Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 710
Filtrar
1.
R Soc Open Sci ; 7(1): 191541, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32218971

RESUMO

We introduce the set of quasi-Herglotz functions and demonstrate that it has properties useful in the modelling of non-passive systems. The linear space of quasi-Herglotz functions constitutes a natural extension of the convex cone of Herglotz functions. It consists of differences of Herglotz functions and we show that several of the important properties and modelling perspectives are inherited by the new set of quasi-Herglotz functions. In particular, this applies to their integral representations, the associated integral identities or sum rules (with adequate additional assumptions), their boundary values on the real axis and the associated approximation theory. Numerical examples are included to demonstrate the modelling of a non-passive gain medium formulated as a convex optimization problem, where the generating measure is modelled by using a finite expansion of B-splines and point masses.

2.
Nat Commun ; 10(1): 5409, 2019 11 27.
Artigo em Inglês | MEDLINE | ID: mdl-31776335

RESUMO

Machine learning algorithms can be trained to estimate age from brain structural MRI. The difference between an individual's predicted and chronological age, predicted age difference (PAD), is a phenotype of relevance to aging and brain disease. Here, we present a new deep learning approach to predict brain age from a T1-weighted MRI. The method was trained on a dataset of healthy Icelanders and tested on two datasets, IXI and UK Biobank, utilizing transfer learning to improve accuracy on new sites. A genome-wide association study (GWAS) of PAD in the UK Biobank data (discovery set: [Formula: see text], replication set: [Formula: see text]) yielded two sequence variants, rs1452628-T ([Formula: see text], [Formula: see text]) and rs2435204-G ([Formula: see text], [Formula: see text]). The former is near KCNK2 and correlates with reduced sulcal width, whereas the latter correlates with reduced white matter surface area and tags a well-known inversion at 17q21.31 (H2).


Assuntos
Envelhecimento , Encéfalo/diagnóstico por imagem , Encéfalo/fisiologia , Aprendizado Profundo , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Bases de Dados Factuais , Estudo de Associação Genômica Ampla , Humanos , Islândia , Imageamento por Ressonância Magnética , Pessoa de Meia-Idade , Redes Neurais de Computação , Testes Neuropsicológicos , Polimorfismo de Nucleotídeo Único , Reino Unido , Adulto Jovem
3.
Diabet Med ; 36(11): 1375-1383, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-30264481

RESUMO

AIMS: To investigate whether the N-terminal truncated glutamic acid decarboxylase 65 (GAD65) isoform is as well recognized by people with stiff person syndrome as it is by people with Type 1 diabetes, and whether conformational GAD65 antibody epitopes are displayed properly by the isoform. METHODS: GAD65 antibody-positive healthy individuals (n=13), people with stiff-person syndrome (n=15) and children with new-onset Type 1 diabetes (n=654) were analysed to determine binding to full-length GAD65 and the N-terminal truncated GAD65 isoform in each of these settings. GAD65 autoantibody epitope specificity was correlated with binding ratios of full-length GAD65/N-terminal truncated GAD65. RESULTS: The N-terminal truncated GAD65 isoform was significantly less recognized in GAD65Ab-positive people with stiff-person syndrome (P=0.002) and in healthy individuals (P=0.0001) than in people with Type 1 diabetes. Moreover, at least two specific conformational GAD65Ab epitopes were not, or were only partially, presented by the N-terminal truncated GAD65 isoform compared to full-length GAD65. Finally, an N-terminal conformational GAD65Ab epitope was significantly less recognized in DQ8/8 positive individuals with Type 1 diabetes (P=0.02). CONCLUSIONS: In people with stiff person syndrome preferred binding to the full-length GAD65 isoform over the N-terminal truncated molecule was observed. This binding characteristic is probably attributable to reduced presentation of two conformational epitopes by the N-terminal truncated molecule. These findings support the notion of disease-specific GAD65Ab epitope specificities and emphasize the need to evaluate the applicability of novel assays for different medical conditions.


