Testing the sensitivity of the medaka Transgenic Eleuthero-embryonic THYroid-Specific assay (TETHYS) to different mechanisms of action.

There are many concerns about the impacts of Endocrine-Disrupting Chemicals on both wildlife and human populations. A plethora of chemicals have been shown to interfere with the Hypothalamic-Pituitary-Thyroid (HPT) axis in vertebrates. Disruption of the HPT axis is one of main endocrine criteria considered for the regulation of chemicals, along with the estrogen axis, androgen axis and steroidogenesis (EATS).

How the Xenopus eleutheroembryonic thyroid assay compares to the amphibian metamorphosis assay for detecting thyroid active chemicals.

The Xenopus Eleutheroembryonic Thyroid Assay (XETA) was recently published as an OECD Test Guideline for detecting chemicals acting on the thyroid axis. However, the OECD validation did not cover all mechanisms that can potentially be detected by the XETA. This study was therefore initiated to investigate and consolidate the applicability domain of the XETA regarding the following mechanisms: thyroid hormone receptor (THR) agonism, sodium-iodide symporter (NIS) inhibition, thyroperoxidase (TPO) inhibition, deiodinase (DIO) inhibition, glucocorticoid receptor (GR) agonism, and uridine 5'-diphospho-glucuronosyltransferase (UDPGT) induction.

A Novel Transgenic Model to Study Thyroid Axis Activity in Early Life Stage Medaka.

Identifying endocrine disrupting chemicals in order to limit their usage is a priority and required according to the European Regulation. There are no Organization for Economic Co-operation and Development (OECD) test guidelines based on fish available for the detection of Thyroid axis Active Chemicals (TACs). This study aimed to fill this gap by developing an assay at eleuthero-embryonic life stages in a novel medaka () transgenic line.

Evaluation of the endocrine activity of surface water samples using aquatic eleuthero-embryos-A comparison with in vitro assays.

Over the previous decade, numerous new approach methodologies (NAMs) have been developed and validated for the detection of endocrine activity of individual chemicals or environmental samples. These NAMs can be largely separated into three categories, in silico tools, in vitro assays, and in vivo assays using organisms or life stages not considered as laboratory animals, each with their own advantages and disadvantages. While in vitro assays provide more mechanistic information, the use of whole organisms such as fish or amphibian embryos provides a more holistic view of the net effects of an environmental sample on hormonal activity.

Transgenic Medaka Identify Embryonic Periods Sensitive to Disruption of Sex Determination.

Gonadal development in medaka (Oryzias latipes) is dependent on the synergy between estrogens and androgens. Disruption of steroid hormone levels can lead to ovo-testis. To determine the sensitive windows for hormonally induced sex reversal in medaka, we developed a novel 42sp50-GFP_ChgH-GFP transgenic medaka line, allowing the identification of female gonadal tissue by fluorescence present in developing oocytes.

Using short-term bioassays to evaluate the endocrine disrupting capacity of the pesticides linuron and fenoxycarb.

Several short-term whole-organism bioassays based on transgenic aquatic models are now under validation by the OECD (Organization for Economic Co-operation and Development) to become standardized test guidelines for the evaluation of the endocrine activity of substances. Evaluation of the endocrine disrupting capacity of pesticides will be a domain of applicability of these future reference tests. The herbicide linuron and the insecticide fenoxycarb are two chemicals commonly used in agricultural practices.

Oestrogen reporter transgenic medaka for non-invasive evaluation of aromatase activity.

Vertebrate reproduction involves complex steroid hormone interplay and inter-conversion. A critical element in maintaining sex steroid levels is the enzyme aromatase (cytochrome P450 19A1) which converts androgens to oestrogens. In turn oestrogen signalling is targeted by numerous chemicals, from pharmaceuticals to agricultural chemicals, both frequent sources of contamination in waste waters and consequently rivers.

Future water quality monitoring--adapting tools to deal with mixtures of pollutants in water resource management.

Environmental quality monitoring of water resources is challenged with providing the basis for safeguarding the environment against adverse biological effects of anthropogenic chemical contamination from diffuse and point sources. While current regulatory efforts focus on monitoring and assessing a few legacy chemicals, many more anthropogenic chemicals can be detected simultaneously in our aquatic resources. However, exposure to chemical mixtures does not necessarily translate into adverse biological effects nor clearly shows whether mitigation measures are needed.

