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1.
Mol Biol Evol ; 40(8)2023 08 03.
Artigo em Inglês | MEDLINE | ID: mdl-37603463

RESUMO

Understanding the evolutionary factors that impact the genetic architecture of traits is a central goal of evolutionary genetics. Here, we investigate how quantitative trait variation accumulated over time in populations that colonized a novel environment. We compare the genetic architecture of flowering time in Arabidopsis populations from the drought-prone Cape Verde Islands and their closest outgroup population from North Africa. We find that trait polygenicity is severely reduced in the island populations compared to the continental North African population. Further, trait architectures and reconstructed allelic histories best fit a model of strong directional selection in the islands in accord with a Fisher-Orr adaptive walk. Consistent with this, we find that large-effect variants that disrupt major flowering time genes (FRI and FLC) arose first, followed by smaller effect variants, including ATX2 L125F, which is associated with a 4-day reduction in flowering time. The most recently arising flowering time-associated loci are not known to be directly involved in flowering time, consistent with an omnigenic signature developing as the population approaches its trait optimum. Surprisingly, we find no effect in the natural population of EDI-Cvi-0 (CRY2 V367M), an allele for which an effect was previously validated by introgression into a Eurasian line. Instead, our results suggest the previously observed effect of the EDI-Cvi-0 allele on flowering time likely depends on genetic background, due to an epistatic interaction. Altogether, our results provide an empirical example of the effects demographic history and selection has on trait architecture.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , África do Norte , Alelos , Arabidopsis/genética , Evolução Biológica , Demografia , Proteínas de Arabidopsis/genética
2.
Mol Biol Evol ; 40(3)2023 03 04.
Artigo em Inglês | MEDLINE | ID: mdl-36788455

RESUMO

Energy production and metabolism are intimately linked to ecological and environmental constraints across the tree of life. In plants, which depend on sunlight to produce energy, the link between primary metabolism and the environment is especially strong. By governing CO2 uptake for photosynthesis and transpiration, leaf pores, or stomata, couple energy metabolism to the environment and determine productivity and water-use efficiency (WUE). Although evolution is known to tune physiological traits to the local environment, we lack knowledge of the specific links between molecular and evolutionary mechanisms that shape this process in nature. Here, we investigate the evolution of stomatal conductance and WUE in an Arabidopsis population that colonized an island with a montane cloud scrubland ecosystem characterized by seasonal drought and fog-based precipitation. We find that stomatal conductance increases and WUE decreases in the colonizing population relative to its closest outgroup population from temperate North Africa. Genome-wide association mapping reveals a polygenic basis of trait variation, with a substantial contribution from a nonsynonymous single-nucleotide polymorphism in MAP KINASE 12 (MPK12 G53R), which explains 35% of the phenotypic variance in WUE in the island population. We reconstruct the spatially explicit evolutionary history of MPK12 53R on the island and find that this allele increased in frequency in the population due to positive selection as Arabidopsis expanded into the harsher regions of the island. Overall, these findings show how adaptation shaped quantitative eco-physiological traits in a new precipitation regime defined by low rainfall and high humidity.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Arabidopsis/genética , Arabidopsis/metabolismo , Ecossistema , Estudo de Associação Genômica Ampla , Proteínas de Arabidopsis/genética , Folhas de Planta , Fotossíntese/genética , Água/metabolismo , Genômica , Secas
3.
Mol Biol Evol ; 38(4): 1498-1511, 2021 04 13.
Artigo em Inglês | MEDLINE | ID: mdl-33247723

RESUMO

Genomic variation in the model plant Arabidopsis thaliana has been extensively used to understand evolutionary processes in natural populations, mainly focusing on single-nucleotide polymorphisms. Conversely, structural variation has been largely ignored in spite of its potential to dramatically affect phenotype. Here, we identify 155,440 indels and structural variants ranging in size from 1 bp to 10 kb, including presence/absence variants (PAVs), inversions, and tandem duplications in 1,301 A. thaliana natural accessions from Morocco, Madeira, Europe, Asia, and North America. We show evidence for strong purifying selection on PAVs in genes, in particular for housekeeping genes and homeobox genes, and we find that PAVs are concentrated in defense-related genes (R-genes, secondary metabolites) and F-box genes. This implies the presence of a "core" genome underlying basic cellular processes and a "flexible" genome that includes genes that may be important in spatially or temporally varying selection. Further, we find an excess of intermediate frequency PAVs in defense response genes in nearly all populations studied, consistent with a history of balancing selection on this class of genes. Finally, we find that PAVs in genes involved in the cold requirement for flowering (vernalization) and drought response are strongly associated with temperature at the sites of origin.


