Assessment of the impacts of glyphosate and its commercial formulation Roundup® on the respiratory tree of the sea cucumber Holothuria forskali using a multivariate biomarker approach

Assessment of single and combined effects of bisphenol-A and its analogue bisphenol-S on biochemical and histopathological responses of sea cucumber Holothuria poli

Bisphenols (BPs) are among emerging pollutants that have been frequently detected in different compartments of marine ecosystems and elicited great concern due to their potential toxicity to marine organisms. This work aimed to investigate the toxicity of bisphenol A (BPA) and bisphenol S (BPS) on oxidative stress markers, neurotoxicity and histopathological alterations in sea cucumbers (Holothuria poli). The results showed that exposure to 200 μg/L of BPA and BPS produced oxidative stress, neurotoxicity in the digestive tract and respiratory tree, and several types of histopathological lesions in tissues of the respiratory tree of the sea cucumber, posing a health hazard to this aquatic organism. In addition, BPA has greater effects than BPS on the generation of oxidative stress marked by the inductions of catalase (CAT), glutathione S-transferase (GST) and malondialdehyde (MDA) levels and neurotoxicity shown by the decrease in acetylcholinesterase activity (AChE). The respiratory tree of sea cucumbers might be an appropriate tissue for assessing CAT, MDA and AChE activity levels, which are reliable biomarkers that may be useful in marine biomonitoring studies. Evaluation of histopathological lesions of the respiratory tree suggests that BPA and BPS and their mixture cause various tissue alterations that may be associated with oxidative stress damage and neurotoxicity. In conclusion, this study showed that oxidative stress (CAT and MDA) and neurotoxicity (AChE) markers, as well as respiratory tree lesions, are sensitive biomarkers for the assessment of BPA and BPS toxicity in sea cucumbers.

Can Glyphosate and Temperature Affect the Nutritional Lipid Quality in the Mussel Mytilus galloprovincialis?

Mussels are an important source of the essential omega-3 polyunsaturated fatty acids (n-3 PUFAs), which play a critical role in human health, preventing a variety of diseases. This study aimed to evaluate, for the first time, the combined effect of glyphosate (Gly) and culturing temperature on the lipid content and fatty acid (FA) profile of the Mediterranean mussel M. galloprovincialis. In addition, a number of lipid nutritional quality indices (LNQIs) were applied as important tools to assess the nutritional value of food. Mussels were exposed for 4 days to two Gly concentrations (1 mg/L, 10 mg/L) and two temperatures (T°: 20-26 °C). Statistical analysis showed significant effects of T°C, Gly, and T°C × Gly interaction (p < 0.05) on the lipid and FA profiles of M. galloprovincialis. Mussels exposed to 10 mg/L Gly at 20 °C showed a decrease in eicosapentaenoic (EPA, from 14.6% to 12% of total FAs) and docosahexaenoic acids (DHA, from 10% to 6.4% of total FAs), compared to the control mussels. Both stressors caused a considerable decrease in n-3 PUFAs, which resulted in a less favorable n-6/n-3 PUFA ratio. Overall, this study demonstrated a decline in the nutritive values of mussels, most prominently in groups exposed to 10 mg/L Gly at a temperature of 20 °C and in those exposed to a temperature of 26 °C. This was confirmed by such LNQIs as EPA + DHA, PUFA/Saturated FAs, atherogenic and thrombogenic indices (AI and TI), the health promoting index (HPI), and the unsaturation index (UI). Further investigations into chronic exposure to both stressors are desirable to predict the impacts on aquatic ecosystems and food quality.

The potential adverse effects of acrylamide on the oxidative stress response, fatty acids profile, and histopathological aspect of the Mediterranean Holothuria forskali respiratory tree

