Size structures of demersal catches in a multispecies multigear tropical fishery

The overall size structure of catches was studied in the multispecific, multigear, demersal fishery of Martinique (Lesser Antilles). The results show that the fishery is presently based not only on small-sized species, but also on small- or medium-sized individuals of these species. Most of the catch is made up of species able to withstand its selectivity and effort, with larger species having been eliminated through overfishing. An exponential decrease of lenght frequencies for aggregated catches or samples was observed in the 2 years sampled, and could be due to some inherent size structure of the fish community. Such integrated analyses are useful complements to single-species assessment approaches inadequate to describe the dynamics of highly multispecific resources such as reef fish communities. (Résumé d'auteur

Quelques aspects socio-économiques de la pêcherie artisanale béninoise de Pointe-Noire (Congo)

La pêcherie artisanale étrangère de Pointe-Noire, dite "béninoise", a significativement évolué depuis ses débuts, dans les années 1950, tant par ses effectifs en hommes et en pirogues, que par les moyens techniques et socio-économiques mis en oeuvre. La pêche de la sardinelle au filet maillant de surface, qui en est l'activité principale, repose sur la propriété et l'épargne collectives, qui assurent le réinvestissement partiel des revenus, les pêches où les risques sont plus élevés (filet dormant de fond) ne sont pratiquées qu'à titre individuel. Outre son rôle essentiel d'approvisionnement en poisson de la région de Pointe-Noire et les emplois indirects qu'elle crée, la pêcherie béninoise emploie de nombreux pêcheurs congolais, de façon permanente ou très occasionnelle; cependant, aucun effet d'entraînement ne semble s'être produit au profit de la pêche artisanale locale. (Résumé d'auteur

Production relative des pêcheries côtières en Martinique

Dans les régions tropicales coralliennes, on a parfois recours au potentiel de production halieutique par unité de surface là où les méthodes classiques d'évaluation s'appliquent difficilement. Dans la région Caraïbe, de nombreuses estimations de production halieutique relative, tant potentielle que réelle, sont disponibles sans qu'il soit possible de les comparer de façon rigoureuse. En Martinique, les pêcheries côtières ont produit en 1987 en moyenne 1.14 t.km-2.an-1 d'espèces démersales, avec des productions par strate comprises entre 0.24 et 8.45 t.km-2.an-1. La production relative moyenne pour les espèces néritiques est de 1.68 t.km-2.an-1. La comparaison des productions relatives observées d'un secteur ou d'une île à l'autre est susceptible de contribuer de façon importante à l'évaluation de l'état d'exploitation des ressources, à condition que les méthodologies d'estimation soient explicitées et qu'une connaissance suffisante de l'effort de pêche et du contexte écologique soit disponible. (Résumé d'auteur

Control of the attosecond synchronization of XUV radiation with phase-optimized mirrors

International audienceWe report on the advanced amplitude and phase control of attosecond radiation allowed by specifically-designed multilayer XUV mirrors. We first demonstrate that such mirrors can compensate for the intrinsic chirp of the attosecond emission over a large bandwidth of more than 20 eV. We then show that their combination with metallic foils introduces a third-order dispersion that is adjustable through the mirror's incidence angle. This results in a controllable beating allowing the radiation to be shaped from a single to a series of sub-100 as pulses

Genomic and transcriptomic landscape of conjunctival melanoma.

Conjunctival melanoma (CJM) is a rare but potentially lethal and highly-recurrent cancer of the eye. Similar to cutaneous melanoma (CM), it originates from melanocytes. Unlike CM, however, CJM is relatively poorly characterized from a genomic point of view. To fill this knowledge gap and gain insight into the genomic nature of CJM, we performed whole-exome (WES) or whole-genome sequencing (WGS) of tumor-normal tissue pairs in 14 affected individuals, as well as RNA sequencing in a subset of 11 tumor tissues. Our results show that, similarly to CM, CJM is also characterized by a very high mutation load, composed of approximately 500 somatic mutations in exonic regions. This, as well as the presence of a UV light-induced mutational signature, are clear signs of the role of sunlight in CJM tumorigenesis. In addition, the genomic classification of CM proposed by TCGA seems to be well-applicable to CJM, with the presence of four typical subclasses defined on the basis of the most frequently mutated genes: BRAF, NF1, RAS, and triple wild-type. In line with these results, transcriptomic analyses revealed similarities with CM as well, namely the presence of a transcriptomic subtype enriched for immune genes and a subtype enriched for genes associated with keratins and epithelial functions. Finally, in seven tumors we detected somatic mutations in ACSS3, a possible new candidate oncogene. Transfected conjunctival melanoma cells overexpressing mutant ACSS3 showed higher proliferative activity, supporting the direct involvement of this gene in the tumorigenesis of CJM. Altogether, our results provide the first unbiased and complete genomic and transcriptomic classification of CJM

Comprehensive Genetic Landscape of Uveal Melanoma by Whole-Genome Sequencing.

Uveal melanoma (UM) is a rare intraocular tumor that, similar to cutaneous melanoma, originates from melanocytes. To gain insights into its genetics, we performed whole-genome sequencing at very deep coverage of tumor-control pairs in 33 samples (24 primary and 9 metastases). Genome-wide, the number of coding mutations was rather low (only 17 variants per tumor on average; range 7-28), thus radically different from cutaneous melanoma, where hundreds of exonic DNA insults are usually detected. Furthermore, no UV light-induced mutational signature was identified. Recurrent coding mutations were found in the known UM drivers GNAQ, GNA11, BAP1, EIF1AX, and SF3B1. Other genes, i.e., TP53BP1, CSMD1, TTC28, DLK2, and KTN1, were also found to harbor somatic mutations in more than one individual, possibly indicating a previously undescribed association with UM pathogenesis. De novo assembly of unmatched reads from non-coding DNA revealed peculiar copy-number variations defining specific UM subtypes, which in turn could be associated with metastatic transformation. Mutational-driven comparison with other tumor types showed that UM is very similar to pediatric tumors, characterized by very few somatic insults and, possibly, important epigenetic changes. Through the analysis of whole-genome sequencing data, our findings shed new light on the molecular genetics of uveal melanoma, delineating it as an atypical tumor of the adult for which somatic events other than mutations in exonic DNA shape its genetic landscape and define its metastatic potential