Assuntos
Arabidopsis/genética , Variação Estrutural do Genoma , Seleção Genética , Defesa das Plantas contra Herbivoria/genética , Metabolismo Secundário/genética
4.
Proc Natl Acad Sci U S A ; 114(20): 5213-5218, 2017 05 16.
Artigo em Inglês | MEDLINE | ID: mdl-28473417

RESUMO

Over the past 20 y, many studies have examined the history of the plant ecological and molecular model, Arabidopsis thaliana, in Europe and North America. Although these studies informed us about the recent history of the species, the early history has remained elusive. In a large-scale genomic analysis of African A. thaliana, we sequenced the genomes of 78 modern and herbarium samples from Africa and analyzed these together with over 1,000 previously sequenced Eurasian samples. In striking contrast to expectations, we find that all African individuals sampled are native to this continent, including those from sub-Saharan Africa. Moreover, we show that Africa harbors the greatest variation and represents the deepest history in the A. thaliana lineage. Our results also reveal evidence that selfing, a major defining characteristic of the species, evolved in a single geographic region, best represented today within Africa. Demographic inference supports a model in which the ancestral A. thaliana population began to split by 120-90 kya, during the last interglacial and Abbassia pluvial, and Eurasian populations subsequently separated from one another at around 40 kya. This bears striking similarities to the patterns observed for diverse species, including humans, implying a key role for climatic events during interglacial and pluvial periods in shaping the histories and current distributions of a wide range of species.


Assuntos
Arabidopsis/genética , Genômica/métodos , África , África Subsaariana , Sequência de Bases , Evolução Biológica , Europa (Continente) , Evolução Molecular , Variação Genética/genética , Genética Populacional/métodos , Genoma de Planta/genética , Haplótipos/genética , Filogenia , Análise de Componente Principal
5.
Mol Biol Evol ; 35(3): 564-574, 2018 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-29216397

RESUMO

The study of model organisms on islands may shed light on rare long-range dispersal events, uncover signatures of local evolutionary processes, and inform demographic inference on the mainland. Here, we sequenced the genomes of Arabidopsis thaliana samples from the oceanic island of Madeira. These samples include the most diverged worldwide, likely a result of long isolation on the island. We infer that colonization of Madeira happened between 70 and 85 ka, consistent with a propagule dispersal model (of size ≥10), or with an ecological window of opportunity. This represents a clear example of a natural long-range dispersal event in A. thaliana. Long-term effective population size on the island, rather than the founder effect, had the greatest impact on levels of diversity, and rates of coalescence. Our results uncover a selective sweep signature on the ancestral haplotype of a known translocation in Eurasia, as well as the possible importance of the low phosphorous availability in volcanic soils, and altitude, in shaping early adaptations to the island conditions. Madeiran genomes, sheltered from the complexities of continental demography, help illuminate ancient demographic events in Eurasia. Our data support a model in which two separate lineages of A. thaliana, one originating in Africa and the other from the Caucasus expanded and met in Iberia, resulting in a secondary contact zone there. Although previous studies inferred that the westward expansion of A. thaliana coincided with the spread of human agriculture, our results suggest that it happened much earlier (20-40 ka).

6.
New Phytol ; 219(4): 1194-1198, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-29862511

RESUMO

Contents Summary 1194 I. Introduction 1194 II. Origin of the A. thaliana species 1194 III. The classic model of the history of A. thaliana 1195 IV. New genomic data from outside Eurasia challenge our view of A. thaliana history 1195 V. Conclusions 1197 Acknowledgements 1197 References 1197 SUMMARY: Natural variation in Arabidopsis thaliana has contributed to discoveries in diverse areas of plant biology. While A. thaliana has typically been considered a weed associated primarily with human-mediated environments, including agricultural and urban sites and railways, it has recently been shown that it is also native in remote natural areas, including high altitude sites in Eurasia and Africa, from the Atlas mountains in Morocco to the afro-alpine regions in Eastern and South Africa to Yunnan in China, the Himalayas and the Tibetan Plateau. This finding suggests that while A. thaliana has been extensively studied in Europe and Western Asia there are still many open questions about its population history, genotype-phenotype relationships and mechanisms of adaptation.


