In vitro effects of triclosan and methyl-triclosan on the marine gastropod Haliotis tuberculata

Metabolic disturbance and transcriptomic changes induced by methyl triclosan in human hepatocyte L02 cells

PURPOSE

Methyl triclosan (MTCS) is one of the biomethylated by-products of triclosan (TCS). With the increasing use of TCS, the adverse effects of MTCS have attracted extensive attention in recent years. The purpose of this study was to investigate the cytotoxicity of MTCS and to explore the underlining mechanism using human hepatocyte L02 cells as in vitro model.

RESULTS

The cytotoxicity results revealed that MTCS could inhibit cell viability, disturb the ratio of reduced glutathione (GSH) and oxidized glutathione (GSSG), and reduce the mitochondrial membrane potential (MMP) in a dose-dependent manner. In addition, MTCS exposure significantly promoted the cellular metabolic process, including enhanced conversion of glucose to lactic acid, and elevated content of intracellular triglyceride (TG) and total cholesterol (TC). RNA-sequencing and bioinformatics analysis indicated disorder of glucose and lipid metabolism was significantly induced after MTCS exposure. Protein-protein interaction network analysis and node identification suggested that Serine hydroxy methyltransferase 2 (SHMT2), Methylenetetrahydrofolate dehydrogenase 2 (MTHFD2), Asparagine synthetase (ASNS) and Phosphoglycerate dehydrogenase (PHGDH) are potential molecular markers of metabolism imbalance induced by MTCS.

CONCLUSION

These results demonstrated that oxidative stress and metabolism dysregulation might be involved in the cytotoxicity of MTCS in L02 cells.

Vitamin D3/VDR inhibits inflammation through NF-κB pathway accompanied by resisting apoptosis and inducing autophagy in abalone Haliotis discus hannai

Vitamin D3 is believed to be a contributing factor to innate immunity. Vitamin D receptor (VDR) has a positive effect on inhibiting nuclear factor κB (NF-κB)-mediated inflammation. The underlying molecular mechanisms remain unclear, particularly in mollusks. Consequently, this study will investigate the process of vitamin D3/VDR regulating NF-κB pathway and further explore their functions on inflammation, autophagy, and apoptosis in abalone Haliotis discus hannai. Results showed that knockdown of VDR by using siRNA and dsRNA of VDR in vitro and in vivo led to more intense response of NF-κB signaling to lipopolysaccharide and higher level of apoptosis and autophagy. In addition, 1,25(OH)2D3 stimulation after VDR silencing could partially alleviate apoptosis and induce autophagy. Overexpression of VDR restricted the K48-polyubiquitin chain-dependent inhibitor of κB (IκB) ubiquitination and apoptosis-associated speck-like protein containing CARD (ASC) oligomerization. Besides, VDR silencing resulted in increase of ASC speck formation. In further mechanistic studies, we showed that VDR can directly bind to IκB and IKK1 in vitro and in vivo. In the feeding trial, H&E staining, TUNEL, and electron microscope results showed that vitamin D3 deficiency (0 IU/kg) could recruit more basophilic cells and increase more TUNEL-positive apoptotic cells and lipid droplets (LDs) than vitamin D3 supplement (1000 IU/kg and 5000 IU/kg). In summary, abalone VDR plays a negative regulator role in NF-κB-mediated inflammation via interacting with IκB and inhibiting ubiquitin-dependent degradation of IκB. Vitamin D3 in combination with VDR is essential to establish a delicate balance between autophagy and apoptosis in response to inflammation.

Identification of Novel Organophosphate Esters in Hydroponic Lettuces (Lactuca sativa L.): Biotransformation and Acropetal Translocation

