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Abstracts

  1. Magnus Alm Rosenblad
  2. Carl André
  3. Anders Blomberg
  4. Anna Bockelmann
  5. Jackie DeFaveri
  6. Narimane Dorey
  7. Sam Dupont
  8. Per Jonsson
  9. David Kleinhans
  10. Anna-Sara Krång
  11. Scott MacCairns
  12. Helen Nilsson Sköld
  13. Göran Nylund
  14. Olga Ortega-Martinez
  15. Thorsten Reusch
  16. Takahito Shikano


Barnacle pheromones and the first gigabases of genomic sequences

Magnus Alm Rosenblad
Department of Cell and Molecular Biology, University of Gothenburg

The genome sequencing of the barnacle Balanus improvisus has begun and we present the project and some preliminary data. One group of barnacle proteins that are very interesting are pheromones used to attract individuals from the same species to settle close to potential mating partners. Using transcripts from EST libraries to identify partial putative homologues, we have successfully cloned seven genes from two families, one of which sequences have not yet been published.

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Ecotype transcriptomics in Littorina saxatilis
Carl André, Marina Panova and Kerstin Johannesson

Carl André
Department of Marine Ecology, University of Gothenburg

Littorina saxatilis form distinct ecotypes in different habitats on European shores. Snails living in wave-exposed areas are smaller and have a thinner shell, whereas snails in sheltered areas with high densities of predatory crabs typically are larger and more thick-shelled. Breeding experiments show that these ecotype differences are to some extent inherited, but the genes involved are not described.

We used analyses of gene expression to search for genes involved in the ecotype formation. Field-collected snails representing the exposed (E) ecotype and the sheltered “Crab” (S) ecotype from different localities were acclimatized to similar conditions in the lab, and then exposed to either crab smell or used as control. RNA was extracted, converted to cDNA and hybridized against a Nimblegen 12-plex microarray with 26 000 putative genes in L. saxatilis. The genes used can be find in the database LSD at http://mbio-serv2.mbioekol.lu.se/Littorina/. Preliminary analyses show that a high number of genes were differentially expressed in the two ecotypes, but also that many genes are differentially expressed in snails from different localities.

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Genome sequencing of the pennate diatom Surirella brebissonii reveals interesting biological features

Anders Blomberg
Department of Cell and Molecular Biology, University of Gothenburg

The genome of the pennate diatom Surirella brebissoni was sequenced by a shot-gun sequencing approach using Illumina technology. Two different DNA libraries of size 150bp and 3,000bp were paired-end sequenced to roughly 400-fold coverage (total genome sequence information about 40Gbp). In parallel, RNA was extracted and a cDNA library generated for sequencing of the expressed portion of the genome. We find several interesting features that are of relevance for our understanding of the biology of this benthic diatom. In particular, we found evidence for genes/proteins taken part in all aspects of cell-wall synthesis, including silicate transporters, cingulins (silaffin-like proteins) and cytoskeleton components. In addition, we could reconstruct the whole chloroplast genome and comparison to other finished chloroplast revealed many similarities. However, we could also show the first reported intron (group II) - in the petB gene in the chloroplast. We also find evidence for bacterial genomes in our material, and their potential role as symbionts or contaminants will be discussed. 

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Seagrass diseases: Curse or blessing?

Anna Bockelmann
Experimental Ecology, Leibniz-Institute of Marine Sciences, Kiel University

Seagrass beds are among the most threatened and at the same time functionally important communities worldwide. The world largest losses of Zostera marina have been reported as a consequence of wasting disease, an infection with the protist Labyrinthula zosterae. In the 1930s, during one of the most extended epidemic in the marine realm, extended eelgrass beds on both sides of the Atlantic died-off within two years. Recent results show that the wasting disease pathogen is still present in contemporary Z. marina populations of Northern Europe.
Using quantitative PCR with specific ITS-primers, we found 15-fold differences in abundance among sites, and prevalence between 10-65% without any signs of lethal infection. As a next step, we used infection trials to study the interaction between Z. marina leaf growth and decay and L. zosterae infection. Preliminary results suggest that although Z. marina plants quickly develop lesions and reduce growth after infection, L. zosterae concentration is low in leaves formed post-infection, indication that the plants can normally keep infection at a sub-lethal concentration in the longer run. The transition between a commensalistic or even mutualistic and pathogenic behavior may explain the difference between the L. zosterae infection we observe nowadays and the 1930ies epidemic.

