assessment-impact-cadmium-on-redox-status-metabolic-profile-sea

Assessment of the Impact of Cadmium on the Redox Status and Metabolic Profile of the Sea Urchin <em>Paracentrotus lividus</em>

Cadmium (Cd) is one of the most harmful heavy metals to aquatic organisms and a widespread pollutant in marine biota. Because of its high bioavailability, ...

University Tunis El Manar

Teleost fish are ectothermic vertebrates. Their metabolism, physiology and behavior rely on the external temperature. This study, on the retina of the sea bass Dicentrarchus labrax, reports on the impact of temperature on the fatty acid composition and mRNA abundance of key enzymes of lipid metabolism: fatty acid desaturase-2 (FADS2), fatty acid elongase-5 (ELOVL5), sterol regulatory element-binding protein-1 (SREBP-1), triglyceride lipase and phospholipase A2 (PLA2). We also report on the effects on the photopigment molecule rhodopsin and on enzymes of the melatonin synthesis pathway, namely arylalkylamine N-acetyltransferases 1a and 1b and acetylserotonin methyltransferase. Juvenile fish were placed for 30 days at 18, 23 or 28 °C. At 23 °C, the fatty acid composition of D. labrax retina showed, as generally reported for the retina of other fish species, particularly high amounts of docosahexaenoic (DHA), palmitic and oleic acids. The fatty acids composition was not significantly (P > 0.05) altered between 23 and 28 °C, but did increase at 18 °C compared to 23 and 28 °C. At 18 °C there were noticeable increases in total DHA, ecosapentaenoic, arachidonic, oleic, linoleic, palmitoleic and stearic acids. A negative correlation was found in the abundance of neutral (NL) vs. polar (PL) lipids: 18 °C induced an increase in NL and a decrease in PL, while 28 °C induced higher PL with decreased NL. In NL the changes affected mainly triglycerides. FADS2 and ELOVL5 mRNA abundance decreased from 18° to 28 °C while SREBP-1 and triglyceride lipase mRNA remained stable. Conversely PLA2 mRNA was more abundant at 23 than at 18 and 28 °C. Temperature increased and decreased rhodopsin mRNA abundance, at 28 °C and 18 °C respectively, while there was no effect on mRNA from the melatonin synthesis enzymes. In conclusion the data indicate a temperature induced redistribution of fatty acids among the lipid classes that might affect the physical properties of the plasma membranes as well as functions associated with photoreception or generation of intracellular second messengers. In addition, the results suggest that temperature targets only the proteins and activities of retinal melatonin production. This study opens new lines of investigation related to the role temperature and fatty acids play in fish visual perception. They are relevant in the context of the global warming of seas affecting both the wild and the aquaculture species.

Impact of temperature on sea bass, Dicentrarchus labrax, retina: Fatty acid composition, expression of rhodopsin and enzymes of lipid and melatonin metabolism.

Mercury (Hg) is among the most deleterious contaminant in the aquatic environment and presents a serious risk to humans and ecosystems. This study evaluated the effects of Hg on oxidative stress biomarkers, DNA integrity and histological structure of the respiratory tree of  exposed to different concentrations of mercury chloride HgCl (0.04, 0.08 and 0.16 mg L) for 96 h. Exposure of  to Hg led to oxidative stress with an increase in Malondialdehyde (MDA), hydrogen peroxide (HO), advanced oxidation protein product (AOPP) and protein carbonyls (PCO) levels in the treated groups. Alteration of the antioxidant system was also confirmed by the significant increase in glutathione (GSH), nonprotein thiol (NPSH) and vitamin C contents. Moreover, the enzymatic activity of superoxide dismutase (SOD), Glutathione peroxidase (GPX) and Catalase (CAT) increased significantly. Our research revealed that total Metallothionein (MTs) content enhanced in a dose-dependent manner. Interestingly, the exposure to this metal provoked a decrease in Acetylcholinesterase (AChE) activity. Hg genotoxicity was further evidenced by a random DNA degradation that was observed in the treated groups. The histopathological findings confirmed the biochemical results. Overall, our results indicated that mercury-induced genotoxicity, oxidative damage and histopathological injuries in the respiratory tree of 

Mercury disrupts redox status, up-regulates metallothionein and induces genotoxicity in respiratory tree of sea cucumber ().

