| 81. |
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| 82. |
- Larsson, Michael, et al.
(författare)
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Syntheses of the sixteen stereoisomers of 3,7,11-trimethyl-2-tridecanol, including the (2S,3S,7S,11R) and (2S,3S,7S,11S) stereoisomers identified as pheromone precursors in females of the pine sawfly Microdiprion pallipes (Hymenoptera : Diprionidae). : Diprionidae)
- 2001
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Ingår i: European Journal of Organic Chemistry. - 1434-193X .- 1099-0690. ; :2, s. 353-363
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Tidskriftsartikel (refereegranskat)abstract
- All sixteen stereoisomers of 3,7,11-trimethyl-2-tridecanol were synthesised in high stereoisomerical purities (> 95%), for use in the identification of the stereoisomers present in females of the pine sawfly Microdiprion pallipes (Fallen) (Hymenoptera: Diprionidae) as the precursor of the actual sex pheromone (which is the propionate), and also for investigation of the biological activities of the esters. The key step in the syntheses was the coupling of each of the enantiomers of cis-3,4-dimethyl-gamma -butyrolactone with each of the four pure stereoisomers of 1-lithio-2,6-dimethyloctanes. The four corresponding alcohols were obtained by lipase-catalysed (Amano PS) kinetic separation, based on selective acylation of either (2R/S,6S)- or (2R/S,GR)-2,6-dimethyl-1-octanol (obtained from the optically pure enantiomers of citronellal). Additionally, a mixture of the 16 possible stereoisomers of 3,7,11-trimethyl-2-tridecanol was also prepared.
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| 83. |
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| 84. |
- Lassance, Jean-Marc, et al.
(författare)
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Allelic variation in a fatty-acyl reductase gene causes divergence in moth sex pheromones
- 2010
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 466:7305, s. 486-489
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Tidskriftsartikel (refereegranskat)abstract
- Pheromone-based behaviours are crucial in animals from insects to mammals, and reproductive isolation is often based on pheromone differences. However, the genetic mechanisms by which pheromone signals change during the evolution of new species are largely unknown. In the sexual communication system of moths (Insecta: Lepidoptera), females emit a species-specific pheromone blend that attracts males over long distances. The European corn borer, Ostrinia nubilalis, consists of two sex pheromone races, Z and E, that use different ratios of the cis and trans isomers of acetate pheromone components. This subtle difference leads to strong reproductive isolation in the field between the two races, which could represent a first step in speciation. Female sex pheromone production and male behavioural response are under the control of different major genes, but the identity of these genes is unknown. Here we show that allelic variation in a fatty-acyl reductase gene essential for pheromone biosynthesis accounts for the phenotypic variation in female pheromone production, leading to race-specific signals. Both the cis and trans isomers of the pheromone precursors are produced by both races, but the precursors are differentially reduced to yield opposite ratios in the final pheromone blend as a result of the substrate specificity of the enzymes encoded by the Z and E alleles. This is the first functional characterization of a gene contributing to intraspecific behavioural reproductive isolation in moths, highlighting the importance of evolutionary diversification in a lepidopteran-specific family of reductases. Accumulation of substitutions in the coding region of a single biosynthetic enzyme can produce pheromone differences resulting in reproductive isolation, with speciation as a potential end result.
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| 85. |
- Lebreton, Sebastien, et al.
(författare)
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A Drosophila female pheromone elicits species-specific long-range attraction via an olfactory channel with dual specificity for sex and food
- 2017
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Ingår i: BMC Biology. - : Springer Science and Business Media LLC. - 1741-7007. ; 15:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Mate finding and recognition in animals evolves during niche adaptation and involves social signals and habitat cues. Drosophila melanogaster and related species are known to be attracted to fermenting fruit for feeding and egg-laying, which poses the question of whether species-specific fly odours contribute to long-range premating communication. Results: We have discovered an olfactory channel in D. melanogaster with a dual affinity to sex and food odorants. Female flies release a pheromone, (Z)-4-undecenal (Z4-11Al), that elicits flight attraction in both sexes. Its biosynthetic precursor is the cuticular hydrocarbon (Z,Z)-7,11-heptacosadiene (7,11-HD), which is known to afford reproductive isolation between the sibling species D. melanogaster and D. simulans during courtship. Twin olfactory receptors, Or69aB and Or69aA, are tuned to Z4-11Al and food odorants, respectively. They are co-expressed in the same olfactory sensory neurons, and feed into a neural circuit mediating species-specific, long-range communication; however, the close relative D. simulans, which shares food resources with D. melanogaster, does not respond to Z4-11Al. Conclusion: The Or69aA and Or69aB isoforms have adopted dual olfactory traits. The underlying gene yields a collaboration between natural and sexual selection, which has the potential to drive speciation.
