| 1. |
- Kulma, Katarzyna, et al.
(författare)
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Malaria-infected female collared flycatchers (Ficedula albicollis) do not pay the cost of late breeding
- 2014
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9:1, s. e85822-
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Tidskriftsartikel (refereegranskat)abstract
- Life-history theory predicts that the trade-off between parasite defense and other costly traits such as reproduction may be most evident when resources are scarce. The strength of selection that parasites inflict on their host may therefore vary across environmental conditions. Collared flycatchers (Ficedula albicollis) breeding on the Swedish island Oland experience a seasonal decline in their preferred food resource, which opens the possibility to test the strength of life-history trade-offs across environmental conditions. We used nested-PCR and quantitative-PCR protocols to investigate the association of Haemosporidia infection with reproductive performance of collared flycatcher females in relation to a seasonal change in the external environment. We show that despite no difference in mean onset of breeding, infected females produced relatively more of their fledglings late in the season. This pattern was also upheld when considering only the most common malaria lineage (hPHSIB1), however there was no apparent link between the reproductive output and the intensity of infection. Infected females produced heavier-than-average fledglings with higher-than-expected recruitment success late in the season. This reversal of the typical seasonal trend in reproductive output compensated them for lower fledging and recruitment rates compared to uninfected birds earlier in the season. Thus, despite different seasonal patterns of reproductive performance the overall number of recruits was the same for infected versus uninfected birds. A possible explanation for our results is that infected females breed in a different microhabitat where food availability is higher late in the season but also is the risk of infection. Thus, our results suggest that another trade-off than the one we aimed to test is more important for explaining variation in reproductive performance in this natural population: female flycatchers appear to face a trade-off between the risk of infection and reproductive success late in the season.
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| 2. |
- Bertrand, Yann, et al.
(författare)
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First Dating of a Recombination Event in Mammalian Tick-borne Flaviviruses
- 2012
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Ingår i: PLoS ONE. - San Francisco : Public Library of Science (PLoS). - 1932-6203. ; 7:2
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Tidskriftsartikel (refereegranskat)abstract
- The mammalian tick-borne flavivirus group (MTBFG) contains viruses associated with important human and animal diseases such as encephalitis and hemorrhagic fever. In contrast to mosquito-borne flaviviruses where recombination events are frequent, the evolutionary dynamic within the MTBFG was believed to be essentially clonal. This assumption was challenged with the recent report of several homologous recombinations within the Tick-borne encephalitis virus (TBEV). We performed a thorough analysis of publicly available genomes in this group and found no compelling evidence for the previously identified recombinations. However, our results show for the first time that demonstrable recombination (i.e., with large statistical support and strong phylogenetic evidences) has occurred in the MTBFG, more specifically within the Louping ill virus lineage. Putative parents, recombinant strains and breakpoints were further tested for statistical significance using phylogenetic methods. We investigated the time of divergence between the recombinant and parental strains in a Bayesian framework. The recombination was estimated to have occurred during a window of 282 to 76 years before the present. By unravelling the temporal setting of the event, we adduce hypotheses about the ecological conditions that could account for the observed recombination.
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| 3. |
- Griesser, Michael, et al.
(författare)
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Understanding Animal Group-Size Distributions
- 2011
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- One of the most striking aspects of animal groups is their remarkable variation in size, both within and between species. While a number of mechanistic models have been proposed to explain this variation, there are few comprehensive datasets against which these models have been tested. In particular, we only vaguely understand how environmental factors and behavioral activities affect group-size distributions. Here we use observations of House sparrows (Passer domesticus) to investigate the factors determining group-size distribution. Over a wide range of conditions, we observed that animal group sizes followed a single parameter distribution known as the logarithmic distribution. This single parameter is the mean group size experienced by a randomly chosen individual (including the individual itself). For sparrows, the experienced mean group size, and hence the distribution, was affected by four factors: morning temperature, place, behavior and the degree of food spillage. Our results further indicate that the sparrows regulate the mean group size they experience, either by groups splitting more or merging less when local densities are high. We suggest that the mean experienced group size provides a simple but general tool for assessing the ecology and evolution of grouping.
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| 4. |
- Elmabsout, Ali Ateia, et al.
