scholarly journals Single olfactory receptors set odor detection thresholds

2018 ◽  
Author(s):  
Adam Dewan ◽  
Annika Cichy ◽  
Jingji Zhang ◽  
Kayla Miguel ◽  
Paul Feinstein ◽  
...  
Keyword(s):  
Sensory Neurons ◽  
Odorant Receptor ◽  
Olfactory Receptors ◽  
Detection Thresholds ◽  
Behavioral Threshold ◽  
Odor Detection ◽  
Biologically Relevant ◽  
Species Survival ◽  
Highly Sensitive ◽  
Behavioral Sensitivity

ABSTRACTIn many species, survival depends on olfaction, yet the mechanisms that underlie olfactory sensitivity are not well understood. Here, we examine how a conserved subset of olfactory receptors, the trace amine-associated receptors (TAARs) determine odor detection thresholds of mice to amines. We find that deleting all TAARs, or even single TAARs, results in significant odor detection deficits. This finding is not limited to TAARs, as the deletion of a canonical odorant receptor reduced behavioral sensitivity to its preferred ligand. Remarkably, behavioral threshold is set solely by the most sensitive receptor, with no contribution from other highly sensitive receptors. In addition, increasing the number of sensory neurons (and glomeruli) expressing a threshold-determining TAAR does not improve detection, indicating that sensitivity is not limited by the typical complement of sensory neurons. Our findings demonstrate that olfactory thresholds are set by the single highest affinity receptor, and suggest that TAARs are evolutionarily conserved because they determine the sensitivity to a class of biologically relevant chemicals.

scholarly journals Coordination of two enhancers drives expression of olfactory trace amine-associated receptors

2020 ◽  
Author(s):  
Aimei Fei ◽  
Wanqing Wu ◽  
Longzhi Tan ◽  
Cheng Tang ◽  
Zhengrong Xu ◽  
...  
Keyword(s):  
Gene Expression ◽  
Sensory Neurons ◽  
Transgene Expression ◽  
Molecular Mechanisms ◽  
Odorant Receptor ◽  
Olfactory Receptors ◽  
Interaction Network ◽  
Coordinated Control ◽  
Gene Repertoire ◽  
Trace Amine

SummaryOlfactory sensory neurons (OSNs) are functionally defined by their expression of a unique odorant receptor (OR). Mechanisms underlying singular OR expression are well studied, and involve a massive cross-chromosomal enhancer interaction network. Trace amine-associated receptors (TAARs) form a distinct family of olfactory receptors, and here we find that mechanisms regulating Taar gene choice display many unique features. The epigenetic signature of Taar genes in TAAR OSNs is different from that in OR OSNs. We further identify that two TAAR enhancers conserved across placental mammals are absolutely required for expression of the entire Taar gene repertoire. Deletion of either enhancer dramatically decreases the expression probabilities of different Taar genes, while deletion of both enhancers completely eliminates the TAAR OSN populations. In addition, both of the enhancers are sufficient to drive transgene expression in the partially overlapped TAAR OSNs. We also show that the TAAR enhancers operate in cis to regulate Taar gene expression. Our findings reveal a coordinated control of Taar gene choice in OSNs by two remote enhancers, and provide an excellent model to study molecular mechanisms underlying formation of an olfactory subsystem.

scholarly journals Odor coding in the mammalian olfactory epithelium

2021 ◽  
Author(s):  
Smija M. Kurian ◽  
Rafaella G. Naressi ◽  
Diogo Manoel ◽  
Ann-Sophie Barwich ◽  
Bettina Malnic ◽  
...  
Keyword(s):  
Sensory Neurons ◽  
Olfactory Epithelium ◽  
New Technologies ◽  
Odorant Receptor ◽  
Olfactory Mucosa ◽  
Odorant Receptors ◽  
Odor Coding ◽  
New Era ◽  
Odor Detection ◽  
Receptor Interactions

AbstractNoses are extremely sophisticated chemical detectors allowing animals to use scents to interpret and navigate their environments. Odor detection starts with the activation of odorant receptors (ORs), expressed in mature olfactory sensory neurons (OSNs) populating the olfactory mucosa. Different odorants, or different concentrations of the same odorant, activate unique ensembles of ORs. This mechanism of combinatorial receptor coding provided a possible explanation as to why different odorants are perceived as having distinct odors. Aided by new technologies, several recent studies have found that antagonist interactions also play an important role in the formation of the combinatorial receptor code. These findings mark the start of a new era in the study of odorant-receptor interactions and add a new level of complexity to odor coding in mammals.

scholarly journals Coordination of two enhancers drives expression of olfactory trace amine-associated receptors

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Aimei Fei ◽  
Wanqing Wu ◽  
Longzhi Tan ◽  
Cheng Tang ◽  
Zhengrong Xu ◽  
...  
Keyword(s):  
Gene Expression ◽  
Sensory Neurons ◽  
Transgene Expression ◽  
Molecular Mechanisms ◽  
Odorant Receptor ◽  
Olfactory Receptors ◽  
Interaction Network ◽  
Coordinated Control ◽  
Gene Repertoire ◽  
Trace Amine

