Characterization of the effects of triclosan on sperm and embryos of Mytilus and Perna mussel species.

The Greenshell™ mussel (GSM), Perna canaliculus, is a culturally and commercially important species in New Zealand. Declines in spat settlement of GSM have been observed in important growing areas and the cause(s) have not been identified. One hypothesis is that chemical contaminants could be a contributing factor. The aim to this study was to investigate the effects of acute exposure on early life stages using the anti-microbial triclosan (TCS) as a benchmark toxicant and the blue mussel (BM), Mytilus galloprovincialis, as a reference species. Sperm and embryos of BM and GSM were exposed to TCS for 1 h and 48 h, respectively. Following exposures, a range of parameters were investigated including spermatozoa cellular characteristics via flow cytometry, fertilization success, larval mortality and size. Exposure to TCS negatively impacted functional parameters of sperm, reduced the fertilization success and larval size, and increased larval mortality in both BM and GSM with LC5048h of 94.3 and 213 µg L-1, respectively. Triclosan increased sperm ROS production in both species, which could cause destabilisation of mitochondrial and other cellular membranes, resulting in reduced mitochondrial membrane potential (BM) and increased sperm size (GSM), leading to apoptosis in both species. Fertilization success of GSM was only affected at the highest TCS concentration tested (391 µg L-1), but development of larvae derived from exposed sperm was affected from the lowest concentrations tested (0.5 and 5.2 µg L-1) in both species. This highlights the importance of assessing the sensitivity of contaminants across developmental stages. Results of this study confirm that TCS causes oxidative stress and has membranotropic effects, and that early life stages of the endemic GSM are suitable to assess ecotoxicity of contaminants such as TCS.

Investigating the Ecotoxicity of Select Emerging Organic Contaminants Toward the Marine Copepod Gladioferens pectinatus.

Estuarine ecosystems are recipients of anthropogenic stressors released from land-based activities. The aim of the present study was to investigate the ecotoxicological hazards of organic contaminants toward the estuarine copepod Gladioferens pectinatus using acute and chronic testing. Most chemicals demonstrated acute toxicity and influenced development of the copepods. Further research should be conducted to investigate these chemicals and their mixtures using long-term, multigenerational testing to characterize mechanisms of toxicity. Environ Toxicol Chem 2022;41:792-799. © 2022 SETAC.

First transcriptome of the copepod Gladioferens pectinatus subjected to chronic contaminant exposures.

Contaminants are often at low concentrations in ecosystems and their effects on exposed organisms can occur over long periods of time and across multiple generations. Alterations to subcellular mechanistic pathways in response to exposure to contaminants can provide insights into mechanisms of toxicity that methods measuring higher levels of biological may miss. Analysis of the whole transcriptome can identify novel mechanisms of action leading to impacts in exposed biota. The aim of this study was to characterise how exposures to copper, benzophenone and diclofenac across multiple generations altered molecular expression pathways in the marine copepod Gladioferens pectinatus. Results of the study demonstrated differential gene expression was observed in cultures exposure to diclofenac (569), copper (449) and benzophenone (59). Pathways linked to stress, growth, cellular and metabolic processes were altered by exposure to all three contaminants with genes associated with oxidative stress and xenobiotic regulation also impacted. Protein kinase functioning, cytochrome P450, transcription, skeletal muscle contraction/relaxation, mitochondrial phosphate translocator, protein synthesis and mitochondrial methylation were all differentially expressed with all three chemicals. The results of the study also suggested that using dimethyl sulfoxide as a dispersant influenced the transcriptome and future research may want to investigate it's use in molecular studies. Data generated in this study provides a first look at transcriptomic response of G. pectinatus exposed to contaminants across multiple generations, future research is needed to validate the identified biomarkers and link these results to apical responses such as population growth to demonstrate the predictive capacity of molecular tools.

Plastic additives: challenges in ecotox hazard assessment.

The risk of plastic debris, and specifically micro(nano)plastic particles, to ecosystems remains to be fully characterized. One particular issue that warrants further characterization is the hazards associated with chemical additives within micro(nano)plastic as they are not chemically bound within the polymers and can be persistent and biologically active. Most plastics contain additives and are therefore potential vectors for the introduction of these chemicals into the environment as they leach from plastic, a process that can be accelerated through degradation and weathering processes. There are knowledge gaps on the ecotoxicological effects of plastic additives and how they are released from parent plastic materials as they progressively fragment from the meso to micro and nano scale. This review summarizes the current state of knowledge of the ecotoxicity of plastic additives and identifies research needs to characterize the hazard they present to exposed biota. The potential ecological risk of chemical additives is of international concern so key differences in governance between the European Union and New Zealand to appropriately characterize their risk are highlighted.