The absorption, translocation, and biotransformation behaviors of organophosphate esters (OPEs) and diesters (OPdEs) in a hydroponic system were investigated. The lateral root was found as the main accumulation and biotransformation place of OPEs and OPdEs in lettuce. The nontarget analysis using high-resolution mass spectrometry revealed five hydroxylated metabolites and five conjugating metabolites in the OPE exposure group, among which methylation, acetylation, and palmitoyl conjugating OPEs were reported as metabolites for the first time. Particularly, methylation on phosphate can be a significant process for plant metabolism, and methyl diphenyl phosphate (MDPP) accounted for the majority of metabolites. The translocation factor values of most identified OPE metabolites are negatively associated with their predicted logarithmic octanol-water partitioning coefficient (log Kow) values (0.75-2.45), indicating that hydrophilicity is a dominant factor in the translocation of OPE metabolites in lettuce. In contrast, palmitoyl conjugation may lead to an enhanced acropetal translocation and those with log Kow values < 0 may have limited translocation potential. Additionally, OPE diesters produced from the biotransformation of OPEs in lettuce showed a higher acropetal translocation potential than those exposed directly. These results further emphasize the necessity to consider biotransformation as an utmost important factor in the accumulation and acropetal translocation potential of OPEs in plants.

Status in molluscan cell line development in last one decade (2010–2020): impediments and way forward

Despite the attempts that have started since the 1960s, not even a single cell line of marine molluscs is available. Considering the vast contribution of marine bivalve aquaculture to the world economy, the prevailing viral threats, and the dismaying lack of advancements in molluscan virology, the requirement of a marine molluscan cell line is indispensable. This synthetic review discusses the obstacles in developing a marine molluscan cell line concerning the choice of species, the selection of tissue and decontamination, and cell culture media, with emphasis given on the current decade 2010-2020. Detailed accounts on the experiments on the virus cultivation in vitro and molluscan cell immortalization, with a brief note on the history and applications of the molluscan cell culture, are elucidated to give a holistic picture of the current status and future trends in molluscan cell line development.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10616-022-00539-x.

Hormesis Effect of Methyl Triclosan on Cell Proliferation and Migration in Human Hepatocyte L02 Cells

Methyl triclosan (mTCS) is a methylated derivative of triclosan (TCS), which is extensively used as an antimicrobial component of various nursing products and disinfectants. Current research studies of mTCS mainly focused on the environmental persistence and bioaccumulation potential. Knowledge regarding the toxicity and carcinogenicity of mTCS is limited until now. In this study, the human hepatocyte L02 cells were used to investigate the cellular effects of mTCS under different concentrations (0.1-60 μM). The hormesis effect was observed where a low dose of mTCS (≤5 μM) exposure stimulated the cell proliferation ability, while high-dose exposure (≥20 μM) inhibited cell proliferation. In the same time, low doses of mTCS (0.5 and 1 μM) induced enhanced anchorage-independent proliferation ability and cell migration ability, indicating a positive effect on malignant transformation in L02 cells. Moreover, reactive oxygen species productions were significantly increased after mTCS exposure (≥1 μM), as compared with the control group. Furthermore, expressions of tumor-related genes, mouse double minute 2 (MDM2), matrix metalloproteinase 9 (MMP9), and proliferating cell nuclear antigen (PCNA), and proto-oncogene MYC (c-Myc), Jun, and FosB were significantly upregulated, while no significant changes were observed on expressions of apoptosis-related and cell cycle-related genes in L02 cells after exposure of low-dose mTCS. In conclusion, these results indicated that a low dose of mTCS had a hormesis effect in L02 cells on cell proliferation and malignant transformation in vitro, which might be mediated through oxidative stress response.

Stem cells of aquatic invertebrates as an advanced tool for assessing ecotoxicological impacts