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From global to local: genetics of local adaptation in sticklebacks
(Talk 2 from the Helsinki group)

Jacquelin DeFaveri
Ecological Genetics Research Unit - EGRU, Department of Bioscience, University of Helsinki

Classifying functional genetic variation is continuing to advance our understanding of the genetic processes involved in adaptation. By exploring the patterns of divergence and signals of selection at functional loci in paired marine and freshwater populations of threespine sticklebacks (Gasterosteus aculeatus) across their global distribution, we have identified several genes that appear to be important in adaptation to freshwater. By screening these same loci on a local scale in the Baltic Sea - characterized by a steep salinity gradient - we are aiming to identify regions of local adaption and uncover cryptic population structuring in an apparent panmictic and continuous system. Following up with next-gen sequencing approaches will allow us to move beyond single loci and explore genomic regions under divergent selection, and with the aid of common garden experiments we will also investigate divergence at the transcriptomic level.

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Strongylocentrotus droebachiensis’ energy budget under acidified conditions
N. Dorey, P. Lançon, S. Dupont

Narimane Dorey
Department of Marine Ecology, University of Gothenburg

For organisms, energy is found in food and spent in various processes like growth (synthesis of new soft or hard tissues), storage (lipidic or reproductive) and loss (respiration or feces). Energy incomes are not infinite and a lack of energy or an increased demand of it – caused by environmental perturbations – can potentially lead to death or sub-lethal but irreversible damages. Understanding how energy is allocated, how much plasticity is available within the frame of energy re-allocation and how mechanisms underlying energy budgets are driven is a key to understand impacts of future global changes on the ecosystems. In this study, we evaluated the effects of a range of pH (8.1 to 6.5) on the mortality, growth and respiration of the larvae of the sea urchin Strongylocentrotus droebachiensis, a common species of Nordic waters.

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Me, myself and I - cloning and budding in sea urchin larvae
Chan K, Arnberg M, Thorndyke M, Grünbaum D & Dupont S

Sam Dupont
Department of Marine Ecology, University of Gothenburg

Budding and cloning (asexual reproduction) by free-living invertebrate larvae is a rare and enigmatic phenomenon and, although it is known to occur in some taxonomic groups, it has only been detected in sea urchin in 2003 despite more than a century of intensive study (Eaves & Palmer 2003). Cloning can be surprisingly frequent and we will show that under certain environmental conditions (e.g. lack of the relevant chemical cues and/or ocean acidification), budding and cloning can be induced in a vast majority of larvae in the sea urchins Brissopsis lyrifera and Strongylocentrotus purpuratus. This may be a strategy to directly or indirectly reduce metabolism under stress. This presentation will also highlight the importance of hunch and exploration in science.

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Dispersal in the seascape and the potential for local adaptations

Per Jonsson
Department of Marine Ecology, University of Gothenburg

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The role of explicit space in ecological modelling

David Kleinhans
Department of Marine Ecology, University of Gothenburg

The spatial structure of habitats and populations plays an important role in understanding ecological processes, also in the marine environment. Although this fact is known to experimentalists for a long time already, the effort of involving explicit space in models only has been intensified quite recently. This contribution aims to discuss why.

After a general introduction to the topic I focus on two recent examples for including explicit space in modelling: spatially explicit metapopulation models and recent approaches for modelling genetic patterns of species in the Baltic. Based on these examples the perspectives and the limitations of modelling spatially explicit processes relevant for ecological problems are discussed.

