Updated Chronic Copper Bioavailability Models for Invertebrates and Algae.

Chronic copper (Cu) bioavailability models have been successfully implemented in European risk assessment frameworks and compliance evaluations. However, they were developed almost two decades ago, which calls for an update. In the study, we present updated chronic Cu bioavailability models for invertebrates and algae.

Assessment of the contribution of surfactants to mixture toxicity in French surface waters.

Surfactants are widely used 'down-the-drain' chemicals with the potential to occur at high concentrations in local water bodies and to be part of unintentional environmental mixtures. Recently, increased regulatory focus has been placed on the impacts of complex mixtures in aquatic environments and the substances that are likely to drive mixture risk. This study assessed the contribution of surfactants to the total mixture pressure in freshwater ecosystems.

Ecotoxicity of Lead to a Phytoplankton Community: Effects of pH and Phosphorus Addition and Implications for Risk Assessment.

Ecological risk assessment and water quality criteria for lead (Pb) are increasingly making use of bioavailability-based approaches to account for the impact of toxicity-modifying factors, such as pH and dissolved organic carbon. For phytoplankton, which are among the most Pb-sensitive freshwater species, a Pb bioavailability model has previously been developed based on standard single-species exposures at a high phosphorus (P) concentration and pH range of 6.0 to 8.

Updating the Chronic Freshwater Ecotoxicity Database and Biotic Ligand Model for Nickel for Regulatory Applications in Europe.

Bioavailability has been taken into account in the regulation of nickel in freshwater ecosystems in Europe for over a decade; during that time a significant amount of new information has become available covering both the sensitivity of aquatic organisms to nickel toxicity and bioavailability normalization. The ecotoxicity database for chronic nickel toxicity to freshwater organisms has been updated and now includes 358 individual data points covering a total of 53 different species, all of which are suitable for bioavailability normalization to different water chemistry conditions. The bioavailability normalization procedure has also been updated to include updates to the bioavailability models that enable more sensitive water chemistry conditions to be covered by the model predictions.

European freshwater silver monitoring data do not suggest a potential European-wide risk.

European legislations frequently focus on substances that are of potential concern to human or environmental health, such as "priority substances" under the Water Framework Directive 2000/60/EC ("WFD") that are identified as substances posing a significant risk to or via the aquatic environment. The EU REACH regulation also requires the assessment of the environmental risks of chemicals put on the EU market. To properly assess the potential risk of a substance, high-quality representative monitoring data should be compared with a safe threshold concentration.

Decoding the activated stem cell phenotype of the neonatally maturing pituitary.

The pituitary represents the endocrine master regulator. In mouse, the gland undergoes active maturation immediately after birth. Here, we in detail portrayed the stem cell compartment of neonatal pituitary.

Exploring stem cell biology in pituitary tumors and derived organoids.

Pituitary tumorigenesis is highly prevalent and causes major endocrine disorders. Hardly anything is known on the behavior of the local stem cells in this pathology. Here, we explored the stem cells' biology in mouse and human pituitary tumors using transcriptomic, immunophenotyping and organoid approaches.

Development of Organoids from Mouse Pituitary as In Vitro Model to Explore Pituitary Stem Cell Biology.

The pituitary is the master endocrine gland regulating key physiological processes, including body growth, metabolism, sexual maturation, reproduction, and stress response. More than a decade ago, stem cells were identified in the pituitary gland. However, despite the application of transgenic in vivo approaches, their phenotype, biology, and role remain unclear.

Transnasal transsphenoidal pituitary surgery in a large tertiary hospital, a retrospective study.

Objectives: Pituitary adenomas (PAs), although being small tumours, can have quite an impact on patients' lives causing hormonal and visual disturbances, for which surgery must be performed. As a large peripheral hospital with specialists in pituitary surgery, an assessment of the efficacy and safety of transnasal transsphenoidal pituitary surgery was made.

Methods: A retrospective analysis of neurosurgical reports as well as pre and postoperative imaging was made to evaluate the presenting symptoms, tumoural variables, peri-operative morbidity, and long-term outcome.

Interleukin-6 is an activator of pituitary stem cells upon local damage, a competence quenched in the aging gland.