Environmental stressors are assessed through methods that quantify their impacts on a wide range of metrics including species density, growth rates, reproduction, behaviour and physiology, as on host-pathogen interactions and immunocompetence. Environmental stress may induce additional sublethal effects, like mutations and epigenetic signatures affecting offspring via germline mediated transgenerational inheritance, shaping phenotypic plasticity, increasing disease susceptibility, tissue pathologies, changes in social behaviour and biological invasions. The growing diversity of pollutants released into aquatic environments requires the development of a reliable, standardised and 3R (replacement, reduction and refinement of animals in research) compliant in vitro toolbox. The tools have to be in line with REACH regulation 1907/2006/EC, aiming to improve strategies for potential ecotoxicological risks assessment and monitoring of chemicals threatening human health and aquatic environments. Aquatic invertebrates' adult stem cells (ASCs) are numerous and can be pluripotent, as illustrated by high regeneration ability documented in many of these taxa. This is of further importance as in many aquatic invertebrate taxa, ASCs are able to differentiate into germ cells. Here we propose that ASCs from key aquatic invertebrates may be harnessed for applicable and standardised new tests in ecotoxicology. As part of this approach, a battery of modern techniques and endpoints are proposed to be tested for their ability to correctly identify environmental stresses posed by emerging contaminants in aquatic environments. Consequently, we briefly describe the current status of the available toxicity testing and biota-based monitoring strategies in aquatic environmental ecotoxicology and highlight some of the associated open issues such as replicability, consistency and reliability in the outcomes, for understanding and assessing the impacts of various chemicals on organisms and on the entire aquatic environment. Following this, we describe the benefits of aquatic invertebrate ASC-based tools for better addressing ecotoxicological questions, along with the current obstacles and possible overhaul approaches.

A Review on the Fate of Legacy and Alternative Antimicrobials and Their Metabolites during Wastewater and Sludge Treatment

Antimicrobial compounds are used in a broad range of personal care, consumer and healthcare products and are frequently encountered in modern life. The use of these compounds is being reexamined as their safety, effectiveness and necessity are increasingly being questioned by regulators and consumers alike. Wastewater often contains significant amounts of these chemicals, much of which ends up being released into the environment as existing wastewater and sludge treatment processes are simply not designed to treat many of these contaminants. Furthermore, many biotic and abiotic processes during wastewater treatment can generate significant quantities of potentially toxic and persistent antimicrobial metabolites and byproducts, many of which may be even more concerning than their parent antimicrobials. This review article explores the occurrence and fate of two of the most common legacy antimicrobials, triclosan and triclocarban, their metabolites/byproducts during wastewater and sludge treatment and their potential impacts on the environment. This article also explores the fate and transformation of emerging alternative antimicrobials and addresses some of the growing concerns regarding these compounds. This is becoming increasingly important as consumers and regulators alike shift away from legacy antimicrobials to alternative chemicals which may have similar environmental and human health concerns.

Comparison of Transcriptomics Changes Induced by TCS and MTCS Exposure in Human Hepatoma HepG2 Cells

Triclosan (TCS) has been a widely used antibacterial agent in medical and personal care products in the last few decades. Methyl TCS (MTCS) is the major biotransformation product of TCS through replacement of the hydroxyl group with methoxy. Previous studies revealed that MTCS showed reduced toxicity but enhanced environmental persistence, when compared with TCS. Till date, the toxicological molecular mechanisms of TCS and MTCS remain to be clarified. This study aimed to investigate the transcriptomic changes in HepG2 cells induced by TCS and MTCS using microarray chips and to identify key target genes and related signal pathways. The microarray data showed that there were 1664 and 7144 differentially expressed genes (DEGs) in TCS- and MTCS-treated groups, respectively. Gene ontology (GO) enrichment and Kyoto Encyclopedia of genes and genomes (KEGG) analysis revealed that TCS and MTCS induced overlapping as well as distinct transcriptome signatures in HepG2 cells. Both TCS and MTCS could result in various biological responses in HepG2 cells mainly responding to biosynthetic and metabolic processes but probably through different regulatory pathways. Among the selected 50 GO terms, 9 GO terms belonging to the cellular component category were only enriched in the MTCS group, which are mainly participating in the regulation of cellular organelle's function. KEGG analysis showed that 19 and 59 pathway terms were separately enriched in TCS and MTCS groups, with only seven identical pathways. The selected 10 TCS-specific signal pathways are mainly involved in cell proliferation and apoptosis, while the selected 10 MTCS-specific pathways mainly take part in the regulation of protein synthesis and modification. The overall data suggested that MTCS induced more enriched DEGs, GO terms, and pathway terms than TCS. In conclusion, compared with TCS, MTCS presents lower polarity and stronger lipophilicity, enabling MTCS to cause more extensive transcriptomic changes in HepG2 cells, activate differentiated signal pathways, and finally lead to differences in biological responses.

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.

