<p>Symbiosis is a widely common phenomenon in nature and has undoubtedly contributed to the evolution of all organisms on earth. Symbiotic associations can be of varying character, such as parasitic or mutualistic, but all imply a close relationship. To study the evolution of genomes of insect endosymbionts, we have sequenced the genomes of the mutualist <i>Buchnera aphidicola</i> from the aphid <i>Schizaphis graminum</i> (Sg) and the reproductive manipulator <i>Wolbachia pipientis</i> strain wRi from <i>Drosophila simulans</i> that show strikingly different evolutionary patterns. </p><p>The comparison between the genome of <i>B.aphidicola</i> (Sg) and the genome of <i>B.aphidicola</i> from the aphid <i>Acyrthosiphon pisum</i> (Ap), that are believed to have diverged 50 million years ago, revealed a perfect gene order conservation and loss of only 14 genes in either of the lineages. In contrast, the rate of nucleotide turnover is very fast probably due to relaxed selection and loss of DNA repair genes. The genomic stasis observed in <i>Buchnera</i> was attributed to the loss of repeats and of the gene <i>recA</i>. </p><p>In striking contrast to the genomes of <i>B.aphidicola</i>, a vast amount of repeats were found in the genome sequence of <i>W.pipientis</i> strain wMel. The comparison between the genomes of <i>W.pipientis</i> strain wRi and <i>W.pipientis</i> strain wMel shows that a lot of rearrangements have occurred since their divergence. The massive amount of repeats might stem from relaxed selection pressure but possibly also from selection to create variability via recombination. </p><p>Comparisons between pairs of genomes from closely related bacteria showed that the stability of gene order and content is connected to an intracellular lifestyle and indicated that homologous recombination between repeats is an important mechanisms for causing intrachromosomal rearrangements. Our studies show that the lifestyle of a bacterium to a great extent shapes the evolution of their genetic material and future capabilities to adapt to new environments.</p>

This thesis deals with effects of climate on tree growth of the dominating conifer species, Picea abies (L) Karst. (Norway spruce) and Pinus sylvestris L (Scots pine), in central Norway and Fennoscandia. Both species are sampled along major environmental gradients, i.e. altitude and oceanicity, and growth responses to climate, i.e. temperature and precipitation, are examined along these gradients. Additionally, time is considered as an environmental gradient and temporal responses are carefully deciphered. Special attention is given to large-scale climate oscillation and their effect on tree growth. In the individual papers the specific aims have been to: 1. identify climate variables (all seasons) with significant influence on radial tree growth of P. abies and P. sylvestris along major environmental gradients (Paper I-IV) 2. identify if and how the growth response to climate has changed through time along these gradients (Paper I-IV) 3. make interregional comparisons of P. sylvestris growth pattern across Fennoscandia from oceanic western Norway to continental eastern Finland (Paper III) 4. analyse to what degree large-scale circulation patterns of air masses are registered in regional tree growth of both P. abies and P. sylvestris (Paper I, III and IV) 5. discuss possible effects on radial tree growth of a predicted warmer climate (Paper I, III and IV)