(författare)
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Cloning and Functional Studies of a Splice Variant of CYP26B1 Expressed in Vascular Cells
- 2012
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Ingår i: Plos One. - San Francisco, USA : Public Library of Science (PLoS). - 1932-6203. ; 7:5
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Tidskriftsartikel (refereegranskat)abstract
- Background: All-trans retinoic acid (atRA) plays an essential role in the regulation of gene expression, cell growth and differentiation and is also important for normal cardiovascular development but may in turn be involved in cardiovascular diseases, i.e. atherosclerosis and restenosis. The cellular atRA levels are under strict control involving several cytochromes P450 isoforms (CYPs). CYP26 may be the most important regulator of atRA catabolism in vascular cells. The present study describes the molecular cloning, characterization and function of atRA-induced expression of a spliced variant of the CYP26B1 gene. Methodology/Principal Findings: The coding region of the spliced CYP26B1 lacking exon 2 was amplified from cDNA synthesized from atRA-treated human aortic smooth muscle cells and sequenced. Both the spliced variant and full length CYP26B1 was found to be expressed in cultured human endothelial and smooth muscle cells, and in normal and atherosclerotic vessel. atRA induced both variants of CYP26B1 in cultured vascular cells. Furthermore, the levels of spliced mRNA transcript were 4.5 times higher in the atherosclerotic lesion compared to normal arteries and the expression in the lesions was increased 20-fold upon atRA treatment. The spliced CYP26B1 still has the capability to degrade atRA, but at an initial rate one-third that of the corresponding full length enzyme. Transfection of COS-1 and THP-1 cells with the CYP26B1 spliced variant indicated either an increase or a decrease in the catabolism of atRA, probably depending on the expression of other atRA catabolizing enzymes in the cells. Conclusions/Significance: Vascular cells express the spliced variant of CYP26B1 lacking exon 2 and it is also increased in atherosclerotic lesions. The spliced variant displays a slower and reduced degradation of atRA as compared to the full-length enzyme. Further studies are needed, however, to clarify the substrate specificity and role of the CYP26B1 splice variant in health and disease.
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| 5. |
- 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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| 6. |
- Buongermino Pereira, Mariana, 1982, et al.
(författare)
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Differences in the Binding Affinities of ErbB Family: Heterogeneity in the Prediction of Resistance Mutants
- 2013
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203 .- 1932-6203. ; 8:10, s. e77054-
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Tidskriftsartikel (refereegranskat)abstract
- The pressure exerted by drugs targeted to a protein in any therapy inevitably leads to the emergence of drug resistance. One major mechanism of resistance involves the mutation of key residues in the target protein. Drugs that competitively replace a natural substrate are often made ineffective by mutations that reduce the drug’s affinity relative to that of the natural substrate. Hence atomic level understanding of the mechanisms that underlie this behavior is of utmost importance in efforts to design new drugs that can target such mutant proteins. Methods that can predict these mutations before they appear in clinic would be a major advance in the selection of the ppropriate treatment strategy in patients. The present computational approach aims to model this emergence in EGFR and ErbB2 after treatment with the drug lapatinib, by investigating the structural, dynamic and energetic effects on these kinases when bound to the natural substrate ATP andto lapatinib. The study reveals binding modes and subpopulations that are presumably normally cryptic and these have been analyzed extensively here with respect to sites that are predicted to be hotspots for resisting mutations. These positions are compared in the context of currently available data from laboratory-based experiments and mechanistic details, at the atomistic level, of the origin of resistance are developed. The prediction of novel mutations, if validated by their emergence in the clinic, will make these methods as a powerful predictive tool which can be used in the design of new kinase inhibitors.
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| 7. |
- Tedersoo, Leho, et al.
(författare)
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Tidying up international nucleotide sequence databases: ecological, geographical and sequence quality annotation of ITS sequences of mycorrhizal fungi
- 2011
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 6:9
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Tidskriftsartikel (refereegranskat)abstract
- Sequence analysis of the ribosomal RNA operon, particularly the internal transcribed spacer (ITS) region, provides a powerful tool for identification of mycorrhizal fungi. The sequence data deposited in the International Nucleotide Sequence Databases (INSD) are, however, unfiltered for quality and are often poorly annotated with metadata. To detect chimeric and low-quality sequences and assign the ectomycorrhizal fungi to phylogenetic lineages, fungal ITS sequences were downloaded from INSD, aligned within family-level groups, and examined through phylogenetic analyses and BLAST searches. By combining the fungal sequence database UNITE and the annotation and search tool PlutoF, we also added metadata from the literature to these accessions. Altogether 35,632 sequences belonged to mycorrhizal fungi or originated from ericoid and orchid mycorrhizal roots. Of these sequences, 677 were considered chimeric and 2,174 of low read quality. Information detailing country of collection, geographical coordinates, interacting taxon and isolation source were supplemented to cover 78.0%, 33.0%, 41.7% and 96.4% of the sequences, respectively. These annotated sequences are publicly available via UNITE (http://unite.ut.ee/) for downstream biogeographic, ecological and taxonomic analyses. In European Nucleotide Archive (ENA; http://www.ebi.ac.uk/ena/), the annotated sequences have a special link-out to UNITE. We intend to expand the data annotation to additional genes and all taxonomic groups and functional guilds of fungi.
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| 8. |
- Bartels, Pia, et al.
