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  • Ding, Baojian, et al. (författare)
  • Sequence variation determining stereochemistry of a delta-11 desaturase active in moth sex pheromone biosynthesis
  • 2016
  • Ingår i: Insect Biochemistry and Molecular Biology. - : Elsevier. - 1879-0240 .- 0965-1748. ; 74, s. 68-75
  • Tidskriftsartikel (refereegranskat)abstract
    • A Δ11 desaturase from the oblique banded leaf roller moth Choristoneura rosaceana takes the saturated myristic acid and produces a mixture of (E)-11-tetradecenoate and (Z)-11-tetradecenoate with an excess of the Z isomer (35:65). A desaturase from the spotted fireworm moth Choristoneura parallela also operates on myristic acid substrate but produces almost pure (E)-11-tetradecenoate. The two desaturases share 92% amino acid identity and 97% amino acid similarity. There are 24 amino acids differing between these two desaturases. We constructed mutations at all of these positions to pinpoint the sites that determine the product stereochemistry. We demonstrated with a yeast functional assay that one amino acid at the cytosolic carboxyl terminus of the protein (258E) is critical for the Z activity of the C. rosaceana desaturase. Mutating the glutamic acid (E) into aspartic acid (D) transforms the C. rosaceana enzyme into a desaturase with C. parallela-like activity, whereas the reciprocal mutation of the C. parallela desaturase transformed it into an enzyme producing an intermediate 64:36 E/Z product ratio. We discuss the causal link between this amino acid change and the stereochemical properties of the desaturase and the role of desaturase mutations in pheromone evolution.
  • Jacobsen Ellerstrand, Simon (författare)
  • Humlorna & konsekvenserna av deras genetik
  • 2022
  • Ingår i: Yrfän. - : Sveriges Entomologiska Förening. - 2002-1151. ; 2022:4, s. 26-30
  • Tidskriftsartikel (populärvet., debatt m.m.)
  • Mansourian, Suzan (författare)
  • Drosophila Sensory Neuroethology
  • 2018
  • Doktorsavhandling (övrigt vetenskapligt)abstract
    • Animals, like humans, need to perceive their surroundings via their senses in order to make sensible behavioral decisions, reproduce successfully, and survive. Animals are equipped with audition, vision, thermosensation, hygrosensation, mechanosensation, magnetoception, gustation, and olfaction, which detects physical and chemical changes in their habitats. Among these senses, olfaction is likely the most ancient sensory modality. Insects, the most abundant and successful group of the animal kingdom, predominantly use olfaction to find food, mates, breeding sites, and to avoid dangers. Moreover, hygrosensation is vital for insects to find a suitable habitat and to avoid risks of dehydration. Our understanding of the molecular, neuronal, and morphological organization of the insect olfactory system is today substantial, in large parts thanks to Drosophila melanogaster (vinegar fly) and the wealth of sophisticated genetic tools available in this classic model system. Our knowledge regarding the functional and molecular basis of insect hygrosensation, is, however, limited. In this thesis, I show that the vinegar fly olfactory system do not detect odor molecules randomly, but capture and process specific odors associated with needs and dangers. I demonstrate how the olfactory system cope with toxic and harmful matters in the natural habitat and I identify an olfactory circuit that mediates repellency towards phenol, which is produced by pathogenic bacteria, predominantly present in carnivore feces. Furthermore, I show that flies have an innate and species-specific ability to find suitable humidity levels, related to their native habitat. Vinegar flies can sense humidity changes in their environment through a trio of ionotropic receptors expressed in the sacculus of the antennae. Although D. melanogaster is known as a generalist, I show that wild populations of D. melanogaster from a mopane forest within the potential ancestral habitat have a strong breeding preference towards marula fruit. This fruit is seasonally abundant, native to Southern Africa, and is presumably the ancestral host of the vinegar fly. I also argue that marula drove the D. melanogaster to become a human commensal. In summary, the research presented in my thesis enhances our understanding of how the olfactory system operates, the behavior of wild flies, and introduces the genetic and neural basis underlying humidity sensation in insects. These findings might lead us to better strategies for controlling insect pests, as well as human disease vectors.
