Biomarcadores de estrés oxidativo en las branquias del bivalvo Mactra stultorum expuesto a acrilamida

Acrylamide (ACR) is among the most deleterious pollutants in the environment and presents a serious risk to humans and ecosystems. The purpose of this study was to assess its effects when administered at different concentrations (5, 10 and 20 mg L–1) to evaluate antioxidant status in the gills of Mactra stultorum. Our results showed, after five days of treat­ment, an increase in malondialdehyde (MDA), lipid hydroperoxides (LOOH), advanced oxidation protein products (AOPP), reduced glutathione (GSH), ascorbic acid (Vit C) and metallothionein (MDA) levels in gills of treated clams compared with controls. Moreover, an increase in superoxide dismutase (SOD) and a significant decrease in glutathione peroxidase (GPx) activities were also observed. Acrylamide induced neurotoxicity, as evidenced by the inhibition of acetylcholinesterase (AChE) activity in a dose-dependent manner. Overall, our results indicated that oxidative stress may be considered one of the mechanisms behind acrylamide toxicity in bivalves, although the subject requires more research.La acrilamida (ACR) es uno de los contaminantes más perjudiciales en el medio ambiente y presenta un grave riesgo para los seres humanos y los ecosistemas. El objetivo de este estudio es evaluar los efectos del ACR administrado a diferentes concentraciones (5, 10 y 20 mg L–1) con el fin de evaluar el estado antioxidante en las branquias de Mactra stulto­rum. Nuestros resultados mostraron, después de 5 días de tratamiento, un aumento en los niveles de malondialdehído (MDA), hidroperóxidos lipídicos (LOOH), proteínas de oxidación avanzada (AOPP), glutatión reducido (GSH), ácido ascórbico (vit C) y metalotioneínas (MTs) en las branquias de las almejas tratadas en comparación con los controles. Además, también se observó un aumento en la superóxidodismutasa (SOD) y una disminución significativa en las actividades de glutatión pero­xidasa (GPx). La acrilamida indujo neurotoxicidad como lo demuestra la inhibición de la actividad de la acetilcolinesterasa (AChE) de una manera dependiente de la dosis. En general, nuestros resultados indicaron que el estrés oxidativo puede con­siderarse como uno de los mecanismos detrás de la toxicidad por ACR en los bivalvos, aunque el tópico debería beneficiarse de más investigaciones

AVALIAÇÃO DA CAPTAÇÃO DE OLIGOELEMENTOS NO CARANGUEJO INVASIVO PORTUNUS SEGNIS HEPATOPANCREAS USANDO UMA ABORDAGEM BIOQUÍMICA MULTIVARIADA

