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OBJECTIVES: We studied the short- and long-term effects of imatinib in hospitalized COVID-19 patients. METHODS: Participants were randomized to receive standard of care (SoC) or SoC with imatinib. Imatinib dosage was 400 mg daily until discharge (max 14 days). Primary outcomes were mortality at 30 days and 1 year. Secondary outcomes included recovery, quality of life and long COVID symptoms at 1 year. We also performed a systematic review and meta-analysis of randomized trials studying imatinib for 30-day mortality in hospitalized COVID-19 patients. RESULTS: We randomized 156 patients (73 in SoC and 83 in imatinib). Among patients on imatinib, 7.2% had died at 30 days and 13.3% at 1 year, and in SoC, 4.1% and 8.2% (adjusted HR 1.35, 95% CI 0.47-3.90). At 1 year, self-reported recovery occurred in 79.0% in imatinib and in 88.5% in SoC (RR 0.91, 0.78-1.06). We found no convincing difference in quality of life or symptoms. Fatigue (24%) and sleep issues (20%) frequently bothered patients at one year. In the meta-analysis, imatinib was associated with a mortality risk ratio of 0.73 (0.32-1.63; low certainty evidence). CONCLUSIONS: The evidence raises doubts regarding benefit of imatinib in reducing mortality, improving recovery and preventing long COVID symptoms in hospitalized COVID-19 patients.
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Tratamento Farmacológico da COVID-19 , COVID-19 , Hospitalização , Mesilato de Imatinib , Qualidade de Vida , SARS-CoV-2 , Humanos , Mesilato de Imatinib/uso terapêutico , Feminino , Masculino , Pessoa de Meia-Idade , COVID-19/mortalidade , Hospitalização/estatística & dados numéricos , Idoso , Resultado do Tratamento , AdultoRESUMO
BACKGROUND: Caring for ageing populations creates new challenges for society. Obstructive pulmonary diseases, asthma and especially COPD, are responsible for considerable morbidity, mortality, and financial costs in the elderly. We present the change in the burden of asthma and COPD in those aged ≥60 years in Finland from 1996 to 2018. METHODS: We collected national register data from 1996 to 2018 from Statistics Finland, Care Register for Health Care, and the Social Insurance Institution. We estimated the prevalence of asthma and severe COPD, use of healthcare, social services, reimbursed inhalation medications, and societal costs. RESULTS: In subjects aged ≥60 years, the prevalence was 8% for asthma with reimbursed medication and 0·7% for severe COPD in 2018. In 1996-2018, total costs increased from 33 M to 58 M (+57%) for asthma and decreased from 38 M to 30 M (-27%) for COPD. Costs per patient decreased for asthma from 720 to 460 (-57%) and remained stable for COPD (2700 in 2018). Potential years of life lost (PYLL) increased in COPD from 5000 to 6400 (+28%) and the number of emergency department visits increased from 3700 to 6000 (+62%). CONCLUSIONS: In a population aged ≥60 years, the total burden caused by asthma decreased but remained stable and high in COPD. PYLL and visits in emergency care increased in COPD.
