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Molecular Basis of Olfactory Chemoreception in the Common Bed Bug, Cimex lectularius

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ABSTRACT

As one of the most notorious ectoparasites, bed bugs rely heavily on human or animal blood sources for survival, mating and reproduction. Chemoreception, mediated by the odorant receptors on the membrane of olfactory sensory neurons, plays a vital role in their host seeking and risk aversion processes. We investigated the responses of odorant receptors to a large spectrum of semiochemicals, including human odorants and plant-released volatiles and found that strong responses were sparse; aldehydes/ketones were the most efficient stimuli, while carboxylic acids and aliphatics/aromatics were comparatively less effective in eliciting responses from bed bug odorant receptors. In bed bugs, both the odorant identity and concentrations play important roles in determining the strength of these responses. The odor space constructed based on the responses from all the odorant receptors tested revealed that odorants within the same chemical group are widely dispersed while odorants from different groups are intermingled, suggesting the complexity of odorant encoding in the bed bug odorant receptors. This study provides a comprehensive picture of the olfactory coding mechanisms of bed bugs that will ultimately contribute to the design and development of novel olfactory-based strategies to reduce both the biting nuisance and disease transmission from bed bugs.

No MeSH data available.


Dose-dependent activity of odorant receptors.Normalized responses of 15 ORs to a subset of 14 odorants displaying dose-dependent characteristics. Odorants are listed on the Z-axis sequentially from trans-2-octen-1-ol to β-caryophyllene (n = 3–6).
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f6: Dose-dependent activity of odorant receptors.Normalized responses of 15 ORs to a subset of 14 odorants displaying dose-dependent characteristics. Odorants are listed on the Z-axis sequentially from trans-2-octen-1-ol to β-caryophyllene (n = 3–6).

Mentions: Numerous studies have indicated that concentration is a critical factor in determining the responses of ORs to odorants151618. Our results confirmed this: the responses of ORs were dramatically influenced by the odorant concentrations, with low concentrations eliciting very weak responses from ORs while high doses (1:103 or 1:104 v/v) activated a large number of ORs (Fig. 6). To further compare the sensitivity of ORs to the odorant stimuli, the EC50 value of odorants for different ORs were calculated (Fig. 7). The dose-response curves of ORs to different odorants revealed that certain ORs only responded to certain odorants at high doses. For example, OR17 and OR11 only displayed strong responses to coumarin and 2-decanone at a dose of 1:104 v/v. However, other ORs appeared to be extremely sensitive to odorants with a low dose: OR36 was activated by (+)-menthone and (−)-menthone with EC50 values of 9.67 × 10−8 and 1.64 × 10−7 v/v, respectively, and OR37 was activated by citral and (+)-menthone with EC50 values of 3.32 × 10−8 and 1.93 × 10−7 v/v, respectively (Fig. 7, Fig. S1). As all these EC50 values are in the nanomolar range, they are likely to be the cognate ligands for these ORs21.


Molecular Basis of Olfactory Chemoreception in the Common Bed Bug, Cimex lectularius
Dose-dependent activity of odorant receptors.Normalized responses of 15 ORs to a subset of 14 odorants displaying dose-dependent characteristics. Odorants are listed on the Z-axis sequentially from trans-2-octen-1-ol to β-caryophyllene (n = 3–6).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5382537&req=5

f6: Dose-dependent activity of odorant receptors.Normalized responses of 15 ORs to a subset of 14 odorants displaying dose-dependent characteristics. Odorants are listed on the Z-axis sequentially from trans-2-octen-1-ol to β-caryophyllene (n = 3–6).
Mentions: Numerous studies have indicated that concentration is a critical factor in determining the responses of ORs to odorants151618. Our results confirmed this: the responses of ORs were dramatically influenced by the odorant concentrations, with low concentrations eliciting very weak responses from ORs while high doses (1:103 or 1:104 v/v) activated a large number of ORs (Fig. 6). To further compare the sensitivity of ORs to the odorant stimuli, the EC50 value of odorants for different ORs were calculated (Fig. 7). The dose-response curves of ORs to different odorants revealed that certain ORs only responded to certain odorants at high doses. For example, OR17 and OR11 only displayed strong responses to coumarin and 2-decanone at a dose of 1:104 v/v. However, other ORs appeared to be extremely sensitive to odorants with a low dose: OR36 was activated by (+)-menthone and (−)-menthone with EC50 values of 9.67 × 10−8 and 1.64 × 10−7 v/v, respectively, and OR37 was activated by citral and (+)-menthone with EC50 values of 3.32 × 10−8 and 1.93 × 10−7 v/v, respectively (Fig. 7, Fig. S1). As all these EC50 values are in the nanomolar range, they are likely to be the cognate ligands for these ORs21.

View Article: PubMed Central - PubMed

ABSTRACT

As one of the most notorious ectoparasites, bed bugs rely heavily on human or animal blood sources for survival, mating and reproduction. Chemoreception, mediated by the odorant receptors on the membrane of olfactory sensory neurons, plays a vital role in their host seeking and risk aversion processes. We investigated the responses of odorant receptors to a large spectrum of semiochemicals, including human odorants and plant-released volatiles and found that strong responses were sparse; aldehydes/ketones were the most efficient stimuli, while carboxylic acids and aliphatics/aromatics were comparatively less effective in eliciting responses from bed bug odorant receptors. In bed bugs, both the odorant identity and concentrations play important roles in determining the strength of these responses. The odor space constructed based on the responses from all the odorant receptors tested revealed that odorants within the same chemical group are widely dispersed while odorants from different groups are intermingled, suggesting the complexity of odorant encoding in the bed bug odorant receptors. This study provides a comprehensive picture of the olfactory coding mechanisms of bed bugs that will ultimately contribute to the design and development of novel olfactory-based strategies to reduce both the biting nuisance and disease transmission from bed bugs.

No MeSH data available.