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| 86. |
- Liedtke, H. Christoph, et al.
(författare)
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Alarm pheromones and chemical communication in nymphs of the tropical bed bug Cimex hemipterus (Hemiptera: Cimicidae)
- 2011
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 6:3, s. e18156-
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Tidskriftsartikel (refereegranskat)abstract
- The recent resurge of bed bug infestations (Cimex spp.; Cimicidae) and their resistance to commonly used pesticides calls for alternative methods of control. Pheromones play an important role in environmentally sustainable methods for the management of many pest insects and may therefore be applicable for the control of bed bugs. The tropical bed bug, Cimex hemipterus, is a temporary ectoparasite on humans and causes severe discomfort. Compared to the common bed bug, Cimex lectularius, little is known about the chemical signalling and pheromone-based behaviour of the tropical species. Here, we show that the antennal morphology and volatile emission of C. hemipterus closely resembles those of C. lectularius and we test their behavioural responses to conspecific odour emissions. Two major volatiles are emitted by male, female and nymph C. hemipterus under stress, (E)-2-hexenal and (E)-2-octenal. Notably, nymph emissions show contrasting ratios of these compounds to adults and are further characterized by the addition of 4-oxo-(E)-2-hexenal and 4-oxo-(E)-2-octenal. The discovery of this nymph pheromone in C. hemipterus is potentially the cause of a repellent effect observed in the biotests, where nymph odours induce a significantly stronger repellent reaction in conspecifics than adult odours. Our results suggest that pheromone-based pest control methods developed for C. lectularius could be applicable to C. hemipterus, with the unique nymph blend showing promising practical properties.
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| 87. |
- Liénard, Marjorie, et al.
(författare)
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Key biosynthetic gene subfamily recruited for pheromone production prior to the extensive radiation of Lepidoptera
- 2008
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Ingår i: BMC Evolutionary Biology. - : Springer Science and Business Media LLC. - 1471-2148. ; 8:270
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Tidskriftsartikel (refereegranskat)abstract
- Background Moths have evolved highly successful mating systems, relying on species-specific mixtures of sex pheromone components for long-distance mate communication. Acyl-CoA desaturases are key enzymes in the biosynthesis of these compounds and to a large extent they account for the great diversity of pheromone structures in Lepidoptera. A novel desaturase gene subfamily that displays Δ11 catalytic activities has been highlighted to account for most of the unique pheromone signatures of the taxonomically advanced ditrysian species. To assess the mechanisms driving pheromone evolution, information is needed about the signalling machinery of primitive moths. The currant shoot borer, Lampronia capitella, is the sole reported primitive non-ditrysian moth known to use unsaturated fatty-acid derivatives as sex-pheromone. By combining biochemical and molecular approaches we elucidated the biosynthesis paths of its main pheromone component, the (Z,Z)-9,11-tetradecadien-1-ol and bring new insights into the time point of the recruitment of the key Δ11-desaturase gene subfamily in moth pheromone biosynthesis. Results The reconstructed evolutionary tree of desaturases evidenced two ditrysian-specific lineages (the Δ11 and Δ9 (18C>16C)) to have orthologs in the primitive moth L. capitella despite being absent in Diptera and other insect genomes. Four acyl-CoA desaturase cDNAs were isolated from the pheromone gland, three of which are related to Δ9-desaturases whereas the fourth cDNA clusters with Δ11-desaturases. We demonstrated that this transcript (Lca-KPVQ) exclusively accounts for both steps of desaturation involved in pheromone biosynthesis. This enzyme possesses a Z11-desaturase activity that allows transforming the palmitate precursor (C16:0) into (Z)-11-hexadecenoic acid and the (Z)-9-tetradecenoic acid into the conjugated intermediate (Z,Z)-9,11-tetradecadienoic acid. Conclusion The involvement of a single Z11-desaturase in pheromone biosynthesis of a non-ditrysian moth species, supports that the duplication event leading to the origin of the Lepidoptera-specific Δ11-desaturase gene subfamily took place before radiation of ditrysian moths and their divergence from other heteroneuran lineages. Our findings uncover that this novel class of enzymes affords complex combinations of unique unsaturated fatty acyl-moieties of variable chain-lengths, regio- and stereo-specificities since early in moth history and contributes a notable innovation in the early evolution of moth-pheromones.
