High-content analysis of larval phenotypes for the screening of xenobiotic toxicity using Phallusia mammillata embryos

Nanoplastic-Induced Developmental Toxicity in Ascidians: Comparative Analysis of Chorionated and Dechorionated Phallusia mammillata Embryos

Nanoplastics pose a growing threat to marine ecosystems, particularly affecting the early developmental stages of marine organisms. This study investigates the effects of amino-modified polystyrene nanoparticles (PS-NH2, 50 nm) on the embryonic development of Phallusia mammillata, a model ascidian species. Both chorionated and dechorionated embryos were exposed to increasing concentrations of PS-NH2 so morphological alterations could be assessed with a high-content analysis of the phenotypes and genotoxicity. PS-NH2 induced the same morphological alterations in both chorionated and dechorionated embryos, with dechorionated embryos being more sensitive (EC50 = 3.0 μg mL-1) than chorionated ones (EC50 = 6.26 μg mL-1). Interestingly, results from the morphological analysis showed two concentration-dependent mechanisms of action: (i) at concentrations near the EC50, neurodevelopmental abnormalities resembling the ones induced by exposure to known endocrine disruptors (EDs) were observed, and (ii) at higher concentrations (15 μg mL-1 and 7.5 μg mL-1 for chorionated and dechorionated embryos, respectively), a nonspecific toxicity was evident, likely due to general oxidative stress. The phenotypes resulting from the PS-NH2 treatment were not related to DNA damage, as revealed by a genotoxicity assay performed on neurula embryos. Our data suggest that PS-NH2-induced toxicity is primarily mediated through oxidative stress, probably triggered by interactions between the positive charges of the PS NPs and the negative charges on the cell membranes. The lack of a protective chorion further exacerbated these effects, highlighting its role in mitigating/protecting against NP-induced damage.

Exploring BPA alternatives - Environmental levels and toxicity review

Bisphenol A alternatives are manufactured as potentially less harmful substitutes of bisphenol A (BPA) that offer similar functionality. These alternatives are already in the market, entering the environment and thus raising ecological concerns. However, it can be expected that levels of BPA alternatives will dominate in the future, they are limited information on their environmental safety. The EU PARC project highlights BPA alternatives as priority chemicals and consolidates information on BPA alternatives, with a focus on environmental relevance and on the identification of the research gaps. The review highlighted aspects and future perspectives. In brief, an extension of environmental monitoring is crucial, extending it to cover BPA alternatives to track their levels and facilitate the timely implementation of mitigation measures. The biological activity has been studied for BPA alternatives, but in a non-systematic way and prioritized a limited number of chemicals. For several BPA alternatives, the data has already provided substantial evidence regarding their potential harm to the environment. We stress the importance of conducting more comprehensive assessments that go beyond the traditional reproductive studies and focus on overlooked relevant endpoints. Future research should also consider mixture effects, realistic environmental concentrations, and the long-term consequences on biota and ecosystems.

A broad-taxa approach as an important concept in ecotoxicological studies and pollution monitoring

Aquatic invertebrates play a pivotal role in (eco)toxicological assessments because they offer ethical, cost-effective and repeatable testing options. Additionally, their significance in the food chain and their ability to represent diverse aquatic ecosystems make them valuable subjects for (eco)toxicological studies. To ensure consistency and comparability across studies, international (eco)toxicology guidelines have been used to establish standardised methods and protocols for data collection, analysis and interpretation. However, the current standardised protocols primarily focus on a limited number of aquatic invertebrate species, mainly from Arthropoda, Mollusca and Annelida. These protocols are suitable for basic toxicity screening, effectively assessing the immediate and severe effects of toxic substances on organisms. For more comprehensive and ecologically relevant assessments, particularly those addressing long-term effects and ecosystem-wide impacts, we recommended the use of a broader diversity of species, since the present choice of taxa exacerbates the limited scope of basic ecotoxicological studies. This review provides a comprehensive overview of (eco)toxicological studies, focusing on major aquatic invertebrate taxa and how they are used to assess the impact of chemicals in diverse aquatic environments. The present work supports the use of a broad-taxa approach in basic environmental assessments, as it better represents the natural populations inhabiting various ecosystems. Advances in omics and other biochemical and computational techniques make the broad-taxa approach more feasible, enabling mechanistic studies on non-model organisms. By combining these approaches with in vitro techniques together with the broad-taxa approach, researchers can gain insights into less-explored impacts of pollution, such as changes in population diversity, the development of tolerance and transgenerational inheritance of pollution responses, the impact on organism phenotypic plasticity, biological invasion outcomes, social behaviour changes, metabolome changes, regeneration phenomena, disease susceptibility and tissue pathologies. This review also emphasises the need for harmonised data-reporting standards and minimum annotation checklists to ensure that research results are findable, accessible, interoperable and reusable (FAIR), maximising the use and reusability of data. The ultimate goal is to encourage integrated and holistic problem-focused collaboration between diverse scientific disciplines, international standardisation organisations and decision-making bodies, with a focus on transdisciplinary knowledge co-production for the One-Health approach.

Ciona spp. and ascidians as bioindicator organisms for evaluating effects of endocrine disrupting chemicals: A discussion paper

In context of testing, screening and monitoring of endocrine-disrupting (ED) type of environmental pollutants, tunicates could possibly represent a particularly interesting group of bioindicator organisms. These primitive chordates are already important model organisms within developmental and genomics research due to their central position in evolution and close relationship to vertebrates. The solitary ascidians, such as the genus Ciona spp. (vase tunicates), could possibly be extra feasible as ED bioindicators. They have a free-swimming, tadpole-like larval stage that develops extremely quickly (<20 h under favorable conditions), has a short life cycle (typically 2-3 months), are relatively easy to maintain in laboratory culture, have fully sequenced genomes, and transgenic embryos with 3D course data of the embryo ontogeny are available. In this article, we discuss possible roles of Ciona spp. (and other solitary ascidians) as ecotoxicological bioindicator organisms in general but perhaps especially for effect studies of contaminants with presumed endocrine disrupting modes of action.