Stem cells in the adult pituitary are quiescent yet show acute activation upon tissue injury. The molecular mechanisms underlying this reaction are completely unknown. We applied single-cell transcriptomics to start unraveling the acute pituitary stem cell activation process as occurring upon targeted endocrine cell-ablation damage.

Setting a Protective Threshold Value for Silver Toward Freshwater Organisms.

Driven by Regulation (EC) No. 1272/2008 and the European Water Framework Directive 2000/60/EC, we have re-evaluated the available chronic freshwater ecotoxicity data for ionic silver (Ag) using strict data quality criteria. In addition, we generated new chronic ecotoxicity data for species potentially sensitive to Ag (the rotifer Brachionus calyciflorus, the cyanobacteria Anabaena flos-aquae, and the aquatic plant Lemna minor) using Ag nitrate as the test substance.

Pituitary disease and recovery: How are stem cells involved?

The pituitary gland embodies our endocrine hub and rigorously regulates hormone balances in the body, thereby ruling over vital developmental and physiological processes. Pituitary dysfunction and disease strongly impact the organism's biology. Physical damage, tumour development and ageing all negatively affect pituitary state and functionality.

Demonstrating the Reliability of bio-met for Determining Compliance with Environmental Quality Standards for Metals in Europe.

The importance of considering the bioavailability of metals in understanding and assessing their toxicity in freshwaters has been recognized for many years. Currently, biotic ligand models (BLMs) are being applied for the derivation and implementation of environmental quality standards (EQS) for metals under the Water Framework Directive in Europe. bio-met is a simplified tool that was developed for implementing bioavailability-based EQS for metals in European freshwaters.

A Generalized Bioavailability Model (gBAM) for Predicting Chronic Copper Toxicity to Freshwater Fish.

The generalized bioavailability model (gBAM) has been proposed as an alternative to the biotic ligand model (BLM) for modeling bioavailability and chronic toxicity of copper (Cu). The gBAM combines a log-linear effect of pH on free Cu ion toxicity with BLM-type parameters for describing the protective effects of major cations (calcium [Ca] , magnesium [Mg] , and sodium [Na] ). In the present study, a Windermere Humic Aqueous Model (WHAM) VII-based gBAM for fish was parametrized based on an existing chronic (30-d) dataset of juvenile rainbow trout (Oncorhynchus mykiss).

The Effects of Nickel on the Structure and Functioning of a Freshwater Plankton Community Under High Dissolved Organic Carbon Conditions: A Microcosm Experiment.

In the present study, we aimed to test the protectiveness of the bioavailability-normalization procedure, with its associated hazardous concentrations for x% of the species (HCx), that is currently implemented to derive environmental threshold concentrations for nickel (Ni) in European environmental legislative frameworks. We exposed a natural plankton-dominated community to 3 constant Ni concentrations, that is, a control with no Ni added (background Ni of 1.2-4 µg/L) and the bioavailability-normalized HC5 and HC50 of 24 and 97 µg dissolved Ni/L, respectively, during a 56-d microcosm experiment under high dissolved organic carbon (DOC) conditions (DOC of 14 mg/L at test initiation).

Organoids from pituitary as a novel research model toward pituitary stem cell exploration.

The pituitary is the master endocrine gland, harboring stem cells of which the phenotype and role remain poorly characterized. Here, we established organoids from mouse pituitary with the aim to generate a novel research model to study pituitary stem cell biology. The organoids originated from the pituitary cells expressing the stem cell marker SOX2 were long-term expandable, displayed a stemness phenotype during expansive culture and showed specific hormonal differentiation ability, although limited, after subrenal transplantation.

Ecotoxicological and biochemical mixture effects of an herbicide and a metal at the marine primary producer diatom Thalassiosira weissflogii and the primary consumer copepod Acartia tonsa.

Mixture effects of chemicals and their potential synergistic interactions are of great concern to the public and regulatory authorities worldwide. Intensive agricultural activities are leading to discharges of chemical mixtures to nearby estuarine and marine waters with possible adverse effects on the aquatic communities and for the trophic food web interlinking these communities. Further information about the impacts of these stressors on aquatic organisms is needed.

A framework for ecological risk assessment of metal mixtures in aquatic systems.