Assuntos
Autoantígenos/imunologia , Diabetes Mellitus Tipo 1/imunologia , Epitopos/imunologia , Glutamato Descarboxilase/sangue , Fragmentos de Peptídeos/sangue , Rigidez Muscular Espasmódica/imunologia , Adolescente , Adulto , Idoso , Análise de Variância , Especificidade de Anticorpos , Autoanticorpos/sangue , Autoantígenos/sangue , Biomarcadores/sangue , Criança , Pré-Escolar , Diabetes Mellitus Tipo 1/sangue , Diabetes Mellitus Tipo 1/genética , Diabetes Mellitus Tipo 1/fisiopatologia , Feminino , Inquéritos Epidemiológicos , Voluntários Saudáveis , Humanos , Lactente , Masculino , Pessoa de Meia-Idade , Isoformas de Proteínas/sangue , Rigidez Muscular Espasmódica/sangue , Rigidez Muscular Espasmódica/genética , Rigidez Muscular Espasmódica/fisiopatologia , Suécia
4.
Nat Mater ; 17(7): 610-617, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-29891892

RESUMO

High-temperature alloys are crucial to many important technologies that underpin our civilization. All these materials rely on forming an external oxide layer (scale) for corrosion protection. Despite decades of research on oxide scale growth, many open questions remain, including the crucial role of the so-called reactive elements and water. Here, we reveal the hitherto unknown interplay between reactive elements and water during alumina scale growth, causing a metastable 'messy' nano-structured alumina layer to form. We propose that reactive-element-decorated, hydroxylated interfaces between alumina nanograins enable water to access an inner cathode in the bottom of the scale, at odds with the established scale growth scenario. As evidence, hydride-nanodomains and reactive element/hydrogen (deuterium) co-variation are observed in the alumina scale. The defect-rich alumina subsequently recrystallizes to form a protective scale. First-principles modelling is also performed to validate the RE effect. Our findings open up promising avenues in oxidation research and suggest ways to improve alloy properties.

5.
Clin Microbiol Infect ; 24(9): 1004-1009, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-29326011

RESUMO

OBJECTIVES: To analyse Klebsiella pneumoniae (KP) isolates from an outbreak of extended-spectrum ß-lactamase (ESBL)-producing KP and Escherichia coli (EC) among infants admitted to neonatal intensive care units and to determine the duration of the intestinal colonization. METHODS: We performed a prospective cohort study of intestinal ESBL-KP/ESBL-EC colonized neonates after a 5-month outbreak in two neonatal intensive care units. Whole genome sequencing, multilocus sequence typing, core genome multilocus sequence typing, pulsed-field electrophoresis and PCR for blaCTX-M were performed on the first isolates. Stool cultures were performed every second month after discharge until 2 years after discharge and at 5 years of age. The last positive samples were analysed with pulsed-field gel electrophoresis and PCR for blaCTX-M. The intestinal relative dominance of ESBL-producing Enterobacteriaceae was determined. RESULTS: Thirteen of 17 patients colonized with ESBL-KP/ESBL-EC survived. Isolates from 16 of 17 patients were available for analysis and featured the same strain type of ESBL-KP: sequence type 101. The strain had capsule type K29 and harboured blaCTX-M-15. The virulence genes irp1, irp2, iutA, kfu and mrk were detected in all isolates. The median length of colonization was 12.5 months (range, 5-68 months). After 2 years, two of 13 patients were carriers of ESBL-KP and one of 13 of ESBL-EC. At 5 years of age, one neonate was colonized with ESBL-EC. No infant experienced an ESBL-KP/EC-infection during follow-up. CONCLUSIONS: Two years after discharge, almost one fourth of the study participants were ESBL/KP-EC carriers. ESBL-KP sequence type 101 persisted in two of 13 children for 23 to 26 months. One patient was colonized with ESBL-EC at age 5 years.


Assuntos
Infecções por Enterobacteriaceae/diagnóstico , Enterobacteriaceae/classificação , Enterobacteriaceae/isolamento & purificação , Intestinos/microbiologia , beta-Lactamases/metabolismo , Pré-Escolar , Surtos de Doenças , Enterobacteriaceae/enzimologia , Enterobacteriaceae/genética , Infecções por Enterobacteriaceae/epidemiologia , Escherichia coli/genética , Escherichia coli/isolamento & purificação , Feminino , Seguimentos , Genoma Bacteriano , Humanos , Lactente , Recém-Nascido , Unidades de Terapia Intensiva Neonatal , Klebsiella pneumoniae/genética , Klebsiella pneumoniae/isolamento & purificação , Masculino , Tipagem de Sequências Multilocus , Estudos Prospectivos , Sequenciamento Completo do Genoma
6.
Eur Psychiatry ; 51: 98-103, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-29331486

