| 1. |
- Bichao, H., et al.
(författare)
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Five types of olfactory receptor neurons in the strawberry blossom weevil Anthonomus rubi : Selective responses to inducible host-plant volatiles
- 2005
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Ingår i: Chemical Senses. - : Oxford University Press (OUP). - 0379-864X .- 1464-3553. ; 30:2, s. 153-170
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Tidskriftsartikel (refereegranskat)abstract
- Plants release hundreds of volatiles that are important in the interaction with herbivorous animals, but which odorants are detected by which species? In this study, single receptor neurons on the antenna of the oligophagous strawberry blossom weevil Anthonomus rubi were screened for sensitivity to naturally produced plant compounds by the use of gas chromatography linked to electrophysiological recordings from single cells. The narrow tuning of the neurons was demonstrated by responses solely to a few structurally related sesquiterpenes, aromatics or monoterpene hydrocarbons out of hundreds of plant constituents tested. We present five olfactory receptor neuron types, identified according to one primary odorant i.e. the compound to which the neurons are most sensitive. These odorants, (-)-germacrene D, (-)-beta-caryophyllene, methyl salicylate, E-beta-ocimene and (3E)-4,8-dimethyl-1,3,7-nonatriene, present in the intact strawberry plant, are induced in higher amounts by weevil feeding. This suggests that these compounds can provide information about the presence of conspecifics. We used protocols especially designed to allow comparison with previously investigated species. Striking similarities, but also differences, are demonstrated between receptor neuron specificity in the strawberry weevil and moths.
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| 2. |
- Bichao, H., et al.
(författare)
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Identification of plant odours activating receptor neurones in the weevil Pissodes notatus F. (Coleoptera, Curculionidae)
- 2003
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Ingår i: Journal of Comparative Physiology A. Sensory, neural, and behavioral physiology. - : Springer Science and Business Media LLC. - 0340-7594 .- 1432-1351. ; 189:3, s. 203-212
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Tidskriftsartikel (refereegranskat)abstract
- Plants release complex mixtures of volatiles important in the interaction with insects and other organisms. In the search for compounds that contribute to the perception of odour quality in the weevil Pissodes notatus, single olfactory receptor neurones on the antennae were screened for sensitivity to naturally produced plant volatiles by the use of gas chromatography linked to single cell recordings. We here present 60 olfactory neurones responding to 25 of the numerous compounds released by host and non-host plants. All the neurones show high selectivity and are classified into 12 distinct types. The two most abundant types respond to alpha-pinene, beta-pinene, and 3-carene (n = 17), and to isopinocamphone and pinocamphone (n = 17), respectively. Other neurone types respond to limonene (n = 9), beta-phellandrene (n = 3), and fenchone (n = 4). Responses to beta-caryophyllene (n = 1) and to ethanol (n = 4) are also shown. Except for two pairs, the neurone types do not show overlap of the molecular receptive range. The active compounds are present in the host, Pinus pinaster, as well as in non-hosts, supporting the idea that plant odour quality is mediated by the ratio of the compounds rather than specific odorants.
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| 3. |
- Bichao, H., et al.
(författare)
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Molecular receptive ranges of olfactory receptor neurones responding selectively to terpenoids, aliphatic green leaf volatiles and aromatic compounds, in the strawberry blossom weevil Anthonomus rubi
- 2005
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Ingår i: Chemoecology. - : Springer Science and Business Media LLC. - 0937-7409 .- 1423-0445. ; 15:4, s. 211-226
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Tidskriftsartikel (refereegranskat)abstract
- An important question in insect-plant interactions is which of the numerous plant compounds contribute to the perception of odour qualities in herbivorous insects and are likely to be used as cues in host-searching behaviour. In order to identify which plant-produced volatiles the strawberry blossom weevil Anthonomus rubi detects, we have used electrophysiological recordings from single olfactory neurones linked to gas chromatography and mass spectrometry. We here present 15 receptor neurone types specialised for naturally produced compounds present in the host and nonhost plants and two types for two aggregation pheromone components. The active compounds were terpenoids, aromatic and aliphatic esters, alcohols and aldehydes, some of which are induced by feeding activity of the weevils. The neurones were characterised by a strong response to one or two primary odorants and weaker responses to a few others having similar chemical structure. With one exception, the molecular receptive range of each neurone type was within one chemical group. Enantiomers of linalool separated on a chiral column activated two neurone types with different enantioselectivity. Inhibition by linalool of another neurone type, excited by alpha-pinene, indicated an additional mechanism for coding the information about this compound. Altogether, detection of 54 compounds by olfactory receptor neurones is shown, of which 40 have been chemically identified in this study. Thus A. rubi has the ability to detect a large number of odorants that may be used in host selection behaviour.