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Asma , Doença Pulmonar Obstrutiva Crônica , Idoso , Humanos , Doença Pulmonar Obstrutiva Crônica/tratamento farmacológico , Asma/tratamento farmacológico , Asma/epidemiologia , Custos de Cuidados de Saúde , Finlândia/epidemiologiaRESUMO
Copy number variants (CNVs) are a major source of genetic variation and can disrupt genes or affect gene dosage. They are known to be causal or underlie predisposition to various diseases. However, the role of CNVs in inherited breast cancer susceptibility has not been thoroughly investigated. To address this, we performed whole-exome sequencing based analysis of rare CNVs in 98 high-risk Northern Finnish breast cancer cases. After filtering, selected candidate alleles were validated and characterized with a combination of orthogonal methods, including PCR-based approaches, optical genome mapping and long-read sequencing. This revealed three recurrent alterations: a 31 kb deletion co-occurring with a retrotransposon insertion (delins) in RAD52, a 13.4 kb deletion in HSD17B14 and a 64 kb partial duplication of RAD51C. Notably, all these genes encode proteins involved in pathways previously identified as essential for breast cancer development. Variants were genotyped in geographically matched cases and controls (altogether 278 hereditary and 1983 unselected breast cancer cases, and 1229 controls). The RAD52 delins and HSD17B14 deletion both showed significant enrichment among cases with indications of hereditary disease susceptibility. RAD52 delins was identified in 7/278 cases (2.5%, P = 0.034, OR = 2.86, 95% CI = 1.10-7.45) and HSD17B14 deletion in 8/278 cases (2.9%, P = 0.014, OR = 3.28, 95% CI = 1.31-8.23), the frequency of both variants in the controls being 11/1229 (0.9%). This suggests a role for RAD52 and HSD17B14 in hereditary breast cancer susceptibility. The RAD51C duplication was very rare, identified only in 2/278 of hereditary cases and 2/1229 controls (P = 0.157, OR = 4.45, 95% CI = 0.62-31.70). The identification of recurrent CNVs in these genes, and especially the relatively high frequency of RAD52 and HSD17B14 alterations in the Finnish population, highlights the importance of studying CNVs alongside single nucleotide variants when searching for genetic factors underlying hereditary disease predisposition.
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Neoplasias da Mama , Humanos , Feminino , Neoplasias da Mama/genética , Sequenciamento do Exoma , Variações do Número de Cópias de DNA/genética , Predisposição Genética para Doença , 17-Hidroxiesteroide Desidrogenases/genéticaRESUMO
The masking theory states that genes expressed in a haploid stage will be under more efficient selection. In contrast, selection will be less efficient in genes expressed in a diploid stage, where the fitness effects of recessive deleterious or beneficial mutations can be hidden from selection in heterozygous form. This difference can influence several evolutionary processes such as the maintenance of genetic variation, adaptation rate, and genetic load. Masking theory expectations have been confirmed in single-cell haploid and diploid organisms. However, in multicellular organisms, such as plants, the effects of haploid selection are not clear-cut. In plants, the great majority of studies indicating haploid selection have been carried out using male haploid tissues in angiosperms. Hence, evidence in these systems is confounded with the effects of sexual selection and intraspecific competition. Evidence from other plant groups is scarce, and results show no support for the masking theory. Here, we have used a gymnosperm Scots pine megagametophyte, a maternally derived seed haploid tissue, and four diploid tissues to test the strength of purifying selection on a set of genes with tissue-specific expression. By using targeted resequencing data of those genes, we obtained estimates of genetic diversity, the site frequency spectrum of 0-fold and 4-fold sites, and inferred the distribution of fitness effects of new mutations in haploid and diploid tissue-specific genes. Our results show that purifying selection is stronger for tissue-specific genes expressed in the haploid megagametophyte tissue and that this signal of strong selection is not an artifact driven by high expression levels.
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Evolução Biológica , Seleção Genética , Haploidia , Mutação , Diploide , PlantasRESUMO
The genomic landscape of Stone Age Europe was shaped by multiple migratory waves and population replacements, but different regions do not all show similar patterns. To refine our understanding of the population dynamics before and after the dawn of the Neolithic, we generated and analyzed genomic sequence data from human remains of 56 individuals from the Mesolithic, Neolithic, and Eneolithic across Central and Eastern Europe. We found that Mesolithic European populations formed a geographically widespread isolation-by-distance zone ranging from Central Europe to Siberia, which was already established 10,000 years ago. We found contrasting patterns of population continuity during the Neolithic transition: people around the lower Dnipro Valley region, Ukraine, showed continuity over 4000 years, from the Mesolithic to the end of the Neolithic, in contrast to almost all other parts of Europe where population turnover drove this cultural change, including vast areas of Central Europe and around the Danube River.