Assuntos
Arabidopsis/classificação , Filogenia , Arabidopsis/genética , Genética Populacional , Genoma de Planta , Geografia , Modelos Biológicos
7.
Mol Ecol ; 25(15): 3525-6, 2016 08.
Artigo em Inglês | MEDLINE | ID: mdl-27463237

RESUMO

In recent years, amid growing concerns that changing climate is affecting species distributions and ecosystems, predicting responses to rapid environmental change has become a major goal. In this issue, Franks and colleagues take a first step towards this objective (Franks et al. 2016). They examine genomewide signatures of selection in populations of Brassica rapa after a severe multiyear drought. Together with other authors, Franks had previously shown that flowering time was reduced after this particular drought and that the reduction was genetically encoded. Now, the authors have sequenced previously stored samples to compare allele frequencies before and after the drought and identify the loci with the most extreme shifts in frequencies. The loci they identify largely differ between populations, suggesting that different genetic variants may be responsible for reduction in flowering time in the two populations.


Assuntos
Brassica rapa , Secas , Adaptação Fisiológica , Mudança Climática , Pool Gênico
8.
Mol Ecol ; 24(17): 4348-70, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26184487

RESUMO

Landscape genomics is an emerging research field that aims to identify the environmental factors that shape adaptive genetic variation and the gene variants that drive local adaptation. Its development has been facilitated by next-generation sequencing, which allows for screening thousands to millions of single nucleotide polymorphisms in many individuals and populations at reasonable costs. In parallel, data sets describing environmental factors have greatly improved and increasingly become publicly accessible. Accordingly, numerous analytical methods for environmental association studies have been developed. Environmental association analysis identifies genetic variants associated with particular environmental factors and has the potential to uncover adaptive patterns that are not discovered by traditional tests for the detection of outlier loci based on population genetic differentiation. We review methods for conducting environmental association analysis including categorical tests, logistic regressions, matrix correlations, general linear models and mixed effects models. We discuss the advantages and disadvantages of different approaches, provide a list of dedicated software packages and their specific properties, and stress the importance of incorporating neutral genetic structure in the analysis. We also touch on additional important aspects such as sampling design, environmental data preparation, pooled and reduced-representation sequencing, candidate-gene approaches, linearity of allele-environment associations and the combination of environmental association analyses with traditional outlier detection tests. We conclude by summarizing expected future directions in the field, such as the extension of statistical approaches, environmental association analysis for ecological gene annotation, and the need for replication and post hoc validation studies.


Assuntos
Meio Ambiente , Genética Populacional/métodos , Genômica/métodos , Modelos Genéticos , Adaptação Fisiológica/genética , Alelos , Frequência do Gene , Interação Gene-Ambiente , Genótipo , Modelos Lineares , Modelos Logísticos , Fenótipo , Software , Estatística como Assunto
9.
BMC Pregnancy Childbirth ; 15: 230, 2015 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-26415952

RESUMO

BACKGROUND: Postpartum haemorrhage (PPH) is the leading cause of maternal mortality in low-income countries and severe maternal morbidity in many high-income countries. Poor outcomes following PPH are often attributed to delays in the recognition and treatment of PPH. Experts have suggested that improving the accuracy and reliability of blood loss estimation is the crucial step in preventing death and morbidity from PPH. However, there is little guidance on how this can be achieved. The aim of this integrative review was to evaluate the various methods of assessing maternal blood loss during childbirth. METHODS: A systematic, integrative review of published research studies was conducted. All types of studies were included if they developed, tested, or aimed to improve methods and skills in quantifying blood loss during childbirth, or explored experiences of those involved in the process. RESULTS: Thirty-six studies were included that evaluated the accuracy of visual estimation; tested methods to improve skills in measurement; examined their effect on PPH diagnosis and treatment, and / or explored additional factors associated with blood loss evaluation. The review found that health professionals were highly inaccurate at estimating blood loss as a volume. Training resulted in short term improvements in skills but these were not retained and did not improve clinical outcomes. Multi-faceted interventions changed some clinical practices but did not reduce the incidence of severe PPH or the timing of responses to excessive bleeding. Blood collection bags improved the accuracy of estimation but did not prevent delays or progression to severe PPH. Practitioners commonly used the nature and speed of blood flow, and the condition of the woman to indicate that the blood loss was abnormal. CONCLUSIONS: Early diagnosis of PPH should improve maternal outcomes, but there is little evidence that this can be achieved through improving the accuracy of blood loss volume measurements. The diagnosis may rely on factors other than volume, such as speed of blood flow and nature of loss. A change in direction of future research is required to explore these in more detail.


