Analytical challenges related to the measurement of chlorothalonil in serum in the perspective of human biomonitoring studies.

Chlorothalonil (CTN) is a popular fungicide widely used in the world. However, its determination in serum samples is highly challenging, preventing a reliable investigation of human CTN internal exposure. We first investigated CTN's behaviour all along this analytical process on spiked serum samples.

Comparison of the In Vivo Biotransformation of Two Emerging Estrogenic Contaminants, BP2 and BPS, in Zebrafish Embryos and Adults.

Zebrafish embryo assays are increasingly used in the toxicological assessment of endocrine disruptors. Among other advantages, these models are 3R-compliant and are fit for screening purposes. Biotransformation processes are well-recognized as a critical factor influencing toxic response, but major gaps of knowledge exist regarding the characterization of functional metabolic capacities expressed in zebrafish.

Maternal and Fetal Pharmacokinetics of Oral Radiolabeled and Authentic Bisphenol A in the Rhesus Monkey.

The present study was conducted in pregnant rhesus monkeys to determine the rapidity and extent to which BPA reaches the fetal compartment following oral ingestion, and the 24-hr fate of BPA. To assess metabolism changes during the course of pregnancy, we compared BPA biotransformation during the second and third trimesters in the same animals, measuring the levels of sulfated, gluronidated, and free BPA in maternal serum, amniotic fluid, and fetal serum. All animals showed measurable unconjugated and conjugated BPA in the fetal compartment and slow clearance compared to maternal serum.

Halogenated bisphenol-A analogs act as obesogens in zebrafish larvae (Danio rerio).

Obesity has increased dramatically over the past decades, reaching epidemic proportions. The reasons are likely multifactorial. One of the suggested causes is the accelerated exposure to obesity-inducing chemicals (obesogens).

Parallel biotransformation of tetrabromobisphenol A in Xenopus laevis and mammals: Xenopus as a model for endocrine perturbation studies.

The flame retardant tetrabromobisphenol A (TBBPA) is a high production flame retardant that interferes with thyroid hormone (TH) signaling. Despite its rapid metabolism in mammals, TBBPA is found in significant amounts in different tissues. Such findings highlight first a need to better understand the effects of TBBPA and its metabolites and second the need to develop models to address these questions experimentally.

Characterization of novel ligands of ERα, Erβ, and PPARγ: the case of halogenated bisphenol A and their conjugated metabolites.

The capability of the flame retardants tetrabromobisphenol A (TBBPA) and tetrachlorobisphenol A (TCBPA) to activate peroxysome proliferator-activated receptors (PPARs) α, β, and γ and estrogen receptors (ERs) α and β has been recently investigated, but the activity of their biotransformation products and of their lower molecular weight analogues formed in the environment remains unexplored. The aim of this study was to investigate the relationship between the degree of halogenation of BPA analogues and their affinity and activity towards human PPARγ and ERs and to characterize active metabolites of major marketed halogenated bisphenols. The biological activity of all compounds was studied using reporter cell lines expressing these nuclear receptors (NRs).

Active metabolism of thyroid hormone during metamorphosis of amphioxus.

Thyroid hormones (THs), and more precisely the 3,3',5-triiodo-l-thyronine (T(3)) acetic derivative 3,3',5-triiodothyroacetic acid (TRIAC), have been shown to activate metamorphosis in amphioxus. However, it remains unknown whether TRIAC is endogenously synthesized in amphioxus and more generally whether an active TH metabolism is regulating metamorphosis. Here we show that amphioxus naturally produces TRIAC from its precursors T(3) and l-thyroxine (T(4)), supporting its possible role as the active TH in amphioxus larvae.

Use of reconstituted metabolic networks to assist in metabolomic data visualization and mining.

Metabolomics experiments seldom achieve their aim of comprehensively covering the entire metabolome. However, important information can be gleaned even from sparse datasets, which can be facilitated by placing the results within the context of known metabolic networks. Here we present a method that allows the automatic assignment of identified metabolites to positions within known metabolic networks, and, furthermore, allows automated extraction of sub-networks of biological significance.

Effects of diquat and fomesafen applied alone and in combination with a nonylphenol polyethoxylate adjuvant on Lemna minor in aquatic indoor microcosms.

The influence of tank-mix adjuvants on pesticide toxicity remains largely unknown. Agral 90, a nonylphenol polyethoxylated tank-mix adjuvant, has been used with diquat (bipyridylium herbicide) and fomesafen (diphenyl-ether herbicide) in aquatic indoor microcosms in order to compare the toxicity of the single compounds and of binary herbicide-adjuvant mixtures to Lemna minor. Twenty-four microcosms were used and treatments were performed with substances alone or with herbicide-adjuvant binary mixtures, at two concentrations levels (44.

Characterization of biliary metabolites of fluoranthene in the common sole (Solea solea).

Fluoranthene is one of the most abundant polycyclic aromatic hydrocarbon (PAH) pollutants in the environment. Studies of the metabolism of PAHs have highlighted the importance of the gallbladder in concentrating xenobiotics in fish before excretion in feces. Analysis of bile metabolites can be considered useful for monitoring and assessing the exposure of fish to PAHs.

3-Methylcholanthrene displays dual effects on estrogen receptor (ER) alpha and ER beta signaling in a cell-type specific fashion.

The biological effects of 17beta-estradiol (E(2)) are mediated by the two estrogen receptor (ER) isoforms ERalpha and ERbeta. These receptors are ligand-inducible transcription factors that belong to the nuclear receptor superfamily. These receptors are also targets for a broad range of natural and synthetic compounds that induce ER activity, including dietary compounds, pharmaceuticals, and various types of environmental pollutants such as bisphenols and polychlorinated hydroxy-biphenyls.

Steroid receptor profiling of vinclozolin and its primary metabolites.

Several pesticides and fungicides commonly used to control agricultural and indoor pests are highly suspected to display endocrine-disrupting effects in animals and humans. Endocrine disruption is mainly caused by the interference of chemicals at the level of steroid receptors: it is now well known that many of these chemicals can display estrogenic effects and/or anti-androgenic effects, but much less is known about the interaction of these compounds with other steroid receptors. Vinclozolin, a dicarboximide fungicide, like its primary metabolites 2-[[(3,5-dichlorophenyl)-carbamoyl]oxy]-2-methyl-3-butenoic acid (M1), and 3',5'-dichloro-2-hydroxy-2-methylbut-3-enanilide (M2), is known to bind androgen receptor (AR).