In the current investigation, we evaluated the biological consequences of trace elements contamination in the two Tunisian gulfs (Gabes gulf and Tunis gulf) on the blue swimming crabs hepatopancreas (Portunus segnis). The concentrations of three trace elements (cadmium, copper, and lead) in the hepatopancreas P.segnis were evaluated. Additionally, acetylcholinesterase (AChE), metallothioneins (MTs), hydroxide peroxidase (H2O2) and advanced oxidation protein products (AOPP) levels, were chosen as measurements to evaluate the environmental effects on the two crabs’ populations from different gulfs. Macromolecular (lipids, proteins, and DNA) were also determined in P.segnis hepatopancreas. The results of trace elements bioaccumulation in soft P. segnis hepatopancreas showed a high pollution in the Gabes gulf as evidence by significant accumulation of cadmium, cooper, and lead. These findings were confirmed by significant increases of metal pollution index (MPI) and metallothioneins (MTs) levels in the hepatopancreas of P. segnis from Gabes gulf than these from Tunis gulf. Consequently, the trace elements accumulation in P.segnis from Gabes gulf conduct to the generation of lipid peroxidation processes as documented by the high levels of H2O2and LOOH. A significant decrease of AChE activity was recorded in crabs collected from Gabes gulf as compared to these from Tunis gulf. The present study revealed depletion of proteins and lipids contents, while DNA showed significant degradation on crab hepatopancreas collected from Gabes gulf comparing to Tunis gulf. These evidences must be taken in consideration when using P. segnis as an ecological indicator species in the biomonitoring programs.Na investigação atual, avaliamos as consequências biológicas da contaminação por oligoelementos nos dois golfos tunisinos (Golfo de Gabes e Golfo de Tunísia) sobre os caranguejos nados azuis hepatopâncreas (Portunus segnis). Foram avaliadas as concentrações de três oligoelementos (cádmio, cobre e chumbo) no hepatopâncreas P.segnis. Além disso, os níveis de acetilcolinesterase (AChE), metalotioninas (MTs), peroxidase hidróxida (H2O2) e produtos de proteína de oxidação avançada (AOPP) foram escolhidos como medidas para avaliar os efeitos ambientais nas populações dos dois caranguejos de diferentes golfos. Macromoleculares (lipídios, proteínas e DNA) também foram determinados em P.segnis hepatopâncreas. Os resultados da bioacumulação de elementos vestigiais em P. segnis hepatopancreas mole mostraram uma alta poluição no Golfo de Gabes como evidência pelo acúmulo significativo de cádmio, cobre e chumbo. Estes resultados foram confirmados por aumentos significativos do índice de poluição de metais (MPI) e dos níveis de metalotioninas (MTs) no hepatopâncreas de P. segnis do Golfo de Gabes do que estes do Golfo de Tunísia. Consequentemente, o acúmulo de elementos vestigiais em P.segnis do Golfo de Gabes conduz à geração de processos de peroxidação lipídica, como documentado pelos altos níveis de H2O2e LOOH. Uma diminuição significativa da atividade de AChE foi registrada em caranguejos coletados do Golfo de Gabes em comparação com estes do Golfo de Tunísia. O presente estudo revelou esgotamento de proteínas e conteúdo de lipídios, enquanto o DNA mostrou degradação significativa no hepatopâncreas de caranguejo coletado do Golfo de Gabes em comparação com o Golfo de Tunísia. Estas evidências devem ser levadas em consideração ao utilizar P. segnis como uma espécie indicadora ecológica nos programas de biomonitoramento

Evaluación del estrés oxidativo, genotoxicidad y respuestas histopatológicas en la glándula digestiva Ruditapes decussatus recolectada de las lagunas del norte de Túnez

The aim of the present study was to investigate the combined effects of seasonality and anthropogenic pressure on a battery of oxidative stress, lipid peroxidation, protein oxidation, DNA damage and histological alterations in the native clam Ruditapes decussatus collected from a less contaminated area (LCA), Ghar El Melh, a moderately contaminated area (MCA), the North Lake, and a highly contaminated area (HCA), the South Lake, all located in the southern Mediterranean Sea. The accumulation of cadmium, lead, copper, iron and zinc was higher in the digestive glandsof clams collected from the MCA and the HCAthan in those from the LCA, particularly during the warm season. Our results reveal that metallothionein, lipid peroxidation, protein oxidation levels and antioxidant defence systems were higher, while acetylcholinesterase activity was lower, in clams from the MCAand HCAthan in those from the LCA. The results also indicate that clams from the MCA and the HCAare characterized by histological alterations and DNA damage. In conclusion, the evident changes of antioxidant defence systems and macromolecules between the studied lagoons reveal the perturbation of the physiological states of clams from polluted sites thatcope with seasonal changes and trace element accumulations.El objetivo del presente estudio es investigar los efectos combinados de la estacionalidad y la presión antropogénica en una batería de estrés oxidativo, peroxidación lipídica, oxidación de proteínas, daños en el DNA y alteraciones histológicas en la almeja nativa Ruditapes decussata recolectada de un área menos contaminada (Ghar El Melh «LCA») y de dos sitios con diferentes niveles de contaminación (la laguna norte «MCA» y la laguna sur «HCA» de Túnez) en el sur del mar Mediterráneo. La acumulación de cadmio, plomo, cobre, hierro y zinc fue mayor en la glándula digestiva de las almejas recolectadas de la MCA y la HCA en comparación con las de la LCA, particularmente durante la estación cálida. Nuestros resultados revelan que la metalotioneína, la peroxidación lipídica, los niveles de oxidación de proteínas y los sistemas de defensa antioxidante aumentaron, mientras que la actividad de la acetilcolinesterasa disminuyó en las almejas del área moderadamente y altamente contaminada en comparación con la menos contaminada. Los resultados también indican que las almejas del MCA y el HCA se caracterizan por varias alteraciones histológicas y daños en el ADN. En conclusión, los cambios evidentes de los sistemas de defensa antioxidante y las macromoléculas entre las lagunas estudiadas revelan la perturbación de los estados fisiológicos de las almejas de los sitios contaminados que hacen frente a los cambios estacionales y las acumulaciones de metales