Towards FAIR nanosafety data.

Nanotechnology is a key enabling technology with billions of euros in global investment from public funding, which include large collaborative projects that have investigated environmental and health safety aspects of nanomaterials, but the reuse of accumulated data is clearly lagging behind. Here we summarize challenges and provide recommendations for the efficient reuse of nanosafety data, in line with the recently established FAIR (findable, accessible, interoperable and reusable) guiding principles. We describe the FAIR-aligned Nanosafety Data Interface, with an aggregated findability, accessibility and interoperability across physicochemical, bio-nano interaction, human toxicity, omics, ecotoxicological and exposure data. Overall, we illustrate a much-needed path towards standards for the optimized use of existing data, which avoids duplication of efforts, and provides a multitude of options to promote safe and sustainable nanotechnology.

Investigating the Impact of Manufacturing Processes on the Ecotoxicity of Carbon Nanofibers: A Multi-Aquatic Species Comparison.

Manufactured nanomaterial production is outpacing the ability to investigate environmental hazard using current regulatory paradigms, causing a backlog of materials requiring testing. To ameliorate this issue, regulatory bodies have proposed integrating safety into the production of novel nanomaterials, allowing for hazards to be identified early in development rather than aftermarket release. In addition, there is a growing interest in short-term ecotoxicity testing to rapidly identify environmental hazards. In this sense, the present study investigated 3 carbon nanofibers (CNFs), created with different production methods, using short-term in vitro and in vivo exposures on fish cell lines, mussel hemocytes, crustacea, and algae. The present study investigated if differences in ecotoxicity hazard between the CNFs could be identified and, if so, which product could be considered less hazardous. A major challenge in assessing the potential hazards posed by manufactured nanomaterials is standardizing the preparation for testing. Standardized operating protocols have been proposed using protein to facilitate the preparation of stable stock suspension, which is not environmentally representative. As such, the study also assessed the potential impacts these standardized protocols (with or without the use of protein) could have on the interpretation of environmental hazard. The results demonstrated that there were clear differences between the 3 CNFs and that the dispersion protocol influenced the interpretation of hazard, demonstrating a need for caution when interpreting ecotoxicity in a regulatory context. Environ Toxicol Chem 2019;38:2314-2325. © 2019 SETAC.

Investigating a transcriptomic approach on marine mussel hemocytes exposed to carbon nanofibers: An in vitro/in vivo comparison.

Manufactured nanomaterials are an ideal test case of the precautionary principle due to their novelty and potential environmental release. In the context of regulation, it is difficult to implement for manufactured nanomaterials as current testing paradigms identify risk late into the production process, slowing down innovation and increasing costs. One proposed concept, namely safe(r)-by-design, is to incorporate risk and hazard assessment into the design process of novel manufactured nanomaterials by identifying risks early. When investigating the manufacturing process for nanomaterials, differences between products will be very similar along key physicochemical properties and biological endpoints at the individual level may not be sensitive enough to detect differences whereas lower levels of biological organization may be able to detect these variations. In this sense, the present study used a transcriptomic approach on Mytilus edulis hemocytes following an in vitro and in vivo exposure to three carbon nanofibers created using different production methods. Integrative modeling was used to identify if gene expression could be in linked to physicochemical features. The results suggested that gene expression was more strongly associated with the carbon structure of the nanofibers than chemical purity. With respect to the in vitro/in vivo relationship, results suggested an inverse relationship in how the physicochemical impact gene expression.

Investigating the establishment of primary cultures of hemocytes from Mytilus edulis.

Anthropogenic influences on the environment have been become a focal point for many social and political endeavors. With an ever-increasing rate of new contaminants being introduced into the environment every year, regulatory policies have begun to shift to prevention rather than mitigation. However, current in vivo testing strategies, in addition to ethical considerations, are too expensive and time consuming to adequately screen potential contaminants within a realistic timeframe. As a result, in vitro testing on cell cultures has been identified as an ideal alternative testing strategy for emerging contaminants. In the context of ecotoxicology, in vitro testing has had limited use particularly with marine invertebrates like the marine mussel Mytilus edulis mainly due to difficulties in establishing longer term cell cultures and cell lines. The aim of this study was to define an optimal technique (extraction and maintenance) for establishing a primary cell culture on M. edulis hemocytes that could be used for screening contaminants.