  • Mansourian, Suzan, et al. (författare)
  • Wild African Drosophila melanogaster are seasonal specialists on marula fruits
  • 2018
  • Ingår i: Current Biology. - : Elsevier. - 1879-0445. ; 28:24, s. 3-3968
  • Tidskriftsartikel (refereegranskat)abstract
    • Although the vinegar fly Drosophila melanogaster isarguably the most studied organism on the planet,fundamental aspects of this species’ natural ecologyhave remained enigmatic [1]. We have here investigateda wild population of D. melanogaster from amopane forest in Zimbabwe. We find that these fliesare closely associated with marula fruit (Sclerocaryabirrea) and propose that this seasonally abundantand predominantly Southern African fruit is a keyancestral host of D. melanogaster. Moreover, whenfruiting, marula is nearly exclusively used byD. melanogaster, suggesting that these forest-dwellingD. melanogaster are seasonal specialists, in asimilar manner to, e.g., Drosophila erecta on screwpine cones [2]. We further demonstrate that themain chemicals released by marula activate odorantreceptors that mediate species-specific host choice(Or22a) [3, 4] and oviposition site selection (Or19a)[5]. The Or22a-expressing neurons—ab3A—respondstrongly to the marula ester ethyl isovalerate, a volatilerarely encountered in high amounts in other fruit.We also show that Or22a differs among African populationssampled from a wide range of habitats, inline with a function associated with host fruit usage.Flies from Southern Africa, most of which carry adistinct allele at the Or22a/Or22b locus, have ab3Aneurons that are more sensitive to ethyl isovaleratethan, e.g., European flies. Finally, we discuss thepossibility that marula, which is also a culturallyand nutritionally important resource to humans,may have helped the transition to commensalism inD. melanogaster.
  • Yuvaraj, Jothi Kumar, et al. (författare)
  • Characterization of odorant receptors from a non-ditrysian moth, Eriocrania semipurpurella sheds light on the origin of the sex pheromone receptors in Lepidoptera
  • 2017
  • Ingår i: Molecular biology and evolution. - : Oxford University Press. - 0737-4038 .- 1537-1719. ; 34:11, s. 2733-2746
  • Tidskriftsartikel (refereegranskat)abstract
    • Pheromone receptors (PRs) are essential in moths to detect sex pheromones for mate finding. However, it remainsunknown from which ancestral proteins these specialized receptors arose. The oldest lineages of moths, so-callednon-ditrysian moths, use short-chain pheromone components, secondary alcohols, or ketones, so called Type 0 pheromonesthat are similar to many common plant volatiles. It is, therefore, possible that receptors for these ancestralpheromones evolved from receptors detecting plant volatiles. Hence, we identified the odorant receptors (ORs) from anon-ditrysian moth, Eriocrania semipurpurella (Eriocraniidae, Lepidoptera), and performed functional characterizationof ORs using HEK293 cells. We report the first receptors that respond to Type 0 pheromone compounds; EsemOR3displayed highest sensitivity toward (2S, 6Z)-6-nonen-2-ol, whereas EsemOR5 was most sensitive to the behavioralantagonist (Z)-6-nonen-2-one. These receptors also respond to plant volatiles of similar chemical structures, but withlower sensitivity. Phylogenetically, EsemOR3 and EsemOR5 group with a plant volatile-responding receptor from thetortricid moth Epiphyas postvittana (EposOR3), which together reside outside the previously defined lepidopteran PRclade that contains the PRs from more derived lepidopteran families. In addition, one receptor (EsemOR1) that falls atthe base of the lepidopteran PR clade, responded specifically to b-caryophyllene and not to any other additional plant orpheromone compounds. Our results suggest that PRs for Type 0 pheromones have evolved from ORs that detectstructurally-related plant volatiles. They are unrelated to PRs detecting pheromones inmore derived Lepidoptera, which,in turn, also independently may have evolved a novel function from ORs detecting plant volatiles.
