Glyphosate affects haemocyte parameters in the clam Ruditapes philippinarum

Exploring the Impact of Contaminants of Emerging Concern on Fish and Invertebrates Physiology in the Mediterranean Sea

In this historical context, the Mediterranean Sea faces an increasing threat from emerging pollutants such as pharmaceuticals, personal care products, heavy metals, pesticides and microplastics, which pose a serious risk to the environment and human health. In this regard, aquatic invertebrates and fish are particularly vulnerable to the toxic effects of these pollutants, and several species have been identified as bio-indicators for their detection. Among these, bivalve molluscs and elasmobranchs are now widely used as bio-indicators to accurately assess the effects of contaminants. The study focuses on the catshark Scyliorhinus canicular and on the Mediterranean mussel Mytilus galloprovincialis. The first one is a useful indicator of localised contamination levels due to its exposure to pollutants that accumulate on the seabed. Moreover, it has a high trophic position and plays an important role in the Mediterranean Sea ecosystem. The bivalve mollusc Mytilus galloprovincialis, on the other hand, being a filter-feeding organism, can acquire and bioaccumulate foreign particles present in its environment. Additionally, because it is also a species of commercial interest, it has a direct impact on human health. In conclusion, the increasing presence of emerging pollutants in the Mediterranean Sea is a serious issue that requires immediate attention. Bivalve molluscs and elasmobranchs are two examples of bio-indicators that must be used to precisely determine the effects of these pollutants on the marine ecosystem and human health.

Hemocytes: A Useful Tool for Assessing the Toxicity of Microplastics, Heavy Metals, and Pesticides on Aquatic Invertebrates

Invertebrates have long been an important tool for assessing water pollution due to their characteristics as intermediate consumers in aquatic ecosystem food chains. Most of the time, the effects of contaminants are measured by their effect on oxidative status or by mortality, although there already exists an easier tool-hemocytes. Hemocytes are circulating cells with a very important role in the immune system of invertebrates, which can be found within the hemolymph, analogous to the blood in vertebrates. The collection of hemolymph samples is easy, fast, minimally invasive, and poses no danger to the life of invertebrates. The purpose of this review was to highlight the advantages of using hemolymph for toxicity assays of various substances, including heavy metals, micro- and nano-plastics, pesticides, hydrocarbons, and oil spills. A literature search was conducted for this purpose using the most common and most often used databases, with a focus on the most recent and relevant studies. Bivalve mollusks, crustaceans, and gastropods were chosen for this investigation. This review found a growing number of studies choosing to use hemolymph as the standard methodology for toxicology assays, confirming their qualities as reliable tools.

Glyphosate and its breakdown product AMPA elicit cytoprotective responses in haemocytes of the Mediterranean mussel (Mytilus galloprovincialis)

This study investigates the effects of glyphosate (GLY) and its metabolite AMPA on cytoprotective and detoxification mechanisms in haemocytes of Mytilus galloprovincialis. Cells were treated in vitro with 0.1 and 1.0 µg/L GLY, 0.1 µg/L, 0.1 and 1.0 µg/L AMPA, or two mixtures GLY+AMPA (0.1 µg/L GLY + 0.1 µg/L AMPA, 1.0 µg/L GLY + 1.0 µg/L AMPA). GLY and AMPA increased MXR efflux activity and modulated expression of the ABCB transcript encoding a MXR related ABC transporter P-glycoprotein. The mixtures GLY+AMPA reduced efflux activity with ABCB down-regulation (at 1 µg/L GLY/AMPA). Modulation of lysosomal and immune related transcripts generally agree with known effects of the chemicals on these physiological functions. Given their cumulative action as chemosensitizers of the MXR system, and their interactive effects on haemocyte parameters, glyphosate and AMPA at environmental concentrations should be addressed as a concern factor for the biological vulnerability of marine habitats.

