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Träfflista för sökning "WFRF:(Chávez María a) "

Search: WFRF:(Chávez María a)

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2.
  • 2019
  • Journal article (peer-reviewed)
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3.
  • Santangelo, James S., et al. (author)
  • Global urban environmental change drives adaptation in white clover
  • 2022
  • In: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 375
  • Journal article (peer-reviewed)abstract
    • Urbanization transforms environments in ways that alter biological evolution. We examined whether urban environmental change drives parallel evolution by sampling 110,019 white clover plants from 6169 populations in 160 cities globally. Plants were assayed for a Mendelian antiherbivore defense that also affects tolerance to abiotic stressors. Urban-rural gradients were associated with the evolution of clines in defense in 47% of cities throughout the world. Variation in the strength of clines was explained by environmental changes in drought stress and vegetation cover that varied among cities. Sequencing 2074 genomes from 26 cities revealed that the evolution of urban-rural dines was best explained by adaptive evolution, but the degree of parallel adaptation varied among cities. Our results demonstrate that urbanization leads to adaptation at a global scale.
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4.
  • Beal, Jacob, et al. (author)
  • Robust estimation of bacterial cell count from optical density
  • 2020
  • In: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
  • Journal article (peer-reviewed)abstract
    • Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data.
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5.
  • Benjet, Corina, et al. (author)
  • A longitudinal study on the impact of Internet gaming disorder on self‐perceived health, academic performance, and social life of first‐year college students
  • 2023
  • In: American Journal on Addictions. - : John Wiley & Sons. - 1055-0496 .- 1521-0391. ; 32:4, s. 343-351
  • Journal article (peer-reviewed)abstract
    • Background and objectives: Internet gaming disorder (IGD) is associated with health, social, and academic problems but whether these are consequences of the disorder rather than precursors or correlates is unclear. We aimed to evaluate whether IGD in the 1st year of university predicts health, academic and social problems 1 year later, controlling for baseline health, academic and social problems, demographics, and mental health symptoms.Methods: In a prospective cohort study, 1741 university students completed both a baseline online survey in their 1st year and a follow-up survey 1 year later. Log-binomial models examined the strength of prospective associations between baseline predictor variables (IGD, baseline health, academic and social problems, sex, age, and mental health symptoms) and occurrence of health, academic and social problems at follow-up.Results: When extensively adjusted by the corresponding outcome at baseline, any mental disorder symptoms, sex, and age, baseline IGD was associated only with severe school impairment and poor social life (risk ratio [RR] = 1.77; 95% confidence interval [CI] = 1.14-2.75, p = .011; RR = 1.22; 95% CI = 1.07-1.38, p = .002, respectively).Conclusions and scientific significance: University authorities and counselors should consider that incoming 1st-year students that meet criteria for IGD are likely to have increased academic and social impairments during their 1st year for which they may want to intervene. This study adds to the existing literature by longitudinally examining a greater array of negative outcomes of IGD than previously documented.
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6.
  • Dale, Virginia H., et al. (author)
  • Status and prospects for renewable energy using wood pellets from the southeastern United States
  • 2017
  • In: Global Change Biology Bioenergy. - : Wiley-Blackwell. - 1757-1693 .- 1757-1707. ; 9:8, s. 1296-1305
  • Journal article (peer-reviewed)abstract
    • The ongoing debate about costs and benefits of wood-pellet based bioenergy production in the southeastern United States (SE USA) requires an understanding of the science and context influencing market decisions associated with its sustainability. Production of pellets has garnered much attention as US exports have grown from negligible amounts in the early 2000s to 4.6 million metric tonnes in 2015. Currently, 98% of these pellet exports are shipped to Europe to displace coal in power plants. We ask, 'How is the production of wood pellets in the SE USA affecting forest systems and the ecosystem services they provide?' To address this question, we review current forest conditions and the status of the wood products industry, how pellet production affects ecosystem services and biodiversity, and what methods are in place to monitor changes and protect vulnerable systems. Scientific studies provide evidence that wood pellets in the SE USA are a fraction of total forestry operations and can be produced while maintaining or improving forest ecosystem services. Ecosystem services are protected by the requirement to utilize loggers trained to apply scientifically based best management practices in planning and implementing harvest for the export market. Bioenergy markets supplement incomes to private rural landholders and provide an incentive for forest management practices that simultaneously benefit water quality and wildlife and reduce risk of fire and insect outbreaks. Bioenergy also increases the value of forest land to landowners, thereby decreasing likelihood of conversion to nonforest uses. Monitoring and evaluation are essential to verify that regulations and good practices are achieving goals and to enable timely responses if problems arise. Conducting rigorous research to understand how conditions change in response to management choices requires baseline data, monitoring, and appropriate reference scenarios. Long-term monitoring data on forest conditions should be publicly accessible and utilized to inform adaptive management.