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Fluxo Gênico , Genoma , Humanos , Europa (Continente) , Europa Oriental , Dinâmica PopulacionalRESUMO
BACKGROUND: We studied asthma, COPD, and asthma-COPD overlap (ACO) to predict mortality in a cohort of Finnish adults with an 18-year follow up. METHODS: A national health examination survey representing Finnish adults aged ≥30 years was performed in 2000-2001. The study cohort included 5922 participants (73.8% of the sample) with all relevant data, including a comprehensive clinical examination and spirometry. These participants were followed continuously from baseline until end of 2018 for total, cardiovascular, cancer, and respiratory mortality through a record linkage. Asthma, COPD, and ACO were defined based on the survey data, including spirometry and register data. There were three separate groups of obstructive subjects (one definition excluding the others). RESULTS: Asthma and COPD were significantly associated with higher total mortality in Cox's model adjusted for sex, age, smoking, education level, BMI, leisure time physical activity, cardiovascular disease, diabetes, and hypertension. Hazard ratios (HR) (95% confidence interval [CI]) for asthma, COPD, and ACO were 1.29 (1.05-1.58), 1.50 (1.20-1.88), and 1.26 (0.97-1.65), respectively. Additionally, asthma (HR 1.47, 95% CI 1.09-1.97) and COPD (HR 1.53, 95% CI 1.08-2.16) were associated with cardiovascular mortality. Although ACO did not predict mortality in the whole cohort, there was a significant association with mortality risk among those with hs-CRP 1-2.99 mg/l. CONCLUSIONS: Asthma or COPD predicts higher total mortality and premature death from cardiovascular diseases.
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Asma , Doenças Cardiovasculares , Diabetes Mellitus , Doença Pulmonar Obstrutiva Crônica , Adulto , Humanos , Seguimentos , Pulmão , FinlândiaRESUMO
TINF2 is a critical subunit of the shelterin complex, which protects and maintains the length of telomeres. Pathogenic missense and truncating TINF2 mutations are causative for dyskeratosis congenita (DC), a rare, dominantly inherited bone marrow failure syndrome characterized by mucocutaneous abnormalities and cancer predisposition. Recent reports indicate that specific TINF2 truncating mutations act as high penetrance cancer predisposition alleles outside DC context, including breast cancer in their tumor spectrum. Here, we have evaluated the role of germline mutations in TINF2 and other shelterin genes in inherited breast cancer susceptibility using exome sequencing data from 98 Northern Finnish breast cancer cases with indication of inherited disease predisposition as a discovery cohort. A single protein truncating variant, TINF2 p.Tyr312Ter, was identified in one of the cases (1/98), and four more carriers were observed in the subsequently genotyped unselected breast cancer cohort (4/1904). None of the carriers were reported to have DC. TINF2 p.Tyr312Ter resulted in stable short form of mRNA transcript, and normal telomere length has been indicated by a recent report. Although recurrent in cases (total of 5/2095), TINF2 p.Tyr312Ter is also present in Finnish population controls (8/12,517), and the observed 4-fold higher frequency in cases falls at most into the range of moderate breast cancer risk alleles (OR 3.74, 95% CI 1.22-11.45, p = 0.029). Current results indicate that not all TINF2 truncating variants are high cancer risk alleles and add further evidence that different TINF2 mutations can have very diverse effects on the disease phenotype.
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Disceratose Congênita , Neoplasias , Humanos , Complexo Shelterina , Telômero/metabolismo , Telômero/patologia , Mutação , Disceratose Congênita/genética , Disceratose Congênita/metabolismo , Disceratose Congênita/patologia , Genótipo , Proteínas de Ligação a Telômeros/genéticaRESUMO
Chronic obstructive pulmonary disease (COPD) is a slowly developing non-communicable disease (NCD), causing non-reversible obstruction and leading to marked morbidity and mortality. Besides traditional risk factors such as smoking, some environmental substances can augment the risk of COPD. The European Human Biomonitoring Initiative (HBM4EU) is a program evaluating citizens' exposure to various environmental substances and their possible health impacts. Within the HBM4EU, eighteen priority substances or substance groups were chosen. In this scoping review, seven of these substances or substance groups are reported to have an association or a possible association with COPD. Main exposure routes, vulnerable and high-exposure risk groups, and matrices where these substances are measured are described. Pesticides in general and especially organophosphate and carbamate insecticides, and some herbicides, lead (Pb), and polycyclic aromatic hydrocarbons (PAHs) showed an association, and cadmium (Cd), chromium (Cr and CrVI), arsenic (As), and diisocyanates, a possible association with COPD and/or decreased lung function. Due to long latency in COPD's disease process, the role of chemical exposure as a risk factor for COPD is probably underestimated. More research is needed to support evidence-based conclusions. Generally, chemical exposure is a growing issue of concern, and prompt action is needed to safeguard public health.