Investigation of mechanisms of toxicity and exclusion by transporters of the preservatives triclosan and propylparaben using batteries of Schizosaccharomyces pombe strains

Triclosan (TCS) and propylparaben (PPB) are antimicrobials widely used. They present many similarities in their applications and also in their human and environmental health risks. In order to investigate the mechanisms of toxic action and the efflux pumps involved in their detoxication, we used a strategy with batteries of Schizosaccharomyces pombe yeast strains, either defective in cell signalling, in detoxification pumps, or in cell surveillance mechanisms. Yeast were exposed up to 20 h in solid medium or in liquid medium in 96-well plates. The mechanisms of action investigated were spindle defects (mph1), stress (pmk1), DNA interference (rad3) or diverse effects (MDR-sup). The efflux pumps investigated were Bfr1, Pmd1, Mfs1 and Caf5 or the Pap1 transcription factor. Here we show that TCS was 75 times more toxic than PPB in the wild type fission yeast. More oxidative stress and less protection by exclusion pumps were observed for TCS than for PPB. The cytotoxicity produced by TCS decreased from bfr1>mfs1>pmd1 > pap1 and caf5A deficient strains. In contrast, cytotoxic concentrations of PPB caused only a mild stress. The protection provided for PPB by the transporters was more marked than for TCS, decreasing from Pmd1, Caf5, Mfs1 and Bfr1. Furthermore, microtubule and DNA interferences were revealed for PPB, according to the cytotoxicity of mph1 and rad3 defective cells, respectively. As both compounds present complex adverse effects at concentrations close to exposure, and their combination clearly causes a strong potentiation, more exhaustive controls and regulations in their use should be considered.

In vitro metabolism of triclosan studied by liquid chromatography-high-resolution tandem mass spectrometry

Triclosan (TCS) is an antibacterial and antifungal compound found in many hygiene products, including toothpaste, soap, and detergents. However, this molecule can act as an endocrine disruptor and can induce harmful effects on human health and the environment. In this study, triclosan was biotransformed in vitro using human and rat liver fractions, to evaluate oxidative metabolism, the formation of reactive metabolites via the detection of GSH adducts, as well as glucuronide and sulfate conjugates using liquid chromatography coupled to high-resolution tandem mass spectrometry (LC-HRMS/MS). A deuterated analog of triclosan was also employed for better structural elucidation of specific metabolic sites. Several GSH adducts were found, either via oxidative metabolism of triclosan or its cleavage product, 2,4-dichlorophenol. We also detected glucuronide and sulfated conjugates of triclosan and its cleaved product. This study was aimed at understanding the routes of detoxification of this xenobiotic, as well as investigating any potential pathways related to additional toxicity via reactive metabolite formation. Graphical abstract.

Occurrence, fate and risk assessment of biocides in wastewater treatment plants and aquatic environments in Thailand

This study investigated the occurrence and fate of 19 biocides in 8 wastewater treatment plants and receiving aquatic environments (both freshwater and estuarine systems) in Thailand. The predominant compound in wastewater and surface water was methylparaben with the maximum concentration of 15.2 μg/L detected in the receiving river, while in sludge and sediment was triclocarban with the maximum concentration of 8.47 μg/g in sludge. Triclosan was the main contaminants in the fish samples with the maximum concentration of 1.20 μg/g. Similar results of biocides were found in the estuarine system in Pattaya city, with the maximum concentration of 185 ng/L in sea water for methylparaben, and 242 ng/g in estuarine sediment for triclocarban. The aqueous removal rates for the biocides ranged from 15% to 95% in average. The back estimated-usage and total estimated emission of Ʃ19 biocides in Thailand was 279 and 202 tons/year, respectively. Preliminary ecological risk assessment showed that clotrimazole and triclosan could pose high risks to aquatic organisms in the receiving aquatic environments.