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| 4. |
- Mozuraitis, R., et al.
(författare)
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(-)-germacrene D increases attraction and oviposition by the tobacco budworm moth Heliothis virescens
- 2002
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Ingår i: Chemical Senses. - : Oxford University Press (OUP). - 0379-864X .- 1464-3553. ; 27:6, s. 505-509
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Tidskriftsartikel (refereegranskat)abstract
- The sesquiterpene germacrene D (GD) activates a major type of olfactory receptor neuron on the antennae of the heliothine moths. In Heliothis virescens females, 80% of the recordings have shown activity of one neuron type responding with high sensitivity and selectivity to GD. With the aim of determining the behavioural significance of this sesquiterpene, we have used a two-choice wind-tunnel to study the preference of mated H. virescens females for host plants with and without (-)-GD added. Tobacco plants containing dispensers with low release rate of (-)-GD had a greater attractiveness than tobacco plants without this substance. In addition, a significant increase of oviposition was found on the plants with (-)-GD.
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| 5. |
- Rostelien, T., et al.
(författare)
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Olfactory receptor neurons in two heliothine moth species responding selectively to aliphatic green leaf volatiles, aromatic compounds, monoterpenes and sesquiterpenes of plant origin
- 2005
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Ingår i: Chemical Senses. - : Oxford University Press (OUP). - 0379-864X .- 1464-3553. ; 30:5, s. 443-461
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Tidskriftsartikel (refereegranskat)abstract
- Moths of the subfamily Heliothinae are suitable models for comparative studies of plant odour information encoded by the olfactory system. Here we identify and functionally classify types of olfactory receptor neurons by means of electrophysiological recordings from single receptor neurons linked to gas chromatography and to mass spectrometry. The molecular receptive ranges of 14 types in the two polyphagous species Heliothis virescens and Helicoverpa armigera are presented. The receptor neurons are characterized by a narrow tuning, showing the best response to one primary odorant and weak responses to a few chemically related compounds. The most frequently occurring of the 14 types constituted the receptor neurons tuned to (+)-linalool, the enantioselectivity of which was shown by testing two samples with opposite enantiomeric ratios. These neurons, also responding to dihydrolinalool, were found to be functionally similar in the two related species. The primary odorants for 10 other receptor neuron types were identified as (3Z)-hexenyl acetate, (+)-3-carene, trans-pinocarveol, trans-verbenol, vinylbenzaldehyde, 2-phenylethanol, methyl benzoate, alpha-caryophyllene and caryophyllene oxide, respectively. Most odorants were present in several host and non-host plant species, often in trace amounts. The specificity as well as the co-localization of particular neuron types so far recorded in both species showed similarities of the olfactory systems receiving plant odour information in these two species of heliothine moths.
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| 6. |
- Rostelien, T., et al.