(författare)
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Water transparency drives intra-population divergence in Eurasian perch (Perca fluviatilis)
- 2012
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Ingår i: PLOS ONE. - San Francisco : Public Library of Science (PLoS). - 1932-6203. ; 7:8
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Tidskriftsartikel (refereegranskat)abstract
- Trait combinations that lead to a higher efficiency in resource utilization are important drivers of divergent natural selection and adaptive radiation. However, variation in environmental features might constrain foraging in complex ways and therefore impede the exploitation of critical resources. We tested the effect of water transparency on intra-population divergence in morphology of Eurasian perch (Perca fluviatilis) across seven lakes in central Sweden. Morphological divergence between near-shore littoral and open-water pelagic perch substantially increased with increasing water transparency. Reliance on littoral resources increased strongly with increasing water transparency in littoral populations, whereas littoral reliance was not affected by water transparency in pelagic populations. Despite the similar reliance on pelagic resources in pelagic populations along the water transparency gradient, the utilization of particular pelagic prey items differed with variation in water transparency in pelagic populations. Pelagic perch utilized cladocerans in lakes with high water transparency and copepods in lakes with low water transparency. We suggest that under impaired visual conditions low utilization of littoral resources by littoral perch and utilization of evasive copepods by pelagic perch may lead to changes in morphology. Our findings indicate that visual conditions can affect population divergence in predator populations through their effects on resource utilization.
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| 9. |
- Boberg, Johanna, et al.
(författare)
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Nitrogen and Carbon Reallocation in Fungal Mycelia during Decomposition of Boreal Forest Litter
- 2014
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Ingår i: PLOS ONE. - : Public Library of Science. - 1932-6203. ; 9:3, s. e92897-
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Tidskriftsartikel (refereegranskat)abstract
- Boreal forests are characterized by spatially heterogeneous soils with low N availability. The decomposition of coniferous litter in these systems is primarily performed by basidiomycete fungi, which often form large mycelia with a well-developed capacity to reallocate resources spatially-an advantageous trait in heterogeneous environments. In axenic microcosm systems we tested whether fungi increase their biomass production by reallocating N between Pinus sylvestris (Scots pine) needles at different stages of decomposition. We estimated fungal biomass production by analysing the accumulation of the fungal cell wall compound chitin. Monospecific systems were compared with systems with interspecific interactions. We found that the fungi reallocated assimilated N and mycelial growth away from well-degraded litter towards fresh litter components. This redistribution was accompanied by reduced decomposition of older litter. Interconnection of substrates increased over-all fungal C use efficiency (i.e. the allocation of assimilated C to biomass rather than respiration), presumably by enabling fungal translocation of growth-limiting N to litter with higher C quality. Fungal connection between different substrates also restricted N-mineralization and production of dissolved organic N, suggesting that litter saprotrophs in boreal forest ecosystems primarily act to redistribute rather than release N. This spatial integration of different resource qualities was hindered by interspecific interactions, in which litters of contrasting quality were colonised by two different basidiomycete species. The experiments provide a detailed picture of how resource reallocation in two decomposer fungi leads to a more efficient utilisation of spatially separated resources under N-limitation. From an ecosystem point of view, such economic fungal behaviour could potentially contribute to organic matter accumulation in the litter layers of boreal forests.
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| 10. |
- Brönmark, Christer, et al.
(författare)
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Costs of inducible defence along a resource gradient.
- 2012
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Ingår i: PloS one. - : Public Library of Science (PLoS). - 1932-6203. ; 7:1
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Tidskriftsartikel (refereegranskat)abstract
- In addition to having constitutive defence traits, many organisms also respond to predation by phenotypic plasticity. In order for plasticity to be adaptive, induced defences should incur a benefit to the organism in, for example, decreased risk of predation. However, the production of defence traits may include costs in fitness components such as growth, time to reproduction, or fecundity. To test the hypothesis that the expression of phenotypic plasticity incurs costs, we performed a common garden experiment with a freshwater snail, Radix balthica, a species known to change morphology in the presence of molluscivorous fish. We measured a number of predator-induced morphological and behavioural defence traits in snails that we reared in the presence or absence of chemical cues from fish. Further, we quantified the costs of plasticity in fitness characters related to fecundity and growth. Since plastic responses may be inhibited under limited resource conditions, we reared snails in different densities and thereby levels of competition. Snails exposed to predator cues grew rounder and thicker shells, traits confirmed to be adaptive in environments with fish. Defence traits were consistently expressed independent of density, suggesting strong selection from predatory molluscivorous fish. However, the expression of defence traits resulted in reduced growth rate and fecundity, particularly with limited resources. Our results suggest full defence in predator related traits regardless of resource availability, and costs of defence consequently paid in traits related to fitness.
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