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Praguicidas , Doença Pulmonar Obstrutiva Crônica , Monitoramento Biológico , Exposição Ambiental/efeitos adversos , Exposição Ambiental/análise , Monitoramento Ambiental , Humanos , Praguicidas/toxicidade , Doença Pulmonar Obstrutiva Crônica/induzido quimicamente , Doença Pulmonar Obstrutiva Crônica/epidemiologiaRESUMO
BACKGROUND: In the current century, sleep apnoea has become a significant public health problem due to the obesity epidemic. To increase awareness, improve diagnostics, and improve treatment, Finland implemented a national sleep apnoea programme from 2002 to 2010. Here, we present changes in the societal burden caused by sleep apnoea from 1996 to 2018. METHODS: National register data were collected from the Care Register for Health Care, Statistics Finland, the Social Insurance Institution of Finland, and the Finnish Centre for Pensions. Disease prevalence, use of healthcare and social services, and societal costs were estimated. FINDINGS: The number of sleep apnoea patients increased in secondary care from 8 600 in 1996 to 61 000 in 2018. There was a continuous increase in outpatient visits in secondary care from 9 700 in 1996 to 122 000 in 2018 (1 160%) and in primary care from 10 000 in 2015 to 29 000 in 2018 (190%). Accordingly, the cumulative annual number of days off work for sleep apnoea increased from 1 100 to 46 000. However, disability pensions for sleep apnoea decreased from 820 to 550 (33%) during the observation period. Societal costs per patient decreased over 50% during the observation period (2 800 to 1 200). INTERPRETATION: The number of sleep apnoea patients in Finland increased remarkably during the observation period. To control this burden, diagnostic methods and treatment were revised and follow up was reorganised. Consequently, there was a significant decrease in societal costs per patient. The decrease in disability pensions suggests earlier diagnosis and improved treatment. The national sleep apnoea programme was one of the initiators for these improved outcomes. FUNDING: The Finnish Institute for Health and Welfare and the Hospital District of Helsinki and Uusimaa (HUH), Helsinki, Finland.
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This study focussed on harmful exposures and mental and musculoskeletal symptoms in organic and conventional farming using interview data of Finnish farmers over the winter of 2014-2015. The data consisted of 2,169 full-time farmers, out of whom 231 (11%) practiced organic farming and 1,938 (89%) conventional farming. Exposure to poisonous and irritating substances was less frequent while exposures to vibration and mould ('smell of root cellar') were more frequent on organic farms. Mental and musculoskeletal symptoms were slightly more common among organic farmers, but the associations were not statistically significant in regression modelling. Risk factors for mental symptoms included animal production, hired labour, female gender, constant hurry, working alone, economic uncertainty, and inadequate recovery from workdays. Risk factors for musculoskeletal symptoms included older age, female gender, constant hurry, economic uncertainty, difficult working postures, heavy lifting and carrying, and inadequate recovery. Workload and recovery, managing the transition period and better follow-up of the occupational well-being were identified as concerns among organic farmers. Practitioner summary: Converting from conventional to organic farming has become increasingly common. Farmer interviews indicated that exposure to poisonous and irritating substances was less frequent while exposures to vibration and mould were more frequent on organic farms. Mental and musculoskeletal symptoms and risk factors were similar in both types of farming.