(författare)
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Selective receptor neurone responses to E-beta-ocimene, beta-myrcene, E,E-alpha-farnesene and homo-farnesene in the moth Heliothis virescens, identified by gas chromatography linked to electrophysiology
- 2000
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Ingår i: Journal of Comparative Physiology A. Sensory, neural, and behavioral physiology. - : Springer Science and Business Media LLC. - 0340-7594 .- 1432-1351. ; 186:9, s. 833-847
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Tidskriftsartikel (refereegranskat)abstract
- An important question in olfaction is for which odorants receptor neurones have evolved. In the present study, olfactory receptor neurones on the antennae of the tobacco budworm moth Heliothis virescens were screened for sensitivity to naturally occurring plant-produced volatiles by the use of gas chromatography linked to electrophysiology. Volatiles of host as well as non-host: plants collected by headspace techniques were used for stimulating the neurones, sequentially via two columns, one polar and one nonpolar installed in parallel in the gas chromatograph. Three types of neurones presented in this paper responded to one, two or three compounds for which the retention times were determined ill both column types. The chemical structures of the active components were determined on the basis of mass spectrometry linked to gas chromatography, indicating E-beta -ocimene and beta -myrcene as stimulants for neurone type 1, E,E,alpha -farnesene for neurone type 2 and homo-farnesene for neurone type 3. Re-testing authentic materials verified the identifications for the type I neurones. The results demonstrate a high specificity for the three types of neurones by strong responses to one or two structurally similar compounds out of hundreds present in a large variety of plants. The study exemplifies plant odour detection by narrowly tuned receptor neurones in a polyphagous moth species.
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| 7. |
- Rostelien, T., et al.
(författare)
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The plant sesquiterpene germacrene D specifically activates a major type of antennal receptor neuron of the tobacco budworm moth Heliothis virescens
- 2000
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Ingår i: Chemical Senses. - : Oxford University Press (OUP). - 0379-864X .- 1464-3553. ; 25:2, s. 141-148
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Tidskriftsartikel (refereegranskat)abstract
- Plants release hundreds of volatiles that are important in interactions with insects or other organisms. However, knowledge is scarce as to which of the compounds are detected by the organism's olfactory receptor neurons. In the present study, single receptor neurons on the antennae of the tobacco budworm moth, Heliothis virescens, were screened far their sensitivities to naturally produced plant volatiles by the use of gas chromatography linked to electrophysiological recordings from single cells (GC-SCR). Plant volatiles, collected by aeration of host and non-host plants, were tested on each receptor neuron via parallel GC-columns. Thus, simultaneous recordings of the gas chromatogram and the neuron responses to each component were obtained. One type of receptor neuron, appearing in 80% of all experiments, responded with high sensitivity and selectivity to one particular component, present in host as well as non-host mixtures. The component, identified as a sesquiterpene hydrocarbon by linked gas chromatography-mass spectrometry, was isolated from a sesquiterpene fraction of cubebe oil and identified by NMR as germacrene D. The purified compound was then re-tested via gas chromatography on the same receptor neuron type, verifying the identification. A weaker response to another sesquiterpene hydrocarbon was also recorded.
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| 8. |
- Stranden, M., et al.
(författare)
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(-)-germacrene D receptor neurones in three species of heliothine moths : structure-activity relationships
- 2003
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Ingår i: Journal of Comparative Physiology A. Sensory, neural, and behavioral physiology. - : Springer Science and Business Media LLC. - 0340-7594 .- 1432-1351. ; 189:7, s. 563-577
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Tidskriftsartikel (refereegranskat)abstract
- Specificity of olfactory receptor neurones plays an important role in food and host preferences of a species, and may have become conserved or changed in the evolution of polyphagy and oligophagy. We have identified a major type of plant odour receptor neurones responding to the sesquiterpene germacrene D in three species of heliothine moths, the polyphagous Heliothis virescens and Helicoverpa armigera and the oligophagous Helicoverpa assulta. The neurones respond with high sensitivity and selectivity to (-)-germacrene D, as demonstrated by screening via gas chromatography with numerous mixtures of plant volatiles. Germacrene D was present in both host and non-host plants, but only in half of the tested species. The specificity of the neurones was similar in the three species, as shown by the 'secondary' responses to a few other sesquiterpenes. The effect of (-)-germacrene D was about ten times stronger than that of the (+)-enantiomer, which again was about ten times stronger than that of (-)-alpha-ylangene. Weaker effects were obtained for (+)-beta-ylangene, (+)-alpha-copaene, beta-copaene and two unidentified sesquiterpenes. The structure-activity relationship shows that the important properties of (-)-germacrene D in activating the neurones are the ten-membered ring system and the three double bonds acting as electron-rich centres, in addition to the direction of the isopropyl-group responsible for the different effects of the germacrene D enantiomers.
