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Biology subjects

Johansson, A.

Publications and source records attributed to Johansson, A..

6 recordsLinked to original sources

Using synthetic semiochemicals to train canines to detect bark beetle-infested trees

In this proof of concept study, we report the off season training of two detection dogs on a series of synthetic semiochemicals associated with Ips typographus pest bark beetle infestations of spruce trees. Scent detection training allowed dogs to discriminate between physiologically-relevant infestation (target) odours, quantified by GC-MS using extracted ion chromatogram to be bio-active at levels of < 10-4 ng /15 min or lower, and natural non-target odours that might be encountered in the forest. Detection dogs trained to recognize four different synthetic pheromone compounds in the winter time, well before beetle flight, were able to detect natural infested spruce trees unknown to humans the following summer. The trained detection dogs were able to detect an infested spruce tree from the first hour of bark beetle attack until several weeks after the attack. Trained detection dogs appear to be more efficient than humans in detecting early bark beetle infestations because the canines ability to cover a greater area and by olfaction detect infestations from a far greater distance than can humans. Infested spruce trees could be detected by trained detection dogs out to more than 100 m.\n\nKey MessageO_LIDetection dogs were rapidly trained to locate release of synthetic bark beetle pheromone components\nC_LIO_LISynthetics allowed dog training off-season both in laboratory and field\nC_LIO_LIDogs trained on synthetics detected naturally target pest insect attacked trees at a distance of more than 100 m.\nC_LIO_LIThe method allows rapid removal of single, first attacked trees before offspring emergence, thus curbing local pest increase and lowering spread of attacks in the landscap\nC_LI

ecology

Genome-wide association study of body fat distribution identifies novel loci and sex-specific effects

Body mass and body fat composition are of clinical interest due to their links to cardiovascular- and metabolic diseases. Fat stored in the trunk has been suggested as more pathogenic compared to fat stored in other compartments of the body. In this study, we performed genome-wide association studies (GWAS) for the proportion of body fat distributed to the arms, legs and trunk estimated from segmental bio-electrical impedance analysis (sBIA) for 362,499 individuals from the UK Biobank. A total of 97 loci, were identified to be associated with body fat distribution, 40 of which have not previously been associated with an anthropometric trait. A high degree of sex-heterogeneity was observed and associations were primarily observed in females, particularly for distribution of fat to the legs or trunk. Our findings also implicate that body fat distribution in females involves mesenchyme derived tissues and cell types, female endocrine tissues a well as several enzymatically active members of the ADAMTS family of metalloproteinases, which are involved in extracellular matrix maintenance and remodeling.

genetics

Genome-wide association analysis identifies 26 novel loci for asthma, hay fever and eczema

The disease risk for asthma, hay fever and eczema include both environmental and genetic risk factors and the comorbidity between the diseases are large. Heritability estimates suggest that the risk of asthma, hay fever and eczema is largely due to genetic factors. In this GWAS, we include 346,545 Caucasian participants from the UK Biobank to increase power to identify novel loci for asthma, hay fever and eczema. We also investigate if associated lead SNPs have a significantly larger effect for one disease phenotype compared to the other phenotypes, to highlight possible disease specific effects.\n\nThis study identifies 141 loci, of which 41 are novel to this study, to be associated (P[&le;]3x10-8) with asthma, hay fever or eczema, analysed separately or combined as a single phenotype. At four of the novel loci, TNFRSF8, MYRF, TSPAN8, and BHMG1, the lead SNPs were in LD (> 0.8) with potentially casual missense variants. For seven of the novel GWAS loci, the lead SNP was in LD (> 0.8) with genetic variants associated with gene expression (eQTL) where, for example, increased levels of TMEM258 as well as decreased levels of HHEX and ADAM19 was associated with decreased odds for asthma.\n\nOur study shows that a large amount of the genetic contribution to asthma, hay fever and eczema is shared between the diseases. Nonetheless, a number of SNPs have a significantly larger effect on one of the phenotypes suggesting that part of the genetic contribution is more phenotype specific.

genetics

Natural variation at FLOWERING LOCUS T2 mediates local adaptation in a key life history trait in European aspen

