Insights into the differential proteome landscape of a newly isolated Paramecium multimicronucleatum in response to cadmium stress.

Employing microbial systems for the bioremediation of contaminated waters represent a potential option, however, limited understanding of the underlying mechanisms hampers the implication of microbial-mediated bioremediation. The omics tools offer a promising approach to explore the molecular basis of the bioremediation process. Here, a mass spectrometry-based quantitative proteome profiling approach was conducted to explore the differential protein levels in cadmium-treated Paramecium multimicronucleatum. The Proteome Discoverer software was used to identify and quantify differentially abundant proteins. The proteome profiling generated 7,416 peptide spectral matches, yielding 2824 total peptides, corresponding to 989 proteins. The analysis revealed that 29 proteins exhibited significant (p ≤ 0.05) differential levels, including a higher abundance of 6 proteins and reduced levels of 23 proteins in Cd2+ treated samples. These differentially abundant proteins were associated with stress response, energy metabolism, protein degradation, cell growth, and hormone processing. Briefly, a comprehensive proteome profile in response to cadmium stress of a newly isolated Paramecium has been established that will be useful in future studies identifying critical proteins involved in the bioremediation of metals in ciliates. SIGNIFICANCE: Ciliates are considered a good biological indicator of chemical pollution and relatively sensitive to heavy metal contamination. A prominent ciliate, Paramecium is a promising candidate for the bioremediation of polluted water. The proteins related to metal resistance in Paramecium species are still largely unknown and need further exploration. In order to identify and reveal the proteins related to metal resistance in Paramecia, we have reported differential protein abundance in Paramecium multimicronucleatum in response to cadmium stress. The proteins found in our study play essential roles during stress response, hormone processing, protein degradation, energy metabolism, and cell growth. It seems likely that Paramecia are not a simple sponge for metals but they could also transform them into less toxic derivatives or by detoxification by protein binding. This data will be helpful in future studies to identify critical proteins along with their detailed mechanisms involved in the bioremediation and detoxification of metal ions in Paramecium species.

Ecotoxicity of chrysene and phenanthrene on meiobenthic nematodes with a case study of Terschellingia longicaudata: Taxonomics, toxicokinetics, and molecular interactions modelling.

Polycyclic aromatic hydrocarbons (PAHs) are toxic for humans and marine fauna alike. The current study assessed the impact of PAHs on the migratory behaviour of meiobenthic nematodes collected from the Bizerte lagoon, Tunisia. The experiment lasted for 15 days and was carried in open microcosms, which comprised a lower, contaminated and an upper, uncontaminated compartment. Three treatments were used, for each of them an untreated control was set up: sediment contaminated with chrysene (116 ng g-1 dry weight (DW), with phenanthrene (116 ng g-1 DW) and a mixture of both. The results showed a significant decrease in diversty and abundance in the lower, contaminated compartments compared to the upper zones. The results also highlighted that under an increased stress some species progressively increased in number, these were considered PAH-tolerant species such as Odontophora villoti, some others had an occasionally increased in number were considered as opportunistic species, such as Paracomesoma dubium and the species that showed a progressive decreased in number, such as Metoncholaimus pristiurus and Steineria sp., Terschellingia. longicaudata, and Oncholaimellus sp. were classified as PAH-sensitive. Moreover, an increase in the activity of biochemical biomarkers was observed following the exposure of males and gravid females of T. longicaudata to 29, 58 and 87 ng g-1 DW of chrysene and phenanthrene paralleled by a higher vulnerability of the latter demographic category. Besides, a significant decrease in fertility of females and an increase in pharyngeal sucking power were observed for both types of PAHs considered. The sex ratio was also significantly imbalanced in the favor of males, which suggest that chrysene and phenanthrene affect also the hormone system of T. longicaudata. The high affinities of these PAHs and their molecular interactions with both germ line development protein 3 (GLD-3) and sex-determining protein (SDP) may justify these results and explain the toxicokinetic attributes.

