New insight into the toxic effects of lithium in the ragworm Perinereis cultrifera as revealed by lipidomic biomarkers, redox status, and histopathological features.

Lithium (Li) is a toxic monovalent alkaline metal used in household items common to industrial applications. The present work was aimed at investigating the potential toxic effects of LiCl on the redox status, fatty acid composition, and histological aspects of the marine ragworm Perinereis cultrifera. Sea worms were exposed to LiCl graded doses (20, 40, and 80 mg/L) for 48 h. Compared with the control group, the saturated fatty acids (SFA) decreased while monounsaturated (MUFA) and polyunsaturated fatty acids (PUFA) increased upon exposure to LiCl. The increase in PUFA n-3 and PUFA n-6 was concomitant to an increase in docosahexaenoic (DHA: C22:6n-3), eicosapentaenoic (EPA: C20:5n-3), and docosapentaenoic acid (C22:5n-6) fatty acids. Results showed that LiCl-treated specimens accumulate lithium with increasing exposure gradient. Indeed, the exposure to LiCl doses promoted oxidative stress with an increase of the ferric reducing antioxidant power (FRAP), malondialdehyde (MDA), hydrogen peroxide (H2O2), advanced oxidation protein product (AOPP), and protein carbonyl (PCO) as well as the enzymatic and non-enzymatic antioxidants (non-protein thiols (NPSH), catalase (CAT), superoxide dismutase (SOD), reduced glutathione (GSH), glutathione peroxidase (GPx), glutathione S-transferase (GST), and metallothionein (MT)) levels in all treated groups. Our biochemical findings have been affirmed by the histopathological observations showing hyperplasia and loss of the intestine structure in treated specimens. Overall, our findings give new insights on the toxic effect of LiCl on the redox status of P. cultrifera body tissue and highlighted the usefulness of the FA composition as an early sensitive bioindicators to better understand LiCl mechanism of toxicity in marine polychaetes.

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

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

Incorporation of ω3 fatty acids in the diets of Nile tilapia juvenile (Oreochromis niloticus L.): effects on growth performance, fatty acid composition, and tolerance to low temperature.

In order to increase the low-temperature resistance of Nile tilapia, the purpose of this study was to determine the potential effect of ω3 fatty acid incorporation in Oreochromis niloticus diet. To perform this, two experimental diets containing soybean oil (D1) and cod liver oil (D2) have been supplied to juvenile tilapia for 30 days. According to our results, similar improvements in the two diets have been recorded for growth performance of O. niloticus including the final body mass, specific growth rate, and feed conversion ratio. Our results showed that fish fed with diet D2 promoted high polyunsaturated fatty acids mainly n-3 series (PUFA (n-3)) percent, highlighting the increased levels of docosahexaenoic (DHA) and eicosapentaenoic (EPA) as well as the activation of their conversion enzyme ratios D5D and D6D desaturases. The second objective was to assess the effect of the two experimental diets on low water temperature tolerance. This was done by exposing juvenile fish at the end of the first experiment to 16, 14, 12, 10, and 8 °C for 12 h, 24 h, and 48 h. The sub-lethal LT50 of O. niloticus fed with diet D1 was 10.6, 11.4, and 13 °C respectively, after 12 h, 24 h, and 48 h. This pattern was commonly observed for O. niloticus fed with D2, showing that the subLT50 were 10.3, 11.1, and 12 °C during the same period. These results demonstrate that O. niloticus juveniles fed with diet D2 are more tolerant to low temperatures than those fed with diet D1.

Molecular signature of phylogenetic relationships and demographic history of Tunisian Mactra stultorum: Evidence from mitochondrial and nuclear DNA data.

The genetic structure of Mactra stultorum is inferred from partial sequence of a mitochondrial cox1gene and of the internal transcribed spacer region ITS1. The samples with two colors of shell (white and brown) were collected from three sites belonging to the Tunisian coasts: Kalaât El Andalous (KA) and Soliman (SM) and Gabes (GM)). The phylogenetic trees obtained from the 2 markers are similar and subdivided samples into 3 distinct clades; clade (1) regrouped GM, clade (2) regrouped KS (KS contains samples from SM and KAa) and clade (3) is formed by KAb. Using the external sequences from genbank, it can be suggested that M. stultorum from the three clades KS, GM and KAb are three subspecies. The two sympatric M. stultorum from KA (KAa and KAb) appear to be genetically isolated showing a high genetic distance and no common haplotypes where the shell color serves for segregating marker. A total of 29 and 18 haplotypes were detected in the examined cox1 and ITS1 regions, respectively. Our study revealed higher levels of genetic diversity for ITS1 compared to cox1. For both markers, significant clinal changes in haplotypes frequencies between the north and the south populations supported by the absence of common haplotypes were observed. The demographic history of M. stultorum populations has been assessed using neutral tests and mismatch distribution for cox1 marker. A unimodal curve of the Mismatch's distribution and negative significant neutral tests suggested a recent sudden demographic expansion for GM.

