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

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

Essential oils, chemical composition, and biological activities of Eucalyptus oleosa F. Muell. : A review

Many Eucalyptus species are growing in the border of oasis areas. Eucalyptus sp. are generally known for their richness in essential oils and their virtues and economic interests. However, the great taxonomic diversity affects the quantity and quality of these oils. This study is designed to summarize the chemical composition of Eucalyptus oleosa and their biological activities. The yield of essential oils in the leaves of this species varies from 0.45% to 6.7%. These oils contain many chemical compounds of which 1,8-cineole is the main component (15.31% – 89.4%) followed by α-pinene (1%– 24.7%).  Eucalyptus oleosa essential oils exhibited antioxidant, antibacterial, anti-fungal and insecticidal activities with high variability. This variability is associated to many factors such as subspecific diversity, geographical location, part of plant and essential oil’s extraction method

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

Reproductive cycle and gonad development of the commercial clam Donax trunculus from the Bay of Tunis (Northern Tunisia, South Mediterranean coast): Effects of environmental variability

In Tunisia the commercial exploitation of Donax trunculus is limited to the unregulated catches which threaten the biological sustainability of this species. Knowledge of the gametogenic development of a species is a prerequisite for proper management and sustainable exploitation of this fishery. The reproductive cycle of D. trunculus from the Bay of Tunis was carried out between November 2006 and January 2008, using the dry weight changes, the histological examination of the gonad and the measurement of oocyte size. Results showed that, sex ratio were in favor of males without any hermaphroditism. The gametogenesis activity of both sexes, started with decreasing seawater temperature during late autumn and the main spawning event took place from June to October when temperatures rose. During this time, clams loose, gradually, their weights and condition and maturity indices reached their lowest values immediately after spawning period. The mean oocyte diameter varied significantly between 12.1 ± 9.8 urn in early gametogenesis and 45.9 ±13.6 um during maturity. Considering these data, a closed season from May to July coinciding with the most intensive gamete release should be considered for the preservation and the management of the natural stock of D. trunculus from the Bay of Tunis.Peer Reviewe

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

Quantification of total phenols, flavonoides and tannins from Ziziphus jujuba (mill.) and Ziziphus lotus (l.) (Desf). Leaf extracts and their effects on antioxidant and antibacterial activities

This work was performed to determine the biochemical composition, antioxidant and antimicrobial activities of leaf extracts collected from four different provenances: Mahdia and Mahres (Ziziphus jujuba); Kairouan and Rouhia (Ziziphus lotus). Total phenols, flavonoids, tannins contents and antioxidant activity were evaluated using the Folin ciocalteux, Aluminum trichloride, vanillin and scavenging activity on 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radicals methods, respectively. The antimicrobial activity was evaluated against three bacterial strains (Escherichia coli, Staphylococcus aureus and klebsiella pneumoniea) and three fungal strains (Fusarium culmorum, Fusarium solani and Botrytis cinerea), according to well Agar diffusion method. Total phenols and flavonoids were present at levels of 21.98 mg GAE /g DW and 7.80 mg ER/g DW; respectively in Ziziphus lotus. These levels did not exceeded 13.70 mg GAE /g DW and 6.73 mg ER/g DW for Ziziphus jujuba. The tannin contents were present in equal levels (7.9 mg EC/g DW) in two species. The high antioxidant activity (0.01 µg/ml) was noted in Rouhia provenance. The Ziziphus lotus leaf extracts showed promising efficiency against all tested microorganisms with a zone of inhibition ranging between 22 and 23.5 mm. This study could validate the medicinal potential of Ziziphus specie and explain why tunisian people traditionally use it in medicine to treat several pathologies. Ziziphus leaf extracts may be suggested in foods and pharmaceutical industries. Leaf extracts proved also to be effective against tested microorganisms. So, an adequate toxicological study must be carried out to verify the possibility of using these plants for fighting microorganisms