In this study, the potential hazardous impacts of the technical grade glyphosate acid (GLY) and its commercial formulation roundup (RD®) were evaluated for the first time on holothurians. To do this, redox status, fatty acid (FA) profile, and histopathology aspects were assessed in the respiratory tree tissue of the sea cucumber Holothuria forskali following short-term exposure (96 h) to a series of concentrations (10, 100 and 1000 μg L) of GLY and RD® (glyphosate acid equivalent). Our results showed that both GLY and RD® promoted oxidative stress highlighted with an increase of hydrogen peroxide (HO), malondialdehyde (MDA), lipid peroxides (LOOH) and advanced oxidation protein product (AOPP) levels in all treated groups. In addition, both glyphosate forms were found to perturb the FA composition. However, changes in saturated (SFA) and polyunsaturated (PUFA) including some essential FA (LA, ARA, EPA and DHA) revealed differential compensatory/adaptive processes in H. forskali depending on the treatment. GLY and RD® were also found to modulate the enzymatic (glutathione S-transferases, glutathione peroxidase and catalase) and non-enzymatic (reduced glutathione and ascorbic acid) antioxidant defense status. Taken together, our results revealed that the commercial formulation produced more pronounced effects on H. forskali respiratory tree than the pure form. This finding was further confirmed by the histological observations.

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.

Parasitic copepod Lernaeocera lusci is a common mesoparasite of the hake Merluccius merluccius. Although widely distributed throughout the Mediterranean, little is known about this pathogen. The current study was designed to assess the impact of different L. lusci infection loads on lipid classes and their fatty acid (FA) composition in both parasite and the host organs (gills, liver, and muscle). Results showed a significant decrease in total lipid, neutral lipid (NL), and polar lipid (PL) contents in all analyzed host's organs in relationship with parasite intensity. Gills appeared to be the most impacted organ under the lowest parasite intensity (loss of 50% of NL and PL amounts). At the highest parasitic infection, a loss of about 80% of lipid moieties was recorded in all analyzed organs. Simultaneously, no significant differences were found for the parasite reflecting its ability to sustain an appropriate lipid amount required for its survival and development. Significant changes in the FA composition were recorded in both host and parasite. Particularly, we have noticed that for L. lusci, the intraspecific competition has resulted in an increased level of some essential FA such as C22:6n-3 (docosahexaenoic acid, DHA), C20:5n-3 (eicosapentaenoic acid, EPA), and C20:4n-6 (arachidonic acid, ARA). This probably reflects that in addition to a direct host FA diversion, L. Lusci can modulate its FA composition by increasing the activity of desaturation. Within the host, liver PL appeared to be the less impacted fraction which may mirror an adaptive strategy adopted by the host to preserve the structural and functional integrity of this vital organ.

Polar and neutral lipid composition of the copepod Lernaeocera lusci and its host Merluccius merluccius in relationship with the parasite intensity.

