Multi- and transgenerational effects of environmental chemicals on mollusks: An underexplored experimental design in aquatic (eco)toxicological studies.

(Eco)toxicological studies frequently evaluate the effects of chemicals in one life stage of organisms, but the use of these outcomes can only partially estimate populational effects. In this regard, multi- and/or transgenerational studies should be performed in order to provide information on contaminant effects in a populational functioning context. The present review aimed to summarize and critically evaluate the current knowledge regarding multi- and/or transgenerational effects of traditional and emerging environmental chemicals on mollusks. Results showed that these kinds of studies were performed in aquatic mollusks (bivalve and gastropod), being Gastropoda the mollusk Class most frequently studied. Additionally, freshwater species and multigenerational studies were more common for this class. For the Bivalvia class, only marine species were evaluated, and transgenerational exposure was more commonly assessed. The effects were reported for 15 species, highlighting the marine bivalves Crassostrea gigas and Saccostrea glomerata, and the freshwater gastropod Lymnaea stagnalis. Multi- and transgenerational effects were described for 8 environmental chemical groups, mainly metals, pesticides, and pharmaceuticals. In general, multi- and transgenerational exposure induced biometric, developmental, and reproductive impairments in mollusks, indicating that environmental chemicals might lead to generational impairments, reduced population growth and reproductive capacity, and decreased fitness. The current study indicated that bivalves and gastropods are suitable organism models to assess the multi- and transgenerational adverse effects induced by traditional and emerging environmental chemicals.

Polystyrene nanoplastics induce developmental impairments and vasotoxicity in zebrafish (Danio rerio).

The exponential use of plastics has significantly increased environmental pollution by nanoplastics (NPs). In the aquatic environment, NPs interact and bioaccumulate in the biota, posing a potential ecotoxicological risk. The present study investigated the developmental toxicity, vasotoxicity, cytotoxicity, ROS induction, and behavioral impairments in zebrafish (Danio rerio) exposed to environmentally relevant polystyrene NPs (PS-NPs) concentrations (0.04, 34 ng L-1, and 34 µg L-1) for 144 h through multiple biomarkers response (mortality, frequency of spontaneous contractions, heart rate, and morphological changes). Furthermore, vasotoxicity (head, yolk sac, tail, and branchial vessels) was evaluated using the transgenic zebrafish tg(Fli1:eGFP). Results showed that PS-NPs interacted mainly with zebrafish chorion, gills, tail, and larvae head. PS-NPs at 34 ng L-1 and 34 µg L-1 induced neurotoxicity (decreased frequency of spontaneous contractions), cardiotoxicity (bradycardia), and morphological changes in the eyes and head, indicating that PS-NPs induce developmental impairments in zebrafish. In addition, cytotoxicity in the caudal region (34 ng L-1), ROS production, decreased mean swimming speed, and distance covered were observed in all tested concentrations. PS-NPs also induced vasotoxicity (yolk sac region) in transgenic zebrafish. Overall, the present study demonstrates the harmful effects of PS-NPs on the early developmental stages of freshwater fish, indicating their environmental risk.

Bioaccumulation and ecotoxicological impact of micro(nano)plastics in aquatic and land snails: Historical review, current research and emerging trends.

Microplastics (MPs) and nanoplastics (NPs) are ubiquitous emerging pollutants in the environment. Although MPs/NPs' hazardous effects have been described at different trophic levels, little attention has been given to how they can affect gastropod communities. Thus, the current study aimed to summarize and critically address data available in the scientific literature about micro(nano)plastics' ecotoxicological impact on snails. The analyzed data has evidenced MP/NP bioaccumulation in 40 gastropod species collected in the field; 15 gastropod species were used to assess the potential toxicity of MPs/NPs. Asia accounted for the highest level of MPs/NPs bioaccumulated in gastropods; it was followed by the South American, European and Antarctic continents. MPs/NPs' toxicity depends on their composition, shape and size, as well as on differences in methodological approaches adopted by different studies. Results have shown that MPs/NPs induce several impairments - such as behavioral changes, developmental toxicity, dysbiosis, histopathological alterations, oxidative stress -, generate ecological impairments, as well as act as pollutant vector and increase chiral chemicals' toxicity. Research gaps and recommendations for future research were highlighted to help better understanding MPs/NPs' toxicity in gastropods, given the extremely important role played by them in studies focused on investigating how MPs/NPs can affect invertebrate communities living in terrestrial and aquatic environments.

