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The effect of frozen storage at a commercial temperature (−30°C) on the nutritional characteristics of the blue swimming crab Portunus segnis for a period of 120 days was investigated. Lipid and protein oxidation was investigated by analyses of peroxide value, thiobarbituric acid reactive substances, free fatty acids, and advanced oxidation protein products. Results showed significant lipid deterioration with extended storage time and changes in fatty acids composition and lipid classes. From a nutritional standpoint, it would be preferable for human consumption to eat frozen crabs for no more than 30 days as they retain a higher nutritional value. [ABSTRACT FROM AUTHOR]

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. Integrated 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. [ABSTRACT FROM AUTHOR]

Lead (Pb) is one of the most toxic heavy metals that affect the physiological status of aquatic organisms. The present investigation evaluated the possible toxic effect of lead chloride (PbCl2) on biomarkers responses, DNA damage and histological alterations in Venus verrucosa gills and digestive gland. Three concentrations of PbCl2 (D1:1µgL−1, D2: 10µgL−1 and D3: 100µgL−1) were chosen for V. verrucosa exposure during six days. At the end of the trial, it was found that Pb tended to accumulate in both gills and digestive gland in a dose-dependent manner. However, gill tissues exhibited the highest metal burden. Our results showed an increase of malondialdehyde, protein carbonyls and advanced oxidation protein product levels in both organs following PbCl2exposure. The induction of both non-enzymatic and enzymatic antioxidant systems; as well as the decrease of the acetylcholinesterase activity and degradation of DNA structure was recorded in the gills and digestive gland. The histopathological alterations observed in gills (disruption of lamellas and cilia filaments ...) and digestive gland (lumens occlusion, necrosis and fibrosis) confirmed the aforementioned results. Our data highlighted the short-term toxicity effects of PbCl2 on V. verrucosa and pointed out a high sensitivity of gills towards this metal. [ABSTRACT FROM AUTHOR]

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 Holothuria forskali exposed to different concentrations of mercury chloride HgCl2 (0.04, 0.08 and 0.16 mg L−1) for 96 h. Exposure of H. forskali to Hg led to oxidative stress with an increase in Malondialdehyde (MDA), hydrogen peroxide (H2O2), 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 H. forskali. [ABSTRACT FROM AUTHOR]

Mercury (Hg) is a ubiquitous and a major environmental metal pollutant in the aquatic ecosystem. The present study was performed to evaluate the effect of mercury graded doses exposure on oxidative stress, redox status, metallothionein levels and genotoxicity in the intestine of sea cucumber Holothuria forskali. Specimens were exposed for 96 h to three concentrations of Hg (40, 80 and 160 µg/L). Exposure of H. forskali to Hg promoted oxidative stress with an increase in malondialdehyde (MDA), protein carbonyl (PCO) and advanced oxidation protein products (AOPP) levels. An increase of glutathione (GSH), vitamin C (ViteC) and non-protein thiols (NPSH) contents was also observed. Additionally, antioxidant activities of catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPx) increased especially with the highest doses of Hg indicating a great defense of the antioxidant system. Our investigation revealed an increase in total Metallothionein (MT) content which was more pronounced at the sharpest concentrations of Hg. A significant decline of AChE activity was also observed. In the intestine of Hg-treated H. forskali genotoxicity was confirmed by DNA degradation. [ABSTRACT FROM AUTHOR]

This work aims to examine the reproductive cycle of the bivalve Mactra corallina inhabiting the Gulf of Tunis (Tunisia). Histological analysis indicated that the reproductive cycle is composed of six stages and was synchronous between sexes. Gonadal development began in January. From April to July, an increase in temperature (from 16 to 28°C) and a rise in chlorophyll a (from 3.25 to 6.35 mg/L) marked the period of sexual maturity in both sexes, which was also confirmed by an elevation in condition index (CI). Partial spawning started in April for males and in May for females, peaking in late summer indicating a prolonged reproductive period. The reproductive cycle of M. corallina finished with an inactive stage during autumn. From the total number of animals used in this study, we identified 104 females (52%) and 96 males (48%) corresponding to a sex ratio 1:0.92 that did not differ significantly from a 1:1 ratio. [ABSTRACT FROM AUTHOR]

Bivalves are known for their high nutritional value and are considered a healthy food for human consumption. The effect of different cooking methods (steaming, boiling, grilling, and frying) on proximate and fatty acid composition ofArca noae(Bivalvia: Linnaeus 1758) were determined. The comparison of raw and cooked Ark shell showed that the cooking had considerable effects on the nutritional quality of this species. Significant changes in moisture (%), protein (mg/g of flesh), total lipid (mg/g of flesh), and fatty acid composition (mg/g dry weight) were observed after cooking as compared to fresh Ark shell (p < 0.05). However, the analysis of malondialdehyde (MDA) and peroxide value (PV) showed that all cooking treatments led to lipid oxidation. Steaming, boiling, and grilling were found to be a suitable and healthier cooking processes forA. noae, since they conserve the amount of n-3 PUFA better as compared to frying. [ABSTRACT FROM PUBLISHER]