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1.
  • 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. ; 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.
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2.
  • Griffith, Simon C., et al. (författare)
  • Variation in reproductive success across captive populations: Methodological differences, potential biases and opportunities
  • 2017
  • Ingår i: Ethology. - : Wiley-Blackwell. - 1439-0310. ; 123:1, s. 1-29
  • Tidskriftsartikel (refereegranskat)abstract
    • Our understanding of fundamental organismal biology has been disproportionately influenced by studies of a relatively small number of ‘model’ species extensively studied in captivity. Laboratory populations of model species are commonly subject to a number of forms of past and current selection that may affect experimental outcomes. Here, we examine these processes and their outcomes in one of the most widely used vertebrate species in the laboratory – the zebra finch (Taeniopygia guttata). This important model species is used for research across a broad range of fields, partly due to the ease with which it can be bred in captivity. However despite this perceived amenability, we demonstrate extensive variation in the success with which different laboratories and studies bred their subjects, and overall only 64% of all females that were given the opportunity, bred successfully in the laboratory. We identify and review several environmental, husbandry, life-history and behavioural factors that potentially contribute to this variation. The variation in reproductive success across individuals could lead to biases in experimental outcomes and drive some of the heterogeneity in research outcomes across studies. The zebra finch remains an excellent captive animal system and our aim is to sharpen the insight that future studies of this species can provide, both to our understanding of this species and also with respect to the reproduction of captive animals more widely. We hope to improve systematic reporting methods and that further investigation of the issues we raise will lead both to advances in our fundamental understanding of avian reproduction as well as to improvements in future welfare and experimental efficiency.
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3.
  • Mansourian, Suzan (författare)
  • Drosophila Sensory Neuroethology
  • 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.
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4.
  • Mansourian, Suzan, et al. (författare)
  • Wild African Drosophila melanogaster are seasonal specialists on marula fruits
  • 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.
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5.
  • Salmon, Pablo, et al. (författare)
  • Effects of the Urban Environment on Oxidative Stress in Early Life : Insights from a Cross-fostering Experiment
  • 2018
  • Ingår i: Integrative and Comparative Biology. - : Oxford University Press. - 1557-7023. ; , s. 986-994
  • Tidskriftsartikel (refereegranskat)abstract
    • As urban areas expand rapidly worldwide, wildlife is exposed to a wide range of novel environmental stressors, such as increased air pollution and artificial light at night. Birds in highly polluted and/or urbanized habitats have been found to have increased antioxidant protection, which is likely important to avoid accumulation of oxidative damage, which can have negative fitness consequences. Yet, the current knowledge about the ontogeny of antioxidant protection in urban areas is limited; i.e., is the capacity to up-regulate the antioxidant defences already established during pre-natal development, or does it manifest itself during post-natal development? We cross-fostered great tit (Parus major) nestlings within and between urban and rural habitats, to determine if oxidative stress (measured as non-enzymatic total antioxidant capacity, superoxide dismutase (SOD), and plasma lipid peroxidation) is affected by habitat of origin and/or by habitat of rearing. The results demonstrate that being reared in the urban environment triggers an increase in SOD (an intracellular, enzymatic antioxidant) independent of natal habitat. Oxidative damage increased with hatching date in urban-reared nestlings, but there was little seasonal change in rural-reared nestlings. Total antioxidant capacity was neither affected by habitat of rearing or habitat of origin, but we observed a decline with hatching date in both rearing habitats. Taken together, our results support the growing evidence that the urban environment induces a direct plastic adjustment in antioxidant protection, but that up-regulation is not sufficient to avoid increased oxidative damage in late-hatched broods. Future studies should explore the underlying causes for this effect in late-hatched broods and whether it has any negative long-term implications, both at the individual- and the population level.
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6.
  • 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. ; 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.
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7.
  • 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.
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8.