Seasonal variation of biochemical composition of Noah's ark shells (Arca noae L. 1758) in a Tunisian coastal lagoon in relation to its reproductive cycle and environmental conditions

The seasonal changes in biochemical composition of the edible bivalve Arca noae harvested from a Mediterranean coastal lagoon (Bizerte lagoon, Tunisia) were investigated from October 2013 to September 2014. Potential food sources and nutritional quality indices (NQI) were determined by analyzing the fatty acid profiles of their tissues during an annual reproductive cycle. Results showed that A. noae had moisture (73.8–82%) and protein (24.1–58.6% dry weight) as major components, followed by lipid (10.4–28.8% dry weight) and glycogen (4.05–14.6% dry weight). A. noae accumulated lipid and glycogen for gonadal development during both maturation periods (late autumn/late spring–summer) to be used during spawning periods (winter/late summer–early autumn). However, proteins were mainly used to support reproductive allocation and played an important role on the energetic maintenance. Lipid and glycogen were found to be significantly related to temperature, salinity and chlorophyll a (p < 0.05). An increase of condition index (CI) was observed during spring and early summer when both temperature and food supply increased. The total fatty acid (TFA) profile of Ark shells was dominated by polyunsaturated fatty acids (PUFA) (33.8–49.6%), followed by saturated (SFA) (29.1–43.1%) and monounsaturated fatty acids (MUFA) (20.77–28.3%). A. noae soft tissues were also rich in macro-minerals (Na, Ca and Mg). The analysis of fatty acid trophic markers revealed that the diet of A. noae during the year of study was based on mixture food mainly on phytoplankton followed by zooplankton and other sources (bacteria, seagrass and macroalgae). Furthermore, the nutritional quality indices have revealed that A. noae is an excellent source of nutrients and a healthy food for human consumption. These data are useful to the conservation of natural stocks of A. noae and the development of sustainable aquaculture production of this shellfish species in the Bizerte lagoon

Effects of increasing temperatures on biomarker responses and accumulation of trace elements in the Ark shell (Arca noae) from Bizerte lagoon