Investigations into the Antifungal, Photocatalytic, and Physicochemical Properties of Sol-Gel-Produced Tin Dioxide Nanoparticles.

Transmission electron microscopy (TEM), atomic force microscopy (AFM), X-ray diffraction (XRD), energy dispersive X-ray (EDX), scanning electron microscopy (SEM), diffuse reflectance spectroscopy (DRS), and Fourier transform infrared (FTIR) spectroscopy were applied to evaluate the tin dioxide nanoparticles (SnO2 NPs) amalgamated by the sol-gel process. XRD was used to examine the tetragonal-shaped crystallite with an average size of 26.95 (±1) nm, whereas the average particle size estimated from the TEM micrograph is 20.59 (±2) nm. A dose-dependent antifun3al activity was performed against two fungal species, and the activity was observed to be increased with an increase in the concentration of SnO2 NPs. The photocatalytic activity of SnO2 NPs in aqueous media was tested using Rhodamine 6G (Rh-6G) under solar light illumination. The Rh-6G was degraded at a rate of 0.96 × 10-2 min for a total of 94.18 percent in 350 min.

The response of meiobenthinc sediment-dwelling nematodes to pyrene: Results from open microcosms, toxicokinetics and in silico molecular interactions.

An experiment conducted with 'open microcosm' made by connected sedimentary compartments with different qualities was for 30 days to evaluate the migratory behaviour of nematodes as induced by exposure to pyrene. The nematofauna was collected along with sediment from a reference site in Bizerte lagoon. Following one week acclimatization period, the populated sediments were topped with azoic sediments, with a pyrene concentration of 150 µg kg-1. The concentration of pyrene from sediments was measured on a weekly basis. A stable status of nematode assemblages was reached between the upper and lower compartments in each microcosm, whatever the treatment type. An upward exploratory phase was observed during the first two weeks within the assemblages, possibly induced by the repellent chemodetection of pyrene. This observation was confirmed by the toxicokinetic properties and molecular interactions of pyrene with the germ-line development Protein 3 and sex-determining protein of Caenorhabditis elegans as nematode model.

The exposure to polyvinyl chloride microplastics and chrysene induces multiple changes in the structure and functionality of marine meiobenthic communities.

The effects of microplastics and sorbed polycyclic aromatic hydrocarbons at community levels were rarely assessed in laboratory experiments, despite their obvious advantage in reflecting better the natural conditions compared to traditionally single species-focused toxicological experiments. In the current study, the multifaceted effects of polyvinyl chloride and chrysene, acting alone or combined, on general marine meiobenthos, but with a special focus on free-living marine nematode communities were tested in a laboratory experiment carried in microcosms. The meiobenthos was exposed to two polyvinyl chloride (5 and 10 mg.kg-1 Dry Weight 'DW') and chrysene (37.5 and 75 ng.g-1 DW) concentrations, respectively, as well as to a mixture of both compounds, for 30 days. The results highlighted a significant decrease in the abundance of all meiobenthic generic groups, including nematodes, directly with increasing dosages of these compounds when added alone. The addition of chrysene adheres to microplastics, making the sediment matrix glueyer, hence inducing greater mortality among generic meiobenthic groups. Moreover, the nematofauna went through a strong restructuring phase following the exposure to both compounds when added alone, leading to the disappearance of sensitive nematodes and their replacement with tolerant taxa. However, the similarity in nematofauna composition between control and polyvinyl chloride and chrysene mixtures suggests that the toxicity of the latter could be attenuated by its physical bonding to the former pollutant. Other changes in the functional traits within the nematode communities were a decline in the fertility of females and an increase of the pharyngeal pumping power following exposure to both pollutants for the dominant species. The latter results were also supported by additional toxicokinetics analyses and in silico modeling.

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.

Molecular interactions of polyvinyl chloride microplastics and beta-blockers (Diltiazem and Bisoprolol) and their effects on marine meiofauna: Combined in vivo and modeling study.