Exposure of Mactra corallina to acute doses of lead: effects on redox status, fatty acid composition and histomorphological aspect.

The aim of this study is to elucidate the toxicity induced by PbCl2, administered in graded doses (1; 2.5; 5 mg/L), in the redox state, in the fatty acid composition and in the histological structure of Mactra corallina digestive glands. Our findings showed a progressive accumulation of Pb in the M. corallina digestive glands in all treated groups. After 5 days of treatment with PbCl2, an increase in H2O2, MDA, PCO, GSH, NPSH and MT levels was observed in the digestive glands of treated groups. Moreover, activities of antioxidant enzymes, such as GPx and CAT, increased while SOD activity decreased in all treated groups, indicating a failure of the antioxidant defense system. Furthermore, the cholinergic function was evaluated by assessing the acetylcholinesterase activity, which was inhibited in all the treated digestive glands compared to the control group. In our experiment, the levels of n-3 (Omega-3) and n-6 (Omega-6) polyunsaturated fatty acids were greatly altered in the groups treated with 5 mg/L of PbCl2 (p < 0.001). Indeed, DHA and EPA decreased significantly in the digestive glands treated with 2.5 and 5 mg/L of PbCl2, respectively. On the other hand, under exposure to the medium and high doses (2.5 and 5 mg/L), arachidonic acid (ARA) and linoleic acid (LA) significantly increased (p < 0.001). These changes in PUFA were confirmed by significant modifications in the polyene and peroxidation indices. The histological findings confirmed the biochemical results.HighlightsIntegrated parameters were used to explore the toxic effect of PbCl2 graded doses in Mactra corallina digestive gland.Metals accumulation in digestive glands of M. corallina was greatly dependent to dose of PbCl2.Metabolic and macromolecules damaging of clams digestive glands were more sensitive at higher PbCl2 doses.Fatty acids composition especially polyunsaturated fatty acids (PUFA) and essentials fatty acids such as docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) in clams digestive glands were intensively altered at higher PbCl2 doses.Inflammation responses revealed in studied tissue.

Nutritional quality traits of raw and cooked Ark shell (Bivalvia: Arcidae): balancing the benefits and risks of seafood consumption.

Biochemical composition and fatty acid profile of raw Ark shells (RA) were compared to Ark shells submitted to three different cooking methods (BA: baking in the oven; PF: pan-frying in butter and MW: cooking in a microwave). Moisture (%) was significantly higher in RA (79.66) with respect to PF (65.09), BA (48.63) and MW (47.02). Protein (mg/g of flesh) decreased significantly from 18.62 in RA to 15.40 in MW, 13.76 in PF and 13.33 in BA. However, lipids significantly increased in MW (43.32 mg/g of flesh) and PF (63.63 mg/g of flesh) with respect to RA (35.05 mg/g of flesh). Pan-frying affected considerably triacylglycerol (TAG) and the fatty acid composition (FA) of Ark shell flesh. The most changes occurred in saturated (SFA), monounsaturated (MUFA) and polyunsaturated (PUFA) fatty acid fractions after this process. The n-3 PUFA decreased significantly from RA (16.40 mg/g dry weight) to PF (10.02 mg/g DW). While, the opposite trend was observed for n-6 PUFA, revealing that this cooking method had considerable effects on the nutritional characteristics of this edible shellfish. The analysis of lipid peroxidation markers such as thiobarbituric acid reactive substances, free fatty acid and peroxide value confirmed that both heat treatment and time of cooking caused lipid degradation, which had been more accentuated during pan-frying treatment. For the populations who consume Ark shells occasionally or frequently, baking and microwave cooking could be then considered as wiser and healthier cooking methods since they conserve better the nutritional value of this marine product. The present study will be of practical value from a health perspective for Mediterranean populations.

Effect of storage temperature and time on the fatty acids and nutritional quality of the commercial mussel (Mytilus galloprovincialis).

The effect of storage time (5, 10 and 15 days) and temperature (- 20 °C and + 4 °C) on the biochemical composition of the Tunisian mussel (Mytilus galloprovincialis) was evaluated by investigating changes in proximate composition, fatty acids, minerals and nutritional quality indices. Lipid and protein degradations were also evaluated through several markers of oxidative damage. Results showed a significant decrease in the biochemical compounds in mussel tissues after both refrigeration and freezing processes (p < 0.01). As regards the fatty acid composition, saturated fatty acids increased significantly after both storage processes. However, polyunsaturated and monounsaturated decreased, especially after 10 and 15 days of storage. The reduction of nutritional quality and mineral contents were detected after both storage processes. Markers of oxidative damage varied remarkably between fresh and stored tissues, revealing that both processes greatly influenced the nutritional quality of mussels. Overall, it is well recommended to consume fresh and stored mussels for no more than 5 days in the refrigerator (+ 4 °C) in order to preserve the better quality of this product and provide more benefits for human health.