RESUMO

OBJECTIVE: To examine prenatal APAP exposure in relation to language development in offspring at 30 months of age. METHOD: A population-based pregnancy cohort study including 754 women who enrolled in the Swedish Environmental Longitudinal, Mother and child, Asthma and allergy (SELMA) study in pregnancy week 8-13. Two exposure measures were used: (1) maternally reported number of APAP tablets taken between conception and enrollment; (2) APAP urinary concentration at enrollment. Language development at 30 months was assessed by nurse's evaluation and parental questionnaire, including the number of words the child used (<25, 25-50 and >50). Main study outcome; parental report of use of fewer than 50 words, termed language delay (LD). RESULTS: 59.2% of women enrolled in weeks 8-13 reported taking APAP between conception and enrollment. APAP was measurable in all urine samples and urinary APAP was correlated with the number of APAP taken during pregnancy (P<0.01). Language delay was more prevalent in boys (12.6%) than girls (4.1%) (8.5% in total). Both the number of APAP tablets and urinary APAP concentration were associated with greater LD in girls but not in boys. The adjusted odds ratio (OR) for LD among girls whose mothers reported >6 vs. 0 APAP tablets was 5.92 (95% confidence interval (CI) 1.10-31.94). The OR for LD in girls whose mothers' urinary APAP was in the highest compared to the lowest quartile was 10.34 (95% CI 1.37-77.86). While it cannot be ruled out, our available data do not support confounding by indication. CONCLUSIONS: Given the prevalence of prenatal APAP use and the importance of language development, these findings, if replicated, would suggest that pregnant women should limit their use of this analgesic during pregnancy.


Assuntos
Acetaminofen , Transtornos do Desenvolvimento da Linguagem , Efeitos Tardios da Exposição Pré-Natal , Acetaminofen/sangue , Acetaminofen/uso terapêutico , Adulto , Pré-Escolar , Estudos de Coortes , Correlação de Dados , Feminino , Humanos , Transtornos do Desenvolvimento da Linguagem/diagnóstico , Transtornos do Desenvolvimento da Linguagem/epidemiologia , Transtornos do Desenvolvimento da Linguagem/etiologia , Estudos Longitudinais , Masculino , Razão de Chances , Gravidez , Efeitos Tardios da Exposição Pré-Natal/induzido quimicamente , Efeitos Tardios da Exposição Pré-Natal/diagnóstico , Efeitos Tardios da Exposição Pré-Natal/prevenção & controle , Efeitos Tardios da Exposição Pré-Natal/psicologia , Prevalência , Fatores de Risco , Fatores Sexuais , Inquéritos e Questionários , Suécia/epidemiologia
7.
Osteoporos Int ; 29(3): 557-566, 2018 03.
Artigo em Inglês | MEDLINE | ID: mdl-29230511

RESUMO

This study used data from the International Costs and Utilities Related to Osteoporotic fractures Study (ICUROS) to estimate the quality of life (QoL) impact of fracture. Hip, vertebral, and distal forearm fractures incur substantial QoL losses. Hip and vertebral fracture results in markedly impaired QoL for at least 18 months. INTRODUCTION: The International Costs and Utilities Related to Osteoporotic fractures Study (ICUROS) is a multinational observational study that aims to describe costs and quality of life (QoL) consequences of osteoporotic fractures. To date, 11 countries have participated in the study: Australia, Austria, Estonia, France, Italy, Lithuania, Mexico, Russia, Spain, the UK, and the USA. The objective of this paper is to describe the QoL impact of hip, vertebral, and distal forearm fracture. METHODS: Data were collected at four time-points for five QoL point estimates: within 2 weeks after fracture (including pre-fracture recall) and at 4, 12, and 18 months after fracture. Quality of life was measured as health state utility values (HSUVs) derived from the EQ-5D-3L. Complete case analysis was conducted as the base case with available case and multiple imputation performed as sensitivity analyses. Multivariate analysis was performed to explore predictors of QoL impact of fracture. RESULTS: Among 5456 patients enrolled using convenience sampling, 3021 patients were eligible for the base case analysis (1415 hip, 1047 distal forearm, and 559 vertebral fractures). The mean (SD) difference between HSUV before and after fracture for hip, vertebral, and distal forearm fracture was estimated at 0.89 (0.40), 0.67 (0.45), and 0.48 (0.34), respectively (p < 0.001 for all fracture types). Eighteen months after fracture, mean HSUVs were lower than before the fracture in patients with hip fracture (0.66 vs. 0.77 p < 0.001) and vertebral fracture (0.70 vs. 0.83 p < 0.001). Hospitalization and higher recalled pre-fracture QoL were associated with increased QoL impact for all fracture types. CONCLUSIONS: Hip, vertebral, and distal forearm fractures incur substantial loss in QoL and for patients with hip or vertebral fracture, QoL is markedly impaired for at least 18 months.