The methyl-triclosan induced caspase-dependent mitochondrial apoptosis in HepG2 cells mediated through oxidative stress

Methyl-triclosan (MTCS) is a dominant transformation product of triclosan (TCS), which has been widely used as an effective antimicrobial ingredient with increasing concentrations in the environment. MTCS shows higher persistence in environment than its parent chemical TCS. The toxic effects of MTCS and toxicological mechanism are not well understood up to now. This study investigated the cytotoxic effects of MTCS in HepG2 cells in terms of cell viability, apoptosis induction, ROS production, GSH/GSSG levels, Mitochondrial Membrane Potential (MMP) reduction, LDH release, glucose uptake and ATP production. Moreover, the related gene transcripts were measured with RT-qPCR assay. Cytotoxic experiments in HepG2 cells revealed that MTCS exposure at micromol per liter levels had toxic effects as evidenced by decreased cell survival, elevated cell apoptosis, reduced MMP and increased LDH release. These toxic effects were associated with increased ROS production and reduced GSH/GSSG ratio. Meanwhile, elevated glucose uptake and ATP production indicated that MTCS induced membrane damages resulted not from a typical mitochondrial uncoupler, but from oxidative stress. Analysis of gene transcripts showed that MTCS exposure induced mRNA expressions alterations associated with oxidative stress response, energy production, cell cycle regulation and cell apoptosis. In general, the caspase-dependent mitochondrial apoptosis pathway might play a role in MTCS induced cytotoxicity in HepG2 cells.

Assessment of the effect of methyl-triclosan and its mixture with triclosan on developing zebrafish (Danio rerio) embryos using mass spectrometry-based metabolomics

Methyl-triclosan (MTCS), as a biodegradation product from antibacterial triclosan (TCS), has been detected in water catchments, and it has also been verified to accumulate in biota due to its hydrophobicity. There is a lack, however, of toxicity studies on MTCS and its effects on organisms in conjunction with TCS. In this study, exposure experiments were conducted to assess the toxicity to embryonic zebrafish of selected concentrations of MTCS (from 1 ng/L to 400 μg/L) and MTCS/TCS mixtures (from 1 μg/L TCS and 100 ng/L MTCS to 300 μg/L TCS and 30 μg/L MTCS). Specimens were extracted using acetonitrile: isopropanol: water (3:3:2; v/v/v) and then analyzed using Gas chromatography-mass spectrometry (GC-MS) to identify the metabolites based on the Fiehn library database. The results showed that MTCS exposure led to the alterations of the metabolomes of the zebrafish embryos, including level changes of l-valine, d-mannose, d-glucose, and other metabolites. Multivariate analysis (PCA, PLS-DA, sPLS-DA) and univariate analysis (one-way ANOVA) indicated differences between the control and exposure groups of the metabolites, indicating that biological pathways, such as amino acid synthesis, pentose phosphate pathway (PPP), starch and sucrose metabolism were influenced. Moreover, when the embryos were exposed to a mix of TCS and MTCS, TCS dominated the mixture's effect on biological pathways because the concentration ratio within the mixture, which mimics environmental ratio of 10 TCS : 1 MTCS, leads to high bioavailability of TCS.

Comparison of hepatotoxicity and mechanisms induced by triclosan (TCS) and methyl-triclosan (MTCS) in human liver hepatocellular HepG2 cells

Triclosan (TCS) is used as an antimicrobial agent and has been widely dispersed and detected in the environment and organisms including human samples. Methyl-triclosan (MTCS) is the predominant bacterial TCS metabolite. At present, the toxicological effects and mechanism of TCS and MTCS are still not fully understood. In this study, the cytotoxic effects of TCS and MTCS in HepG2 cells were investigated in terms of cell proliferation, comet assay, cell cycle, and apoptosis. In addition, the expressions of related proteins were detected with western blotting analysis. The results showed that TCS could significantly inhibit cell proliferation, while MTCS had no obvious effect on cell growth. Both TCS and MTCS caused oxidative injury associated with HO-1 induction and increased DNA strand breaks, which consequently initiated the damage repair process via up-regulation of DNA-PKcs. In addition, TCS blocked the HepG2 cells in S and G2/M phases of cell cycle through down-regulation of cyclin A2 and CDK; while MTCS induced cell cycle arrest at the S phase through up-regulation of cyclin A2 and CDK. Furthermore, TCS activated p53 mediated apoptosis in HepG2 cells in a caspase-independent manner, while MTCS induced apoptosis was dependent on caspase. Moreover, TCS exposure exhibited more severe toxicity in HepG2 cells as compared with MTCS exposure, indicating that the replacement of the ionizable proton in TCS by the methyl group in MTCS is correlated with the cellular toxicity and the molecular mechanism.