The ecotoxicological effects of beta-blockers (i.e. Diltiazem and Bisoprolol) and their interactions with the microplastic polyvinyl chloride on marine meiofauna were tested in laboratory microcosms. An experimental factorial design was applied, using meiobenthic fauna collected from the Old Harbor of Bizerte (NE Tunisia), but with a main focus on the nematode communities. The meiobenthic invertebrates were exposed to two concentrations of Diltiazem and Bisoprolol, of 1.8 µg.L-1 and 1.8 mg.L-1, respectively, and one concentration of polyvinyl chloride (i.e. 20 mg.kg-1), separately and mixed. The overall meiofauna abundance was significantly reduced in all treatments, mainly that of polychaetes and amphipods. Moreover, the juveniles-gravid female ratios of the nematode communities were the lowest in the 1.8 µg.L-1 Bisoprolol treatment and for the 1.8 mg.L-1 mixture of Diltiazem and microplastics, suggesting that different dosages influence the maturity status of the examined species. The demographic results were also supported by in silico approach. The simulation of molecular interactions revealed acceptable binding affinities (up to -8.1 kcal/mol) and interactions with key residues in the germ line development protein 3 and sex-determining protein from Coenorhabditis elegans. Overall, the experimental outcome strongly indicates synergistic interactions among the beta-blockers Diltiazem and Bisoprolol and the microplastic polyvinyl chloride on marine nematode communities.

Effectiveness of Shewanella oneidensis bioaugmentation in the bioremediation of phenanthrene-contaminated sediments and possible consortia with omnivore-carnivore meiobenthic nematodes.

This study was conducted to assess the impact and efficiency of the bioaugmentation as a bioremediation technique in annoying effects of a polycyclic aromatic hydrocarbon (phenanthrene) on a community of free-living nematodes from Bizerte bay (Tunisia). For this purpose, closed microcosms were exposed to three doses of phananthrene (0.1 µg kg-1, 1 µg kg-1 and 10 µg kg-1), in combination or not with a strain of Shewanella oneidensis. After 40 days of the exposure, results were obtained at the numerical, taxonomic and feeding levels. The results of univariate analyses revealed significant decreases in most univariate indices for phenanthrene treated communities compared to controls, with a discernible increase in the proportion of epistrate feeders. After bioaugmentation, similar patterns were observed for univariate and multivariate analyses, with the exception of the highest treatment, which showed no difference from the controls. The results obtained showed that the bioaugmentation with Shewanellea oneidensis was highly effective in reducing the negative impact of the highest dose of phenanthrene (10 µg kg-1 Dry Weight) tested on meiobenthic nematodes. Furthermore, a combination of Shewanellea oneidensis and four omnivore-carnivore nematode taxa could be suggested as an effective method in the bioremediation of phenanthrene-contaminated sediment.

How effective is wastewater treatment? A case study under the light of taxonomic and feeding features of meiobenthic nematodes.

A microcosm bioassay was designed to assess the efficacy of wastewater treatment methods used in sewage plants. The taxonomic and feeding characteristics of a meiobenthic nematode assemblage from Ghar El Melh lagoon (Tunisia) were used to achieve this goal. Nematode assemblages were exposed for 30 days to untreated wastewater (UW) obtained from the sewage treatment plant of Sidi Ahmed (Tunisia) and three mixtures with treated wastewater (TW33 = 33%, TW66 = 66%, and TW100 = 100%). Concerning the nematode abundance, the exposure to either treated wastewater (TW33-100) or untreated wastewater (UW) had no significant effect. In contrast, Shannon-Wiener index and Pielou's Evenness were clearly reduced by contamination with both types of wastewater, with a more pronounced negative impact prior to treatment in the sewage plant. The multivariate analyzes revealed a change in the taxonomic composition of the nematofauna in response to the contamination by untreated or treated wastewater. The relative abundances of species in wastewater replicates compared to controls reflected this taxonomic restructuring. Finally, Ascolaimus elongatus, Terschellingia communis, and Kraspedonema octogoniata were less represented in all experimentally treated units and could be considered as 'sensitive taxa to wastewater'. While, Paracomesoma dubium, appears to be a 'tolerant and/or opportunistic' species, showing increased relative abundances under all wastewater treatments.

