1,720,995 research outputs found
Dataset of "Growth but not corticosterone, oxidative stress or telomere length is negatively affected by microplastic exposure in a filter-feeding amphibian"
No full textPeer reviewe
Telomere dynamics in maturing frogs vary among organs
No full textIt is important to know whether organs age at the same rate and are equally affected by developmental conditions as this provides insights into causes of ageing. However, data on organ-specific telomere dynamics remain scant. In a previous study of the early life of the amphibian Xenopus laevis, we detected changes in telomere lengths in gut cells, while liver, heart and muscle telomeres were unchanged; larval rearing temperature had minimal effects. Here, we extend that study to examine telomere dynamics in the same four organs and larval temperature treatments from 70-day post-metamorphic juvenile Xenopus through to sexually mature (2-year-old) adults. Telomeres shortened from juvenile to adult in the gut, heart and hindlimb muscle. In contrast, liver telomere lengths did not change with age but were shorter if the early life temperature was warm. Organ telomere lengths were influenced by sex only in adults. Warmer larval temperatures were also associated with longer gut telomeres in juveniles. Hence, pre-metamorphic conditions can influence post-metamorphic telomere dynamics, and telomere loss between juvenile and adult life stages occurs in different organs from those affected earlier in life. These findings indicate the existence of organ-dependent ageing rates across lifetimes, potentially related to developmental and environmental history.Pablo Burraco was supported by Marie Sklodowska-Curie Individual Fellowship 797879-METAGE and by Ramón y Cajal Fellowship RYC 2023-044964-I (Spanish Ministry of Science and Innovation). Neil B. Metcalfe was supported by ERC Advanced Grant 834653 and Pat Monaghan by ERC Advanced Grant 101020037 under the European Union’s Horizon 2020.Peer reviewe
Growth but Not Corticosterone, Oxidative Stress, or Telomere Length Is Negatively Affected by Microplastic Exposure in a Filter-Feeding Amphibian
No full textMicroplastics (MPs) are of increasing global concern for species inhabiting aquatic habitats. However, the mechanisms behind animal responses to MPs still require comprehensive exploration. Amphibians are the most threatened vertebrate group with most species having a complex life cycle, commonly with an aquatic larval stage. Here, we investigated whether exposure to an environmentally relevant concentration of MPs affects the growth of filter-feeding larvae of the African clawed frog (Xenopus laevis), and the consequences for their stress physiology (corticosterone [CORT] levels), or health and ageing physiology (oxidative stress and telomere length, the latter in the liver and gut). We conducted a 3 × 2 experiment with three levels of fiber exposure (fibers absent -control-, and MP and cellulose fiber treatments), and two stress levels (CORT absent -control-, and CORT present simulating a stressful condition). We observed a negative impact of MP exposure on larval growth; however, this did not alter the CORT levels, oxidative stress. or telomere length. Our study shows that realistic concentrations of MPs are not enough to induce major alterations on the stress or health and ageing physiology of a filter-feeding amphibian. Whether compensatory growth responses during the post-metamorphic stages could lead to detrimental effects later in life should be explored in amphibians and other organisms with complex life cycles.The German Research Foundation (DFG) project (533973724); a new actor on the stage of global change: A multi-level perspective on the toxicity of microplastics pollution in amphibians) supported C.M. and K.R. Ramón y Cajal Fellowship RYC 2023-044964-I (Spanish Ministry of Science and Innovation) supported P.B.Peer reviewe
Impact of ionizing radiation on the environmental microbiomes of Chornobyl wetlands
No full text© 2023 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).Radioactive contamination has the potential to cause damage to DNA and other biomolecules. Anthropogenic sources of radioactive contamination include accidents in nuclear power plants, such as the one in Chornobyl in 1986 which caused long-term radioactive pollution. Studies on animals within radioactive zones have provided us with a greater understanding of how wildlife can persevere despite chronic radiation exposure. However, we still know very little about the effects of radiation on the microbial communities in the environment. We examined the impact of ionizing radiation and other environmental factors on the diversity and composition of environmental microbiomes in the wetlands of Chornobyl. We combined detailed field sampling along a gradient of radiation together with 16S rRNA high-throughput metabarcoding. While radiation did not affect the alpha diversity of the microbiomes in sediment, soil, or water, it had a significant effect on the beta diversity in all environment types, indicating that the microbial composition was affected by ionizing radiation. Specifically, we detected several microbial taxa that were more abundant in areas with high radiation levels within the Chornobyl Exclusion Zone, including bacteria and archaea known to be radioresistant. Our results reveal the existence of rich and diverse microbiomes in Chornobyl wetlands, with multiple taxonomic groups that are able to thrive despite the radioactive contamination. These results, together with additional field and laboratory-based approaches examining how microbes cope with ionizing radiation will help to forecast the functionality and re-naturalization dynamics of radiocontaminated environments.This work was supported by projects from the Helge Ax:son Johnsons Stiftelse to PB, and Swedish Radiation Protection Agency-SSM (SSM 2018-2038) and Carl TryggersFoundation (CT 16:344) to GO. EV was supported by a fellowship from the Swedish Research Council (2020–00259), PB by a Carl Tryggers Foundation scholarship (CT 16:344) and by a Juan de la Cierva Incorporación fellowship (IJC 2020-044680), and GO by the Spanish Ministry of Science, Innovation and Universities “Ramón y Cajal” grant RYC-2016-20656.Peer reviewe
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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