Triclosan exposure, transformation, and human health effects

Triclosan (TCS) is an antimicrobial used so ubiquitously that 75% of the US population is likely exposed to this compound via consumer goods and personal care products. In September 2016, TCS was banned from soap products following the risk assessment by the US Food and Drug Administration (FDA). However, TCS still remains, at high concentrations, in other personal care products such as toothpaste, mouthwash, hand sanitizer, and surgical soaps. TCS is readily absorbed into human skin and oral mucosa and found in various human tissues and fluids. The aim of this review was to describe TCS exposure routes and levels as well as metabolism and transformation processes. The burgeoning literature on human health effects associated with TCS exposure, such as reproductive problems, was also summarized.

Responses of primary cultured haemocytes derived from the marine gastropod Haliotis tuberculata to an industrial effluent exposure

This study assessed the responses of primary cultured haemocytes from the marine gastropod Haliotis tuberculata exposed to the increasing concentrations of industrial effluent (0, 0.5, 1, 10, 15 and 20%) discharged into the Tunisian coastal area. Analyses showed the presence of metals such as cadmium (Cd), chromium (Cr), copper (Cu), manganese (Mn), zinc (Zn), nickel (Ni) and lead (Pb) in the effluent. The effects of this mixture of pollutants on abalone haemocyte parameters were reflected by a significant decrease of cell viability, phagocytotic activity and reactive oxygen species (ROS) production as well as morphological and lysosomal membrane alterations. Thus, these results indicated that our primary culture system represents a suitable in vitro model for monitoring of anthropogenic contaminants in aquatic environments.

Effects of pharmaceuticals and personal care products on marine organisms: from single-species studies to an ecosystem-based approach

Pharmaceuticals and personal care products (PPCPs) are contaminants of emerging concern that are increasing in use and have demonstrated negative effects on aquatic organisms. There is a growing body of literature reporting the effects of PPCPs on freshwater organisms, but studies on the effects of PPCPs to marine and estuarine organisms are limited. Among effect studies, the vast majority examines subcellular or cellular effects, with far fewer studies examining organismal- and community-level effects. We reviewed the current published literature on marine and estuarine algae, invertebrates, fish, and mammals exposed to PPCPs, in order to expand upon current reviews. This paper builds on previous reviews of PPCP contamination in marine environments, filling prior literature gaps and adding consideration of ecosystem function and level of knowledge across marine habitat types. Finally, we reviewed and compiled data gaps suggested by current researchers and reviewers and propose a multi-level model to expand the focus of current PPCP research beyond laboratory studies. This model includes examination of direct ecological effects including food web and disease dynamics, biodiversity, community composition, and other ecosystem-level indicators of contaminant-driven change.

Antimicrobial agent triclosan is a proton ionophore uncoupler of mitochondria in living rat and human mast cells and in primary human keratinocytes

Triclosan (TCS) is an antimicrobial used widely in hospitals and personal care products, at ~10 mm. Human skin efficiently absorbs TCS. Mast cells are ubiquitous key players both in physiological processes and in disease, including asthma, cancer and autism. We previously showed that non-cytotoxic levels of TCS inhibit degranulation, the release of histamine and other mediators, from rat basophilic leukemia mast cells (RBL-2H3), and in this study, we replicate this finding in human mast cells (HMC-1.2). Our investigation into the molecular mechanisms underlying this effect led to the discovery that TCS disrupts adenosine triphosphate (ATP) production in RBL-2H3 cells in glucose-free, galactose-containing media (95% confidence interval EC50 = 7.5-9.7 µm), without causing cytotoxicity. Using these same glucose-free conditions, 15 µm TCS dampens RBL-2H3 degranulation by 40%. The same ATP disruption was found with human HMC-1.2 cells (EC50 4.2-13.7 µm), NIH-3 T3 mouse fibroblasts (EC50 4.8-7.4 µm) and primary human keratinocytes (EC50 3.0-4.1 µm) all with no cytotoxicity. TCS increases oxygen consumption rate in RBL-2H3 cells. Known mitochondrial uncouplers (e.g., carbonyl cyanide 3-chlorophenylhydrazone) previously were found to inhibit mast cell function. TCS-methyl, which has a methyl group in place of the TCS ionizable proton, affects neither degranulation nor ATP production at non-cytotoxic doses. Thus, the effects of TCS on mast cell function are due to its proton ionophore structure. In addition, 5 µm TCS inhibits thapsigargin-stimulated degranulation of RBL-2H3 cells: further evidence that TCS disrupts mast cell signaling. Our data indicate that TCS is a mitochondrial uncoupler, and TCS may affect numerous cell types and functions via this mechanism. Copyright © 2015 John Wiley & Sons, Ltd.

