1,720,969 research outputs found
Morphometrical alteration of coelomocytes in the earthworm Lumbricus terrestris.
No full textEarthworms are very important organisms for soil formation and organic matter breakdown in most terrestrial environment. They are key species responsible for moving large amounts of soil from deeper horizons to the surface layers in many ecosystems. These organisms ingest large amounts of. organic matter, and are continuously exposed to contaminants trough their body. Because of their strong interaction with soil, earthworm populations are profoundly affected by soil pollution. In recent years the use of earthworms biological responses (i.e. biomarker) to chemical pollutants has known a growing interest for polluted soil risk assessment.
The aim of the present work was the in field validation of a multimarker approach on the bioindicator organism Lumbricus terrestris, a large reddish worm native to Europe. Several biomarkers, either specific or general biomarker, either of exposure or of effect, were determined: metallothionein levels, acetylcholinesterase activity, lysosomal membrane stability, coelomocyte morphometric alterations, micronuclei formation. Animals were sampled in four agricultural soil in the Salento Peninsula (ITALY), characterized by different anthropogenic impacts. In parallel the chemical analysis of heavy metals and aromatic polycyclic hydrocarbons were performed in the soil from the four sites.
Obtained results demonstrated the sensitivity of the Lumbricus terrestris biochemical and cellular responses to bioavailable pollutants present in the soil. Moreover, results clearly showed the applicability of the earthworm multrimarker approach in environmental quality monitoring and assessment of the soil
Pollutant induced alteration in Eisenia fetida coelomocytes: a novel biomarker in soil monitoring
No full textAim: Biological responses to pollutant exposure (i.e. biomarkers) are increasingly investigated in sentinel organisms and proposed as sensitive ‘early warning’ tools in environmental quality assessment. Invertebrate haemolymph and coelomic fluid cells have received increasing attention in last years from a toxicological point of view because they are involved in the internal defence system of the organism; therefore any impairment of their functioning can alter health conditions of the entire organism. The aim of the present work was to investigate possible pollutant induced morphometrical alterations in earthworms coelomocytes in view of future application as sensitive, simple and quick biomarker for soil biomonitoring applications. Eisenia foetida exposed to CuSO4 or pesticide methiocarb was utilized as model organism.
Methods: Coelomocytes were stained with Diff Quick and observed under optical microscope; the images obtained from video camera were digitalised using the LUCIA images analysis software (NIKON). The coelomocyte alterations were investigates together with previously standardized biomarkers such as tissutal levels of metallothioneins, acetylcholinesterase activity, coelomocyte lysosomal membrane stability.
Results: A significant (P<0.001) enlargement of coelomocytes was observed either in CuSO4 or methiocarb exposed animals. These alterations correlate with results obtained with standardised biomarker: a significant increase in metallothioneins was observed in the earthworms treated with copper sulphate with respect to the control group (P<0.001), and an inhibition of acetylcholinesterase was measured in the organisms treated with methiocarb (P<0.0001). Lysosomal membrane stability decreased in both treated groups (P<0.0001).
Conclusion: Obtained results suggest that the pollutant induced morphometrical alterations in coelomocytes can be proposed as potential biomarker of general chemical stress exposure suitable to be used in a biomarker battery in soil sentinel organisms
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
Cytotoxicity of Ether Perfluoro Carboxylic Acid PFAS Congeners in Earthworm Granulocytes.
No full textVariations 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
Neurotoxicity of Novel Peruoroalkyl Ether Carboxylic Acids (PFECAs) in Earthworms (Eisenia foetida)
No full text- …
