Mugilids fisheries of Tunisian coasts and lagoons

With its 1300 km coastline and 110 000 ha of coastal lagoons, Tunisia offers important resources to demersal and pelagic fisheries. Among all the exploited fish species in Tunisia, mugilids are the most widespread. They are known in temperate, subtropical and tropical regions, and occur both in coastal areas, lagoon ecosystems and inland waters. Six mugilids species have been inventoried in Tunisia. Their migratory behavior consists of moving back and forth between brackish and saline environment where they spend a large part of their life cycles. This behavior results in a peculiar high vulnerability to human pressure. Consequently, they require special attention from fisheries managers for sustainable catches. This study was based on the data from the national fishing and aquaculture directorate (DGPA) statistics, and comprised time series from 1995 to 2015. We looked for clear tendencies and correlations between harvest from the coastal sea and lagoons of the different coastal regions, in relation to recruitment in coastal marine waters. We focused on two species, i.e. Mugil cephalus and Liza aurata, which are best appreciated for local consumption and, therefore, most targeted by the fishery in Tunisia. The Tunisian lagoons show a decreasing trend in mugilids landings. This may be explained by the disturbance of migratory ways and the degradation of the coastal habitats, by the harvest of fry used for the inland water-stocking program, and by the multiplication of droughts. Particularly the latter strongly limits the migration of juveniles. The harvest in the coastal zones is relatively stable, follows perfectly the total national landings, with although a clear increase since 2011 as a result of uncontrolled illegal fishing. The negative correlation between the total harvests of mugilids in the coastal sea and coastal lagoon was highly significant (Pearson coefficient r = −0.702, p < 0.001)

Gate-Controlled Skyrmion Chirality

Magnetic skyrmions are localized chiral spin textures, which offer great promise to store and process information at the nanoscale. In the presence of asymmetric exchange interactions, their chirality, which governs their dynamics, is generally considered as an intrinsic parameter set during the sample deposition. In this work, we experimentally demonstrate that this key parameter can be controlled by a gate voltage. We observed that the current-induced skyrmion motion can be reversed by the application of a gate voltage. This local and dynamical reversal of the skyrmion chirality is due to a sign inversion of the interfacial Dzyaloshinskii-Moriya interaction that we attribute to ionic migration of oxygen under gate voltage. Micromagnetic simulations show that the chirality reversal is a continuous transformation, in which the skyrmion is conserved. This gate-controlled chirality provides a local and dynamical degree of freedom, yielding new functionalities to skyrmion-based logic devices.Comment: 4 figure

Exploring a Non-model Teleost Genome Through RAD Sequencing - Linkage Mapping in Common Pandora, Pagellus erythrinus and Comparative Genomic Analysis

Common pandora (Pagellus erythrinus) is a benthopelagic marine fish belonging to the teleost family Sparidae, and a newly recruited species in Mediterranean aquaculture. The paucity of genetic information relating to sparids, despite their growing economic value for aquaculture, provides the impetus for exploring the genomics of this fish group. Genomic tool development, such as genetic linkage maps provision, lays the groundwork for linking genotype to phenotype, allowing fine-mapping of loci responsible for beneficial traits. In this study, we applied ddRAD methodology to identify polymorphic markers in a full-sib family of common pandora. Employing the Illumina MiSeq platform, we sampled and sequenced a size-selected genomic fraction of 99 individuals, which led to the identification of 920 polymorphic loci. Downstream mapping analysis resulted in the construction of 24 robust linkage groups, corresponding to the karyotype of the species. The common pandora linkage map showed varying degrees of conserved synteny with four other teleost genomes, namely the European seabass (Dicentrarchus labrax), Nile tilapia (Oreochromis niloticus), stickleback (Gasterosteus aculeatus), and medaka (Oryzias latipes), suggesting a conserved genomic evolution in Sparidae. Our work exploits the possibilities of genotyping by sequencing to gain novel insights into genome structure and evolution. Such information will boost the study of cultured species and will set the foundation for a deeper understanding of the complex evolutionary history of teleosts

« Halalité » en biomédecine : approches sunnites et chiites ou/ Nouveaux espaces du halal : approches sunnites et chiites en biomédecine

La question du halal en islam, souvent réduite à la question alimentaire, s’avère être plus étendue que la simple liste des aliments autorisés à la consommation des musulmans ou la manière d’abattre les animaux. L’exploration de la question du halal comme objet de recherche peut étonner par la variété des approches qu’elle permet notamment en raison des nouvelles réalités couvertes aujourd’hui par le vocable halal. Il est question, pour les économistes, d’un véritable marché du halal en raiso..