The cell cultures and the use of haemocytes from marine molluscs for ecotoxicology assessment

Among aquatic organisms suitable for biological monitoring, molluscs occupy a prominent place due to their wide geographic distribution, their abundance and accessibility in the field as well as in aquaculture. Molluscs reflect the degree of environmental contamination and are the most useful bioindicator tools. The study of modulation of immune system or immunomodulation in marine molluscs has become one of the privileged ways for evaluating the physiological effects of environmental factors. Physiological responses of molluscs to environmental stresses could be mediated by haemocytes. These cells are continually exposed to the external environment due to the open circulatory system of molluscs and are affected by pollutants. In fact, several studies showed the effects of different environmental contaminants on haemocyte functions (viability, phagocytosis, ROS production) as well as on proteins involved in cytoskeletal structure maintenance using the in vitro approaches. In ecotoxicology, in vitro approach is an alternative to animal testing due to the reduced use of experimental animals, low cost and rapid performance. Although several studies showed the importance of using in vitro cell models to determine the effects of different environmental contaminants on haemocyte parameters in marine molluscs, a few reviews highlight these effects. The main purpose of this paper is to summarize the recent data on the effect of some xenobiotics on haemocyte parameters in some mollusc species and then suggest future research prospects.

Does a short-term exposure to cadmium chloride affects haemocyte parameters of the marine gastropod Haliotis tuberculata?

In this study, a model based on primary cultured haemocytes from the gastropod mollusc Haliotis tuberculata was established to investigate the effects of cadmium chloride in vitro. Cells were exposed for 24 h to CdCl2 concentrations of 0, 1 and 100 μg ml(-1). The effects of cadmium on haemocyte parameters were investigated using morphological, spectrophotometric and flow cytometry analysis. Results showed that cadmium has no significant effects on cell viability and phagocytotic activity under the tested conditions. However, haemocytes became more rounded after cadmium exposure, which could explain the significant decrease of cell area beginning at 1 μg ml(-1) of CdCl2.

Accumulation and Risk of Triclosan in Surface Sediments Near the Outfalls of Municipal Wastewater Treatment Plants

Triclosan is an antimicrobial agent which is widely used in many personal care products. This toxic chemical is frequently found in the aquatic environment. The municipal wastewater treatment plant (WWTP) effluent has been reported to be one of the major sources for triclosan in the aquatic system. The aim of the present study was to investigate the accumulation of triclosan in the surface sediments near the outfalls of the five major municipal WWTPs of Nanjing, China, as well as to evaluate its potential ecological risk. The concentration of triclosan in the sediment samples ranged from 48.3 to 226 ng/g dry weight, which was well correlated with the acute and genetic toxicity by bioassay. The results suggested that triclosan released from municipal WWTPs could accumulate in the surface sediments nearby and may pose undetermined risk to aquatic organisms.