Marine heavy metal pollution is a worldwide serious issue. Like almost all Mediterranean lagoons, the Bizerte lagoon is highly urbanized and suffers from intensive anthropogenic pressure. In the present study, we screened the metal contamination and biomarker responses in the smooth scallop Flexopecten glaber inhabiting this vulnerable ecosystem. To this end, the concentrations of six heavy metals (HM) (i.e., Cu, Pb, Zn, Cd, Hg, and Fe) and a panel of biochemical endpoints including malondialdehyde (MDA), metallothioneins (MT), reduced glutathione (GSH), glutathione peroxidase (GPx), superoxide dismutase (SOD), and catalase (CAT) were determined in the gills and digestive gland across seasons (warm and cold) and sites (S1 and S2). The distribution of almost all analyzed metals in F. glaber tissues varied significantly between sites, seasons, and organs. The highest levels were recorded at S2 during the warm period. Moreover, the digestive gland was found to accumulate greater concentrations of HM than the gills. Marked spatio-temporal variations were also observed for oxidative stress biomarkers, mainly in the gills, while the digestive gland seems to be rather sensitive to seasonal variability. Particularly, we noticed that among the used biomarkers, MT did not show significant variations in the two tested organs across seasons and sites. From the obtained results, F. glaber appears as a sensitive organism to anthropogenic metal contamination and can be proposed as a promising bioindicator species for marine pollution.

Assessment of the heavy metal levels and biomarker responses in the smooth scallop Flexopecten glaber from a heavily urbanized Mediterranean lagoon (Bizerte lagoon).

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.

Impacts of engineered iron nanoparticles on oxidative stress, fatty acid composition, and histo-architecture of 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) 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 (HO), 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.

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

Tebufenpyrad (TUBF) is classified as a pyrazole acaricide and insecticide and is extensively utilized in greenhouse environments in several countries. Nevertheless, limited data exists regarding the potential reproductive toxicity of TUBF, particularly in non-target species. In this study, the fatty acid (FA) composition, the histopathology aspects, and redox status were assessed in the digestive gland of the clam  following short-term exposure (96 h) to a series of concentrations (50, 100, and 200 µgL) of TUBF. Our findings indicated that TUBF induced oxidative stress, as evidenced by elevated levels of hydrogen peroxide (HO), malondialdehyde (MDA), and lipid peroxides (LOOH) in the treated groups. TUBF was also found to disrupt the enzymatic (catalase) and non-enzymatic (reduced glutathione) antioxidant defense systems. Additionally, TUBF was found to disrupt the FA composition. Overall, alterations in saturated (SFA), monounsaturated (MUFA), and polyunsaturated (PUFA) fatty acids, including certain essential FAs (such as LA, ARA, EPA, and DHA), exhibited differential compensatory/adaptive processes in  depending on the concentration of TUBF. Furthermore, both examined organs showed various histological impairments, such as lipofuscin accumulation, infiltrative inflammations, and changes in digestive tubules, which provide additional evidence of TUBF toxic effects.

Article	Year
Impact of temperature on sea bass, Dicentrarchus labrax, retina: Fatty acid composition, expression of rhodopsin and enzymes of lipid and melatonin metabolism. Experimental eye research\| PubMed ID: 28347705	2017
Mercury disrupts redox status, up-regulates metallothionein and induces genotoxicity in respiratory tree of sea cucumber (). Drug and chemical toxicology\| PubMed ID: 30554537	2020
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. Chemosphere\| PubMed ID: 33385670	2021
Polar and neutral lipid composition of the copepod Lernaeocera lusci and its host Merluccius merluccius in relationship with the parasite intensity. Parasitology research\| PubMed ID: 33987737	2021
Assessment of the heavy metal levels and biomarker responses in the smooth scallop Flexopecten glaber from a heavily urbanized Mediterranean lagoon (Bizerte lagoon). Environmental monitoring and assessment\| PubMed ID: 35488006	2022
Impacts of engineered iron nanoparticles on oxidative stress, fatty acid composition, and histo-architecture of the smooth scallop Flexopecten glaber. Environmental science and pollution research international\| PubMed ID: 35688986	2022
Glyphosate exposure modulates lipid composition, histo-architecture and oxidative stress status and induces neurotoxicity in the smooth scallop Flexopecten glaber. Pesticide biochemistry and physiology\| PubMed ID: 35715038	2022
Exposure to tebufenpyrad interrupts histo-architecture and fatty acid compositions of carpet shell clam . International journal of environmental health research\| PubMed ID: 40255148	2025

Imen Rabeh

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