Assuntos
Trabalho de Parto , Parto , Hemorragia Pós-Parto/diagnóstico , Hemorragia Pós-Parto/fisiopatologia , Determinação do Volume Sanguíneo , Diagnóstico Precoce , Feminino , Humanos , Gravidez , Reprodutibilidade dos Testes
10.
PLoS Genet ; 7(4): e1001375, 2011 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-21533023

RESUMO

Humans inhabit a remarkably diverse range of environments, and adaptation through natural selection has likely played a central role in the capacity to survive and thrive in extreme climates. Unlike numerous studies that used only population genetic data to search for evidence of selection, here we scan the human genome for selection signals by identifying the SNPs with the strongest correlations between allele frequencies and climate across 61 worldwide populations. We find a striking enrichment of genic and nonsynonymous SNPs relative to non-genic SNPs among those that are strongly correlated with these climate variables. Among the most extreme signals, several overlap with those from GWAS, including SNPs associated with pigmentation and autoimmune diseases. Further, we find an enrichment of strong signals in gene sets related to UV radiation, infection and immunity, and cancer. Our results imply that adaptations to climate shaped the spatial distribution of variation in humans.


Assuntos
Clima , Genética Populacional , Genoma Humano , Estudo de Associação Genômica Ampla , Polimorfismo de Nucleotídeo Único , Seleção Genética , Aclimatação , Frequência do Gene , Humanos , Temperatura , Raios Ultravioleta
11.
J Craniomaxillofac Surg ; 52(4): 406-412, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38448336

RESUMO

Restrictions to traditional face-to-face meetings were mandated by many government authorities during the COVID-19 pandemic, impacting the delivery of educational training sessions for maxillofacial surgery trainees in the traditional group manner. An online survey was designed to review what effect the pandemic had on the use and uptake of online educational sources amongst a representative cohort of maxillofacial surgery trainees in higher specialist training. Their attitudes and satisfaction with online resources were considered. The use of live sources such as webinars and pre-recorded materials (e.g. YouTube videos) was investigated. Engagement with online sources was considered prior to, and then during the pandemic. Alterations in the behaviour of trainees were demonstrated, with increasing online resource use seen once the COVID-19 pandemic took hold. Online pre-recorded resource use increased by 26% during the pandemic, with the median number of hours watched per month increasing from 1-5 h to 5-10 h (p < 0.001). Engagement with live online sources (webinars) increased by 52% and median time watched increased from 15 h per month to 10-20 h per month (p < 0.001). Trainees expressed satisfaction with the quality and flexibility of the resources. There was a firmly positive response to live webinars with regard to teaching quality, audio and video quality, ease of access and relevance to training needs. Pre-recorded and live online resources may prove a useful alternative or adjunct to face-to-face teaching when regulations limit or restrict social interactions.


Assuntos
COVID-19 , Cirurgia Bucal , Humanos , COVID-19/epidemiologia , COVID-19/prevenção & controle , SARS-CoV-2 , Pandemias/prevenção & controle , Currículo
12.
Women Birth ; 37(1): 15-50, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-37648619

RESUMO

BACKGROUND: In the United Kingdom (UK), a critical shortage of midwives puts pressure on the already overworked midwives working in maternity services. Considering the challenges that midwives in the UK face, this rapid review was conducted to inform a larger-scale initiative to improve the working conditions of midwives in an acute NHS Trust in the Midlands area of the UK. OBJECTIVE: To describe midwives' perceptions and experiences of positive practice environments. METHODS: A search strategy to identify literature about midwives' perceptions and experiences of positive practice environments was conducted in Medline, CINAHL Plus and Embase databases. Literature screening was conducted independently in two steps using an eligibility tool. The articles' quality assessment was conducted using the Mixed Method Appraisal Tool. Data were extracted using the Job Quality framework and managed using NVivo12. RESULTS: Seventy articles were included in this review. Midwives' working conditions can be improved in all seven areas of the Job Quality framework. Most articles in the review reported the negative aspects of midwives' working environments, making it challenging for the team to define a positive practice environment for midwives. Despite this, authors discuss that a positive practice environment is at least sustained by ensuring midwives' ability to provide care; providing good employment conditions; developing respectful organisations; and increasing team resources, such as those that improve team resilience. CONCLUSIONS: Midwives' working conditions are universally challenging. Failure to address the situation will compromise recruitment and retention, increasing the shortage of midwives. Provision of safe and respectful care appears to be directly linked to midwives' safe and respectful working conditions.