Microbiome: A forgotten target of environmental micro(nano)plastics?

Microplastics (MPs) and nanoplastics (NPs) are emerging pollutants in different environmental compartments (air, soil and water) and that may induce several ecotoxicological effects on organisms and their microbiota. A considerable number of studies has been addressing and highlighting the effects of MPs/NPs on biochemical, molecular and behavior effects of aquatic organisms. However, less attention has been focused on microbiota. Here, a critical overview of published studies focusing on microorganisms affected by MPs and NPs after in vitro or in vivo exposure is provided. Available studies regarding the properties of MPs/NPs, microbial phyla, experimental conditions, techniques employed, and effects are summarized. The link between microbiota disruption and other effects on other hosts (e.g., crustaceans, fish, and mammals) as also analyzed. Overall, the literature review shows that most studies with microorganisms were performed in vitro (MPs: 44.11%; NPs: 23.52%) in comparison with in vivo tests (MPs: 32.35%; NPs: 11.76%). The most studied MP/NPs were polystyrene particles, generally spheres, with sizes <50 µm and concentrations ranged between 100 and 1000 mg L-1. The most studied main phyla were Proteobacteria, Bacteroidetes, Firmicutes, and Actinobacteria. MPs/NPs induced microbiome composition disruption, immune response (i.e., immune modulator release, immune cells activation and inflammatory response), enzyme activity changes (i.e., catalase, urease, dehydrogenase, alkaline phosphatase, and fluorescein diacetate hydrolase) and gene expression changes. The immune responses changes were related to microbiome disruption. Research gaps are highlighted and recommendations for future research indicated that microbiome is sensitive to MP/NPs and microbiome disruption can be a valuable tool to assess the risk of plastic particles to human and environmental health.

Gonadal histopathology and inflammatory response in the freshwater snail exposed to iron oxide nanoparticles and ferric chloride: Insights into reproductive nanotoxicity.

Considering that most animals in an aquatic ecosystem are invertebrates, concerns about the ecotoxicological impact of emerging pollutants, such as nanomaterials, in these populations are relevant, which can lead to loss of aquatic biodiversity. However, knowledge concerning the effects of iron-based nanoparticles (IONPs) at cell and tissue-levels on freshwater gastropods remains limited. Thus, the present study aimed to analyse the histopathological changes and inflammatory response in the freshwater snail Biomphalaria glabrata after chronic exposure to gluconic-acid functionalized IONPs (GLA-IONPs) in comparison with their dissolved counterpart (FeCl3). Snails were exposed to both iron forms (1.0, 2.5, 6.25, and 15.62 mg L-1) for 28 days, and the qualitative and quantitative histopathological assessment on hermaphrodite gonads was conducted, following by analysis of histopathological indices and inflammatory responses. Results showed that both iron forms (GLA-IONPs and FeCl3) induced several gonadal histopathologies in the snails, mainly atresic acini, vacuolization of pre-vitellogenic oocytes, and atresic oocytes in a concentration-dependent pattern. GLA-IONPs induced a more intense inflammatory response and high frequency of vacuolized vitellogenic oocytes in comparison with FeCl3. Environmentally relevant concentration (2.5 mg L-1) of GLA-IONPs and FeCl3 induced high gonadal histopathological indices, indicating their potential reproductive toxicity. The current study showed that the chronic exposure of snails to GLA-IONPs and their dissolved counterpart (FeCl3) induced several gonadal histopathological changes and inflammatory responses in B. glabrata, confirming their potential risk to aquatic biodiversity.

Risk assessment of iron oxide nanoparticles in an aquatic ecosystem: A case study on Biomphalaria glabrata.