Essential oils (EO) are plant secondary metabolites that are known for their fragrance and food flavour properties. They consist of a complex mixture of mono- and sesquiterpenes, phenyl propanoids and oxygenated compounds. EOs can be present in different plant organs and materials, and their storage is related to specialised secretory structures. The yield of EOs from plant raw materials by distillation or pressing may on average vary from 0.1 – 1%, thus restricting the major EO production to the plant group of aromatic plants. Due to their function as signalling compounds between different types of organisms and diverse biological systems, their general antimicrobial and antioxidative effects and medicinal activity, EOs offer a promising potential for future applications within the fields of agriculture, medicine, pharmaceutical industry and biotechnology. Changed consumer demands and raised interest in natural product compounds, especially essential oils, have formed the basis for initiating the research project “Norwegian Herb Production (Norsk Urteproduksjon NUP)” to encourage the cultivation, processing, marketing and distribution of aromatic and medicinal plants. The production, composition and quality characteristics of EOs (yield and terpene composition) from chamomile, lemon balm, oregano, peppermint, sachalinmint, thyme and yarrow have been investigated in the project period between 1994-1998. Much focus has been put on the application of solid-phase microextraction (SPME) coupled with gas chromatography-mass spectrometry (GC-MS) for the analysis of EO volatiles from various aromatic and medicinal plants. SPME is a fast, solvent-free and non- destructive sample preparation technique where the analytes are extracted from fluid or solid matrices by headspace (HS) or direct immersion sampling (DI). Apart from EO isolation by common distillation, the applicability and sensitivity of the SPME fibre has made it feasible to carry out qualitative and semi-quantitative HS analyses of aromatic plants with regard to changes of EO metabolism during ontogenesis and plant development. Based on NUP-results from field trials in the period between 1995-1996, the mint species peppermint (Mentha × piperita L.) and sachalinmint (Mentha sachalinensis (Briq.) Kudô) have been studied in detail (Papers B, D and E). Comparative analyses by applying distillation sampling and SPME have been carried out in order to study the advantages and disadvantages of both techniques (Papers B and E). It could be shown, that SPME offers a fast and reliable method for detecting quality-impact compounds from the p-menthane group (menthol, menthone, neomenthol, isomenthone and menthyl acetate). A distinct increase in the menthol/menthone ratio in the basipetal direction could be detected for peppermint and sachalinmint by applying SPME, thus revealing within-plant quality differences according to pharmacopeial requirements. Taking the increase of EO production from the vegetative to the generative growth stage into account, the harvest of mint plants in bloom will result in better EO yield and quality with regard to higher amounts of menthol. When applying HS-SPME on complex EO volatile matrices such as known for yarrow (Achillea millefolium L.; Paper C), one might deal with fibre-partitioning effects of the different mono- and sesquiterpenes due to their physical and chemical properties. Despite these disadvantages, HS-SPME appears to be a sensitive extraction method for the screening of EO volatiles from complex sample matrices. Comparative analyses of volatiles from rose root rhizomes (Rhodiola rosea L.) have been carried out in order to characterize the rose-like odour compounds (Paper F). A total of 75 and 59 compounds have been identified by distillation sampling and HS-SPME, respectively, thus underscoring the excellent extraction properties and applicability of the SPME fibre. Paper A gives a brief overview of EO biosynthesis and chemical structures, plant sources and methods of EO production. Before leading over to the main topic of HS-SPME applications by referring to numerous examples from the research work at The Plant Biocenter in the past 5 years, an introduction of solid-phase microextraction with regard to devices, procedures and extraction parameters is given. The advantages and disadvantages of distillation vs. SPME are outlined on the background of comparative analyses of peppermint, chamomile, basil and dill. Furthermore, the utilization of HS-SPME for quantitative studies with regard to extraction time and analyte concentration is being highlighted. Examples for the screening of chemotypes (hops −Humulus lupulus L.) and cultivars (dill – Anethum graveolens L.) and ontogenetic studies are given (Mentha species; arnica −Arnica montana L.). Finally, the applicability of HS-SPME for the quality assessment of processed herbs (sweet basil −Ocimum basilicum L.) and phytomedicinal preparations (red coneflower – Echinacea purpurea L.) is being discussed. The advantages of HS-SPME over classical distillation and headspace applications are impressive due to drastically reduced analysis time and will introduce new frontiers in plant volatile research with regard to secondary metabolism, plant-insect interactions and in vivo studies. The user-friendliness of operating SPME will initiate the development of future applications and equipment for the monitoring of volatiles for plant biological and environmental studies, extraction automation, on-site sampling and on-fibre storage of analytes. / Paper VI reprinted with kind permission of Elsevier, Sciencedirect, www.sciencedirect.com