Assuntos
Tocologia , Enfermeiros Obstétricos , Gravidez , Feminino , Humanos , Reino Unido , Pesquisa Qualitativa
13.
Proc Natl Acad Sci U S A ; 107 Suppl 2: 8924-30, 2010 May 11.
Artigo em Inglês | MEDLINE | ID: mdl-20445095

RESUMO

Human populations use a variety of subsistence strategies to exploit an exceptionally broad range of ecoregions and dietary components. These aspects of human environments have changed dramatically during human evolution, giving rise to new selective pressures. To understand the genetic basis of human adaptations, we combine population genetics data with ecological information to detect variants that increased in frequency in response to new selective pressures. Our approach detects SNPs that show concordant differences in allele frequencies across populations with respect to specific aspects of the environment. Genic and especially nonsynonymous SNPs are overrepresented among those most strongly correlated with environmental variables. This provides genome-wide evidence for selection due to changes in ecoregion, diet, and subsistence. We find particularly strong signals associated with polar ecoregions, with foraging, and with a diet rich in roots and tubers. Interestingly, several of the strongest signals overlap with those implicated in energy metabolism phenotypes from genome-wide association studies, including SNPs influencing glucose levels and susceptibility to type 2 diabetes. Furthermore, several pathways, including those of starch and sucrose metabolism, are enriched for strong signals of adaptations to a diet rich in roots and tubers, whereas signals associated with polar ecoregions are overrepresented in genes associated with energy metabolism pathways.


Assuntos
Adaptação Fisiológica , Dieta , Frequência do Gene , Animais , Evolução Biológica , Ecologia , Genética Populacional , Haplótipos , Homozigoto , Humanos , Modelos Biológicos , Modelos Genéticos , Seleção Genética
14.
Mol Biol Evol ; 28(1): 601-14, 2011 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-20802238

RESUMO

Production of heat via nonshivering thermogenesis (NST) is critical for temperature homeostasis in mammals. Uncoupling protein UCP1 plays a central role in NST by uncoupling the proton gradients produced in the inner membranes of mitochondria to produce heat; however, the extent to which UCP1 homologues, UCP2 and UCP3, are involved in NST is the subject of an ongoing debate. We used an evolutionary approach to test the hypotheses that variants that are associated with increased expression of these genes (UCP1 -3826A, UCP2 -866A, and UCP3 -55T) show evidence of adaptation with winter climate. To that end, we calculated correlations between allele frequencies and winter climate variables for these single-nucleotide polymorphisms (SNPs), which we genotyped in a panel of 52 worldwide populations. We found significant correlations with winter climate for UCP1 -3826G/A and UCP3 -55C/T. Further, by analyzing previously published genotype data for these SNPs, we found that the peak of the correlation for the UCP1 region occurred at the disease-associated -3826A/G variant and that the UCP3 region has a striking signal overall, with several individual SNPs showing interesting patterns, including the -55C/T variant. Resequencing of the regions in a set of three diverse population samples helped to clarify the signals that we found with the genotype data. At UCP1, the resequencing data revealed modest evidence that the haplotype carrying the -3826A variant was driven to high frequency by selection. In the UCP3 region, combining results from the climate analysis and resequencing survey suggest a more complex model in which variants on multiple haplotypes may independently be correlated with temperature. This is further supported by an excess of intermediate frequency variants in the UCP3 region in the Han Chinese population. Taken together, our results suggest that adaptation to climate influenced the global distribution of allele frequencies in UCP1 and UCP3 and provide an independent source of evidence for a role in cold resistance for UCP3.


