1,721,250 research outputs found
Preface
No full textLatin America is one of the most diverse but also vulnerable regions in the world that is under continuous anthropogenic pressure due to increasing urban, industrial and agricultural developments. Although there are many research groups studying the impacts caused by those pressures, the results and conclusions obtained by many of them are largely unknown because their studies are mostly published at the local or regional scale. Ecotoxicology in Latin America represents an effort to collect and share research performed in Latin America in the area of ecotoxicology and environmental risk assessment, presenting a collection of relevant and innovative studies focused on the following topics: (i) Contaminant entrance, transportation, distribution and fate; (ii) Environmental risk in freshwater ecosystems; (iii) Ecological risk in coastal zones; (iv) Biomonitoring programs: water, sediment and air; (v) Physiological effects and biomarkers; (vi) Soil ecotoxicology; (vii) Bioaccumulation and human risk; (viii) Toxicity of emerging contaminants; and (ix) Frontiers in Ecotoxicology. This selection of topics aims at covering the most important subjects and applications of ecotoxicology, including classical and novel subjects. Therefore, this book contains chapters related to different environmental compartments prone to contamination (water, sediment, soil and air), to different contamination sources (agriculture, industry, urban discharges and natural emissions), and to multiple biological responses at different organizational levels (individual to ecosystems, including human beings). It is envisioned to have an international projection within and beyond Latin American countries, as it is a great opportunity to increase the networks not only among Latin American research teams working on similar subjects, but also with teams from other regions. The idea of this book was to favor the connection among groups to quickly improve the development of methods and their application in ecotoxicological and environmental risk studies in Latin America. This book will be useful to important sectors of environmental sciences and related areas, and to specific target demographics such as students and researchers acting in environmental studies, and decision-makers (i.e., politicians and environmental organizations). Ecotoxicology in Latin America presents 34 chapters authored by 111 researchers from 12 Latin American countries (Argentina, Brazil, Chile, Colombia, Costa Rica, Cuba, Ecuador, Mexico, Panama, Peru, Uruguay, and Venezuela) and from 6 non-Latin American countries (Austria, Belgium, Italy, Portugal, Spain, and USA). (Imprint: Nova
Comment on "Lessons from endocrine disruption and their application to other issues concerning trace organics in the aquatic environment"
No full textIn vitro methodologies in ecotoxicological hazard assessment: the case of bioaccumulation testing for fish.
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Hormone als Schadstoffe?
No full textEndokrine Disruptoren sind Umweltsubstanzen, die in das Hormonsystem von Organismen eingreifen, und dadurch zu schädlichen Wirkungen führen. Sie entfalten ihre Wirkung entweder, indem sie den Hormonstoffwechsel stören oder indem sie die Wirkung von Hormonen imitieren. Eine wichtige Gruppe von endokrinen Disruptoren in der aquatischen Umwelt sind Stoffe, die an Östrogenrezeptoren binden und dadurch wie das weibliche Sexualhormon, 17β-Östradiol wirken. Zu den Umweltöstrogenen gehören sowohl synthetische Chemikalien wie auch natürliche Substanzen. Sowohl Laborversuche wie Felduntersuchungen an Fischen haben gezeigt, dass bereits sehr niedrige Konzentrationen von Umweltöstrogenen in Gewässern in der Lage sind, Störungen des Hormonsystems auszulösen.