The Bizerte lagoon is one of the most studied coastal areas in Tunisia, it is used for shellfish production since 1964 and supports various industry and agriculture activities. This lagoon inhabit a wide diversity of marine invertebrates, among them the valuable shellfish Noah’s ark (Arca noae). The present study examines the influence of increasing temperature on biochemical biomarkers and metal bioaccumulation in the the total edible tissue of Arca noae. Samples were collected during winter 2013 and summer 2014 in the southern sector of the lagoon far from urban and industrial sources of pollution but this site remained influenced by agricultural inputs. After collection, Ark shells were immediately transferred to the laboratory and prepared for analysis. Five oxidative stress biomarkers: metallothioneins (MTs), malondialdehyde (MDA), glutathione peroxidase (GPx), reduced gluthatione (GSH) and acetylcholinesterase (AChE) were monitored as a response to ten trace elements bioaccumulation (Ni, Cr, Cd, Fe, Zn, Mn, Al, Cu, Se and Pb). The rise of temperature from 12°C in December to 28°C in July coincided with the bioaccumulation of trace metals, the high expression of MDA, GPx, GSH and MTs and the inhibition of AChE activity in A. noae tissues. Statistical analysis (Spearman's rank correlation) showed that all trace elements and biomarkers were significantly positively correlated with T, with the exception of Zn, Cd and AChE that was negatively correlated with this parameter. The increase of TE levels in Ark shells during summer may be due to a possible increase in the concentration of metallic elements in the lagoon waters. However, a possible contamination by runoff from adjacent farmland is to be rejected in view of the drought and the scarcity of the rains in this season. Hence, we assume that increasing concentrations of trace elements in A. noae tissues in summer is probably related to the evaporation process due to increased temperature that favors the concentration of these trace elements in the Bizerte lagoon. Thus, T (°C) appears to be a determinant factor on the variability of biomarker responses and metal bioaccumulation in A. noae. Overall, the combined effects of chemical contamination and increased temperature in summer appear to induce a highest metabolic adaptation response and can therefore be used to determine thresholds of effectiveness and facilitate the interpretation of monitoring biomarkers

Investigating otolith mass asymmetry in six benthic and pelagic fish species (Actinopterygii) from the Gulf of Tunis

Otolith mass asymmetry can significantly affect the vestibular system functionalities; usually, the X values of mass asymmetry vary between −0.2 and + 0.2 (−0.2 < X < + 0.2). These values can change during a fish life and therefore they are not related to the fish total length. We collected a total of 404 fish specimens from the Gulf of Tunis, including three pelagic species: Sardina pilchardus (Walbaum, 1792) (74 otolith pairs), Trachurus mediterraneus (Steindachner, 1868) (66 otolith pairs), and Chelon auratus (Risso, 1810) (60 otolith pairs) and three benthic species: Gobius niger Linnaeus, 1758 (77 otolith pairs), Mullus barbatus Linnaeus, 1758 (60 otolith pairs), and Trachinus draco Linnaeus, 1758 (67 otolith pairs). The relation between the total length and the otolith mass asymmetry was first calculated and compared, and then was evaluated. The comparison of the otolith mass asymmetry between benthic and pelagic species showed a significant difference (P < 0.05), where the absolute mean value of X does not exceed the critical value (0.2) for all the studied species. No relation has been found between the magnitude of the otolith mass asymmetry and the length in both benthic and pelagic specimens. Environmental factors have an indirect effect on somatic growth and otolith accretion. The significant difference found in this study can be due to the difference between the benthic and pelagic environments

Metal toxicity and health problems linked to the consumption of ark shells (Arca noae l.) from a Tunisian coastal lagoon

Trace elements (TEs) in coastal systems are a major problem as these elements contribute to the regular degradation of the environment because of their continuous inputs, persistence, toxicity and ability to concentrate in organisms through food webs. The levels of cadmium (Cd), Nickel (Ni), chromium (Cr) and lead (Pb) in the edible tissue of the edible bivalve Arca noae (L. 1758), sampled monthly from the Tunisian coastal lagoon (Bizerte lagoon) during 2013-2014, were determined by inductively coupled plasma mass spectrometry (ICP-MS). The impact of Cd, Ni, Cr and Pb on consumer health was considered and several parameters were used to assess the potential human risk (estimated weekly intake (EWI), target hazard quotient (THQ), total target hazard quotient (TTHQ) and target hazard risk (TR)). Results showed that Cd, Ni, Cr and Pb concentrations on a wet weight basis (mg kg-1 WW) in A. noae flesh from the lagoon of Bizerte were well below international food safety standards. Regarding health risk assessment linked to A. noae consumption, all sanitary indicators (EWI, PTWI, THQ, TTHQ and TR) related to Cd, Ni, Cr and Pb levels bioaccumulated in its flesh were below values considered at risk for human health. It can be concluded that continued consumption over long periods of this shellfish may not represent a potential risk to the health of consumers regarding Cd, Ni, Cr and Pb. Consequently, this shellfish can be considered safe for human consumption and does not pose any sanitary problems. This preliminary study presents prospects for the valorization of this seafood product in Tunisia's food sector

