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

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.

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.

Metal body burden and tissue oxidative status in the bivalve Venerupis decussata from Tunisian coastal lagoons

Coastal transitional waters are exposed to many anthropogenic threats. This study aims to assess the trace metals' pollution status of transitional waters by evaluating its biological effects in the clam Venerupis decussata. Among the studied sites along the Tunisian littoral, South Tunis and Boughrara were the most impacted, since clams from these two lagoons presented significant differences in: (i) trace metal contents, (ii) in-cell hydrogen peroxide, (iii) enzymatic and non-enzymatic defenses, (iv) damage to lipids and proteins, and (v) protein post-translational modifications. These changes related to evident histopathological traits. PCA showed a clear separation between the digestive gland and gills tissues and illustrated an impact gradient in Tunisian coastal lagoons. Water temperature was revealed as an added natural stressor that, when concurring with high pollution, may jeopardize an ecosystem's health and contribute to the accumulation of hazardous metals in organisms.