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| 9. |
- Stranden, M., et al.
(författare)
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Receptor neuron discrimination of the germacrene D enantiomers in the moth Helicoverpa armigera
- 2002
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Ingår i: Chemical Senses. - : Oxford University Press (OUP). - 0379-864X .- 1464-3553. ; 27:2, s. 143-152
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Tidskriftsartikel (refereegranskat)abstract
- Plants release complex mixtures of volatiles, including chiral constituents. In the search for the biologically relevant plant odorants, gas chromatography linked to electrophysiological recordings from single receptor neurons has been employed. In heliothine moths, including the females of the Eurasian cotton bollworm moth Helicoverpa armigera, a major type of receptor neurons is identified, showing high sensitivity and selectivity for the sesquiterpene germacrene D. In the present study, gas chromatography with a chiral column linked to single cell recordings were performed. It was found that all germacrene D neurons belonged to one type; all responded to both enantiomers, but (-)-germacrene D had similar to 10 times stronger effect than (+)-germacrene D. Parallel dose-response curves for the two enantiomers were obtained by direct stimulations. The enantiomeric composition of germacrene D, which differed in six plant species and in different individuals of one species, was determined on the basis of the neuron responses. The results, showing the presence of one neuron type for receiving the information about germacrene D in the various plants, suggests that the two enantiomers mediate the same kind of information to the moth, but with different intensity.
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| 10. |
- Stranden, M., et al.
(författare)
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Receptor neurones in three heliothine moths responding to floral and inducible plant volatiles
- 2003
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Ingår i: Chemoecology. - : Springer Science and Business Media LLC. - 0937-7409 .- 1423-0445. ; 13:3, s. 143-154
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Tidskriftsartikel (refereegranskat)abstract
- Some plant volatiles are produced in response to herbivory of several insect species, including heliothine larvae. In the present study of female heliothine moths, four co-located receptor neurone types were identified, of which three types responded strongest to the inducible compounds E-beta-ocimene, E,E-alpha-farnesene and E,E-TMTT, respectively. The fourth type responded strongest to geraniol, which is a common floral volatile. The narrow tuning of each receptor neurone type was demonstrated by responses to a few structurally-related monoterpenes, sesquiterpenes, homo-terpenes and monoterpene alcohols, respectively, out of hundreds of plant constituents tested. The four neurone types showed the same relation of spike amplitudes and ranking of effective compounds in the three heliothine species; the polyphagous Heliothis virescens and Helicoverpa armigera and the oligophagous Helicoverpa assulta. The results indicate the presence of functionally similar types of plant odour-receptor neurones in the three related species, and suggest conservation or reappearance of functionally similar olfactory receptors in related species, independent of the evolution of polyphagy and oligophagy.
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| 11. |
- Ulland, S., et al.
(författare)
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Discrimination between enantiomers of linalool by olfactory receptor neurons in the cabbage moth Mamestra brassicae (L.)