The potential toxic effects of hexavalent chromium on oxidative stress biomarkers and fatty acids profile in soft tissues of Venus verrucosa.

Hexavalent chromium (chromium (VI)), a highly toxic heavy metal, is a common pollutant of aquatic ecosystems. The present study aimed to elucidate the potential toxic effects of chromium (VI) on oxidative stress biomarkers and fatty acids profile in the gills and digestive gland of Venus verrucosa, an ecologically and economically important bivalve species. Three doses of chromium (VI) (1, 10 and 100 µg.L-1) were chosen for V. verrucosa exposure during 7 days under controlled conditions. A significant increase in the levels of malondialdehyde, lipid hydroperoxides and hydrogen peroxide was observed in the gills and digestive gland of chromium (VI)-exposed V. verrucosa as compared to the control group. Furthermore, an induction of enzymatic antioxidant activities (superoxide dismutase, glutathione peroxidase and glutathione S-transferase) and an enhancement of non-enzymatic antioxidant levels (non-protein thiols, glutathione and vitamin C) were marked. An alteration of fatty acids composition was also noted following chromium (VI) exposure. The obtained results highlighted the importance of assessing oxidative damage biomarkers and fatty acids profile in the study of chromium (VI)-induced toxicity in V. verrucosa.

Assessment of the biochemical and nutritional values of Venerupis decussata from Tunisian lagoons submitted to different anthropogenic ranks.

The present study aimed to evaluate the biochemical status of Venerupis decussata collected seasonally from two Tunisian coastline lagoons (Ghar El Melh and Boughrara) submitted to different anthropogenic levels. Trace elements were significantly higher in clams from Boughrara, especially during the warm season. Fatty acids, proximate compositions, and nutritional value of both clam populations were higher, appearing to be the best for human consumption principally during the spring season. The principal component analysis was determined, including phospholipids and reserve lipids, revealing a great variation with the exogenous and endogenous factors. Generally, clams from Boughrara had a significant alteration in biochemical composition principally due to the anthropogenic levels and physicochemical fluctuation of this lagoon. Our results reflected the healthy benefit of clam consumption and the use of energy reserves and essential fatty acids as a great biomarker to assess ecological risk in lagoons and other coastal ecosystems.

Redox status and fatty acid composition of Mactra corallina digestive gland following exposure to acrylamide.

Acrylamide (ACR), a ubiquitous agent, has various chemical and industrial applications, and it is found in backed or fried carbohydrate-rich food. It has been related to multiple toxicological effects, and it causes high cytotoxicity through oxidative stress. The present study aimed to investigate the potential effect of ACR toxicity administered at different concentrations (5, 10, and 20 mg/L), during 5 days, in order to evaluate the fatty acid (FA) composition and redox state in the digestive gland of Mactra corallina. The results showed, in ACR-treated clams, a significant increase in malondialdehyde, hydrogen peroxide, protein carbonyl, and metallothionein levels, as well as an alteration of the enzymatic (superoxide dismutase, glutathione peroxidase, and catalase) and non-enzymatic (reduced glutathione and ascorbic acid) antioxidant status. However, acetylcholinesterase activity was inhibited in a concentration-dependent manner. In our experiment, the n-3 (Omega-3) and n-6 (Omega-6) polyunsaturated fatty acid levels were significantly changed in all ACR-treated groups. A decrease in eicosapentaenoic acid (C20:5n-3, EPA) and docosahexaenoic acid (C22:6n-3, DHA) was observed in 10-mg/L and 20-mg/L ACR-treated groups. Nevertheless, arachidonic acid (C20:4n-6, ARA) and its precursor linoleic acid (C18:2n-6, LA) were increased. Besides oxidative stress parameters, FA composition may be an additional tool for assessing ACR contamination.

Genetic diversity and phylogenetic analysis of two Tunisian bivalves (Mactridae) Mactra corallina (Linnaeus, 1758) and Eastonia rugosa (Helbling, 1799) based on COI gene sequences.

A partial sequence of mitochondrial cytochrome c oxidase subunit I (COI) was used as a genetic marker for a genetic diversity and phylogenetic analysis (DNA barcoding) of two Mactridae species, Mactra corallina and Eastonia rugosa, collected from the Tunisian coast. These Mactridae species could be distinguished by DNA barcoding techniques and they will be considered as monophyletic clades with the Neighbor-Joining (NJ) tree. The genetic structure detected that E. rugosa presents three haplotypes with a high frequency of HER1 (0.89). However, M. corralina shared 14 haplotypes. The haplotypic diversity (H) was equal to 0.205 and 0.954, respectively, for E. rugosa and M. corallina. While the nucleotide diversity (π) was higher for M. corallina (π=0.0818), the mismatch distribution showed a unimodal curve for E. rugosa (a recent sudden demographic expansion) and a multimodal distribution for M. corallina (size stability).