Acrylamide (ACR), organic compound, has been widely used owing to its broad spectrum of chemical and industrial applications. This study aims at evaluating the response of the antioxidant defense system, fatty acid composition and histopathological aspect in the respiratory trees of Holothuria forskali against ACR exposure under laboratory conditions. Holothuries were exposed to 5, 10, and 20 mg L^-1 ACR concentrations for 5 days. A significant increase in n-6 polyunsaturated fatty acids levels especially the arachidonic acid (ARA, C20:4n-6) and its precursor linoleic acid (LA, C18:2n-6) in ACR-treated organisms. Regarding the n-3 levels, eicosapentaenoic acid (EPA, C20:5n-3) levels were increased in treated groups despite an acute decrease in docosahexaenoic acid (DHA, C22:6n-3) levels was observed. Our results showed a significant increase in hydrogen peroxide, malondialdehyde, protein carbonyl, and metallothionein levels along with an alteration of the antioxidants status in all treated sea cucumbers. The exposure to ACR prompted the inhibition of Acetylcholinesterase activity in a concentration-dependent manner. The histopathological aspect was marked especially with the infiltration of coelomic cells which confirms our biochemical findings. Our study provided novel insights to create a link between redox status and fatty acid composition disruptions to better understand ACR-triggered toxicity.

Fate of Microplastic Fibers in the Coelomic Fluid of the Sea Cucumber Apostichopus japonicus

Sea cucumbers are economical and ecologically important species, playing a crucial role in nutrient recycling in the ocean and providing valuable bioactive compounds for nutrition. Previous research has demonstrated that microplastic fibers, which are widely recognized as emerging contaminants, are transferred to the perivisceral coelomic fluid during respiration in sea cucumbers; however, their fate in sea cucumbers is still not well understood. We tracked the status of sea cucumbers (Apostichopus japonicus) with polyester microplastic fibers in their coelomic fluid in clean water. The results showed that after transferring sea cucumbers to clean water, the number of microplastic fibers transferred significantly decreased in the coelomic fluid, but at least one microplastic fiber was found up to 60 days. In addition, sea cucumbers recovered from the effect of microplastic fiber transfer, as indicated by enzyme levels and histological observations. Furthermore, single microplastic fiber transfer over a 60-day farmed period did not significantly affect the growth of sea cucumbers. However, repetitive microplastic fiber transfer (i.e., twice and thrice a week over 60 days) significantly decreased the growth rate (p < 0.05). Accordingly, increasing microplastic fibers in sea cucumber habitats pose a threat to sea cucumbers because they can disrupt development. Thus, farmers are advised to select locations for farming sea cucumbers where low microplastic fiber concentrations are expected. Environ Toxicol Chem 2023;42:205-212. © 2022 SETAC.

Impacts of engineered iron nanoparticles on oxidative stress, fatty acid composition, and histo-architecture of the smooth scallop Flexopecten glaber

Engineered iron nanoparticles are widely used in environmental remediation, yet their potential toxic effects on marine biota remain poorly elucidated. This study aimed to gain insight into the nanoscale zero-valent iron (NZVI) toxicity mechanisms for marine invertebrates. Aside from the effect on oxidative status and histopathology, the effect of NZVI on lipid metabolism in bivalves was studied for the first time. To this end, specimens of Flexopecten glaber were exposed to ascending concentrations (0.5, 1, and 1.5 mg/L) of NZVI for 96 h. Results illustrate differential patterns of iron accumulation in the gills and the digestive gland. By increasing NZVI concentrations, the total iron level tended to markedly increase in the gills and decrease in the digestive gland, reaching 132 and 37.6 μg/g DW, respectively, in the specimens exposed to 1.5 mg/L. Biochemical and cellular biomarkers highlighted that NZVI caused oxidative stress (measured as hydrogen peroxide, malondialdehyde, and advanced oxidation protein product levels) and alterations of antioxidant defense systems, including reduced glutathione, non-protein thiol, glutathione peroxidase, superoxide dismutase, and catalase. Modulation of lipid metabolism with changed fatty acid compositions (mainly an increase in the saturation and a decrease in unsaturation levels) was also observed in both gills and digestive gland. Moreover, several histological damages, including lipofuscin accumulation, infiltrative inflammations, and digestive tubule alterations, were observed in the two studied organs, providing supplementary evidence regarding the toxic effect of NZVI. This study adds to the growing body of evidence pointing to the hazardous impacts of iron NPs on aquatic ecosystems.