  • Andersson, Stefan (författare)
  • Ecotypic divergence in Crepis tectorum (Asteraceae): inferring trait lability and correlational constraints from hormonally manipulated phenotypes
  • Ingår i: Nordic Journal of Botany. - : Wiley-Blackwell Publishing Ltd. - 1756-1051. ; 37:3
  • Tidskriftsartikel (refereegranskat)abstract
    • Despite long‐standing interest in the evolutionary role of plant hormones, relatively few studies have used hormonally manipulated phenotypes to address questions about phenotypic evolution in plants. In the present investigation, I subjected plants of Crepis tectorum subsp. pumila to simple gibberellin (GA) treatments under both field and greenhouse conditions to assess developmental lability and correlational constraints of phenotypic traits that distinguish this dwarf ecotype from conspecific populations of the much taller weed ecotype (subsp. tectorum). The hormonally manipulated plants largely phenocopied the weed ecotype in leaf shape, plant stature and branching habit, indicative of both high lability and tight integration of traits reflecting gross morphology. Floral size traits sometimes declined after GA application, especially under field conditions. The latter result conflicts with the positive correlations between floral and vegetative size traits seen in previous comparative analyses and point to a tradeoff that could act as a constraint on ecotype divergence. The response to GA was consistent in direction for most traits, as opposed to the magnitude of response, which varied depending on the trait, the population, the growing environment and the timing and level of hormone application. Taken together, the results highlight the potential for simple hormonal changes to cause large, plastic shifts in phenotype, but also illustrate the constrained nature of such influences.
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9.
  • Andreasson, Fredrik, et al. (författare)
  • Experimentally increased nest temperature affects body temperature, growth and apparent survival in blue tit nestlings
  • Ingår i: Journal of Avian Biology. - : Federation of European Neuroscience Societies and Blackwell Publishing Ltd. - 0908-8857. ; 49:2
  • Tidskriftsartikel (refereegranskat)abstract
    • The thermal environment experienced by birds during early postembryonic development may be an important factor shaping growth and survival. However, few studies have directly manipulated nest temperature (T n) during the nestling phase, and none have measured the consequences of experimental heat stress on nestlings’ body temperature (T b). It is therefore not known to what extent any fitness consequences of development in a thermally challenging environment arise as a direct, or indirect, effect of heat stress. We, therefore, studied how experimentally increased T n affected T b in 8–12 d old blue tit Cyanistes caeruleus nestlings, to investigate if increased thermoregulatory demands to maintain normothermic T b influenced nestling growth and apparent long-term survival. Nestlings in heated nest-boxes had significantly higher T b compared to unheated nestlings during most of the experimental period. Yet, despite facing T n  50°C (as measured in the bottom of the nest cup below the nestlings), the highest nestling T b recorded was 43.8°C with nestlings showing evidence of controlled facultative hyperthermia without any increased nestling mortality in heated nests. However, body mass gain was lower in these nestlings compared to nestlings from control nest-boxes. Contrary to our prediction, a larger proportion of nestlings from heated nest-boxes were recaptured during their first winter, or subsequently recruited into the breeding population as first- or second-year breeders. This result should, however, be treated with caution because of low recapture rates. This study highlights the importance of the thermal environment during nestling development, and its role in shaping both growth patterns and possibly also apparent survival.
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10.
  • Arlt, Debora, et al. (författare)
  • Prolonged stopover duration characterises migration strategy and constraints of a long-distance migrant songbird
  • Ingår i: Animal Migration. - : De Gruyter Open. ; 2, s. 47-62
  • Tidskriftsartikel (refereegranskat)abstract
    • Stopover behaviour is a central element of migration strategies. But in recent geolocator studies, despite now being able to track individual songbirds during their entire migration, their stopover behaviour has received little attention. We used light-sensitive geolocators to identify the migratory routes and schedules of 12 northern wheatears (Oenanthe oenanthe) breeding in Sweden. Three geolocators collected temperature data complementing inferences from light data by providing additional information on behaviour during migration. The wheatears performed a slow migration with considerable stopover time (84%/76% of autumn/spring migration), with short stops while traveling through Europe, and a prolonged stopover period in both autumn and spring in the Mediterranean region. Spring migration was faster than autumn migration, mainly because of decreased stopover time. Migration routes and time schedules were similar to those from a German breeding population. Compared to wheatears breeding in Alaska with a three-fold migration distance, Swedish wheatears spent more time during stopovers during autumn and spring migration, suggesting less time constraints and potential flexibility in migration schedules. The finding of prolonged stopovers, similar to other recent geolocator studies, shows that temporary residency periods may be common. This changes our current view on stopover ecology to one where temporary residency periods are part of spatio-temporal strategies optimising resource use during the entire annual cycle.
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