Towards the development of a high throughput screening approach for Mytilus edulis hemocytes: A case study on silicon-based nanomaterials.

To have an understanding of potential mechanistic effects, sublethal endpoints able to discriminate between nanomaterials with similar physical and chemical features need to be used. In this sense, quantitative PCR was used to measure a battery of genes linked to a wide array of different cellular processes. Gene expression was measured in Mytilus edulis hemocytes following an in vitro and in vivo exposure to pure silicon (40 nm) and carbon-coated silicon (40 and 75 nm) after 24 h. Partial least squares discriminant analysis and correlation analysis were used to develop an integrative model, describing the relationship between genes, to identify which genes were important in describing responses to engineered nanomaterial exposure. The results suggested that some discriminations could be made based on the presence of a carbon coating or the alteration of size which could inform industrial patterns on ways to reduce the ecotoxicological impact of their product. The results also indicate that HTS on Mytilus hemocytes may be integrated into a safer-by-design approach but additional characterization of nanomaterial behavior in media is required to determine if it is a suitable alternative to in vivo testing.

Transcriptomic approach: A promising tool for rapid screening nanomaterial-mediated toxicity in the marine bivalve Mytilus edulis-Application to copper oxide nanoparticles.

The extensive development of nanotechnologies will inevitably lead to the release of nanomaterials (NMs) in the environment. As the aquatic environments represent the ultimate sink for various contaminants, it is highly probable that they also constitute a reservoir for NMs and hence aquatic animals represent potential targets. In a regulatory perspective, it is necessary to develop tools to rapidly screen the impact of NMs on model organisms, given that the number of NMs on the market will be increasing. In this context High Throughput Screening approaches represent relevant tools for the investigation of NM-mediated toxicity. The objective of this work was to study the effects of copper oxide nanoparticles (CuONPs) in the marine bivalve Mytilus edulis, using a transcriptomic approach. Mussels were exposed in vivo to CuONPs (10 µg·L-1CuO NPs) for 24 h and analysis of mRNA expression levels of genes implicated in immune response, antioxidant activities, cell metabolism, cell transport and cytoskeleton was investigated by qPCR on hemocytes and gills. Results showed common effects of CuONPs and its ionic counterpart. However, greater effects of CuONPs on GST, SOD, MT, Actin, ATP synthase gene expressions were observed compared to ionic form indicating that toxicity of CuONPs is not solely due to the release of Cu2+. Even though M. edulis genome is not fully characterized, this study provides additional knowledge on the signaling pathways implicated in CuONP-mediated toxicity and demonstrates the reliability of using a qPCR approach to go further in the cellular aspects implicated in response to NPs in marine bivalves.

Baseline levels of biochemical biomarkers in the endobenthic ragworm Hediste diversicolor as useful tools in biological monitoring of estuaries under anthropogenic pressure.

Identification of contamination in estuarine ecosystems that are impacted by anthropogenic pressures, such as the Seine estuary, is difficult to determine without considering the role environmental variation plays on the end points selected. Currently, there is interest in identifying methods in which the influence of confounding factors can be described and accounted for. In this context, the aim of this study was to define a baseline assessment criteria (BAC) for enzymatic biomarkers in ragworms (Hediste diversicolor) collected in a reference site (Authie). The model took into consideration the weight, temperature and salinity of the site. Values collected in the Seine estuary were analyzed with the model to determine if differences between the sites could potentially be due to contamination or were explained by environmental variation. In general, biomarker responses from the Seine estuary fell within the range of BAC, suggesting that environmental variation could explain some of the results.

The role of high-throughput screening in ecotoxicology and engineered nanomaterials.

The field of environmental toxicology developed as a result of growing concerns about anthropogenic influences on the environment and how to ameliorate ecological impact. Many governmental bodies are beginning to emphasize prevention rather than mitigation when addressing novel products, leading to more of a focus on identifying potential toxicity prior to release. With the exponential advances in their development and sale, novel metamaterials and biotechnology are set to dramatically outpace the capabilities of current testing strategies. To address the need for a fast, cost-effective means of testing chemicals, high-throughput screening (HTS) is currently being used in toxicology and being adapted to ecotoxicology in projects such as ToxCast and Tox21. Despite the growth of research using HTS platforms, its role in ecotoxicology is still uncertain, particularly in how it should be applied in regulation. The aim of the present review is to discuss common test strategies used in designing HTS platforms, the current potential applications for ecotoxicological research, its role in regulatory policies, and its ability to address growing concerns such as engineered nanomaterials. Environ Toxicol Chem 2017;36:1704-1714. © 2017 SETAC.