- 2006
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Ingår i: Chemical Senses. - : Oxford University Press (OUP). - 0379-864X .- 1464-3553. ; 31:4, s. 325-334
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Tidskriftsartikel (refereegranskat)abstract
- Plants emit complex blends of volatiles, including chiral compounds that might be detected by vertebrates and invertebrates. Insects are ideal model organisms for studying the underlying receptor neuron mechanisms involved in olfactory discrimination of enantiomers. In the present study, we have employed two-column gas chromatography linked to recordings from single olfactory receptor neurons of Mamestra brassicae, in which separation of volatiles in a polar and a chiral column was performed. We here present the response properties of olfactory receptor neurons tuned to linalool. The narrow tuning of these receptor neurons was demonstrated by their strong responses to (R)-(-)-linalool, the weaker responses to the (+)-enantiomer as well as a few structurally related compounds, and no responses to the other numerous plant released volatiles. The enantioselectivity was verified by parallel dose-response curves, that of (R)-(-)-linalool shifted 1 log unit to the left of the (S)-(+)-linalool curve. A complete overlap of the temporal response pattern was found when comparing the responses of the same strength. Analysis of the spike amplitude and waveform indicated that the responses to the two enantiomers originated from the same neuron.
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| 12. |
- Ulland, S., et al.
(författare)
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Methyl salicylate, identified as primary odorant of a specific receptor neuron type, inhibits oviposition by the moth Mamestra brassicae L. (Lepidoptera, Noctuidae)
- 2008
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Ingår i: Chemical Senses. - : Oxford University Press (OUP). - 0379-864X .- 1464-3553. ; 33:1, s. 35-46
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Tidskriftsartikel (refereegranskat)abstract
- The cabbage moth, Mamestra brassicae L. (Lepidoptera, Noctuidae), is a polyphagous species that is often choosing plants of Brassica as hosts for oviposition. In the search for biologically relevant odorants used by these moths, gas chromatography linked to electrophysiological recordings from single receptor neurons (RNs) has been employed, resulting in classification of distinct types of neurons. This study presents specific olfactory RNs responding to methyl salicylate (MeS) as primary odorant and showing a weak response to methyl benzoate, the 2 aromatic compounds occurring together in several plant species. In 2 cases, the neuron was colocated with another RN type responding to 6 green leaf volatiles: 1-hexanol, (3Z)-hexen-1-ol, (2E)-hexen-1-ol, (3Z)-hexenyl acetate, (2Z)-hexen-1-ol, and an unidentified compound. Whereas the specific RNs detected the minor amounts of MeS in some plants, the compound was not found by gas chromatography linked to mass spectrometry in intact plants, but it was found after herbivore attack. The behavioral effect of MeS was studied in outdoor test arenas with Brassica napus and artificial plants. These experiments indicated that mated M. brassicae females avoid plants with dispensers emitting MeS. As it is induced by caterpillar feeding, this compound may mediate a message to mated M. brassicae females that the plant is already occupied.
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| 13. |
- Ulland, S., et al.
(författare)
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Plant volatiles activating specific olfactory receptor neurons of the cabbage moth Mamestra brassicae L. (Lepidoptera, Noctuidae)
- 2008
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Ingår i: Chemical Senses. - : Oxford University Press (OUP). - 0379-864X .- 1464-3553. ; 33:6, s. 509-522
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Tidskriftsartikel (refereegranskat)abstract
- Herbivore insects are suitable model organisms for studying how plant odor information is encoded in olfactory receptor neurons (RNs). By the use of gas chromatography linked to electrophysiological recordings from single RNs, screening for sensitivity to naturally produced plant odorants is possible in order to determine the molecular receptive ranges of the neurons. Using this method, we have in this study of the cabbage moth, Mamestra brassicae, classified 21 types of olfactory RNs according to their responses to odorants present in the host plants of Brassicae, in the related species of Arabidopsis, as well as in essential oils of nonhost plants like ylang-ylang. Most of the RNs were tuned to one or a few structurally similar compounds, showing minimal overlap of their molecular receptive ranges. Whereas some RNs displayed a novel tuning, others were tuned to the same compounds as neurons in other insect species. We also found colocation in the same sensillum of 3 RN types with the same response characteristics and tuning as 3 colocated types described in heliothine moths living on different host plants. The presence of similar RN types across different insect species implies conservation or reappearance of the RN types, independent of the evolution of host plant ranges.
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