The aims of this study were to investigate the effects of known environmental contaminants on defined behavioural variables in fish, and to discuss properties of these behavioural traits that make them useful as potential indicators of pollution. In studying the effects of pollution, the resulting biochemical and physiological alterations are more commonly measured. However, effects of pollution can manifest itself at all levels of biological organisation, including behaviour. In this respect, behaviour can be considered a valid biomarker of pollution in that it is expected to be both susceptible to pollution and of high ecological significance, as it influences the fitness of the affected individuals. This thesis is based on four individual studies, in which the threespine stickleback Gasterosteus aculeatus was used as a model species. Results from these studies show that antipredator behaviour, feeding behaviour, shoaling behaviour, bottom-dwelling behaviour and reproductive behaviour are all sensitive to exposure to sublethal concentrations of defined environmentally relevant chemicals. The results showed that antipredator behaviour and fright response in threespine stickleback were impaired following exposure to sublethal concentrations of bis(tributyltin)oxide (TBTO). However, for some of the tested antipredator variables the effects were reversed after the ending of exposure. Further, it was shown that feeding motivation in fish exposed to butyl benzyl phthalate (BBP) and/or 2,2-bis(p-chlorophenyl)-1,1-dichloroethylene (DDE) was increased in that exposed fish initiated feeding more often than the controls. Exposure to BBP also caused sticklebacks to aggregate into tight shoals and to spend more time at the bottom of the aquarium compared to the control fish. The reported significant differences between the controls and BBPexposed fish with respect to feeding and shoaling behaviour were shown even though the levels of BBP were below the analytical detection limit. Different suggested explanations, for example, too high detection limit, or degradation to its BBP metabolites are given to this result. 17β-Oestradiol (E2) exposed male sticklebacks started nest building later than non-exposed males, but there were no differences between exposed and control males with respect to the number of males that built nests. Further, the exposed males spent less time displaying paternal care compared to the control males, although there were no differences between the two groups in the number of performed courtship displays. Because of the significant effect upon some but not all reproductive behavioural traits, it was suggested that the different variables might vary in sensitivity, implying that a variety of variables should be studied in order to obtain a more reliable evaluation of the effects of pollution. Chemicals can cause deleterious effects at one or more levels of biological organisation, from biochemical, physiological, individual, population and through to the ecosystem levels. In contrast to the established hypothesis that a pollutant affects the different biological levels in an escalating timedependent pattern, starting at the biochemical level, it is here suggested that biomarkers at the biochemical, physiological and behavioural levels often will respond early and simultaneously in the same individual. Whereas some biochemical responses are specifically related to one class of exposure agents and thus may act as specific indicators of pollution, most behavioural traits may be altered in response to a variety of chemicals. One exception may be alterations in reproductive behaviour caused by endocrine disrupting chemicals, due to effects of the chemicals on hormones that result in immediate reproductive behavioural effects. In spite of the specific action of some biochemical biomarkers, they are often considered to be of little ecological relevance since many of them are not related to individual fitness. In this thesis, it is argued that behavioural variables can be employed as useful and reliable biomarkers of environmental contamination. It is also important to focus on behaviour to map and quantify the resposes. However, to reliably evaluate the effects of pollution, behavioural variables should be used in association with biochemical and physiological traits. Moreover, optimal combination of results from laboratory and field experiments would enhance the ecological relevance of the study. / All papers reprinted with kind permission of Elsevier, sciencedirect.com

The pistil, or the gynoecium, is the female reproductive organ of the angiosperm flower and its ontogeny has been studied in the model plant Arabidopsis thaliana. The mature Arabidopsis gynoecium consists of a basal ovary that contains the ovules, a short style and an apical stigma that serves as the site of pollen adherence and germination. This thesis describes the identification and functional characterisation of genes with roles in the regulation of Arabidopsis gynoecium development. Mutant analyses and sequence similarity database searches led to the identification of a small Arabidopsis gene family, denoted the SHI gene family, the ten members of which encode proteins with zinc finger-like motifs. This class of genes is novel and appears to be unique to plants. Double, triple and quadruple mutant analyses revealed that at least six of the SHI-related genes, STY1, STY2, SHI, SRS4, SRS5, and LRP1, redundantly contribute to the formation of stylar and stigmatic tissues in developing gynoecia. Several of the genes appear also to influence carpel fusion and vascular patterning in the gynoecium. Gynoecia of transgenic plants that express STY1 or STY2 constitutively develop ectopic style cells, confirming a role for the genes in the promotion of style formation. STY1, STY2, SHI and SRS5 are expressed in the apical parts of the developing gynoecium and, hence, likely act cell autonomously. As judged from mutant and overexpression analyses, the SHI-related genes appear also to regulate leaf development. Possibly, SHI family members act in concert with the plant growth hormones gibberellin and auxin.

The bacterial origin of mitochondria from an ancient endosymbiosis is now widely accepted and the mitochondrial ancestor is generally believed to belong to the bacterial subdivision α-proteobacteria. The high fraction of mitochondrial proteins encoded in the nucleus has commonly been explained with a massive transfer of genes from the genome of the ancestral mitochondrion. The aim of this work was to get a better understanding of the mitochondrial origin and evolution by comparative genomics and phylogenetic analyses on mitochondria and α-proteobacteria. To this end, we sequenced the genomes of the intracellular parasites Bartonella henselae and Bartonella quintana, the causative agents of cat-scratch disease and trench fever, and compared them with other α-proteobacteria as well as mitochondrial eukaryotes. Our results suggest that the adaptation to an intracellular life-style is coupled to an increased rate of genome degradation and a reduced ability to accommodate environmental changes. Reconstruction of the α-proteobacterial ancestor and phylogenetic analyses of the mitochondrial proteome in yeast revealed that only a small fraction of the proteins used for mitochondrial functions could be traced to the α-proteobacteria. Furthermore, a substantial fraction of the mitochondrial proteins was of eukaryotic origin and while most of the genes of the α-proteobacterial ancestor have been lost, many of those that have been transferred to the nuclear genome seem to encode non-mitochondrial proteins.