Assuntos
Fraturas por Osteoporose/reabilitação , Qualidade de Vida , Idoso , Idoso de 80 Anos ou mais , Feminino , Traumatismos do Antebraço/reabilitação , Fraturas do Quadril/reabilitação , Hospitalização/estatística & dados numéricos , Humanos , Masculino , Pessoa de Meia-Idade , Psicometria , Recidiva , Fatores Socioeconômicos , Fraturas da Coluna Vertebral/reabilitação
9.
J Fish Biol ; 91(5): 1350-1364, 2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-28905398

RESUMO

In southern Norway, 22 acidified rivers supporting anadromous salmonids were mitigated with lime to improve water quality and restore fish populations. In 13 of these rivers, effects on Salmo trutta and Salmo salar densities were monitored over 10-12 years, grouped into age 0 and age ≥ 1 year fish. These rivers had a mean annual discharge of between 4·9 and 85·5 m3 s-1 , and six of them were regulated for hydro-power production. Salmo salar were lost in six of these rivers prior to liming, and highly reduced in the remaining seven rivers. Post-liming, S. salar became re-established in all six rivers with lost populations, and recovered in the seven other rivers. Salmo trutta occurred in all 13 study rivers prior to liming. Despite the improved water quality, both age 0 and age ≥ 1 year S. trutta densities decreased as S. salar density increased, with an average reduction of >50% after 10 years of liming. For age 0 year S. trutta this effect was less strong in rivers where S. salar were present prior to liming. In contrast, densities of S. trutta increased in unlimed streams above the anadromous stretches in two of the rivers following improved water quality due to natural recovery. Density increases of both age 0 and age ≥ 1 year S. salar showed a positive effect of river discharge. The results suggest that the decline in S. trutta density after liming is related to interspecific resource competition due to the recovery of S. salar. Thus, improved water quality through liming may not only sustain susceptible species, but can have a negative effect on species that are more tolerant prior to the treatment, such as S. trutta.


Assuntos
Recuperação e Remediação Ambiental , Rios/química , Salmo salar/fisiologia , Truta/fisiologia , Animais , Compostos de Cálcio , Conservação dos Recursos Naturais , Noruega , Óxidos
10.
Eur J Pain ; 21(8): 1316-1325, 2017 09.
Artigo em Inglês | MEDLINE | ID: mdl-28418213

RESUMO

OBJECTIVES: Nociceptive thresholds and supra-threshold pain ratings as well as their reduction upon local injection with lidocaine were compared between healthy subjects and patients with erythromelalgia (EM). METHODS: Lidocaine (0.25, 0.50, 1.0 or 10 mg/mL) or placebo (saline) was injected intradermally in non-painful areas of the lower arm, in a randomized, double-blind manner, to test the effect on dynamic and static mechanical sensitivity, mechanical pain sensitivity, thermal thresholds and supra-threshold heat pain sensitivity. RESULTS: Heat pain thresholds and pain ratings to supra-threshold heat stimulation did not differ between EM-patients (n = 27) and controls (n = 25), neither did the dose-response curves for lidocaine. Only the subgroup of EM-patients with mutations in sodium channel subunits NaV 1.7, 1.8 or 1.9 (n = 8) had increased lidocaine sensitivity for supra-threshold heat stimuli, contrasting lower sensitivity to strong mechanical stimuli. This pattern was particularly clear in the two patients carrying the NaV 1.7 I848T mutations in whom lidocaine's hyperalgesic effect on mechanical pain sensitivity contrasted more effective heat analgesia. CONCLUSION: Heat pain thresholds are not sensitized in EM patients, even in those with gain-of-function mutations in NaV 1.7. Differential lidocaine sensitivity was overt only for noxious stimuli in the supra-threshold range suggesting that sensitized supra-threshold encoding is important for the clinical pain phenotype in EM in addition to lower activation threshold. Intracutaneous lidocaine dose-dependently blocked nociceptive sensations, but we did not identify EM patients with particular high lidocaine sensitivity that could have provided valuable therapeutic guidance. SIGNIFICANCE: Acute pain thresholds and supra-threshold heat pain in controls and patients with erythromelalgia do not differ and have the same lidocaine sensitivity. Acute heat pain thresholds even in EM patients with the NaV 1.7 I848T mutation are normal and only nociceptor sensitivity to intradermal lidocaine is changed. Only in EM patients with mutations in NaV 1.7, 1.8 or 1.9 supra-threshold heat and mechanical pain shows differential lidocaine sensitivity as compared to controls.