Biomédecine, religions et droit : étude comparative entre islam et judaïsme

La biomédecine en tant que médecine nouvelle a changé plusieurs réalités dans son contexte occidental original. Dans d'autres contextes dans le monde où la religion est présente au niveau politique et légal, la question biomédicale peut être problématique puisqu'elle peut entrer en conflit avec la normativité religieuse ou la construction religieuse de la réalité sociale. Dans tous les contextes, il incombe au droit positif de répondre à la question biomédicale tout en trouvant un équilibre entre la demande de solutions médicales et les questions ethico-religieuses. L'analyse du droit de la biomédecine dans les contextes étudiées (Egypte, Israël, Tunisie) s'avère être intéressant à plus d'un niveau.D'abord lors de la production de la norme positive entre Etat et religion.Biomedecine as a new form of medecine changed many social realities its original context. In others conttexts of the world where religion is present on a political and legal level, biomedecine can be more that problematic as it may be in contradiction with religious rules or religious consturctions of social realities. In all contexts, it' is up to the law to solve these problems and find a way to balance the need for medical solutions and religious and ethical issues

Relationships between heterozygosity, growth parameters and age in the common pandora Pagellus erythrinus (Sparidae) in the Gabes Gulf (Tunisia)

International audienceThe relationship between heterozygosity and age, as well as growth-related traits, was explored in the common pandora Pagellus erythrinus, a sparid fish subjected to commercial exploitation in the Mediterranean Sea. Allozyme electrophoresis was used to quantify the levels of heterozygosity of 238 adult fish from 3 to 7 yr old, aged by means of otoliths and captured in the Gabes Gulf, located along the south-eastern coast of Tunisia. Analyses were conducted by using individual single-locus and multi-locus heterozygosity and 4 growth-related parameters-standard length, total body weight, otolith length and otolith weight-as well as 2 measures of condition (condition factor and relative condition factor). For the 4 growth-related parameters and 2 condition parameters analyzed at 8 polymorphic loci, heterozygotes had higher average values than homozygotes in 36 out of 48 comparisons. However, since these 6 biometric parameters are highly correlated, this proportion should not be considered globally as strong evidence of a heterozygosity-fitness correlation (HFC). Interpreting these data on a per parameter basis, only otolith weight appeared significantly and positively correlated with multi-locus heterozygosity. Thus, although there was evidence for HFC, it appeared relatively weak for the growth para meters analyzed and may have arisen by chance. The results we obtained relative to survival are more convincing. Although cohorts did not appear genetically differentiated and the whole sample did not display any internal structure after a Bayesian analysis with the STRUCTURE software, multi-locus individual heterozygosity was significantly and positively correlated with fish age. This suggests better survival of heterozygotes and establishes the presence of a heterozygosity-fitness correlation in the Tunisian population of the common pandora

intégration de données de génétique et de morphologie à différentes échelles climatiques et géographiques chez la moule d'eau douce en danger Unio durieui (Bivalvia: Unionidae) endémique du Nord de la Tunisie

International audienceThe freshwater mussel Unio durieui is a rare bivalve endemic to North African watersheds. Although this is an important species from an ecological and conservation perspective, information on its genetic diversity and population structure is lacking. Here, we combine geometric morphometric and molecular genetic analyses to characterize and evaluate the status of populations of this endangered species from four Tunisian watershed basins (Cap Bon, Ichkeul, Northwest and Mejerda River basins). By using a multiparameter approach, we sought to test the hypothesis that populations from these geographic regions could be considered as distinct management units. Shell outline shapes were assessed using elliptic Fourier analysis followed by linear discriminant analysis of principal components. Multivariate analysis applied on normalized Fourier coefficients showed highly significant differences in shell shape among the populations. Population genetic analysis based on inter-simple sequence repeats revealed low levels of diversity and high differentiation between the populations studied. Two groups of populations are clearly evident, thus separating samples from the Northwest from those from the other watersheds. Although there is no evidence for isolation by distance patterns, genetic and phenotypic diversity appeared significantly correlated with climatic variables. These findings suggest isolation by environment and the nominal species U. durieui may constitute two biological species. Conservation programme actions should consider this substructure in establishing effective recovery strategies for this endangered species.néan

Buffer layer annealing effects on the magnetization reversal process in Pd/Co/Pd systems

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