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Transition from sea to land: Olfactory functions and adaptations in land hermit crabs

Anna-Sara Krång
Max Planck Institute for Chemical Ecology, Department of Evolutionary Neuroethology, Jena, Germany

Within anomuran Coenobitidae, there are two terrestrial lines; the land hermit crabs, Coenobita sp., and the robber crab, Birgus latro, with various degrees of terrestriality. A successful transition from aquatic to terrestrial life raises dramatically new demands on the chemosensory system and thus, these land crabs represent an excellent opportunity to investigate the effects of the transition from sea to land on the olfactory system. Although Coenobitidae seem to have quite advanced olfactory systems, evidently functional on land, virtually nothing was known about what type of odorants are detected. We combined electrophysiology and behavioural assays to identify biologically active odorants. Our results show that Coenobita is restricted to mainly water soluble carboxylic acids, aldehydes and amines as olfactory stimuli, whereas B. latro has a much broader odour response profile. Interestingly, different chemical groups elicit reverse EAG-responses; a pattern that also appears for the closely related marine hermit crab Pagurus bernhardus. Furthermore, we showed that water vapour is critical for natural and synthetic odorants to induce attraction or avoidance behaviour in Coenobita clypeatus. Strikingly, also the physiological response was found much greater at higher humidity, whereas no such effect appeared in the terrestrial fruit fly Drosophila melanogaster. In conclusion, our results reveal that the Coenobita chemosensory system is restricted to a limited number of water-soluble odorants, and high humidity is most critical for its function.

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Still spanning the genomic-phenomic divide: the ecological genetics and adaptive potential of transcriptomic variation
(Talk 3 from the Helsinki group)

R.J. Scott McCairns
Ecological Genetics Research Unit - EGRU, Department of Bioscience, University of Helsinki

One of the more surprising results emanating from recent advances in high-throughput sequencing is the small fraction of phenotypic variation associated with coding regions in the genome. These results may be influenced by our limited ability to fully quantify the complex, multidimensional phenotype, an apparent ‘phenomics’ lag relative to a genomics revolution. Alternatively, this could speak to the importance of differential gene expression as a major driver of phenotypic variation. Improved knowledge of regulatory networks and more detailed genome annotations will be the ultimate arbiters of this hypothesis, but more traditional ecological genetics analyses may be informative in the interim, particularly in non-model species. In this talk, we explore this perspective by presenting a ‘sneak-peak’ into some of our ongoing and future work exploring transcriptional variation in the threespine stickleback (Gasterosteus aculeatus). In particular, we present results of a large-scale common garden experiment in which we reveal a substantial amount of additive genetic variation in transcriptional-level variation. Additionally, we present recent findings of a novel phenotypic variant which we hypothesise to be a functionally convergent alternative to freshwater adaptation in the face of constrained genetic variation. We share future research plans as a case study for application of transcritpomics data to elucidate alternative pathways to adaptation, when parallel mechanisms appear lacking.

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Telomerase deficiency in a colonial ascidian after prolonged asexual propagation
Nilsson Sköld H, Asplund ME, Wood CA, Bishop JDD

Helen Nilsson Sköld
Department of Marine Ecology, University of Gothenburg

Reporting for the first time evidence for long-term molecular senescence in asexual lineages of a metazoan, and that only passage between sexual generations provides total rejuvenation permitting indefinite propagation and growth. This study suggests one reason sexual reproduction has been evolutionarily maintained in clonal organisms is to provide a mechanism for rejuvenation and genotype immortality in the face of an inevitable molecular senescence.

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Metabolomic assessment of induced and activated chemical defence in the invasive red alga Gracilaria vermiculophylla

Göran Nylund
Department of Marine Ecology, University of Gothenburg

In comparison with terrestrial plants the mechanistic knowledge of chemical defences is poor for marine macroalgae. This restricts our understanding in the chemically mediated interactions that take place between algae and other organisms. Technical advances such as metabolomics, however, enable new approaches towards the characterisation of the chemically mediated interactions of organisms with their environment. We address defence responses in the red alga Gracilaria vermiculophylla using mass spectrometry based metabolomics in combination with bioassays. Being invasive in the north Atlantic this alga is likely to possess chemical defences according to the prediction that well-defended exotics are most likely to become successful invaders in systems dominated by generalist grazers, such as marine macroalgal communities. We investigated the effect of intense herbivore feeding and simulated herbivory by mechanical wounding of the algae. Both processes led to similar changes in the metabolic profile. Feeding experiments with the generalist isopod grazer Idotea baltica showed that mechanical wounding caused a significant increase in grazer resistance. Structure elucidation of the metabolites of which some were up-regulated more than 100 times in the damaged tissue, revealed known and novel eicosanoids as major components. Among these were prostaglandins, hydroxylated fatty acids and arachidonic acid derived conjugated lactones. Bioassays with pure metabolites showed that these eicosanoids are part of the innate defence system of macroalgae, similarly to animal systems. In accordance with an induced defence mechanism application of extracts from wounded tissue caused a significant increase in grazer resistance and the up-regulation of other pathways than in the activated defence. Thus, this study suggests that G. vermiculophylla chemically deters herbivory by two lines of defence, a rapid wound-activated process followed by a slower inducible defence. By unravelling involved pathways using metabolomics this work contributes significantly to the understanding of activated and inducible defences for marine macroalgae.

