Toxicopathic effects of waterborne Cd in sole juveniles, a prospective pollution monitoring sentinel for estuarine ecosystems

peer reviewedEstuarine ecosystems are under high anthropogenic pressure and receive a wide Q7 variety of contaminants, including metals. They can remain trapped in estuarine sediments at high concentrations for long periods but eventually they can be released to the overlying water and become toxic for the resident benthic biota. As a consequence, biomonitoring programs surveying the health status of estuaries and coastal areas count with benthic species for the assessment of health disturbances in these specific ecosystems. The present investigation aims at recognizing toxicopathic effects elicited in estuarine life stages of the benthic fish Solea senegalensis on exposure to waterborne Cd, a model compound for metal contamination. Biological responses to metal exposure were assessed based on the application of a “biomarker + histopathology” approach. Two-year old sole juveniles were exposed to various concentrations of waterborne Cd for 3 and 7 days (Control; Low Cd: 1 µg/l; Mid Cd: 10 µg/l and High Cd: 1000 µg/l). Liver samples were collected for chemical analysis at day 7. Biological samples were collected at days 3 and 7 for biochemical (brain and liver), histochemical (liver) and histopathological analysis (liver, gills and gonad). Brain acetyl cholinesterase was inhibited after 7 days exposure, indicating neurotoxic effects on exposure to 1000 µg Cd/l. Hepatic catalase and glutathione-S transferase were induced at day 3 and inhibited at day 7, which suggests a bell-shaped response. A dose-dependent lysosomal membrane destabilization in hepatocytes was recorded at day 7. In parallel, histopathological lesions in gills, liver and gonad were more frequent at day 7 in soles exposed to high Cd concentrations. Overall, the “biomarker + histopathology” approach revealed that waterborne Cd causes toxicopathic effects in sole juveniles upon exposure to environmentally relevant concentrations (10 µg Cd/l). The effects were clearly time dependent, and thus it is conceivable that more severe biological effects would be elicited by these low concentrations of Cd at longer exposure periods. Therefore, biomarkers and histopathology in combination provide early-warning indications of altered health status after waterborne Cd exposure in sole juveniles, a prospective sentinel for biological effects assessment of metal contamination in pollution monitoring programs in estuaries and coastal areas

Alternative methods to assess the effects of a realistic Persistent Organic Pollutant mixture (POP Mix) following a chronic exposure in zebrafish larvae (Danio rerio).

There is a growing concern related to the so-called Persistent Organic Pollutants (POPs). These compounds originate from different sources, some of them being synthesized with specific purposes and others just randomly appearing as by-products (e.g. incomplete combustion). The research into POPs has shown that they have several adverse effects. Cancer, metabolic disorders, effects in the nervous system have been described amongst many other adverse health effects after POP exposure. The POPs have been generally studied as single/individual compounds, and data is scarce related to mixtures that are not uncommon in the environment and even within humans. Thus, a realistic-environmentally significant Persistent Organic Pollutant mixture (POP Mix) as found in the serum of a Scandinavian population was tested in zebrafish larvae (Danio rerio). The zebrafish has been commonly used in the toxicology field, mainly for toxicity tests where the endpoint is lethality. In this study, a set of different approaches was used to assess the effects of a POP mix exposure on zebrafish larvae after 96 hours post-fertilization. In our scope, we mainly focused in endpoints such as development of the lateral line system, malformations, etc. Our results suggest that there are no major effects on the development of the lateral line at any of the different concentrations tested. However, some other morphological traits were undergoing deficiencies during development, such as edemas (pericardial or yolk sac). Thus, we have proven that the POP mix has some deleterious effects at realistic concentrations and further analysis is required

A realistic mixture of ubiquitous persistent organic pollutants affects bone and cartilage development in zebrafish by interaction with nuclear receptor signaling.

peer reviewed"Persistent organic pollutants (POPs)" have a plethora of deleterious effects on humans and the environment due to their bioaccumulative, persistent, and mimicking properties. Individually, each of these chemicals has been tested and its effects measured, however they are rather found as parts of complex mixtures of which we do not fully grasp the extent of their potential consequences. Here we studied the effects of realistic, environmentally relevant mixtures of 29 POPs on cartilage and bone development using zebrafish as a model species. We observed developmental issues in cartilage, in the form of diverse malformations such as micrognathia, reduced size of the Meckel's and other structures. Also, mineralized bone formation was disrupted, hence impacting the overall development of the larvae at later life stages. Assessment of the transcriptome revealed disruption of nuclear receptor pathways, such as androgen, vitamin D, and retinoic acid, that may explain the mechanisms of action of the compounds within the tested mixtures. In addition, clustering of the compounds using their chemical signatures revealed structural similarities with the model chemicals vitamin D and retinoic acid that can explain the effects and/or enhancing the phenotypes we witnessed. Further mechanistic studies will be required to fully understand this kind of molecular interactions and their repercussions in organisms. Our results contribute to the already existing catalogue of deleterious effects caused by exposure to POPs and help to understand the potential consequences in at risk populations

A reporter zebrafish line for live fluorescent visualisation of bone extracellular matrix