Iron oxide nanoparticles (IONPs) have been applied in several sectors in the environmental field, such as aquatic nanoremediation, due to their unique superparamagnetic and nanospecific properties. However, the knowledge of chronic toxicity of IONPs on aquatic invertebrate remains limited. Thus, the present study aimed to analyze the chronic toxicity of gluconic acid-functionalized IONPs (GLA-IONPs) and their dissolved counterpart (FeCl3) to freshwater snail Biomphalaria glabrata. GLA-IONPs were synthesized and characterized by multiple techniques, and the snails were exposed to both Fe forms at environmentally relevant concentrations (1.0-15.6 mg L-1) for 28 days. The bioaccumulation, mortality rate, behavior impairments, morphological alterations, fecundity and fertility of snails were analyzed. Results showed that GLA-IONPs induced high iron bioaccumulation in the entire soft tissue portion. Chronic exposure to GLA-IONP increased the behavioral impairments of snails compared to iron ions and control groups. Both Fe forms reduced the fecundity, while the mortality and reduced fertility were observed only after the exposure to GLA-IONPs at 15.6 mg L-1. Overall results indicated the behavioral impairments and reproductive toxicity associated, possibly, to bioaccumulation of GLA-IONPs in the B. glabrata. These results can be useful for the development of eco-friendly nanotechnologies.

A multibiomarker approach in the caged neotropical fish to assess the environment health in a river of central Brazilian Cerrado.

Water safety is a world-wide concern and several efforts have been made in order to ensure the conservation of aquatic ecosystems. Water quality monitoring must be performed with an integrated approach using biomonitor organisms allied to water parameters. Nonetheless, very few studies have focused on biomarker responses in neotropical fish, especially in the freshwater ecosystem of Brazilian Cerrado savanna. In present study, the active biomonitoring of the João Leite river (central Brazilian Cerrado river) was performed through the evaluation of biomarker responses in caged Astyanax lacustris in combination with land use classification and analysis of water parameters. Caged fish were exposed for seven days at four sites along the river and two control groups were kept in a tank under controlled conditions. Results showed that pasture was the predominant land use in the João Leite river basin (54.07%), followed by natural vegetation (34.92%) and other kind of land use (11.01%). Water analyses showed metal concentrations (Mn and Fe) above the maximum allowed by Brazilian regulation, with particularly higher concentrations at Site 2 (near to pasture area). Biomarker responses did not show significant differences for somatic and mutagenic biomarkers between sites. However, the comet assay showed high DNA damage at Sites 2 and 3, indicating genotoxic effects in caged fish at pasture areas. Histopathological analysis showed highest frequency of leukocyte infiltration in liver of fish from Site 2, confirming the ecotoxic effects on A. lacustris in streams impacted by grazing activities. DNA damage and leukocyte infiltration in fish hepatic tissues were sensitive biomarkers in the neotropical fish A. lacustris to assess the environment health of the Cerrado river. These results showed the importance of using a multibiomarker approach in environmental risk assessment, especially in areas more at risk from anthropogenic pollution.

New Insights into the Gametogenesis of Biomphalaria glabrata (Mollusca, Gastropoda, Pulmonata): Implications for Histopathological Assessment

Abstract The reproductive system has a fundamental role in population dynamics and several reproduction strategies have been shaped by the environment over time. Many environmental pressures are generated by releasing pollutants, as endocrine disruptors, that can affect the reproductive system of individuals, among them invertebrates. The freshwater snails Biomphalaria spp. are used as biomonitor in several ecotoxicological studies; however, there are few studies about gametogenesis and morphology of reproductive snail cells, which could be used as a new biomarker. In this sense, the current study aims to characterize Biomphalaria glabrata gametogenesis, bringing new histomorphometric parameters for germinative cells. Results showed that the hermaphrodite tissue is formed by several acini with simple pavement epithelium with germinative and somatic cells. Oogenesis was classified into five developmental stages (OI to OV) according to diameter, nucleus area, total area, and follicular cell development, and then classified into previtellogenic and vitellogenic oocytes. The spermatogenesis was classified into spermatogonia (Spg), spermatocytes (Spc) and spermatids that were subdivided into five stages (Spt I to Spt V) according to cytoplasm losing, and nucleus spiralization along with Sertoli cells development. Thus, the present study highlights the gametogenesis of B. glabrata with new histomorphometric parameters, which can be an important tool for ecotoxicological and molluscicidal developmental further studies.