AKT regulates hemocyte proliferation via glucose metabolism in Eriocheir sinensis

Threonine-serine protein kinase (AKT) plays an important role in the regulation of essential biological processes such as cell metabolism and cell proliferation in several organisms. Eriocheir sinensis is a widely distributed crab that is exposed to complex and diverse biological environments and various diseases. We aimed to elucidate the immune function of AKT and the underlying mechanism in E. sinensis. In this study, we performed bioinformatics analysis of E. sinensis AKT (EsAkt) and found that the AKT protein was highly conserved across species. qRT-PCR showed high AKT expression in the liver and muscle tissues, and low expression in hemocytes. After stimulation with gram-positive Staphylococcus aureus or gram-negative Vibrio parahaemolyticus, E. sinensis AKT (EsAkt) was significantly up-regulated in hemocytes. Further, knockout of the EsAkt gene weakened cell glucose metabolism and inhibited cell proliferation. Taken together, these results suggest that EsAkt plays a key role in regulating hemocyte glucose metabolism and cell proliferation in Eriocheir sinensis.

Effects of a mixture of glyphosate, 17α-ethynylestradiol and amyl salicylate on cellular and biochemical parameters of the mussel Mytilus galloprovincialis

In this study the effects of a mixture of glyphosate (herbicide), 17a-ethinylestradiol (synthetic estrogen) and amyl salicylate (fragrance) to the mussel Mytilus galloprovincialis were evaluated. Mussels were exposed for 7 days to two realistic concentrations of the mixture (10 and 100 ng/L) and the effects on total haemocyte counts, haemocyte diameter and volume, haemocyte proliferation, haemolymph lactate dehydrogenase activity and haemocyte lysate lysozyme activity were measured. In addition, superoxide dismutase, catalase, acetylcholinesterase, glutathione-S-transferase and glutathione reductase activities were measured in gills and digestive gland. The survival-in-air test was also performed. Results demonstrated that the mixture affected both cellular and biochemical biomarkers, but not tolerance to aerial exposure of M. galloprovincialis. The negative effects recorded in this study suggested that more efforts should be done to assess the ecotoxicological risks posed by contaminant mixture to aquatic invertebrates.

DNA damage, immunotoxicity, and neurotoxicity induced by deltamethrin on the freshwater crayfish, Procambarus clarkii

Pyrethroid pesticides are applied to both agricultural and aquacultural industries for pest control. However, information of their impact on the commercial important freshwater crayfish, Procambarus clarkii is scarce. Therefore, the present study aimed to characterize to effects of a commonly used pyrethroid pesticide, deltamethrin on DNA damage, immune response, and neurotoxicity in P. clarkii. Animals were exposed to 7, 14, and 28 ng/L of deltamethrin, which correspond to 1/8, 1/4, and 1/2 of the LC50 (96 hours) of this pyrethroid to P. clarkii. Significant increase of olive tail moment (OTM) and 8-hydroxy-2'-deoxyguanosine (8-OHdG) was found after deltamethrin exposure in a dose-dependent way. Total hemocyte counts (THC) and activities of immune-related enzymes including acid phosphatase (ACP), lysozyme (LZM), and phenoloxidase (PO) were all decreased and significantly lower than control at concentration of 28 ng/L after 96 hours exposure. Acetylcholinesterase (AChE) activity, an indicator of neurotoxic effect was investigated and it was decreased significantly in muscles at 14 and 28 ng/L after 24 hours exposure. The level of intracellular reactive oxygen species (ROS) in hemocytes was also measured and the significant increase of ROS was found at 14 and 28 ng/L concentrations. The results revealed that deltamethrin induced DNA damage, immunotoxicity, and neurotoxicity in P. clarkii by excessive generation of ROS. Because of the dose-dependent responses of all parameters under exposure of deltamethrin at environmentally realistic concentrations, these parameters could be used as sensitive biomarkers for risk assessment of deltamethrin in aquaculture area.

The Effects of Glyphosate and Its Commercial Formulations to Marine Invertebrates: A Review

Glyphosate is the active ingredient of numerous commercial formulations of herbicides applied in different sectors, from agriculture to aquaculture. Due to its widespread use around the world, relatively high concentrations of glyphosate have been detected in soil and aquatic environments. The presence of glyphosate in aquatic ecosystems has aroused the attention of researchers because of its potential negative effects on living organisms, both animals and plants. In this context, this review intends to summarize results of studies aimed at evaluating the effects of glyphosate (both as active ingredient and component of commercial formulations) on marine invertebrates. Generally, data obtained in acute toxicity tests indicate that glyphosate and its commercial formulations are lethal at high concentrations (not environmentally realistic), whereas results of long-lasting experiments indicate that glyphosate can markedly affect biological responses of marine invertebrates. Consequently, more efforts should be addressed at evaluating chronic or sub-chronic effects of such substances to marine invertebrate species.