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Fazendeiros , Agricultura Orgânica , Idoso , Agricultura , Animais , Fazendas , Feminino , Humanos , Estações do AnoRESUMO
Pinus sylvestris (Scots pine) is the most widespread coniferous tree in the boreal forests of Eurasia, with major economic and ecological importance. However, its large and repetitive genome presents a challenge for conducting genome-wide analyses such as association studies, genetic mapping and genomic selection. We present a new 50K single-nucleotide polymorphism (SNP) genotyping array for Scots pine research, breeding and other applications. To select the SNP set, we first genotyped 480 Scots pine samples on a 407 540 SNP screening array and identified 47 712 high-quality SNPs for the final array (called 'PiSy50k'). Here, we provide details of the design and testing, as well as allele frequency estimates from the discovery panel, functional annotation, tissue-specific expression patterns and expression level information for the SNPs or corresponding genes, when available. We validated the performance of the PiSy50k array using samples from Finland and Scotland. Overall, 39 678 (83.2%) SNPs showed low error rates (mean = 0.9%). Relatedness estimates based on array genotypes were consistent with the expected pedigrees, and the level of Mendelian error was negligible. In addition, array genotypes successfully discriminate between Scots pine populations of Finnish and Scottish origins. The PiSy50k SNP array will be a valuable tool for a wide variety of future genetic studies and forestry applications.
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Pinus sylvestris , Traqueófitas , Estudo de Associação Genômica Ampla , Genótipo , Pinus sylvestris/genética , Melhoramento Vegetal , Polimorfismo de Nucleotídeo Único/genética , Traqueófitas/genéticaRESUMO
Asthma is one of the most common chronic diseases worldwide affecting all age groups from children to the elderly. In addition to other factors such as smoking, air pollution and atopy, some environmental chemicals are shown or suspected to increase the risk of asthma, exacerbate asthma symptoms and cause other respiratory symptoms. In this scoping review, we report environmental chemicals, prioritized for investigation in the European Human Biomonitoring Initiative (HBM4EU), which are associated or possibly associated with asthma. The substance groups considered to cause asthma through specific sensitization include: diisocyanates, hexavalent chromium Cr(VI) and possibly p-phenylenediamine (p-PDA). In epidemiological studies, polyaromatic hydrocarbons (PAHs) and organophosphate insecticides are associated with asthma, and phthalates, per- and polyfluoroalkyl substances (PFASs), pyrethroid insecticides, mercury, cadmium, arsenic and lead are only potentially associated with asthma. As a conclusion, exposure to PAHs and some pesticides are associated with increased risk of asthma. Diisocyanates and Cr(VI) cause asthma with specific sensitization. For many environmental chemicals, current studies have provided contradicting results in relation to increased risk of asthma. Therefore, more research about exposure to environmental chemicals and risk of asthma is needed.
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Arsênio , Asma , Poluentes Ambientais , Hidrocarbonetos Aromáticos , Praguicidas , Idoso , Asma/induzido quimicamente , Asma/epidemiologia , Monitoramento Biológico , Criança , Exposição Ambiental/efeitos adversos , Exposição Ambiental/análise , Monitoramento Ambiental , Poluentes Ambientais/análise , Poluentes Ambientais/toxicidade , HumanosRESUMO
Arctic and alpine, high latitude and high elevation environments are one of the most stressful environments for species to inhabit. This harshness manifests itself in lower species richness in comparison to more southern vegetation zones (Francis & Currie, 2003). Furthermore, the climatic oscillations-past and predicted-have the most dramatic effect on these ecosystems. For example, in regions of continental ice sheets-the northernmost part of Western Europe and North America-the Arctic species assemblages are no older than a few thousands of years, which is a relatively short period from an evolutionary perspective. Although similar environments may have existed further south during the Ice Age, allowing some preadaptation for the Arctic species, the current habitat is a unique combination of environmental factors such as the climate, soil, bedrock, and photoperiod. Hence, understanding the evolutionary forces shaping Arctic-alpine species will be important for predicting these vulnerable environments' population viability and adaptive potential in the future. In this issue of Molecular Ecology Resources, Nowak et al. (Molecular Ecology Resources) present extensive genome-wide resources for an Arctic-alpine plant Draba nivalis. This adds a valuable new member into the cabbage family models for evolutionary genetics and adaptation studies, to accompany e.g., Arabidopsis (Nature Genetics, 43, 476; Nature, 408, 796), Arabis (Nature Plants, 1, 14023) and Capsella (Nature Genetics, 45, 831). A whole new avenue will open up for molecular ecological studies not only for D. nivalis, but the whole large Draba genus with its diverse ecological and evolutionary characteristics.
