant difference in their attraction to putrescine or cadaverine, as compared to wild type, and females do not show any significant difference in their aversion to oviposit on polyamine-rich substrate (plain, sugar-free 1% agarose supplemented with either putrescine or cadaverine) versus non-supplemented substrate, as compared to wild type.

Orco1/Orco2 mutants are anosmic and do not display 'weathervaning' (modulation of direction in response to chemotaxis).

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.

Homozygous Orco1 mutant larvae do not have altered preference for larval-treated substrate, compared to controls.

As in wild type, Orco1/Orco2 mutant males exhibit inhibition of the female contact-induced male-male aggression seen in wild type males that have previously been exposed to females.

Orco1/Orco1 Or22-expressing olfactory neurons show a lack of response following odorant stimulation with ethyl butyrate.

In contrast to wild type, homozygous and Orco1/Orco2 flies do not show a preference for ethanol-containing food odors (over food odors without ethanol) in an olfactory choice assay. Homozygous flies prefer food odors over water, and ethanol over water. They show a reduced preference for food vs water compared to wild-type controls.

The social space index of mutant flies is not significantly different from wild-type controls.

Larvae with olfactory input restricted to the Or42a-expressing olfactory receptor neurons (expressing OrcoScer\UAS.cLa under the control of Scer\GAL4Or42a.PF in a Orco1/Orco1 background) follow a concentration path distant from the odour source in an assay to study the response to a stable gradient of the odour ethyl butyrate (30mM odour source). To orbit around the source in this way, the mutant larvae implement small-amplitude turns, which maintain their bearing close to 90[o]. Turns are triggered in the mutant larvae at odour concentrations three times lower than those that trigger turns in the wild type. The targeted concentration does not coincide with the region where the amplitude of the concentration gradient is maximal. In contrast to wild type, turns in the mutant larvae are preceded by episodes where the bearing remains constant. For a low-concentration odour source (7.8mM), the mutant larvae show attraction throughout the odour gradient's range and accumulate near the source. For a high-concentration odour source (125mM), the mutant larvae navigate up-gradient, before they bifurcate to avoid regions of high odour intensities. In contrast, wild-type larvae display invariant attraction to low and high concentrations. The mutant larvae turn towards the gradient for concentrations lower than 0.5μM, but turn away from the gradient at higher concentrations.

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 mutants do not respond to either 2-methylpyrazine or 2-ethylpyrazine.

Homozygous flies show a stronger avoidance response to a number of carboxylic acids (acetic acid, propionic acid and butyric acid) than do control flies in a T-maze choice assay.

Homozygous flies show a stronger avoidance response to pyridine and to 2-3-butanediol than do control flies in a T-maze choice assay.

Homozygous flies show a weaker avoidance response to butyraldehyde than do control flies in a T-maze choice assay.

Homozygous flies show a significant attraction response to ammonia in a T-maze choice assay.

Homozygous flies show a significant attraction response to pentyl acetate in a T-maze choice assay, in contrast to wild-type flies which show an avoidance response to this odour.

Orco1 mutant flies do not exhibit a difference in beer preference compared to wild-type flies. Orco1 flies, with the antennae surgically removed (so removing other ionotropic receptors) still display a preference for beer, although at a reduced level.

Or83b1 mutants cannot detect attractive odorants.

Or83b1 flies exhibit a normal ethanol-induced olfactory startle response.

Or83b1 flies exhibit reduced ethanol-induced hyperactivity during the first ethanol exposure, but an increase in locomotor activity upon repeated ethanol exposure compared to controls. Ethanol sedation sensitivity or sedation tolerance is not affected.

Homozygous and Orco1/Df(3R)ED5156 flies significantly reduced avoidance of citronellal in a direct airborne repellent test (DART) assay.

Mutant flies show a significantly reduced avoidance of benzaldehyde in a DART assay.

ab11 olfactory receptor neurons do not respond to10% citronellal in mutant flies, in contrast to wild type.

Mutants are not able to discriminate between 1-octen-3-ol and 3-octanol, and neither odour is learnable by the mutants in a one-odour training, one-odour test task. The mutant larvae do not show any preference towards either odour after either one-odour or two-odour training.