Triclosan induces Fas receptor-dependent apoptosis in mouse neocortical neurons in vitro

Triclosan (TCS) is a commonly used antimicrobial agent in personal care and sanitizing products, as well as in household items. Numerous studies have demonstrated the presence of TCS in various human tissues. Several studies have reported the accumulation of TCS in fish and human brain tissue. The aim of the present study was to investigate the effect of TCS on apoptosis in mouse neocortical neurons after 7 days of culture in vitro following 3, 6 and 24 h of exposure. To explore the mechanism underlying the effects of TCS in neurons, we studied the activation and protein expression of the Fas receptor (FasR) and caspase-8, caspase-9 and caspase-3, as well as DNA fragmentation in TCS-treated cells. Cultures of neocortical neurons were prepared from Swiss mouse embryos on day 15/16 of gestation. The cells were cultured in phenol red-free Neurobasal medium with B27 and glutamine. The cultures were treated with concentrations of TCS ranging from 1 nM to 100 μM for 3, 6 and 24 h. The level of lactate dehydrogenase (LDH) was measured in the culture medium to exclude the cytotoxic concentrations. The cytotoxic effects were only observed when the highest concentrations of TCS were used (50 and 100 μM). To study apoptosis, the activities of caspase-8, caspase-9 and caspase-3 were measured, and DNA fragmentation was evaluated. Our results are the first time to demonstrate that TCS can induce an apoptotic process in neocortical neurons in vitro. The data demonstrated that TCS caused caspase-3 activation, DNA fragmentation and apoptotic body formation. Non-cytotoxic concentrations of TCS activated the extrinsic apoptotic signaling pathway, which is dependent on FasR and caspase-8 activation. However, it is also possible that TCS may activate the intrinsic apoptotic pathway after long-term exposure. Therefore, further studies on the mechanism underlying the effects of TCS on the nervous system are needed.

Characterization of abalone Haliotis tuberculata-Vibrio harveyi interactions in gill primary cultures

The decline of European abalone Haliotis tuberculata populations has been associated with various pathogens including bacteria of the genus Vibrio. Following the summer mortality outbreaks reported in France between 1998 and 2000, Vibrio harveyi strains were isolated from moribund abalones, allowing in vivo and in vitro studies on the interactions between abalone H. tuberculata and V. harveyi. This work reports the development of primary cell cultures from abalone gill tissue, a target tissue for bacterial colonisation, and their use for in vitro study of host cell-V. harveyi interactions. Gill cells originated from four-day-old explant primary cultures were successfully sub-cultured in multi-well plates and maintained in vitro for up to 24 days. Cytological parameters, cell morphology and viability were monitored over time using flow cytometry analysis and semi-quantitative assay (XTT). Then, gill cell cultures were used to investigate in vitro the interactions with V. harveyi. The effects of two bacterial strains were evaluated on gill cells: a pathogenic bacterial strain ORM4 which is responsible for abalone mortalities and LMG7890 which is a non-pathogenic strain. Cellular responses of gill cells exposed to increasing concentrations of bacteria were evaluated by measuring mitochondrial activity (XTT assay) and phenoloxidase activity, an enzyme which is strongly involved in immune response. The ability of gill cells to phagocyte GFP-tagged V. harveyi was evaluated by flow cytometry and gill cells-V. harveyi interactions were characterized using fluorescence microscopy and transmission electron microscopy. During phagocytosis process we evidenced that V. harveyi bacteria induced significant changes in gill cells metabolism and immune response. Together, the results showed that primary cell cultures from abalone gills are suitable for in vitro study of host-pathogen interactions, providing complementary assays to in vivo experiments.

Expression of biomineralisation genes in tissues and cultured cells of the abalone Haliotis tuberculata

Mollusc shell biomineralisation involves a variety of organic macromolecules (matrix proteins and enzymes) that control calcium carbonate (CaCO3) deposition, growth of crystals, the selection of polymorph, and the microstructure of the shell. Since the mantle and the hemocytes play an important role in the control of shell formation, primary cell cultures have been developed to study the expression of three biomineralisation genes recently identified in the abalone Haliotis tuberculata: a matrix protein, Lustrin A, and two carbonic anhydrase enzymes. Mantle cells and hemocytes were successfully maintained in primary cultures and were evaluated for their viability and proliferation over time using a semi-automated assay (XTT). PCR and densitometric analysis were used to semi-quantify the gene expression and compare the level of expression in native tissues and cultured cells. The results demonstrated that the three genes of interest were being expressed in abalone tissues, with expression highest in the mantle and much lower in the hemocytes and the gills. Biomineralisation genes were also expressed significantly in mantle cells, confirming that primary cultures of target tissues are suitable models for in vitro investigation of matrix protein secretion.