Effects of benzo(a)pyrene on meiobenthic assemblage and biochemical biomarkers in an Oncholaimus campylocercoides (Nematoda) microcosm.

A microcosm experiment was carried out to determine how benzo(a)pyrene (BaP) may affect marine meiofauna community, with a main emphasis on nematode structure and functional traits. Three increasing concentrations of BaP (i.e. 100, 200 and 300 ng/l, respectively) were used for 30 days. The results revealed a gradual decrease in the abundance of all meiobenthic groups (i.e. nematodes, copepods, amphipods, polychaetes and oligochaetes), except for isopods. Starting at concentrations of 200 and 300 ng/l BaP, respectively, significant changes were observed at community level. At taxonomic level, the nematode communities were dominated at the start of the experiment and also after being exposed or not to BaP by Odontophora villoti, explicable through its high ecologic ubiquity and the presence of well-developed chemosensory organs (i.e. amphids), which potentially increased the avoidance reaction following exposure to this hydrocarbon. Moreover, changes in the activity of several biochemical biomarkers (i.e. catalase 'CAT', gluthatione S-transferase 'GST', and ethoxyresorufin-O-deethylase 'EROD') were observed in the nematode species Oncholaimus campylocercoides, paralleled by significant decreases in CAT activity for non-gravid females compared to controls at concentrations of 25 ng/l BaP and associated with significant increase in GST and EROD activities for both types of individuals.

Impacts of nanoparticles and phosphonates in the behavior and oxidative status of the mediterranean mussels (Mytilus galloprovincialis).

The current study investigated the exposure of the Mediterranean mussel (Mytilus galloprovincialis) to gold nanoparticles decorated zinc oxide (Au-ZnO NPs) and phosphonate [Diethyl (3-cyano-1-hydroxy-1-phenyl-2-methylpropyl)] phosphate (PC). The mussels were exposed to concentrations of 50 and 100 µg L-1 of both compounds alone, as well as to a mixture of both pollutants (i.e. Mix). The singular and the combined effect of each pollutant was investigated by measuring the concentration of various metals (i.e., Cu, Fe, Mn, Zn and Au) in the the digestive glands and gills of mussels, their filtration capacity (FC), respiration rate (RR) and the response of oxidative biomarkers, respectively, following 14 days of exposure. The concentrations of Cu, Fe, Mn, Zn and Au increased directly with Au-ZnO NPs in mussel tissues, but significantly only for Zn. In contrast, the mixture of Au-ZnO100 NPs and PC100 did not induce any significant increase in the content of metals in digetsve glands and gills, suggesting antagonistic interactions between contaminants. In addition, FC and RR levels decreased following exposure to Au-ZnO100 NPs and PC100 treatments and no significant alterations were observed after the exposure to 50 µg.L-1 of both contaminants and Mix. Hydrogen peroxide (H2O2) level, GSH/GSSG ratio, superoxide dismutase (SOD), catalase (CAT) and acetylcholinesterase (AChE) activities showed significant changes following the exposure to both Au-ZnO NPs and PC, in the gills and the digestive glands of the mussel. However, no significant modifications were observed in both organs following the exposure to Mix. The current study advances the understanding of the toxicity of NPs and phosphonates on M. galloprovincialis and sets the path for future ecotoxicological studies regarding the synergic effects of these substances on marine species. Moreover, the current experiment suggests that the oxidative stress and the neurotoxic pathways are responsive following the exposure of marine invertebrates to both nanoparticles and phosphonates, with potential antagonist interactions of these substances on the physiology of targeted species.