Impact of field-realistic doses of glyphosate and nutritional stress on mosquito life history traits and susceptibility to malaria parasite infection

Glyphosate is the world's most widely used herbicide. The commercial success of this molecule is due to its nonselectivity and its action, which would supposedly target specific biosynthetic pathways found mainly in plants. Multiple studies have however provided evidence for high sensitivity of many nontarget species to glyphosate and/or to formulations (glyphosate mixed with surfactants). This herbicide, found at significant levels in aquatic systems through surface runoffs, impacts life history traits and immune parameters of several aquatic invertebrates' species, including disease-vector mosquitoes. Mosquitoes, from hatching to emergence, are exposed to aquatic chemical contaminants. In this study, we first compared the toxicity of pure glyphosate to the toxicity of glyphosate-based formulations for the main vector of avian malaria in Europe, Culex pipiens mosquito. Then we evaluated, for the first time, how field-realistic dose of glyphosate interacts with larval nutritional stress to alter mosquito life history traits and susceptibility to avian malaria parasite infection. Our results show that exposure of larvae to field-realistic doses of glyphosate, pure or in formulation, did not affect larval survival rate, adult size, and female fecundity. One of our two experimental blocks showed, however, that exposure to glyphosate decreased development time and reduced mosquito infection probability by malaria parasite. Interestingly, the effect on malaria infection was lost when the larvae were also subjected to a nutritional stress, probably due to a lower ingestion of glyphosate.

In vitro effects of glyphosate-based herbicides and related adjuvants on primary culture of hemocytes from Haliotis tuberculata

Glyphosate-based herbicides are among the most produced and widely-used herbicides. Studies have shown that commercial formulations and adjuvants may be more toxic to non-target organisms than the active ingredients alone, but the mechanisms of action of these chemicals remain unclear. The aim of this study was to investigate the in vitro effects of glyphosate, a commercial formulation and adjuvant alone using primary culture of hemocytes from the European abalone Haliotis tuberculata, a commonly farmed shellfish. Glyphosate was found to have negligible effects on viability, phagocytic activities and lysosome stability even with very high doses (i.e. 100 mg L-1). By contrast, greater effects on viability were observed for the commercial formulation and adjuvant alone, with EC50 values of 41.42 mg L-1 and 1.85 mg L-1, respectively. These results demonstrate that the toxic sublethal effects (i.e. phagocytic activity and destabilization of lysosomal membranes) of formulated glyphosate came from adjuvants and suggest they may be related to cell and organelle membrane destabilization.

The effects of glyphosate and AMPA on the mediterranean mussel Mytilus galloprovincialis and its microbiota

Glyphosate, the most widely used herbicide worldwide, targets the 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) enzyme in the shikimate pathway found in plants and some microorganisms. While the potential for glyphosate to induce a broad range of biological effects in exposed organisms has been demonstrated, the global molecular mechanisms of toxicity and potential effects in bacterial symbionts remain unclear, in particular for ecologically important marine species such as bivalve molluscs. Here, the effects of glyphosate (GLY), its degradation product aminomethylphosphonic acid (AMPA), and a mixture of both (MIX) on the mussel M. galloprovincialis were assessed in a controlled experiment. For the first time, next generation sequencing (RNA-seq and 16S rRNA amplicon sequencing) was used to evaluate such effects at the molecular level in both the host and its respective microbiota. The results suggest that the variable capacity of bacterial species to proliferate in the presence of these compounds and the impairment of host physiological homeostasis due to AMPA and GLY toxicity may cause significant perturbations to the digestive gland microbiota, as well as elicit the spread of potential opportunistic pathogens such as Vibrio spp.. The consequent host-immune system activation identified at the molecular and cellular level could be aimed at controlling changes occurring in the composition of symbiotic microbial communities. Overall, our data raise further concerns about the potential adverse effects of glyphosate and AMPA in marine species, suggesting that both the effects of direct toxicity and the ensuing changes occurring in the host-microbial community must be taken into consideration to determine the overall ecotoxicological hazard of these compounds.