Using the CRISP/Cas9 technology, we targeted the zebrafish col10a1a gene to insert the Gfp coding sequence into its genome, generating a transgenic zebrafish line expressing a secreted Gfp fusion protein in the developing skeleton that reveals the bone extracellular matrix.BIOMEDAQ

(Some) of the nasty effects caused by a chronic exposure to a dirty cocktail

editorial reviewedPersistent Organic Pollutants (POPs) have been widely described as major health threats. Most of the research on them has focused on single compounds, while the environment and individuals are continuously exposed to a variety of substances. Here, we tested a synthetic version of a POP mixture consisting of 29 compounds (Total Mix) that is based on environmentally relevant concentrations found in the blood of Scandinavian people. In addition, we tested sub-mixtures of each separate class of compounds (perfluorinated, chlorinated, and brominated compounds) of such Total Mix. Zebrafish larvae were exposed to seven different mixtures for 4 days and then monitored for their movement behavior, heart rate, cartilage and bones deformations, inflation of swim bladder, and gene expression. Their responses varied significantly depending on the mixture used. The most remarkable effects were seen in those fish treated with the Total Mix, suggesting a distinctive synergistic effect. The perfluorinated-containing class of compounds induced the most remarkable defects in all the assessed endpoints. Our results add up to the already existing catalogue of toxic effects described for POPs, paving the way to a much deeper understanding on how POP mixtures may affect wildlife and humans

(Some) of the nasty effects caused by a chronic exposure to a dirty cocktail

editorial reviewedPersistent Organic Pollutants (POPs) have been widely described as major health threats. Most of the research on them has focused on single compounds, while the environment and individuals are continuously exposed to a variety of substances. Here, we tested a synthetic version of a POP mixture consisting of 29 compounds (Total Mix) that is based on environmentally relevant concentrations found in the blood of Scandinavian people. In addition, we tested sub-mixtures of each separate class of compounds (perfluorinated, chlorinated, and brominated compounds) of such Total Mix. Zebrafish larvae were exposed to seven different mixtures for 4 days and then monitored for their movement behavior, heart rate, cartilage and bones deformations, inflation of swim bladder, and gene expression. Their responses varied significantly depending on the mixture used. The most remarkable effects were seen in those fish treated with the Total Mix, suggesting a distinctive synergistic effect. The perfluorinated-containing class of compounds induced the most remarkable defects in all the assessed endpoints. Our results add up to the already existing catalogue of toxic effects described for POPs, paving the way to a much deeper understanding on how POP mixtures may affect wildlife and humans

Exposure biomarkers and organochloride pesticides in captive crododiles

editorial reviewe

A Realistic Mixture of Persistent Organic Pollutants Affects Zebrafish Development, Behavior, and Specifically Eye Formation by Inhibiting the Condensin I Complex

peer reviewedPersistent organic pollutants (POPs) are posing major environmental and health threats due to their stability, ubiquity, and bioaccumulation. Most of the numerous studies of these compounds deal with single chemicals, although real exposures always consist of mixtures. Thus, using different tests, we screened the effects on zebrafish larvae caused by exposure to an environmentally relevant POP mixture. Our mixture consisted of 29 chemicals as found in the blood of a Scandinavian human population. Larvae exposed to this POP mix at realistic concentrations, or sub-mixtures thereof, presented growth retardation, edemas, retarded swim bladder inflation, hyperactive swimming behavior, and other striking malformations such as microphthalmia. The most deleterious compounds in the mixture belong to the per- and polyfluorinated acids class, although chlorinated and brominated compounds modulated the effects. Analyzing the changes in transcriptome caused by POP exposure, we observed an increase of insulin signaling and identified genes involved in brain and eye development, leading us to propose that the impaired function of the condensin I complex caused the observed eye defect. Our findings contribute to the understanding of POP mixtures, their consequences, and potential threats to human and animal populations, indicating that more mechanistic, monitoring, and long-term studies are imperative.PROTECTion against Endocrine Disruptor

Testing biological actions of medicinal plants from northern Vietnam on zebrafish embryos and larvae: Developmental, behavioral, and putative therapeutical effects.

Evaluating the risks and benefits of using traditional medicinal plants is of utmost importance for a huge fraction of the human population, in particular in Northern Vietnam. Zebrafish are increasingly used as a simple vertebrate model for testing toxic and physiological effects of compounds, especially on development. Here, we tested 12 ethanolic extracts from popular medicinal plants collected in northern Vietnam for their effects on zebrafish survival and development during the first 4 days after fertilization. We characterized more in detail their effects on epiboly, hatching, growth, necrosis, body curvature, angiogenesis, skeletal development and mostly increased movement behavior. Finally, we confirm the effect on epiboly caused by the Mahonia bealei extract by staining the actin filaments and performing whole genome gene expression analysis. Further, we show that this extract also inhibits cell migration of mouse embryo fibroblasts. Finally, we analyzed the chemical composition of the Mahonia bealei extract and test the effects of its major components. In conclusion, we show that traditional medicinal plant extracts are able to affect zebrafish early life stage development to various degrees. In addition, we show that an extract causing delay in epiboly also inhibits mammalian cell migration, suggesting that this effect may serve as a preliminary test for identifying extracts that inhibit cancer metastasis