Bergenia ciliate-Mediated Mixed-Phase Synthesis and Characterization of Silver-Copper Oxide Nanocomposite for Environmental and Biological Applications.

Bergenia ciliate (B. ciliate) leaf extract was used as a reducing and stabilizing agent for the synthesis of silver-copper oxide nanocomposite (Ag-CuO NC). Scanning and transmission electron microscopies (SEM and TEM) were used to examine the structural morphology, and the average particle size was determined to be 47.65 nm. The phase confirmation and crystalline structure were examined through the X-ray diffraction (XRD) technique, where cubic and monoclinic geometries were assigned to Ag and CuO. The energy dispersive X-ray (EDX), Fourier transform infrared (FTIR) and ultra-violet and visible (UV-Visible) spectroscopies were operated to analyse the elemental composition, functional groups and light absorption phenomena of the Ag-CuO NC. Under the full light spectrum, the photodegradation of Rhodamine 6G was recorded, and 99.42 percent of the dye degraded in 80 min. The Agar well diffusion method was followed to perform antibacterial activity against selected pathogens, and the activity was found to increase with increasing concentration of Ag-CuO NC. The ABTS free radical scavenging activity suggests that the activity of Ag-CuO NC is higher than ascorbic acid.

Does Lake Balaton affected by pollution? Assessment through surface water quality monitoring by using different assessment methods.

In order to maintain a good environmental status of surface waters, an assessment of water quality carried out at specific intervals to monitor the changes of water quality in function of time. Human knowledge and experience are currently focused on using assessment methods, especially the integration of multiple constraining factors and considering them in conjugation with the correct decision-making process concerning the environment. When surface water is highly exposed to human activities, either from recreational or economic activity, the degree of vulnerability is high, and the quality of surface water is highly compromised. In case of Lake Balaton, there are many activities that can disrupt water dynamics. The first goal of this study is to determine the location of the least and most polluted sites around Lake Balaton. The processing of data was carried out by using multi-criteria decision techniques and environmental impact assessment method based on physical-chemical parameters in comparison with the limiting parameters. Based on the results of those methods water quality needs to be improved in western parts of the lake by using several geoengineering treatment techniques. This work covers a novel approach to comparing methods based on sum of ranking differences, whereas many method comparison studies suffer from ambiguity or from comparisons not being quite fair. This problem can be avoided if there are differences between ideal and actual rankings.

Molecular Characterization and Demographic Study on Infectious Bursal Disease Virus in Faisalabad District.

The re-emergence of virulent strains of the Infectious Bursal Disease Virus (IBDV) leads to significant economic losses of poultry industry in Pakistan during last few years. This disease causes the infection of bursa, which leads to major immune losses. A total number of 30 samples from five IBD outbreaks during the period of 2019-20 were collected from different areas of Faisalabad district, Pakistan and assayed by targeting the IBD virus VP2 region through RT-PCR. Among all the outbreaks, almost 80% of poultry birds were found positive for the IBDV. The bursa tissues were collected from the infected birds and histopathological examination of samples revealed severe lymphocytic depletion, infiltration of inflammatory cells, and necrosis of the bursa of Fabricius (BF). Positive samples were subjected to re-isolation and molecular characterization of IBDV. The Pakistan IBDV genes were subjected to DNA sequencing to determine the virus nucleotide sequences. The sequences of 100 Serotype-I IBDVs showing nearest homology were compared and identified with the study sequence. The construction of the phylogenetic tree for nucleotide sequences was accomplished by the neighbor-joining method in MEGA-6 with reference strains. The VP2 segment reassortment of IBDVs carrying segment A were identified as one important type of circulating strains in Pakistan. The findings indicated the molecular features of the Pakistan IBDV strains playing a role in the evolution of new strains of the virus, which will contribute to the vaccine selection and effective prevention of the disease.

Volatile oil of Teucrium alopecurus sensitizes colon cancer cells to TRAIL-induced cell death.