AbstractOlfactory sensory neurons (OSNs) are functionally defined by their expression of a unique odorant receptor (OR). Mechanisms underlying singular OR expression are well studied, and involve a massive cross-chromosomal enhancer interaction network. Trace amine-associated receptors (TAARs) form a distinct family of olfactory receptors, and here we find that mechanisms regulating Taar gene choice display many unique features. The epigenetic signature of Taar genes in TAAR OSNs is different from that in OR OSNs. We further identify that two TAAR enhancers conserved across placental mammals are absolutely required for expression of the entire Taar gene repertoire. Deletion of either enhancer dramatically decreases the expression probabilities of different Taar genes, while deletion of both enhancers completely eliminates the TAAR OSN populations. In addition, both of the enhancers are sufficient to drive transgene expression in the partially overlapped TAAR OSNs. We also show that the TAAR enhancers operate in cis to regulate Taar gene expression. Our findings reveal a coordinated control of Taar gene choice in OSNs by two remote enhancers, and provide an excellent model to study molecular mechanisms underlying formation of an olfactory subsystem.

scholarly journals Single olfactory receptors set odor detection thresholds

2018 ◽  
Vol 9 (1) ◽  
Author(s):  
Adam Dewan ◽  
Annika Cichy ◽  
Jingji Zhang ◽  
Kayla Miguel ◽  
Paul Feinstein ◽  
...  
Keyword(s):  
Olfactory Receptors ◽  
Detection Thresholds ◽  
Odor Detection

scholarly journals Odor Coding in the Mammalian Olfactory Epithelium

2020 ◽  
Author(s):  
Smija M. Kurian ◽  
Rafaella G. Naressi ◽  
Diogo Manoel ◽  
Ann-Sophie Barwich ◽  
Bettina Malnic ◽  
...  
Keyword(s):  
Sensory Neurons ◽  
Olfactory Epithelium ◽  
New Technologies ◽  
Odorant Receptor ◽  
Olfactory Mucosa ◽  
Odorant Receptors ◽  
Odor Coding ◽  
New Era ◽  
Odor Detection ◽  
Receptor Interactions

Noses are extremely sophisticated chemical detectors allowing animals to use scents to interpret and navigate their environments. Odor detection starts with the activation of odorant receptors (ORs), expressed in mature olfactory sensory neurons (OSNs) populating the olfactory mucosa. Different odorants, or different concentrations of the same odorant, activate unique ensembles of ORs. This mechanism of combinatorial receptor coding provided a possible explanation as to why different odorants are perceived as having distinct odors. Aided by new technologies, several recent studies have found that antagonist interactions also play an important role in the formation of the combinatorial receptor code. These findings mark the start of a new era in the study of odorant-receptor interactions and add a new level of complexity to odor coding in mammals.

scholarly journals Trace amines inhibit insect odorant receptor function through antagonism of the co-receptor subunit

F1000Research ◽  
2014 ◽  
Vol 3 ◽  
pp. 84 ◽  
Author(s):  
Sisi Chen ◽  
Charles W. Luetje
Keyword(s):  
Odorant Receptor ◽  
Olfactory Receptors ◽  
Single Species ◽  
Insect Species ◽  
Receptor Subunit ◽  
Trace Amines ◽  
Vector Mosquito ◽  
Exogenous Compounds ◽  
Potent Antagonist ◽  
High Degree

Many insect behaviors are driven by olfaction, making insect olfactory receptors (ORs) appealing targets for insect control.  Insect ORs are odorant-gated ion channels, with each receptor thought to be composed of a representative from a large, variable family of odorant binding subunits and a highly conserved co-receptor subunit (Orco), assembled in an unknown stoichiometry.  Synthetic Orco directed agonists and antagonists have recently been identified.  Several Orco antagonists have been shown to act via an allosteric mechanism to inhibit OR activation by odorants.  The high degree of conservation of Orco across insect species results in Orco antagonists having broad activity at ORs from a variety of insect species and suggests that the binding site for Orco ligands may serve as a modulatory site for compounds endogenous to insects or may be a target of exogenous compounds, such as those produced by plants.  To test this idea, we screened a series of biogenic and trace amines, identifying several as Orco antagonists.  Of particular interest were tryptamine, a plant-produced amine, and tyramine, an amine endogenous to the insect nervous system.  Tryptamine was found to be a potent antagonist of Orco, able to block Orco activation by an Orco agonist and to allosterically inhibit activation of ORs by odorants.  Tyramine had effects similar to those of tryptamine, but was less potent.  Importantly, both tryptamine and tyramine displayed broad activity, inhibiting odorant activation of ORs of species from three different insect orders (Diptera, Lepidoptera and Coleoptera), as well as odorant activation of six diverse ORs from a single species (the human malaria vector mosquito, Anopheles gambiae).  Our results suggest that endogenous and exogenous natural compounds serve as Orco ligands modulating insect olfaction and that Orco can be an important target for the development of novel insect repellants.

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