  • Yuvaraj, Jothi K., et al. (författare)
  • Putative ligand binding sites of two functionally characterized bark beetle odorant receptors
  • 2021
  • Ingår i: BMC Biology. - : BioMed Central (BMC). - 1741-7007. ; 19
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Bark beetles are major pests of conifer forests, and their behavior is primarily mediated via olfaction. Targeting the odorant receptors (ORs) may thus provide avenues towards improved pest control. Such an approach requires information on the function of ORs and their interactions with ligands, which is also essential for understanding the functional evolution of these receptors. Hence, we aimed to identify a high-quality complement of ORs from the destructive spruce bark beetle Ips typographus (Coleoptera, Curculionidae, Scolytinae) and analyze their antennal expression and phylogenetic relationships with ORs from other beetles. Using 68 biologically relevant test compounds, we next aimed to functionally characterize ecologically important ORs, using two systems for heterologous expression. Our final aim was to gain insight into the ligand-OR interaction of the functionally characterized ORs, using a combination of computational and experimental methods. Results: We annotated 73 ORs from an antennal transcriptome of I. typographus and report the functional characterization of two ORs (ItypOR46 and ItypOR49), which are responsive to single enantiomers of the common bark beetle pheromone compounds ipsenol and ipsdienol, respectively. Their responses and antennal expression correlate with the specificities, localizations, and/or abundances of olfactory sensory neurons detecting these enantiomers. We use homology modeling and molecular docking to predict their binding sites. Our models reveal a likely binding cleft lined with residues that previously have been shown to affect the responses of insect ORs. Within this cleft, the active ligands are predicted to specifically interact with residues Tyr84 and Thr205 in ItypOR46. The suggested importance of these residues in the activation by ipsenol is experimentally supported through site-directed mutagenesis and functional testing, and hydrogen bonding appears key in pheromone binding. Conclusions: The emerging insight into ligand binding in the two characterized ItypORs has a general importance for our understanding of the molecular and functional evolution of the insect OR gene family. Due to the ecological importance of the characterized receptors and widespread use of ipsenol and ipsdienol in bark beetle chemical communication, these ORs should be evaluated for their potential use in pest control and biosensors to detect bark beetle infestations.
  • Zhang, Dan-Dan, et al. (författare)
  • Receptor for detection of a Type II sex pheromone in the winter moth Operophtera brumata
  • 2016
  • Ingår i: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 6
  • Tidskriftsartikel (refereegranskat)abstract
    • How signal diversity evolves under stabilizing selection in a pheromone-based mate recognitionsystem is a conundrum. Female moths produce two major types of sex pheromones, i.e., long-chainacetates, alcohols and aldehydes (Type I) and polyenic hydrocarbons and epoxides (Type II), alongdifferent biosynthetic pathways. Little is known on how male pheromone receptor (PR) genes evolvedto perceive the different pheromones. We report the identification of the first PR tuned to Type IIpheromones, namely ObruOR1 from the winter moth, Operophtera brumata (Geometridae). ObruOR1clusters together with previously ligand-unknown orthologues in the PR subfamily for the ancestralType I pheromones, suggesting that O. brumata did not evolve a new type of PR to match the novel TypeII signal but recruited receptors within an existing PR subfamily. AsegOR3, the ObruOR1 orthologuepreviously cloned from the noctuid Agrotis segetum that has Type I acetate pheromone components,responded significantly to another Type II hydrocarbon, suggesting that a common ancestor with TypeI pheromones had receptors for both types of pheromones, a preadaptation for detection of Type II sexpheromone.
  • Hedrén, Mikael, et al. (författare)
  • Evolution and systematics of polyploid Nigritella (Orchidaceae)
  • 2018
  • Ingår i: Nordic Journal of Botany. - : Wiley-Blackwell. - 0107-055X. ; 36:3
  • Tidskriftsartikel (refereegranskat)abstract
    • Members of the orchid genus Nigritella are widespread in European mountains, but species circumscriptions and evolutionary patterns in the genus are subjects to conflicting opinions. We analyzed a representative material of Nigritella for differentiation at nuclear and plastid marker loci. In agreement with predictions from embryological studies, diploid members of Nigritella are sexual and mostly out-crossing, whereas triploid, tetraploid and pentaploid members are apomicts. The diploid taxa were poorly differentiated in the investigated molecular markers, except for the western N. gabasiana, which was separated in plastid haplotypes. Polyploid Nigritella aggregate into three groups and within each of these groups apomictic polyploids have given rise to new species. Within the N. nigra group, the tetraploid N. nigra subsp. austriaca is somewhat differentiated from the triploid subsp. nigra at nuclear as well as plastid loci. Fusion of an unreduced egg cell from subsp. nigra with a haploid microgamete from Gymnadenia conopsea gave rise to Gymnigritella runei. Within the N. widderi group, N. archiducis-joannis is poorly separated from N. widderi in molecular markers, and the pentaploid N. buschmanniae has evolved by fusion of an unreduced egg cell from N. widderi with a haploid microgamete from a diploid Nigritella. Within the N. miniata group, N. stiriaca is somewhat differentiated from N. miniata at nuclear loci, but no other segregates of N. miniata are supported at species level. Polyploid Nigritella species accumulate genetic diversity by somatic mutations. In the widespread N. nigra subsp. austriaca and N. miniata this diversity is correlated to geography. Although some polyploids may be of recent origins, each polyploid contain genetic markers no longer encountered in diploid members of the genus. According to plastid marker data, Nigritella and Gymnadenia may constitute monophyletic sister genera.