Trace elements and oxidative stress in the Ark shell Arca noae from a Mediterranean coastal lagoon (Bizerte lagoon, Tunisia): are there health risks associated with their consumption?

The current study examined the concentrations of ten trace elements (TE) (nickel, chromium, cadmium, iron, zinc, manganese, aluminum, copper, selenium and lead) in the edible tissue of the Ark shell Arca noae (L. 1758) from a Mediterranean coastal lagoon, the Bizerte lagoon during 2013–2014. The analysis of several redox status biomarkers, metallothioneins (MTs), malondialdehyde (MDA), glutathione peroxidase (GPx), reduced glutathione (GSH) and acetylcholinesterase (AChE), was monitored as a response to TE bioaccumulation and environmental parameters variability. Significant differences (p < 0.05) were observed between mean seasonal TE concentrations in A. noae soft tissue. The highest TE concentrations in A. noae soft tissues were recorded during summer, which coincided with the increase of body dry weight (BDW) and the gonad index (GI). During this season, biomarker responses were enhanced, revealing significant increases of MTs, MDA and GSH levels as well as GPx activity in A. noae tissues, while a decrease of AChE activity was observed. The levels of TE analyzed in A. noae and several parameters used to assess the potential human risk (estimated weekly intake, target hazard quotient and target hazard risk) were lower than the permissible limits for safe seafood consumption. Consequently, this shellfish can be considered safe for human consumption. This preliminary study presents prospects for the valorization of this seafood product in Tunisia’s food sector. It also gives basal information for future environmental assessment studies in which A. noae could be used as early warning tools in the field of biomonitoring programs and confirms the usefulness of biomarkers to monitor the health status of aquatic organisms

Seasonal variation of biochemical composition of Noah's ark shells (

The seasonal changes in biochemical composition of the edible bivalve Arca noae harvested from a Mediterranean coastal lagoon (Bizerte lagoon, Tunisia) were investigated from October 2013 to September 2014. Potential food sources and nutritional quality indices (NQI) were determined by analyzing the fatty acid profiles of their tissues during an annual reproductive cycle. Results showed that A. noae had moisture (73.8–82%) and protein (24.1–58.6% dry weight) as major components, followed by lipid (10.4–28.8% dry weight) and glycogen (4.05–14.6% dry weight). A. noae accumulated lipid and glycogen for gonadal development during both maturation periods (late autumn/late spring–summer) to be used during spawning periods (winter/late summer–early autumn). However, proteins were mainly used to support reproductive allocation and played an important role on the energetic maintenance. Lipid and glycogen were found to be significantly related to temperature, salinity and chlorophyll a (p < 0.05). An increase of condition index (CI) was observed during spring and early summer when both temperature and food supply increased. The total fatty acid (TFA) profile of Ark shells was dominated by polyunsaturated fatty acids (PUFA) (33.8–49.6%), followed by saturated (SFA) (29.1–43.1%) and monounsaturated fatty acids (MUFA) (20.77–28.3%). A. noae soft tissues were also rich in macro-minerals (Na, Ca and Mg). The analysis of fatty acid trophic markers revealed that the diet of A. noae during the year of study was based on mixture food mainly on phytoplankton followed by zooplankton and other sources (bacteria, seagrass and macroalgae). Furthermore, the nutritional quality indices have revealed that A. noae is an excellent source of nutrients and a healthy food for human consumption. These data are useful to the conservation of natural stocks of A. noae and the development of sustainable aquaculture production of this shellfish species in the Bizerte lagoon