Assuntos
Aclimatação/genética , Regulação da Temperatura Corporal/genética , Clima Frio , Genética Populacional , Canais Iônicos/genética , Proteínas Mitocondriais/genética , Etnicidade/genética , Frequência do Gene , Genótipo , Homeostase , Humanos , Polimorfismo de Nucleotídeo Único , Proteína Desacopladora 1 , Proteína Desacopladora 2 , Proteína Desacopladora 3
15.
Microsurgery ; 32(1): 68-76, 2012 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-22121054

RESUMO

BACKGROUND: Since the birth of reconstructive microvascular surgery, attempts have been made to shorten the operative time while maintaining patency and efficacy. Several devices have been developed to aid microsurgical anastomoses. This article investigates each of the currently available technologies and attempts to provide objective evidence supporting their use. METHODS: Techniques of microvascular anastomosis were investigated by performing searches of the online databases Medline and Pubmed. Returned results were assessed according to the criteria for ranking medical evidence advocated by the Oxford Centre for Evidence Based Medicine. Emphasis was placed on publications with quantifiable endpoints such as unplanned return to theatre, flap salvage, and complication rates. RESULTS: There is a relative paucity of high-level evidence supporting any form of assisted microvascular anastomosis. Specifically, there are no randomized prospective trials comparing outcomes using one method versus any other. However, comparative retrospective cohort studies do exist and have demonstrated convincing advantages of certain techniques. In particular, the Unilink™/3M™ coupler and the Autosuture™ Vessel Closure System® (VCS®) clip applicator have been shown to have level 2b evidence supporting their use, meaning that the body of evidence achieves a level of comparative cohort studies. CONCLUSION: Of the available forms of assisted microvascular anastomoses, there is level 2b evidence suggesting a positive outcome with the use of the Unilink™/3M™ coupler and the Autosuture™ VCS® clip applicator. Other techniques such as cyanoacrylates, fibrin glues, the Medtronic™ U-Clip®, and laser bonding have low levels of evidence supporting their use. Further research is required to establish any role for these techniques.


Assuntos
Anastomose Cirúrgica/métodos , Microcirurgia/métodos , Anastomose Cirúrgica/instrumentação , Desenho de Equipamento , Adesivo Tecidual de Fibrina/uso terapêutico , Humanos , Microcirurgia/instrumentação , Microcirurgia/tendências , Adesivos Teciduais/uso terapêutico , Técnicas de Fechamento de Ferimentos/instrumentação
16.
Sci Adv ; 8(20): eabm9385, 2022 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-35584228

RESUMO

Most well-characterized cases of adaptation involve single genetic loci. Theory suggests that multilocus adaptive walks should be common, but these are challenging to identify in natural populations. Here, we combine trait mapping with population genetic modeling to show that a two-step process rewired nutrient homeostasis in a population of Arabidopsis as it colonized the base of an active stratovolcano characterized by extremely low soil manganese (Mn). First, a variant that disrupted the primary iron (Fe) uptake transporter gene (IRT1) swept quickly to fixation in a hard selective sweep, increasing Mn but limiting Fe in the leaves. Second, multiple independent tandem duplications occurred at NRAMP1 and together rose to near fixation in the island population, compensating the loss of IRT1 by improving Fe homeostasis. This study provides a clear case of a multilocus adaptive walk and reveals how genetic variants reshaped a phenotype and spread over space and time.

17.
Nat Commun ; 13(1): 1461, 2022 03 18.
Artigo em Inglês | MEDLINE | ID: mdl-35304466

RESUMO

Understanding how populations adapt to abrupt environmental change is necessary to predict responses to future challenges, but identifying specific adaptive variants, quantifying their responses to selection and reconstructing their detailed histories is challenging in natural populations. Here, we use Arabidopsis from the Cape Verde Islands as a model to investigate the mechanisms of adaptation after a sudden shift to a more arid climate. We find genome-wide evidence of adaptation after a multivariate change in selection pressures. In particular, time to flowering is reduced in parallel across islands, substantially increasing fitness. This change is mediated by convergent de novo loss of function of two core flowering time genes: FRI on one island and FLC on the other. Evolutionary reconstructions reveal a case where expansion of the new populations coincided with the emergence and proliferation of these variants, consistent with models of rapid adaptation and evolutionary rescue.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Flores/genética , Proteínas de Domínio MADS/genética , Mutação
18.
PLoS Genet ; 4(2): e32, 2008 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-18282109