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Regeneration in the brittle star Amphiura filiformis. The road into becoming a model organism.
Ortega-Martinez O, Dupont S, Burns, G Alm Rosenblad M, Thorndyke M

Olga Ortega-Martinez
Department of Marine Ecology, University of Gothenburg

Brittlestars are keystone benthic ecosystem engineers, reaching high densities with several thousand individuals per square meter. As major food source for flatfish and crayfish, they experiences frequent sublethal predation. In consequence, A. filiformis possesses exceptional regenerative abilities and as an adult, being able to rapidly regenerate complete limbs within 5 weeks.

We study regeneration because it is a significant natural process that combines ecological relevance, sensitivity to environmental stressors and great potential for molecular molecular and cellular research on regenerative medicine.

Genomic information about brittle stars and sea stars until now has been extremely scarce. I will present here our results for the first microarray investigation of gene expression during arm regeneration in the brittle star A. filiformis, together with the preliminary results for the 454 EST sequencing project we have developed. We will show the large-scale gene expression changes associated with the complex process of regeneration with over 50% of the clones measured showing a significant change at some point during the process when compared to non-regenerating arms. Our data give an insight into the molecular control required during the various stages of regeneration from the stem cell rich blastema stage through to the highly differentiated regenerate. This work also forms an important basis for future gene expression investigations in this emerging model of adult regeneration.

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Adaptation to global change: two examples from the base of the marine food web

Thorsten B. H. Reusch
Evolutionary Ecology, Leibniz-Institute for Marine Science Kiel, Germany

Will populations and species adapt to global change? - is a key question in marine ecology and evolutionary biology. I present two examples from the base of the marine food web. In seagrasses, we used a space-for time substitution design to address the transcriptomic correlates of thermal adaptation across southern and northern Zostera marina (eelgrass) populations, exposed to a summer heat wave in a common stress garden. Interestingly, the transcriptomic response only diverged after the stress during recovery, consistent with negative effects on photobiology that only appeared after the 3-week heat wave. While southern genotypes rapidly returned to control gene expression patterns, northern ones reacted very differently and revealed many gene functional groups indicative for protein degradation and novel synthesis. Accordingly, we propose transcriptomic resilience, the return to normal (control) gene expression, as one measure of genotypes and populations to cope with global change associated stress. Phytoplankton species are amenable to more direct tests of evolutionary adaptation owing to short (~1 day) generation times. In an experimental evolution approach using the coccolithophore Emiliania huxleyi, we found adaptation to ocean acidification in both, mono-clonal and multiclonal replicated selection lines after 500 generations of asexual propagation. Interestingly, as correlated traits, calcification was partly restored as a result of adaptation, indicating the potential biogeochemical implications of our findings for the ocean’s potential to sequester excess anthropogenic carbon.

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Identification of genomic signatures of selection using targeted hitchhiking mapping: concepts and applications
(Talk 1 from the Helsinki group)

Takahito Shikano

Hitchhiking mapping is widely used to detect genes and genomic regions involved in adaptive population differentiation. While the great advantage of this approach is that it can be performed using molecular markers alone, the undefined link between phenotype and genotype makes it difficult to understand what kinds of selection pressures have been acting on the genomic regions subject to directional selection. Moreover, thousands of genetic markers are required to scan a whole genome. Alternatively, for an effective screening of the genome and a better understanding of selection pressures, we have conducted hitchhiking mappings targeting a large number of genes with known physiological functions, such as growth, osmoregulation and stress response, in the threespine stickleback (Gasterosteus aculeatus). Our results demonstrate a high incidence of selection on these genes in populations inhabiting heterogeneous environmental conditions, as well as in marine populations. I explain how this approach can be applied to non-model organisms.

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Page Manager: Eva Marie Rödström|Last update: 10/4/2011
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