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| 88. |
- Lindström, Mona, et al.
(författare)
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Synthesis of diastereo- and enantiomerically pure anti-3-methyl-1,4-pentanediol via lipase catalysed acylation : Tetrahedron: Asymmetry
- 2005
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Ingår i: Tetrahedron: Asymmetry. - : Elsevier BV. - 0957-4166. ; 16:7, s. 1355-1360
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Tidskriftsartikel (refereegranskat)abstract
- Racemic trans-4,5-dimethylhydrofuran-2(3H)-one was synthesised from 5-methyl-furan-2(3H)-one, (alpha-angelica lactone). The key reaction in the synthesis was the 1,4-conjugate addition of an organocuprate to 5-methylfuran-2(5H)-one (beta-angelica lactone). Different types of organocuprates were tested with the highest anti:syn ratio of 99.4:0.6 being obtained by the use of a Gilman organocuprate reagent. The enantioselective acylation of racemic 3-methyl-pentan-1,4-diol, catalysed by a variety of lipases in organic media, was investigated. The highest enantioselectivity (E > 400) was obtained when Novozyme 435 was used as the catalyst at a water activity of a(w) similar to 0. Thus, both enantiomers, (3S,4R)- and (3R,4S)-3-methyl-pentan-1,4-diol, were obtained in very high diastereomeric (> 99% de) and enantiomeric purities (> 99.8% and > 97.4% ee, respectively).
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| 89. |
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| 90. |
- Ljunggren, Joel, et al.
(författare)
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Antifungal efficiency of individual compounds and evaluation of non-linear effects by recombining fractionated turpentine
- 2020
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Ingår i: Microchemical journal (Print). - : Elsevier BV. - 0026-265X .- 1095-9149. ; 153
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Tidskriftsartikel (refereegranskat)abstract
- A combination between a reductive and a holistic assay was employed to investigate whole fraction, synergistic, antagonistic and individual compound efficacy of vacuumdistilled turpentine fractions against the economically important brown-rot fungus Coniophora puteana. The fungus was subjected to recombinations of turpentine fractions at a concentration of 1000 ppm. All combinations exhibited useful antifungal properties, but some antifungal mixtures showed a more pronounced effect than the expected level of inhibition. Synergistic effects by a two-fold factor and minor antagonistic effects were observed. Complete growth inhibition of C. puteana was observed by a fraction obtained after distilling 1 L turpentine at 111–177°C (0.5 mbar) as well as by mixing it with another fraction withdrawn at 70–79°C (0.5 mbar). Chemical compositions of distilled fractions were determined through GC–MS analysis and Orthogonal Partial Least Squares (OPLS) multivariate data analysis of GC–MS chromatograms was employed to zoom in on the most active compounds responsible for antifungal activity. Isomers of epicubenol, the hydrocarbon aromatic compound ar-himachalene and α-cadinol are suggested as effective antifungal compounds. In addition, a subsequent fractionation of the most effective fraction was performed with preparatory gas chromatography and subfractions showed similar or better efficacy than previously observed. Our work demonstrates the possibility to retain adequate synergistic antifungal efficiency and offers an opportunity to explore the effects of individual compounds originating from the same crude sample.
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