Suchergebnisse

29 p., 3 tablas, 2 figuras y bibliografía ; Molluscs are sensitive species to the toxic effects of organotin compounds, particularly to masculinization, and both, tributyltin (TBT) and triphenyltin (TPT) have been recently shown to bind to molluscs RXR. Being RXR is involved in lipid homeostasis, exposure to TPT would have an immediate effect on lipid homeostasis. To test this hypothesis, the ramshorn snail Marisa cornuarietis was exposed to environmentally relevant concentrations of TPT (30, 125, 500 ng/L as Sn) in a semi-static water regime for 7-days. Percentage of lipids and total fatty acid content decreased significantly in TPT-exposed females while the activity of peroxisomal acyl-CoA oxidase, involved in fatty acid catabolism, increased. In addition, fatty acid profiles (carbon chain length and unsaturation degree) were significantly altered in exposed females but not in males. This work highlights the ability of TPT to disrupt lipid metabolism in M. cornuarietis at environmentally realistic concentrations and the higher susceptibility of females in comparison to males. ; This study was supported by the European Union (COMPRENDO-Project, EVK1-CT-2002-00129) and the Spanish National Plan for Research (Project Ref CGL2005-02846).

4 pages, 2 figures.-- PMID: 15178065 [PubMed].-- Printed version published in issue Aug-Dec 2004.-- Issue title: "Twelfth International Symposium on Pollutant Responses in Marine Organisms" (Tampa Bay, FL, United States, May 9-13, 2003). ; Mussels Mytilus galloprovincialis were exposed to different concentrations of estradiol (20, 200, and 2000 ng/l) in a semi-static regime (1-day dosing intervals) for up to 7 days in an attempt to see how mussels dealt with exogenous estrogenic compounds. Sex hormone levels were determined in whole tissue. Free-estradiol was only significantly elevated at the highest exposure dose (up to 10-fold). Most of the estradiol was in the tissues as fatty acid esters (>78%), which sharply increased in a dose-dependent manner (from 4 ng/g in controls to 258 ng/g at the high exposure group). In contrast, neither free nor esterified testosterone levels showed significant differences between control and exposure groups. The results suggest the existence of mechanisms that allow mussels to maintain their hormonal status, and the important role that fatty acid esterification may play within those mechanisms. Synthesis and conjugation rates of estradiol were further investigated by measuring the activity of P450 aromatase, and palmitoyl-CoA:estradiol acyltransferase, in digestive gland microsomal fractions. Overall, the study contributes to the better knowledge of molluscan endocrinology, and defines new mechanisms of regulation of free steroid-levels in mussels. ; Predoctoral fellowship from the Spanish Government and partial support from EU Project BEEP (ENVK3-CT-2000-00025). ; Peer reviewed

3 pages.-- PMID: 16818253 [PubMed].-- PMCID: PMC1874174. ; This article is part of the monograph "The Ecological Relevance of Chemically Induced Endocrine Disruption in Wildlife". ; Tens of thousands of man-made chemicals are in regular use and discharged into the environment. Many of them are known to interfere with the hormonal systems in humans and wildlife. Given the complexity of endocrine systems, there are many ways in which endocrine-disrupting chemicals (EDCs) can affect the body's signaling system, and this makes unraveling the mechanisms of action of these chemicals difficult. A major concern is that some of these EDCs appear to be biologically active at extremely low concentrations. There is growing evidence to indicate that the guiding principle of traditional toxicology that "the dose makes the poison" may not always be the case because some EDCs do not induce the classical dose–response relationships. The European Union project COMPRENDO (Comparative Research on Endocrine Disrupters—Phylogenetic Approach and Common Principles focussing on Androgenic/Antiandrogenic Compounds) therefore aims to develop an understanding of potential health problems posed by androgenic and antiandrogenic compounds (AACs) to wildlife and humans by focusing on the commonalities and differences in responses to AACs across the animal kingdom (from invertebrates to vertebrates). ; This project is funded by the European Union (COMPRENDO Project, contract EVK1-CT-2002-00129). ; Peer reviewed