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Brassicaceae , Ecossistema , Regiões Árticas , Evolução Biológica , Europa (Continente)RESUMO
Based on earlier studies, farmers have poorer work ability compared to workers in most other occupations. The aim of this study was to explore if organic production has a positive effect on producers' work ability while controlling for demographic and production characteristics. This study used telephone interview data collected by the Finnish Institute of Occupational Health in 2014-2015. The material consisted of 2,164 farmers: 231 in organic production and 1,933 in conventional production. Work ability was measured with a single question regarding the farmers' current work ability compared with their lifetime best on a scale of 0 to 10, with 0 meaning unable to work. The data were analyzed using multivariable logistic regression. Organic production had a negative effect on work ability, while larger farm size, experiencing economic uncertainty rarely/never/occasionally (vs. often), age under 55 years, having occupational health coverage, and experiencing low amounts of physical strain or mental strain had positive effects in a multivariable model. While this study could not consider potential biases from the farmers' existing health status at the time of switching to organic production and other sources, it is clear that greater attention needs to be paid to improving worker health, safety, and wellness in organic farming.
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Fazendeiros , Avaliação da Capacidade de Trabalho , Agricultura , Fazendas , Finlândia , HumanosRESUMO
BACKGROUND: The disability-adjusted life years (DALYs) summarize the burden of years of life lost (YLL) due to premature mortality and years lost due to disability (YLD). Our aim was to estimate the burden of ischemic heart disease (IHD) and chronic obstructive pulmonary disease (COPD) in Finland in 2012, and to examine, how much the YLD are affected by the use of different data sources. METHODS: The YLL were calculated using mortality data for the Finnish 25-74-year-old population in 2012. The YLD were calculated using data from the FINRISK 2012 survey (3041 males, 3383 females aged 25-74 years) and then directly adjusted to the corresponding population. Different administrative registers on 1) hospital inpatient episodes and specialist outpatient visits, 2) entitlement to specially reimbursed medicines, and 3) purchases of prescribed medicines were used for estimation of the YLD in addition to self-reported data. The DALYs were calculated without age-weighting. RESULTS: The YLL for IHD were 37.5 for males and 9.1 for females per 1000 population among 25-74-year-old people in Finland in 2012. The YLD for IHD varied markedly depending on which data sources were used. All data sources combined, the YLD per 1000 were 5.3 for males and 2.5 for females resulting in estimated 42.8 and 11.6 DALYs per 1000 due to IHD among males and females, respectively. For COPD, the YLL were 4.7 for males and 2.0 for females per 1000. Also for COPD, the YLD varied markedly depending on data sources used. The YLD per 1000 based on all data sources combined were 2.0 for males and 1.6 for females. As a result, estimated 6.7 and 3.6 DALYs per 1000 were due to COPD among males and females, respectively. CONCLUSIONS: Especially for COPD, all mild disease cases could probably not be identified from the included registers. Thereby, including survey data improved the coverage of the data. The YLD of IHD and COPD varied markedly between the data sources used in the calculations. However, as YLL constituted a major part of DALYs for these diseases, the variation in YLD did not lead to substantial variation in DALYs.