TNF-related apoptosis-inducing ligand (TRAIL/Apo2L), a member of cytokine family, is known to selectively induce apoptosis in cancer cells. However, developing resistance to TRAIL is a major obstacle in cancer therapy. In this study, the in vitro effect of Teucrium alopecurus (TA) essential oil on inhibition of cancer cell growth and enhancing TRAIL-induced apoptosis were investigated in colon cancer cells. Untreated tumor cell lines are used as controls. TA induced cell death and increased the anticancer effects of TRAIL as observed by cell toxicity, live/dead assay, cleavage of caspases and PARP. Furthermore, the mechanism of anticancer potentiating effect of TA was found to be linked with the upregulation of death receptors (DRs) and reduced expression of TRAIL decoy receptors (DcRs). TA also down-regulated antiapoptotic proteins and induced p53 in colon cancer cells. In addition, we observed upregulation of MAPK signalling pathway (p38 kinase, JNK, ERK) and increased expression of C/EBP homologous transcription factor (CHOP) and specificity protein 1 (SP1) by TA. These findings demonstrate the potent anticancer effect of bioactive constituents of Teucrium alopecurus essential oil.

Multi-biomarker approach in Mytilus galloprovincialis and Ruditapes decussatus as a predictor of pelago-benthic responses after exposure to Benzo[a]Pyrene.

This study evaluated the biomarker responses indicative of exposure to Benzo[a] Pyrene (B[a]P) in Mytilus galloprovincialis and Ruditapes decussatus. A significant increase of the total oxyradical scavenging capacity (TOSC) was observed after seven days of exposure to two concentrations of B[a]P (100 and 300 µg.L-1), in the digestive gland with the lowest concentration tested. The TOSC in the gills increased notably only after the exposure to 300 µg.L-1 of B[a]P. Interestingly, the superoxide dismutase (SOD) and catalase (CAT) activities in gills and digestive gland on one hand and glutathione S-transferase (GST) in gills in the other, were positively correlated with the concentration of B[a]P with a significant induction noticed at the highest concentration. In contrast, a significant increase of the GST activity was observed in the digestive gland following the exposure of bivalves to 100 µg.L-1. In pelagic (M. galloprovincialis) or benthic (R. decussatus) bivalves, the AChE activity decreased discernibly in digestive glands and gills with the increase of B[a]P concentrations as evidence of neurotoxic effects. In clams, the exposure to B[a]P was followed by a significant increase of Malondialdehyde level (MDA) in gills and digestive gland, this does not occur in gills of Mytilus galloprovincialis at the concentration of 100 µg.L-1. Overall, the results found seems to indicate that the mussel was more suitable as a predictor tool of toxicity of B[a]P.

In-Vitro and In-Vivo Tolerance and Therapeutic Investigations of Phyto-Fabricated Iron Oxide Nanoparticles against Selected Pathogens.

The Paeonia emodi (P. emodi)-mediated iron oxide nanoparticles (Fe2O3 NPs) were screened for in-vitro and in-vivo antibacterial activity against the Staphylococcus aureus (S. aureus) (ATCC #: 6538) and Escherichia coli (E. coli) (ATCC #:15224). The synthesized Fe2O3 NPs were characterized via nitrogen adsorption-desorption process, X-ray diffractometer (XRD), transmission and scanning electron microscopies (TEM and SEM), energy dispersive X-ray (EDX) and Fourier transform infrared (FTIR) spectroscopies. The SBET was found to be 94.65 m2/g with pore size of 2.99 nm, whereas the average crystallite and particles size are 23 and 27.64 nm, respectively. The 4 µg/mL is the MIC that inhibits the growth of E. coli, whereas those for S. aureus are below the detection limit (<1.76 µg/mL). The tolerance limit of the mice model was inspected by injecting different concentration of Fe2O3 NPs and bacteria suspensions. The 14 ppm suspension was the tolerated dose and the concentration above were proved lethal. The most severe infection was induced in mice with injection of 3 × 107 CFUs of both bacteria, while the inoculation of higher concentrations of bacterial suspensions resulted in the mice's death. The histopathological and hematological studies reveals that the no/negligible infection was found in the mice exposed to the simultaneous inoculation of Fe2O3 NPs (14 ppm) and bacterial suspensions (3 × 107 CFUs).