Assuntos
Anestésicos Locais/administração & dosagem , Eritromelalgia/genética , Eritromelalgia/fisiopatologia , Lidocaína/administração & dosagem , Limiar da Dor/efeitos dos fármacos , Canais de Sódio/genética , Adulto , Idoso , Idoso de 80 Anos ou mais , Relação Dose-Resposta a Droga , Método Duplo-Cego , Eritromelalgia/complicações , Feminino , Temperatura Alta , Humanos , Masculino , Pessoa de Meia-Idade , Mutação , Nociceptores/efeitos dos fármacos , Dor/diagnóstico , Dor/tratamento farmacológico , Dor/etiologia , Medição da Dor , Adulto Jovem
12.
J Chem Phys ; 146(5): 051101, 2017 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-28178802

RESUMO

Polymer nanocomposite dielectrics are promising materials for electrical insulation in high voltage applications. However, the physics behind their performance is not yet fully understood. We use density functional theory to investigate the electronic properties of the interfacial area in magnesium oxide-polyethylene nanocomposite. Our results demonstrate polyethylene conduction band matching with conduction bands of different surfaces of magnesium oxide. Such band bending results in long range potential wells of up to 2.6 eV deep. Furthermore, the fundamental influence of silicon treatment on magnesium oxide surface properties is assessed. We report a reduction of the surface-induced states at the silicon-treated interface. The simulations provide information used to propose a new model for charge trapping in nanocomposite dielectrics.

13.
Clin Oral Investig ; 21(8): 2561-2568, 2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-28181074

RESUMO

OBJECTIVES: The aims of this study were to quantify salivary concentrations of bisphenol A (BPA) and to assess if presence of dental composite fillings is associated with higher BPA levels in saliva. MATERIALS AND METHODS: Twenty individuals with six or more tooth surfaces filled with polymer-based dental materials (composite group) and 20 individuals without any polymer-based materials (control group) were included in the study. Saliva was collected in polypropylene tubes and stored at -80 °C before analysis. Concentration of free (unconjugated) and total bisphenol A was determined by liquid chromatography/mass spectrometry (LC/MS). Values below limit of detection (0.1 ng/mL) were set to one-half of the limit of detection. Mann-Whitney U test (one sided; the Exact Tests Option in IBM-SPSS version 21) was used for the statistical analyses. RESULTS: The concentration of BPA in saliva was very low. In the composite group, 8 of 20 samples had detectable concentrations of BPA. In the control group, 3 of 20 samples had detectable concentrations of BPA. Statistical analysis indicated that the concentration of unconjugated BPA was slightly higher in the composite group (p = 0.044) than in the control group. CONCLUSIONS: Presence of dental composites may be associated with slightly higher concentration of unconjugated BPA in saliva. However, additional studies using sensitive analytical methods are needed before firm conclusions can be drawn. Influence from other factors, like food intake and time of the day for saliva sampling, must be considered. CLINICAL RELEVANCE: The relative contribution of existing polymer-based dental fillings to total BPA exposure seems to be low.


Assuntos
Compostos Benzidrílicos/análise , Resinas Compostas/química , Fenóis/análise , Saliva/química , Adulto , Cromatografia Líquida , Feminino , Humanos , Masculino , Espectrometria de Massas , Polímeros
14.
Clin Pharmacol Ther ; 101(5): 577-579, 2017 May.
Artigo em Inglês | MEDLINE | ID: mdl-28073148

RESUMO

In the development of highly active anticancer drugs, the European situation may be viewed as paradoxical. Limited data may support marketing authorization, but may be insufficient for the health economic appraisal needed for reimbursement and market uptake. To achieve this, conventional confirmatory studies may be needed. For products of special interest, studies aimed at optimizing cost-effectiveness may be warranted. Efficient designs of studies to meet these objectives constitute challenges to all stakeholders.