Environmental estrogens
Endocrine disrupters are environmental substances which interfere with the hormone system of organisms and thereby induce adverse effects. They exert their biological activity either by disrupting hormone metabolism or by imitating the biological action of the endogenous hormones. In the aquatic environment, an important group of endocrine disrupters is represented by the estrogen-active compounds, which mimic the female sex hormone, 17β-estradiol. Both laboratory experiments and field studies on fishes have demonstrated that already very low concentrations of environmental estrogens are able to induce disturbances in the hormone system and hormone-regulated processes of fishes
Back From the Brink: Alterations in B and T Cell Responses Modulate Recovery of Rainbow Trout From Chronic Immunopathological Tetracapsuloides bryosalmonae Infection
Full text linkProliferative kidney disease (PKD) caused by the myxozoan parasite Tetracapsuloides bryosalmonae is one of the most serious infectious diseases negatively impacting farmed and wild salmonids throughout Europe and North America. PKD pathogenesis results in a massive B cell proliferation and dysregulation with aberrant immunoglobulin production and plasma cell differentiation along with a decrease in myeloid cells and inhibition of innate pathways. Despite the huge immunopathological reaction in the kidney during infection, under specific conditions, fish can survive and return to full fitness. Fish are unique in this ability to recover renal structure and functionality from extensive tissue damage in contrast to mammals. However, only limited knowledge exists regarding the host immune response coinciding with PKD recovery. Moreover, almost no studies of the immune response during disease recovery exist in fish. We utilized the rainbow trout–T. bryosalmonae system as an immunological model of disease recovery. Our results demonstrated that recovery is preceded by an intense immune response at the transcript level, decreasing parasite burden, and an increased degree of kidney inflammation. Later in the recovery phase, the immune response transpired with a significant decrease in lymphocytes and an increase in myeloid cells. These lymphocytes populations contained lower levels of B cells comparative to the control in the anterior and posterior kidney. Additionally, there was downregulation of several transcripts used as markers for plasma cells (blimp1, igt sec, igm sec, igd sec, and cd38) and T cell subsets (cd4, cd8α, cd8β, and tcrβ). The decrease in these T cell transcripts significantly correlated with decreasing parasite intensity. Alternatively, there was strong upregulation of pax-5 and igt mem. This suggests a change in B cell processes during the recovery phase relative to clinical PKD may be necessary for the host to re-establish homeostasis in terms of an arrest in the dominant antibody like response transitioning to a transcriptional profile associated with resting B cells. The knowledge generated here in combination with earlier studies illuminates the full power of analyzing the entire trajectory of disease from the normal healthy state to recovery enabling the measurement of an immune response to pinpoint a specific disease stage
Assessing Fish Immunotoxicity by Means of In Vitro Assays: Are We There Yet?
Full text linkThere is growing awareness that a range of environmental chemicals target the immune system of fish and may compromise the resistance towards infectious pathogens. Existing concepts to assess chemical hazards to fish, however, do not consider immunotoxicity. Over recent years, the application of in vitro assays for ecotoxicological hazard assessment has gained momentum, what leads to the question whether in vitro assays using piscine immune cells might be suitable to evaluate immunotoxic potentials of environmental chemicals to fish. In vitro systems using primary immune cells or immune cells lines have been established from a wide array of fish species and basically from all immune tissues, and in principal these assays should be able to detect chemical impacts on diverse immune functions. In fact, in vitro assays were found to be a valuable tool in investigating the mechanisms and modes of action through which environmental agents interfere with immune cell functions. However, at the current state of knowledge the usefulness of these assays for immunotoxicity screening in the context of chemical hazard assessment appears questionable. This is mainly due to a lack of assay standardization, and an insufficient knowledge of assay performance with respect to false positive or false negative signals for the different toxicant groups and different immune functions. Also the predictivity of the in vitro immunotoxicity assays for the in vivo immunotoxic response of fishes is uncertain. In conclusion, the currently available database is too limited to support the routine application of piscine in vitro assays as screening tool for assessing immunotoxic potentials of environmental chemicals to fish
Zebrafish (Danio rerio) as a model organism for investigating endocrine disruption
No full textEndocrine-disrupting compounds (EDCs) are widespread in the aquatic environment and can cause alterations in development, physiological homeostasis and health of vertebrates. Zebrafish, Danio rerio, has been suggested as a model species to identify targets as well as modes of EDC action. In fact, zebrafish has been found useful in EDC screening, in EDC effects assessment and in studying targets and mechanisms of EDC action. Since many of the environmental EDCs interfere with the sex steroid system of vertebrates, most EDC studies with zebrafish addressed disruption of sexual differentiation and reproduction. However, other targets of EDCs action must not be overlooked. For using a species as a toxicological model, a good knowledge of the biological traits of this species is a pre-requisite for the rational design of test protocols and endpoints as well as for the interpretation and extrapolation of the toxicological findings. Due to the genomic resources available for zebrafish and the long experience with zebrafish in toxicity testing, it is easily possible to establish molecular endpoints for EDC effects assessment. Additionally, the zebrafish model offers a number of technical advantages including ease and cost of maintenance, rapid development, high fecundity, optical transparency of embryos supporting phenotypic screening, existence of many mutant strains, or amenability for both forward and reverse genetics. To date, the zebrafish has been mainly used to identify molecular targets of EDC action and to determine effect thresholds, while the potential of this model species to study immediate and delayed physiological consequences of molecular interactions has been instrumentalized only partly. One factor that may limit the exploitation of this potential is the still rather fragmentary knowledge of basic biological and endocrine traits of zebrafish. Information on species-specific features in endocrine processes and biological properties, however, need to be considered in establishing EDC test protocols using zebrafish, in extrapolating findings from zebrafish to other vertebrate species, and in understanding how EDC-induced gene expression changes translate into disease
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