Toxicity of synthetic Endocrine Disrupting Compounds on meiofauna: Estradiol benzoate as a case study.

An experimental study was carried out to determine the effects of the enrichment of sediments by endocrine perturbators on free-living nematodes from the Ghar El Melh lagoon, Tunisia. For 30 days, four concentrations of Estradiol Benzoate (hereafter EB) (0.43, 4.3, 8.6 and 12.9 ng l-1). The average nematode abundances showed a significant increase after the introduction of EB in their close environment. In contrast, the taxonomic examination has shown a decrease in species diversity of nematodes. The ordination of treatments according to the nMDS showed a clear structural separation of the enriched replicates with EB from controls based on species lists, in particular for concentrations EB3 and EB4. Indeed, under such conditions, the nematofauna exhibited a more remarkable presence of a new record for Science Theristus n. sp. and a decrease in relative abundances of Paracomesoma dubium. On feeding level, a predominance of non-selective deposit-feeders and a decline in proportions of epistrate feeders and carnivorous omnivores was observed with increasing concentrations of EB. Furthermore, in treated replicates with EB, females discernibly showed an increase compared to controls. Overall, EB affect significantly features of meiobenthic nematodes starting from the concentration of 4.3 ng l-1.

Toxicity of hydroxychloroquine, a potential treatment for COVID-19, on free-living marine nematodes.

On March 2020, hydroxychloroquine (HCQ) was recommended as a treatment for COVID-19 high risk patients. Following the massive and widespread use of HCQ worldwide, a discernible high quantity is anticipated to end-up through the sewage systems in marine coastal areas. A closed microcosm study was undertaken herein for 30 days where meiobenthic nematodes were exposed to a range of HCQ concentrations (3.162, 31.62 and 63.24 µg.ml-1). After one month of exposure in HCQ, the total abundances and Shannon-Wiener index of the assemblages decreased, whereas the individual mass and the Trophic Diversity Index increased at the highest concentrations. Overall, a numerical negative impact was observed for the epistrate feeders and non-selective deposit feeders, however, this benefited to the omnivores-carnivores, and particularly to the Oncholaimids. Such responses of the nematodes 2B and the corresponding taxa are bioindicative of current- or post-COVID-19 crisis risks in relation with the bioaccumulation of HCQ in seafood.

Nematode traits after separate and simultaneous exposure to Polycyclic Aromatic Hydrocarbons (anthracene, pyrene and benzo[a]pyrene) in closed and open microcosms.

The majority of experimental studies carried out to date, regarding the effects of pollutants on meiofauna have been conducted by means of closed systems, and rarely using open ones. The current work explored the impact of three Polycyclic Aromatic Hydrocarbons (PAHs), anthracene, pyrene and benzo[a]pyrene, applied alone or combined, on meiobenthic nematodes using both systems. The results revealed that single PAHs impacted the nematofauna similarly in closed or open systems with a higher toxicity observed for benzo[a]pyrene. However, the closed microcosms contaminated with PAHs became organically enriched, resulting in more non-selective deposit feeders and omnivores-carnivores. Taxonomic and functional effects related to combinations of PAHs were close to those of individual treatments in closed systems, however, for open ones, the outcomes were different. The caudal morphology influenced the response of taxa during their avoidance/endurance of hydrocarbons in open systems where the effects of PAHs mixtures appeared not only additive but also synergetic. Based on the results of the study, the use of open systems is preferred to closed ones as the research outcomes were more accurate and representing better conditions prevailing in nature.