Assuntos
Aprovação de Drogas , Órgãos Governamentais , Oncologia/tendências , Projetos de Pesquisa , Antineoplásicos/economia , Antineoplásicos/uso terapêutico , Análise Custo-Benefício , União Europeia , Humanos , Marketing/normas , Oncologia/economia
15.
Acta Neurol Scand ; 135(6): 608-613, 2017 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-27439693

RESUMO

OBJECTIVE: The objective of this nationwide study was to analyze how functional status and socioeconomic status affect return to work (RTW) among younger patients with first-time stroke in a Sweden. MATERIAL AND METHODS: This register-based cohort study included employed patients aged 25-55 with first-time stroke between 2008 and 2011 and primary outcome was RTW within 1 year after stroke. Data regarding functional status and employment status were retrieved from the Swedish Stroke Register, Riksstroke, and socioeconomic data (income, education, and country of birth) from Statistics Sweden. RESULTS: We included 2539 patients who had answered the question on RTW, and 1880 (74.0%) had RTW within 12 months. Patients with low income (69.9% in lowest income group vs 79.9% in highest group, P<.001), patients born in countries outside the Nordic countries (Sweden 75.5%, Nordic countries 74.3%, European countries 61.7%, other countries 57.3%, P<.001), and the youngest patients (25-34, 63.1%; 35-44, 75.9%; 45-55, 74.3%; P=.008) were less likely to RTW. Pain, low mood, and answering the questionnaire with help were more common in low socioeconomic groups, and when adjusting for these variables, together with age and sex, income and country of birth were no longer independent predictors for RTW. CONCLUSION: Patients with low socioeconomic status less often RTW 1 year after stroke.Impaired functional status after stroke is more common in patients with lower socioeconomic status and mediates socioeconomic differences in RTW. Improvement of functional status should be targeted to facilitate RTW among stroke patients with low socioeconomic status.


Assuntos
Retorno ao Trabalho/estatística & dados numéricos , Reabilitação do Acidente Vascular Cerebral/estatística & dados numéricos , Acidente Vascular Cerebral/epidemiologia , Adulto , Idoso , Estudos de Coortes , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Países Escandinavos e Nórdicos
16.
Heredity (Edinb) ; 118(3): 266-275, 2017 03.
Artigo em Inglês | MEDLINE | ID: mdl-27827390

RESUMO

Elucidating barriers to gene flow is important for understanding the dynamics of speciation. Here we investigate pre- and post-zygotic mechanisms acting between the two hybridizing species of Atlantic eels: Anguilla anguilla and A. rostrata. Temporally varying hybridization was examined by analyzing 85 species-diagnostic single-nucleotide polymorphisms (SNPs; FST ⩾0.95) in eel larvae sampled in the spawning region in the Sargasso Sea in 2007 (N=92) and 2014 (N=460). We further investigated whether genotypes at these SNPs were nonrandomly distributed in post-F1 hybrids, indicating selection. Finally, we sequenced the mitochondrial ATP6 and nuclear ATP5c1 genes in 19 hybrids, identified using SNP and restriction site associated DNA (RAD) sequencing data, to test a previously proposed hypothesis of cytonuclear incompatibility leading to adenosine triphosphate (ATP) synthase dysfunction and selection against hybrids. No F1 hybrids but only later backcrosses were observed in the Sargasso Sea in 2007 and 2014. This suggests that interbreeding between the two species only occurs in some years, possibly controlled by environmental conditions at the spawning grounds, or that interbreeding has diminished through time as a result of a declining number of spawners. Moreover, potential selection was found at the nuclear and the cytonuclear levels. Nonetheless, one glass eel individual showed a mismatch, involving an American ATP6 haplotype and European ATP5c1 alleles. This contradicted the presence of cytonuclear incompatibility but may be explained by that (1) cytonuclear incompatibility is incomplete, (2) selection acts at a later life stage or (3) other genes are important for protein function. In total, the study demonstrates the utility of genomic data when examining pre- and post-zyotic barriers in natural hybrids.