  • Hedrén, Mikael, et al. (författare)
  • Orchid colonization: multiple parallel dispersal events and mosaic genetic structure in Dactylorhiza majalis ssp. lapponica on the Baltic island of Gotland.
  • 2018
  • Ingår i: Annals of Botany. - : Oxford University Press. - 0305-7364 .- 1095-8290. ; 122:6, s. 1019-1031
  • Tidskriftsartikel (refereegranskat)abstract
    • Background and AimsThe island of Gotland in the Baltic Sea has had no contact with surrounding continental areas since the withdrawal of the Weichselian ice sheet at approx. 17 ka BP. Plants present on Gotland must have arrived by long-distance dispersal, so populations are expected to exhibit reduced levels of genetic diversity compared with populations on surrounding mainlands. However, orchids have very small seeds, which appear well adapted to long-distance dispersal, and they should therefore be less affected than other plant species by colonization bottlenecks. The aim of this study was to analyse the genetic structure of orchids colonizing isolated islands, using the marsh orchid Dactylorhiza majalis ssp. lapponica as a case study.MethodsMore than 500 samples from 27 populations were analysed for 15 plastid and eight nuclear marker loci. Population diversity and differentiation patterns were compared for nuclear and plastid marker systems and analysed in relation to geographical location.Key ResultsWe found high genetic diversity but no clear geographical structure of genetic differentiation between populations on Gotland. However, the between-population differentiation in plastid and nuclear markers were correlated and the greatest diversity was found at sites at comparatively high elevations, which were the first to emerge above the water after the Ice Age.ConclusionsThe regional population on Gotland has been established by a minimum of four dispersal events from continental regions. Subsequent gene flow between sites has not yet homogenized the differentiation pattern originating from initial colonization. We conclude that long-distance seed dispersal in orchids has a strong impact on structuring genetic diversity during periods of expansion and colonization, but contributes less to gene flow between populations once a stable population structure has been achieved.
  • Hellgren, Olof, et al. (författare)
  • Evolution of a cluster of innate immune genes (beta-defensins) along the ancestral lines of chicken and zebra finch
  • 2010
  • Ingår i: Immunome Research. - : OMICS Publishing Group. - 1745-7580. ; 6:3
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND: Avian beta-defensins (AvBDs) represent a group of innate immune genes with broad antimicrobial activity. Within the chicken genome, previous work identified 14 AvBDs in a cluster on chromosome three. The release of a second bird genome, the zebra finch, allows us to study the comparative evolutionary history of these gene clusters between from two species that shared a common ancestor about 100 million years ago.RESULTS: A phylogenetic analysis of the beta-defensin gene clusters in the chicken and the zebra finch identified several cases of gene duplication and gene loss along their ancestral lines. In the zebra finch genome a cluster of 22 AvBD genes were identified, all located within 125 Kbp on chromosome three. Ten of the 22 genes were found to be highly conserved with orthologous genes in the chicken genome. The remaining 12 genes were all located within a cluster of 58 Kbp and are suggested to be a result of recent gene duplication events that occurred after the galliformes- passeriformes split (G-P split). Within the chicken genome, AvBD6 was found to be a duplication of AvBD7, whereas the gene AvDB14 seems to have been lost along the ancestral line of the zebra finch. The duplicated beta-defensin genes have had a significantly higher accumulation of non-synonymous over synonymous substitutions compared to the genes that have not undergone duplication since the G-P split. The expression patterns of avian beta-defensin genes seem to be well conserved between chicken and zebra finch.CONCLUSION: The genomic comparisons of the beta-defensins gene clusters of the chicken and zebra finch illuminate the evolutionary history of this gene complex. Along their ancestral lines, several gene duplication events have occurred in the passerine line after the galliformes-passeriformes split giving rise to 12 novel genes compared to a single duplication event in the galliformes line. After the duplication events, the duplicated genes have been subject to a relaxed selection pressure compared to the non-duplicated genes, thus supporting models of evolution by gene duplication.
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