BackgroundThe initiation of growth cessation and dormancy represent critical life-history tradeoffs between survival and growth, and have important fitness effects in perennial plants. Such adaptive life history traits often show strong local adaptation along environmental gradients but despite their importance, the genetic architecture of these traits remains poorly understood.\n\nResultsWe integrate whole genome re-sequencing with environmental and phenotypic data from common garden experiments to investigate the genomic basis of local adaptation across a latitudinal gradient in European aspen (Populus tremula). We discover a single genomic region containing the PtFT2 gene that mediates local adaptation in the timing of bud set and that explains 65% of the observed genetic variation in bud set. This locus is the likely target of a recent selective sweep that originated right before or during colonization of northern Scandinavia following the last glaciation. Field and greenhouse experiments confirm that variation in PtFT2 gene expression affect the phenotypic variation in bud set that we observe in wild natural populations.\n\nConclusionsOur results reveal a major effect locus that determine the timing of bud set and that have facilitated rapid adaptation to shorter growing seasons and colder climates in European aspen. The discovery of a single locus explaining a substantial fraction of the variation in a key life history trait is remarkable given that such traits are generally considered to be highly polygenic. These findings provide a dramatic illustration of how loci of large-effect for adaptive traits can arise and be maintained over large geographical scales in natural populations.

evolutionary biology

Breastfeeding And Risk Of Asthma, Hay Fever And Eczema

BackgroundBreastfeeding is commonly proposed to protect against atopic diseases. However, studies aiming to quantify these protective effects have shown conflicting results.\n\nMethodsTo entrench the effects of breastfeeding on risk of asthma, hay fever and eczema, our study included a large study cohort, UK Biobank (N=502,682). Information was collected on whether participants had been breastfeed and on the prevalence of disease. Disease was tested for association with breastfeeding, adjusting or matching for influential covariates.\n\nFindingsA total of 443,068 participants were included in our analyses of which 71{middle dot}2% had been breastfed. The prevalence of asthma was 11{middle dot}4 % and 12{middle dot}7% in the breastfed and non-breastfed groups, and hay fever or eczema (23{middle dot}9% and 24{middle dot}8 % in the two groups respectively. When correcting or matching for potential confounders, we could not see any association between being breastfed and asthma. However, there were increased odds of hay fever and eczema among participants that had been breastfed (P=7{middle dot}78x10-6).\n\nInterpretationThis study reports that breastfeeding is associated with increased odds of hay fever and eczema but it show no evidence for breastfeeding being associated with asthma diagnosis.\n\nFundingThe Swedish Society for Medical Research (SSMF), the Kjell and Marta Beijers Foundation, Goran Gustafssons Foundation, the Swedish Medical Research Council (Project Number 2015-03327), the Marcus Borgstrom Foundation, the [A]ke Wiberg Foundation and the Vleugels Foundation.\n\nEvidence before this studyAtopic diseases affect quality of life for a large part of the human population and pose a very high socio-economic burden. Genetic, environmental, and a number of lifestyle factors influence our risk of developing atopic disorders and high familial prevalence is one of the strongest known risk factors for disease. Several environmental and lifestyle risk factors have already been well established in the scientific community, such as smoking on the risk of developing asthma. Breastfeeding is commonly argued to be protective against atopic diseases. However, studies aiming to quantify these protective effects have shown conflicting results.\n\nAdded value of this studyOur study is, to our knowledge, the largest investigation on how breastfeeding is associated with being diagnosed with asthma, hay fever and eczema at adult age. The study found breastfeeding to be associated with increased odds of being diagnosed with hay fever and eczema during life, while we found no association between breastfeeding and asthma. Our results for hay fever and eczema is in line with the western world hygiene hypothesis, but contradict the general picture of breastfeeding being protective.\n\nImplications of all the available evidenceTo be able to give parents correct advice on lifestyles choices that will protect their kids against atopic diseases, we need to clarify the currently conflicting results on the effect of breastfeeding on risk of atopic diseases. However, these results should not be used to recommend breastfeeding or to discourage it since the present study only investigates the association between breastfeeding history and being diagnosed with asthma, hay fever and eczema during lifetime.\n\nAbbreviations

epidemiology

SweGen: A whole-genome map of genetic variability in a cross-section of the Swedish population

Here we describe the SweGen dataset, a high-quality map of genetic variation in the Swedish population. This data represents a basic resource for clinical genetics laboratories as well as for sequencing-based association studies, by providing information on the frequencies of genetic variants in a cohort that is well matched to national patient cohorts. To select samples for this study, we first examined the genetic structure of the Swedish population using high-density SNP-array data from a nation-wide population based cohort of over 10,000 individuals. From this sample collection, 1,000 individuals, reflecting a cross-section of the population and capturing the main genetic structure, were selected for whole genome sequencing (WGS). Analysis pipelines were developed for automated alignment, variant calling and quality control of the sequencing data. This resulted in a whole-genome map of aggregated variant frequencies in the Swedish population that we hereby release to the scientific community.

genetics