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Many plants harbor complex mechanisms that promote outcrossing and efficient pollen transfer. These include floral adaptations as well as genetic mechanisms, such as molecular self-incompatibility (SI) systems. The maintenance of such systems over long evolutionary timescales suggests that outcrossing is favorable over a broad range of conditions. Conversely, SI has repeatedly been lost, often in association with transitions to self-fertilization (selfing). This transition is favored when the short-term advantages of selfing outweigh the costs, primarily inbreeding depression. The transition to selfing is expected to have major effects on population genetic variation and adaptive potential, as well as on genome evolution. In the Brassicaceae, many studies on the population genetic, gene regulatory, and genomic effects of selfing have centered on the model plant Arabidopsis thaliana and the crucifer genus Capsella. The accumulation of population genomics datasets have allowed detailed investigation of where, when and how the transition to selfing occurred. Future studies will take advantage of the development of population genetics theory on the impact of selfing, especially regarding positive selection. Furthermore, investigation of systems including recent transitions to selfing, mixed mating populations and/or multiple independent replicates of the same transition will facilitate dissecting the effects of mating system variation from processes driven by demography.
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Brassicaceae/fisiologia , Metagenômica/métodos , Autofertilização , Autoincompatibilidade em Angiospermas , Brassicaceae/genética , Evolução Molecular , Variação Genética , Genética Populacional , Genoma de Planta , Endogamia , Recombinação GenéticaRESUMO
Genetic diversity is shaped by mutation, genetic drift, gene flow, recombination, and selection. The dynamics and interactions of these forces shape genetic diversity across different parts of the genome, between populations and species. Here, we have studied the effects of linked selection on nucleotide diversity in outcrossing populations of two Brassicaceae species, Arabidopsis lyrata and Capsella grandiflora, with contrasting demographic history. In agreement with previous estimates, we found evidence for a modest population size expansion thousands of generations ago, as well as efficient purifying selection in C. grandiflora. In contrast, the A. lyrata population exhibited evidence for very recent strong population size decline and weaker efficacy of purifying selection. Using multiple regression analyses with recombination rate and other genomic covariates as explanatory variables, we can explain 47% of the variance in neutral diversity in the C. grandiflora population, while in the A. lyrata population, only 11% of the variance was explained by the model. Recombination rate had a significant positive effect on neutral diversity in both species, suggesting that selection at linked sites has an effect on patterns of neutral variation. In line with this finding, we also found reduced neutral diversity in the vicinity of genes in the C. grandiflora population. However, in A. lyrata no such reduction in diversity was evident, a finding that is consistent with expectations of the impact of a recent bottleneck on patterns of neutral diversity near genes. This study thus empirically demonstrates how differences in demographic history modulate the impact of selection at linked sites in natural populations.
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Compared to angiosperms, gymnosperms lag behind in the availability of assembled and annotated genomes. Most genomic analyses in gymnosperms, especially conifer tree species, rely on the use of de novo assembled transcriptomes. However, the level of allelic redundancy and transcript fragmentation in these assembled transcriptomes, and their effect on downstream applications have not been fully investigated. Here, we assessed three assembly strategies for short-reads data, including the utility of haploid megagametophyte tissue during de novo assembly as single-allele guides, for six individuals and five different tissues in Pinus sylvestris We then contrasted haploid and diploid tissue genotype calls obtained from the assembled transcriptomes to evaluate the extent of paralog mapping. The use of the haploid tissue during assembly increased its completeness without reducing the number of assembled transcripts. Our results suggest that current strategies that rely on available genomic resources as guidance to minimize allelic redundancy are less effective than the application of strategies that cluster redundant assembled transcripts. The strategy yielding the lowest levels of allelic redundancy among the assembled transcriptomes assessed here was the generation of SuperTranscripts with Lace followed by CD-HIT clustering. However, we still observed some levels of heterozygosity (multiple gene fragments per transcript reflecting allelic redundancy) in this assembled transcriptome on the haploid tissue, indicating that further filtering is required before using these assemblies for downstream applications. We discuss the influence of allelic redundancy when these reference transcriptomes are used to select regions for probe design of exome capture baits and for estimation of population genetic diversity.