Rapid fluorescent detection of (anti)androgens with spiggin-gfp medaka.

Widespread environmental antiandrogen contamination has been associated with negative impacts on biodiversity and human health. In particular, many pesticides are antiandrogenic, creating a need for robust and sensitive environmental monitoring. Our aim was to develop a sensitive and specific transgenic medaka (Oryzias latipes) model bearing an androgen responsive fluorescent reporter construct for whole organism-based environmental screening of pro- and antiandrogens.

The SOLUTIONS project: challenges and responses for present and future emerging pollutants in land and water resources management.

SOLUTIONS (2013 to 2018) is a European Union Seventh Framework Programme Project (EU-FP7). The project aims to deliver a conceptual framework to support the evidence-based development of environmental policies with regard to water quality. SOLUTIONS will develop the tools for the identification, prioritisation and assessment of those water contaminants that may pose a risk to ecosystems and human health.

Optimizing fluorescent protein choice for transgenic embryonic medaka models.

Early-life-stage transgenic medaka are recognized as a pertinent model by the Organisation for Economic Co-operation and Development and are noncompliant with the European definition of a laboratory animal. However, autofluorescence confounds readout of fluorescent biomarkers. The authors determined the fluorescence emission spectrum of different embryonic stages of medaka submitted to a range of excitation wavelengths.

In vivo endocrine disruption assessment of wastewater treatment plant effluents with small organisms.

Surface water receives a variety of micro-pollutants that could alter aquatic organisms' reproduction and development. It is known that a few nanograms per litre of these compounds can induce endocrine-disrupting effects in aquatic species. Many compounds are released daily in wastewater, and identifying the compounds responsible for inducing such disruption is difficult.

An innovative continuous flow system for monitoring heavy metal pollution in water using transgenic Xenopus laevis tadpoles.

While numerous detection methods exist for environmental heavy metal monitoring, easy-to-use technologies combining rapidity with in vivo measurements are lacking. Multiwell systems exploiting transgenic tadpoles are ideal but require time-consuming placement of individuals in wells. We developed a real-time flow-through system, based on Fountain Flow cytometry, which measures in situ contaminant-induced fluorescence in transgenic amphibian larvae immersed in water samples.

Control of axonophilic migration of oligodendrocyte precursor cells by Eph-ephrin interaction.

The migration of oligodendrocyte precursor cells (OPCs) is modulated by secreted molecules in their environment and by cell-cell and matrix-cell interactions. Here, we ask whether membrane-anchored guidance cues, such as the ephrin ligands and their Eph receptors, participate in the control of OPC migration in the optic nerve. We postulate that EphA and EphB receptors, which are expressed on axons of retinal ganglion cells, interact with ephrins on the surface of OPCs.

Cell division and apoptosis in the adult neural stem cell niche are differentially affected in transthyretin null mice.

Thyroid hormones (THs) are fundamental in regulation of growth and development, particularly of the brain. THs are required for full proliferative activity of neural stem cells in the subventricular zone (SVZ) of adult mouse brains, and also affect the normal fate of progenitor cells: apoptosis. Transthyretin (TTR) is a TH distributor protein in the blood and cerebrospinal fluid.

Lipid-mediated siRNA delivery down-regulates exogenous gene expression in the mouse brain at picomolar levels.

Background: Efficient in vivo vectors are needed to exploit the enormous potential of RNA interference (RNAi). Such methods require optimisation for specific delivery routes, tissues and usages. We tested the capacity of different non-viral vectors and formulation methods for inhibition of exogenous (luciferase) gene expression when used to introduce small interfering RNA (siRNA) into the mouse brain in vivo.

Preferential transfection of adult mouse neural stem cells and their immediate progeny in vivo with polyethylenimine.

The subventricular zone of the adult mammalian brain harbors the neural stem cell population with potential neural regeneration and repair capacity. We describe a nonviral technique to preferentially transfect in vivo the adult neural stem cell population and its immediate progeny based on intraventricular injection of PEI/DNA complexes. The transfected population was identified by cellular and ultra-structural evidence showing their proliferating status and expression of the specific markers GFAP and nestin.