Male flies show a reduction in male-male aggression (a significant reduction in lunging behaviour) compared to controls.

Orco1/Orco2 mutant larvae direct turns towards and away from the peak of the gradient with equal probability in an assay to study the response to an exponential gradient of the odorant isoamyl acetate, in contrast to wild-type larvae, which direct more than 63% of turns towards the gradient.

Larvae with olfactory input restricted to the Or42a-expressing olfactory sensory neurons (expressing OrcoScer\UAS.cLa under the control of Scer\GAL4Or42a.PF in a Orco1/Orco2 background) are more sensitive to isoamyl acetate than wild-type animals in an assay to study the response to a radially symmetrical odour gradient, showing significant responses to the odour at source concentrations as low as 0.12M. Mutant and wild-type larvae navigate efficiently along the odorant line (from low to high odorant concentration) in an assay to study the response to an exponential odorant gradient, in response to either isoamyl acetate, isopropyl acetate, 2-hexenal or anisole.

Or83b1/Or83b2 Or67d-expressing olfactory sensory neurons show severely decreased spontaneous activity compared to control neurons.

The frequency of close-proximity encounters at night and in the early morning between male-female pairs (isolated from other flies and entrained to a 12:12 LD cycle) is significantly reduced in Or83b1 homozygous animals.

Olfactory sensory neuron morphology and membrane organization appear normal in Or83b1/Or83b2 mutants.

Or83b1 larvae do not respond to odours to which wild-type larvae respond with strong chemotaxis.

Or83b1 larvae fail to respond to 34 odours and weakly respond to a further 2 odours that wild-type larvae chemotax towards. Or83b1 adults show severely impaired responses to acetoin and are anosmic to 2-phenylethanol.

External Data
Interactions
Show genetic interaction network for Enhancers & Suppressors
Phenotypic Class
Suppressed by
Statement
Reference
Phenotype Manifest In
Additional Comments
Genetic Interactions
Statement
Reference

The increased avoidance behaviour of Orco1 homozygotes to acetic acid is suppressed by Ir8a1/Ir8a1.

Snmp1 Or83b2/Snmp2 Or83b1 double mutant Or67d-expressing olfactory sensory neurons show show severely decreased spontaneous activity compared to control neurons, as is seen in Or83b1/Or83b2 single mutant neurons.

Xenogenetic Interactions
Statement
Reference
Complementation and Rescue Data
Comments

The lack of electrophysiological activity observed in the adult olfactory receptor neurons of Orco1 homozygotes is not rescued by the expression of OrcoUAS.mCherry, OrcoCBSΔ.UAS.mCherry, OrcoW341Δ.UAS.mCherry or OrcoRH344EE.UAS.mCherry under the control of Scer\GAL4Orco.2.642.Hsim\VP22.

The increased avoidance behaviour of Orco1 homozygotes to acetic acid is rescued to wild-type behaviour by Orco+CH322-81L19.

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.

Larvae that express Or83bScer\UAS.cLa under the control of Scer\GAL4Or42a.PF in a Or83b1 background respond to 22 odours out of 36 odours to which control larvae respond. Larvae that express Or83bScer\UAS.cLa under the control of either Scer\GAL4Or1a.PF or Scer\GAL4Or49a.PF in a Or83b1 background fail to respond to 53 different odours. Larvae that express Or83bScer\UAS.cLa under the control of both Scer\GAL4Or1a.PF and Scer\GAL4Or42a.PF in a Or83b1 background exhibit enhanced chemotaxis compared with those that express Or83bScer\UAS.cLa under either single driver alone.

Expression of Or83bScer\UAS.cLa, under the control of Scer\GAL4Or83b.2.642.T:Hsim\VP22, partially restores chemotaxis towards certain odours in Or83b1 mutants.

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Mutant
Wild-type
Stocks (1)
Notes on Origin
Discoverer
External Crossreferences and Linkouts ( 0 )
Synonyms and Secondary IDs (8)
References (43)