RESUMO

Evolutionary pressures due to variation in climate play an important role in shaping phenotypic variation among and within species and have been shown to influence variation in phenotypes such as body shape and size among humans. Genes involved in energy metabolism are likely to be central to heat and cold tolerance. To test the hypothesis that climate shaped variation in metabolism genes in humans, we used a bioinformatics approach based on network theory to select 82 candidate genes for common metabolic disorders. We genotyped 873 tag SNPs in these genes in 54 worldwide populations (including the 52 in the Human Genome Diversity Project panel) and found correlations with climate variables using rank correlation analysis and a newly developed method termed Bayesian geographic analysis. In addition, we genotyped 210 carefully matched control SNPs to provide an empirical null distribution for spatial patterns of allele frequency due to population history alone. For nearly all climate variables, we found an excess of genic SNPs in the tail of the distributions of the test statistics compared to the control SNPs, implying that metabolic genes as a group show signals of spatially varying selection. Among our strongest signals were several SNPs (e.g., LEPR R109K, FABP2 A54T) that had previously been associated with phenotypes directly related to cold tolerance. Since variation in climate may be correlated with other aspects of environmental variation, it is possible that some of the signals that we detected reflect selective pressures other than climate. Nevertheless, our results are consistent with the idea that climate has been an important selective pressure acting on candidate genes for common metabolic disorders.


Assuntos
Aclimatação/genética , Doenças Metabólicas/genética , Algoritmos , Alelos , Antiporters/genética , Teorema de Bayes , Biologia Computacional , Metabolismo Energético/genética , Frequência do Gene , Predisposição Genética para Doença , Humanos , Síndrome Metabólica/genética , Modelos Genéticos , Fenótipo , Polimorfismo de Nucleotídeo Único , Seleção Genética , Pigmentação da Pele/genética
19.
Midwifery ; 101: 103048, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34111806

RESUMO

OBJECTIVE: to assess the effect of implementation of the extended placement option available to midwifery students during the first wave of the COVID-19 pandemic. DESIGN: Online survey open from 2nd June 2020 to 15th July 2020. SETTING: United Kingdom. PARTICIPANTS: Lead Midwives for Education (LMEs). FINDINGS: A total of 38 of 55 LMEs responded (response rate 69%). The majority of Approved Education Institutions (AEIs) offered an extended placement to students, but with some variation in the choices offered, unrelated to geographical location or size of student cohort. AEIs appeared to provide the majority of decisional support for students. Many practice learning environments became unavailable, particularly community, gynaecology/medical wards and neonatal units. LMEs experienced both internal and external pressures to instigate rapid change. KEY CONCLUSIONS: The impact of COVID-19 on midwifery education is significant and will need continual scrutiny to minimise future detriment. The pressures of providing midwifery education throughout the early phase of COVID-19 were substantial, but it is important that we learn from the immediate changes made, value and pursue the changes that have been beneficial, and learn from those that were not. IMPLICATIONS FOR PRACTICE/RESEARCH: Student learning experiences have undergone significant change during the pandemic. It is essential to assess what effect the extended placement has had on student readiness for practice, their confidence, resilience, mental health, and attrition and retention. Educators transitioned to remote working, and rapidly assimilated new skills for online education; exploration of the impact of this is recommended.


Assuntos
COVID-19/psicologia , Tocologia/educação , Estudantes de Enfermagem/psicologia , COVID-19/epidemiologia , Feminino , Humanos , Pandemias , Gravidez , SARS-CoV-2 , Reino Unido
20.
Artigo em Inglês | MEDLINE | ID: mdl-31235396

RESUMO

Postpartum haemorrhage is a major global cause of mortality and morbidity amongst childbearing women. Failure or delay in recognising the severity of bleeding is an important contributory factor in these outcomes. Earlier recognition of haemorrhage would facilitate earlier intervention and treatment, helping resolve the causes of bleeding sooner, and thereby improving outcomes for women. Ways to achieve earlier recognition have traditionally focussed on the clinical skill of assessing the volume of blood loss. However, despite extensive research, the optimum method of assessing blood loss and achieving earlier diagnosis remains unclear. Examination of the psychological literature suggests that clinical decision-making is more complex and highlights some of the reasons why traditional approaches have had a limited effect. Using psychological theories of decision-making to inform solutions may lead to more successful strategies to address the issues than the current focus on volume assessment of blood loss.


Assuntos
Hemorragia Pós-Parto , Feminino , Humanos , Hemorragia Pós-Parto/diagnóstico , Hemorragia Pós-Parto/etiologia , Hemorragia Pós-Parto/terapia , Gravidez
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