No description available.

When the study of this thesis was initiated, hardly any work had been carried out on how plant odour information was encoded by the olfactory RNs in heliothine moths. The method of gas chromatography linked to single cell recordings (GC-SCR) was employed and improved for identifying naturally occurring plant odorants that are detected by single RNs and can be considered as biologically relevant. Three species of the subfamily Heliothinae were included in this work, the two polyphagous H. virescens and H. armigera and the oligophagous H. assulta. The American H. virescens is geographically separated from the other two species. H. armigera and H. assulta are partly sympatric in Asia and Australia. The aims of the thesis elucidated in Papers I-IV were as follows: 1. To identify plant produced volatiles detected by antennal RNs in the three species of the subfamily Heliothinae. 2. To elucidate whether the single RNs can be classified into distinct types according to their specificity. 3. To characterise the plant odour RN types by their molecular receptive ranges, sensitivity and specificity. 4. To compare the specificity of plant odour RN types across the three related species of Heliothinae, with the aim to reveal any differences in the peripheral olfactory system that may have evolved through evolution.

Symbiosis is a widely common phenomenon in nature and has undoubtedly contributed to the evolution of all organisms on earth. Symbiotic associations can be of varying character, such as parasitic or mutualistic, but all imply a close relationship. To study the evolution of genomes of insect endosymbionts, we have sequenced the genomes of the mutualist Buchnera aphidicola from the aphid Schizaphis graminum (Sg) and the reproductive manipulator Wolbachia pipientis strain wRi from Drosophila simulans that show strikingly different evolutionary patterns. The comparison between the genome of B.aphidicola (Sg) and the genome of B.aphidicola from the aphid Acyrthosiphon pisum (Ap), that are believed to have diverged 50 million years ago, revealed a perfect gene order conservation and loss of only 14 genes in either of the lineages. In contrast, the rate of nucleotide turnover is very fast probably due to relaxed selection and loss of DNA repair genes. The genomic stasis observed in Buchnera was attributed to the loss of repeats and of the gene recA. In striking contrast to the genomes of B.aphidicola, a vast amount of repeats were found in the genome sequence of W.pipientis strain wMel. The comparison between the genomes of W.pipientis strain wRi and W.pipientis strain wMel shows that a lot of rearrangements have occurred since their divergence. The massive amount of repeats might stem from relaxed selection pressure but possibly also from selection to create variability via recombination. Comparisons between pairs of genomes from closely related bacteria showed that the stability of gene order and content is connected to an intracellular lifestyle and indicated that homologous recombination between repeats is an important mechanisms for causing intrachromosomal rearrangements. Our studies show that the lifestyle of a bacterium to a great extent shapes the evolution of their genetic material and future capabilities to adapt to new environments.

The tRNALeu (UAA) intron has been recorded in the plastid genome of many algae and land plants and was the first intron to be discovered in cyanobacteria. In all known cases it interrupts the tRNALeu anticodon loop at a conserved position (U-intron-AA). Cyanobacteria are a diverse group of photosynthetic prokaryotes, some involved in symbiotic associations with a wide range of organisms. The most studied associations are those with plants, where strains of Nostoc are the common cyanobacterial partner. In this thesis two aspects of the biology of the cyanobacterial tRNALeu (UAA) intron are focused: first, the use of the intron as a genetic marker for studying the diversity and specificity of two cyanobacterial symbiosis (bryophytes and cycads) and second, the evolutionary patterns of the intron by using the unique data set generated from the diversity analysis. From the studies, many different Nostoc strains are involved in the two symbiotic associations, although no variation was observed within a single bryophyte cavity or cycad coralloid root. Furthermore, a certain level of temporal stability in the cyanobiont composition of the bryophyte population was found and, in the cycad association different coralloid roots from a single specimen may harbor different cyanobacteria. That a minor cyanobiont could have avoided detection is still possible but unlikely. The sequence alignment of the Nostoc tRNALeu (UAA) introns reveals great sequence similarity with size variation only found in the structural element P6b. This element was found to consist of heptanucleotide repeats and of other non-repetitive genetic elements (NIS elements). The sporadic occurrence of the NIS elements indicates recent origins and a mechanism for its dispersal is proposed. In this thesis new insights are given concerning cyanobacterial symbioses and also on the mechanisms involved in the evolution of an old genetic element: the tRNALeu (UAA) intron in cyanobacteria.