Assuntos
Anguilla/genética , Especiação Genética , Hibridização Genética , Anguilla/classificação , Animais , Oceano Atlântico , Fluxo Gênico , Frequência do Gene , Genótipo , Islândia , Polimorfismo de Nucleotídeo Único , Análise de Sequência de DNA , Zigoto
17.
J Fish Biol ; 89(2): 1482-7, 2016 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-27350311

RESUMO

Effect of increased temperature during egg maturation on the mass of single eggs produced by the offspring was investigated experimentally in Atlantic salmon Salmo salar. Mass of eggs produced by next-generation females was larger when their mothers experienced warmer water during the last two months of egg maturation, relative to those that experienced unheated river water. There was no similar trans-generational paternal effect on offspring egg mass.


Assuntos
Óvulo/crescimento & desenvolvimento , Salmo salar/fisiologia , Temperatura , Animais , Feminino , Masculino , Óvulo/citologia , Salmão
18.
Reprod Toxicol ; 61: 114-9, 2016 06.
Artigo em Inglês | MEDLINE | ID: mdl-27049579

RESUMO

BACKGROUND: Anti-Müllerian Hormone (AMH) has been suggested as a marker for ovarian function. Cadmium and lead have been suggested to reduce female fecundity. In this study we aimed to investigate whether environmental exposure to cadmium and lead was associated with alterations in serum-AMH. MATERIALS AND METHOD: The associations between serum-AMH and whole blood cadmium or lead were investigated by general linear models in a population-based sample of 117 pregnant women. RESULTS: The mean concentrations of blood cadmium and lead were 0.71µg/L and 17.4µg/L, respectively. The mean serum-AMH was 17.3pmol/L. No association between lead and AMH was detected. In the cadmium analysis the adjusted mean AMH level (95% CI) in the highest exposure tertile was 12.4 (6.4;23.8) compared to 5.6 (2.7;11.4) in the lowest exposure tertile (p=0.06). CONCLUSION: The study provides suggestive evidence that environmental exposure to cadmium, but not lead, may alter the level of AMH.


Assuntos
Hormônio Antimülleriano/sangue , Cádmio/sangue , Poluentes Ambientais/sangue , Chumbo/sangue , Adulto , Cádmio/efeitos adversos , Exposição Ambiental/efeitos adversos , Exposição Ambiental/análise , Poluentes Ambientais/efeitos adversos , Feminino , Humanos , Gravidez , Adulto Jovem
20.
J Fish Biol ; 88(2): 618-37, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26725985

RESUMO

Annual mean total length (LT) of wild one-sea-winter (1SW) Atlantic salmon Salmo salar of the Norwegian River Imsa decreased from 63 to 54 cm with a corresponding decrease in condition factor (K) for cohorts migrating to sea from 1976 to 2010. The reduction in LT is associated with a 40% decline in mean individual mass, from 2 to 1·2 kg. Hatchery fish reared from parental fish of the same population exhibited similar changes from 1981 onwards. The decrease in LT correlated negatively with near-surface temperatures in the eastern Norwegian Sea, thought to be the main feeding area of the present stock. Furthermore, S. salar exhibited significant variations in the proportion of cohorts attaining maturity after only one winter in the ocean. The proportion of S. salar spawning as 1SW fish was lower both in the 1970s and after 2000 than in the 1980s and 1990s associated with a gradual decline in post-smolt growth and smaller amounts of reserve energy in the fish. In wild S. salar, there was a positive association between post-smolt growth and the sea survival back to the River Imsa for spawning. In addition, among smolt year-classes, there were significant positive correlations between wild and hatchery S. salar in LT, K and age at maturity. The present changes may be caused by ecosystem changes following the collapse and rebuilding of the pelagic fish abundance in the North Atlantic Ocean, a gradual decrease in zooplankton abundance and climate change with increasing surface temperature in the Norwegian Sea. Thus, the observed variation in the life-history traits of S. salar appears primarily associated with major changes in the pelagic food web in the ocean.


Assuntos
Meio Ambiente , Salmo salar/crescimento & desenvolvimento , Temperatura , Migração Animal , Animais , Oceano Atlântico , Tamanho Corporal , Noruega , Rios , Estações do Ano , Zooplâncton
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...