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7.
  • Salas, Emir, et al. (author)
  • A heterogeneous enzymatic assay for quantification of Plasmepsin II activity and the evaluation of its inhibitors
  • 2004
  • In: Journal of Pharmaceutical and Biomedical Analysis. - 0731-7085 .- 1873-264X. ; 34:4, s. 833-840
  • Journal article (peer-reviewed)abstract
    • The emergence and worldwide spreading of Plasmodium falciparum strains that shown to be resistant to traditional drugs is considered a very serious health problem, given the high mortality and morbidity rate of Malaria. In the search for new drugs against this parasite, Hb hydrolyzing enzymes, such as Plasmepsin II (Plm II), have been classified as very promising targets for therapeutic attacks. In this work, it is developed a cheap and high-throughput heterogeneous enzymatic assay for measuring Plasmepsin II activity in order to use it as a tool in the discovery of new inhibitors of this enzyme. In this assay, Plasmepsin II acts upon a solid-phase bound synthetic peptide (DU2) whose sequence comprises the cleavage site F(33)-L(34) present in Hb alpha-chain. The peptide surface density is quantified by means of a classical ELISA-based procedure. In order to estimate the kinetic constants of the system and to quantify both, enzymatic and inhibitory activity, it was used a model for the kinetics of enzyme quasi-saturable systems previously developed by our group, that fitted very well to the experimental data. It was used Pepstatin as a model inhibitor of Plasmepsin II and the resulting dose-response relation agreed with the expected behavior for the Pepstatin-Plasmepsin II pair under the employed experimental conditions.
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9.
  • Sánchez-Guillén, Rosa A., et al. (author)
  • Alternative reproductive strategies and the maintenance of female color polymorphism in damselflies
  • 2017
  • In: Ecology and Evolution. - : Wiley. - 2045-7758. ; 7:15, s. 5592-5602
  • Journal article (peer-reviewed)abstract
    • Genetic polymorphisms are powerful model systems to study the maintenance of diversity in nature. In some systems, polymorphisms are limited to female coloration; these are thought to have arisen as a consequence of reducing male mating harassment, commonly resulting in negative frequency-dependent selection on female color morphs. One example is the damselfly Ischnura elegans, which shows three female color morphs and strong sexual conflict over mating rates. Here, we present research integrating male tactics, and female evolutionary strategies (female mating behavior and morph-specific female fecundity) in populations with different morph-specific mating frequencies, to obtain an understanding of mating rates in nature that goes beyond the mere measure of color frequencies. We found that female morph behavior differed significantly among but not within morphs (i.e., female morph behavior was fixed). In contrast, male tactics were strongly affected by the female morph frequency in the population. Laboratory work comparing morph-specific female fecundity revealed that androchrome females have lower fecundity than both of the gynochrome female morphs in the short term (3-days), but over a 10-day period one of the gynochrome female morphs became more fecund than either of the other morphs. In summary, our study found sex-specific dynamics in response to different morph frequencies and also highlights the importance of studying morph-specific fecundities across different time frames to gain a better understanding of the role of alternative reproductive strategies in the maintenance of female-limited color polymorphism.
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10.
  • Sánchez-Guillén, Rosa A., et al. (author)
  • The evolutionary history of colour polymorphism in Ischnura damselflies
  • 2018
  • In: Journal of evolutionary biology. - 1010-061X.
  • Journal article (peer-reviewed)abstract
    • A major challenge in evolutionary biology consists of understanding how genetic and phenotypic variation is created and maintained. In this study, we investigated the origin(s) and evolutionary patterns of the female-limited colour polymorphism in ischnuran damselflies. These consist of the presence of one to three colour morphs: one androchrome morph with a coloration that is similar to the male and two gynochrome morphs (infuscans and aurantiaca) with female-specific coloration. We (i) documented the colour and mating system of 44 of the 75 taxa within the genus Ischnura, (ii) reconstructed the evolutionary history of colour and mating system to identify the ancestral state, (iii) evaluated the stability of the colour morph status over time and (iv) tested for a correlation between colour and mating system. We found that the ancestral female colour of Ischnura was monomorphic and aurantiaca and that colour morph status changed over time, characterized by many gains and losses across the species tree. Our results further showed that colour polymorphism is significantly more frequent among polyandric species, whereas monandric species tend to be monomorphic. Research on some Ischnura species has shown that colour morphs have evolved to reduce male mating harassment, and our finding that the same phenotypic morphs have evolved multiple times (convergent evolution) suggests that several species in this genus might be experiencing similar selective pressures.
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