Glyphosate exposure modulates lipid composition, histo-architecture and oxidative stress status and induces neurotoxicity in the smooth scallop Flexopecten glaber

Glyphosate is the most sprayed pesticide across the globe. Its toxicity to non-target marine organisms has recently piqued the scientific community's interest. Therefore, the purpose of this study is to investigate the potentially toxic effects of glyphosate on scallops, an ecologically and economically important bivalve group. To do that, specimens of the smooth scallop Flexopecten glaber were exposed to different concentrations (10, 100, and 1000 μg L-1) of the technical-grade glyphosate acid (GLY) for 96 h. The detrimental effects of this pollutant were assayed at cellular and tissular levels. The obtained results showed that the GLY was able to induce oxidative stress in the gills and the digestive gland of F. glaber as revealed by the enhanced hydrogen peroxide (H2O2), protein carbonyls (PCO), malondialdehyde (MDA), and lipid peroxides (LOOH) levels and the altered antioxidant defense system (the glutathione GSH content and the superoxide dismutase (SOD) activity). Additionally, GLY was found to alter the fatty acid profile, to exert a neurotoxic effect through the inhibition of the acetylcholinesterase (AChE) activity, and to provoke several histopathological damages in the two organs studied. The obtained results revealed that the pure form of GLY may exert toxic effects on F. glaber even at relatively low concentrations.

Global transcriptome profiling reveals antagonizing response of head kidney of juvenile common carp exposed to glyphosate

Glyphosate (GLY) frequently detected in various water bodies has imposed a serious risk on fish. Head kidney of fish is an important defense organ, playing a vital part in antagonizing exogenous hazardous matter. The objective of this study was to characterize toxic mechanisms of GLY in head kidney of common carp based on transcriptome profiling. After 45-days exposure of GLY at environmentally relevant concentrations, juvenile common carp were used as experimental subjects to analyze how the head kidney responded to GLY. The transcriptome profiling identified 1381 different expressed genes (DEGs) between the control and exposure groups (5 and 50 mg/L). Functional analysis of DEGs substantiated over-representative pathways mainly involving cellular stress responses, cell proliferation and turnover, apoptosis, lipid metabolism, and innate immune processes in both treated groups compared with the control group. Predicted network of gene regulation indicated that GLY-induced tp53 played a vital role in linking a battery of signals. Furthermore, the expression of 10 candidate genes by qRT-PCR aligned with transcriptional profiling. In addition, western blotting analysis confirmed that GLY-induced apoptosis and cellular proliferation were closely involved in activating MAKP signaling pathway and lipid metabolism pathway in both treated groups. Collectively, these data demonstrate that head kidney of juvenile common carp mainly leverages upregulation of genes related to cell proliferation and turnover, apoptosis, and lipid metabolism to combat sub-chronic exposure of GLY. This study casts new understanding into the risk of GLY in aquatic animals.

Glyphosate disrupts sperm quality and induced DNA damage of rainbow trout (Oncorhynchus mykiss) sperm

As a widespread pollutant, glyphosate (GLY) adversely affects the aquatic environment and can impair the reproductive ability and functions of fish. The purpose of the current study was to assess in vitro effect of GLY on rainbow trout (Oncorhynchus mykiss) sperm cells. The sperm cells were exposed to different GLY concentrations (2.5, 5, 10 mg/L). Sperm motility parameters were analyzed with computer assisted sperm analysis. DNA fragmentation (%) was measured by the comet assay using fluorescence microscopy. With increased GLY concentration, sperm motility and duration decreased after exposure. DNA fragmentation (% DNA in tail) in sperm cells was higher in treatments containing GLY than control (p < 0.05). Consequently, sperm cells are sensitive to low doses of GLY, and this can negatively affect natural populations.

Protective role of Spirulina platensis against glyphosate induced toxicity in marine mussel Mytilus galloprovincialis

Glyphosate is a toxic environmental pollutant that has the ability to induce biochemical and physiological alterations in living organisms. Several studies have focused on the research of protective techniques against the stress induced by this contaminant. In this context, we studied the protective effect of Spirulina against the disturbances induced by glyphosate. A biomarker approach was adopted to determine the impact of glyphosate, Spirulina and their mixture, during two time slots (4 and 7 days), on Mytilus galloprovincialis. Glyphosate treated mussels revealed significantly increased malondialdehyde and decreased acetylcholinesterase (AChE) levels. Spirulina normalized catalase (CAT), glutathione-S-transferase (GST), and AChE activities. Furthermore, it reduced glyphosate-induced malondialdehyde (MDA) levels. The current study suggests a protective effect of Spirulina against glyphosate-induced oxidative stress by strengthening the antioxidant system, sequestering ROS and inhibiting cellular damage.