Although metal mixture toxicity has been studied relatively intensely, there is no general consensus yet on how to incorporate metal mixture toxicity into aquatic risk assessment. We combined existing data on chronic metal mixture toxicity at the species level with species sensitivity distribution (SSD)-based in silico metal mixture risk predictions at the community level for mixtures of Ni, Zn, Cu, Cd, and Pb, to develop a tiered risk assessment scheme for metal mixtures in freshwater. Generally, independent action (IA) predicts chronic metal mixture toxicity at the species level most accurately, whereas concentration addition (CA) is the most conservative model.

The effect of pH on chronic zinc toxicity differs between daphnid species: Development of a preliminary chronic zinc Ceriodaphnia dubia bioavailability model.

In the present study, we observed that the chronic Zn Daphnia magna biotic ligand model (BLM) could not accurately predict the chronic Zn toxicity to Ceriodaphnia dubia in a series of (modified) field waters, although the intrinsic sensitivities of the D. magna BLM were specifically calibrated on the sensitivity of C. dubia.

Systematic Evaluation of Chronic Metal-Mixture Toxicity to Three Species and Implications for Risk Assessment.

Metal contamination generally occurs as mixtures. However, it is yet unresolved how to address metal mixtures in risk assessment. Therefore, using consistent methodologies, we have set up experiments to identify which mixture model applies best at low-level effects, i.

Three-Dimensional Reconstruction of the Tissue-Specific Multielemental Distribution within Ceriodaphnia dubia via Multimodal Registration Using Laser Ablation ICP-Mass Spectrometry and X-ray Spectroscopic Techniques.

In this work, the three-dimensional elemental distribution profile within the freshwater crustacean Ceriodaphnia dubia was constructed at a spatial resolution down to 5 μm via a data fusion approach employing state-of-the-art laser ablation-inductively coupled plasma-time-of-flight mass spectrometry (LA-ICP-TOFMS) and laboratory-based absorption microcomputed tomography (μ-CT). C. dubia was exposed to elevated Cu, Ni, and Zn concentrations, chemically fixed, dehydrated, stained, and embedded, prior to μ-CT analysis.

Comparison of four methods for bioavailability-based risk assessment of mixtures of Cu, Zn, and Ni in freshwater.

Although chemical risk assessment is still mainly conducted on a substance-by-substance basis, organisms in the environment are typically exposed to mixtures of substances. Risk assessment procedures should therefore be adapted to fit these situations. Four mixture risk assessment methodologies were compared for risk estimations of mixtures of copper (Cu), zinc (Zn), and nickel (Ni).

Development and validation of a metal mixture bioavailability model (MMBM) to predict chronic toxicity of Ni-Zn-Pb mixtures to Ceriodaphnia dubia.

Recently, several bioavailability-based models have been shown to predict acute metal mixture toxicity with reasonable accuracy. However, the application of such models to chronic mixture toxicity is less well established. Therefore, we developed in the present study a chronic metal mixture bioavailability model (MMBM) by combining the existing chronic daphnid bioavailability models for Ni, Zn, and Pb with the independent action (IA) model, assuming strict non-interaction between the metals for binding at the metal-specific biotic ligand sites.

Comparison of chronic mixture toxicity of nickel-zinc-copper and nickel-zinc-copper-cadmium mixtures between Ceriodaphnia dubia and Pseudokirchneriella subcapitata.

Although aquatic organisms in the environment are exposed to mixtures of metals, risk assessment for metals is most commonly performed on a metal-by-metal basis. To increase the knowledge about chronic mixture effects, the authors investigated whether metal mixture effects are dependent on the biological species, mixture composition, and metal concentration ratio. The authors evaluated the effects of quaternary Ni-Zn-Cu-Cd and ternary Ni-Zn-Cu mixtures on 48-h algal growth rate (Pseudokirchneriella subcapitata) and 7-d daphnid reproduction (Ceriodaphnia dubia) using a ray design.

Development and validation of a chronic Pb bioavailability model for the freshwater rotifer Brachionus calyciflorus.

The univariate effects of Ca, pH, and dissolved organic carbon (DOC) on chronic (48-h) Pb toxicity to the freshwater rotifer Brachionus calyciflorus were investigated. High pH (8.2) and higher concentrations of DOC were protective against filtered Pb toxicity, whereas Ca was not.