Tracking leatherback turtles from the world's largest rookery: assessing threats across the South Atlantic

addresses: Centre for Ecology and Conservation, School of Biosciences, University of Exeter, Exeter, UK.notes: PMCID: PMC3119016types: Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.Despite extensive work carried out on leatherback turtles (Dermochelys coriacea) in the North Atlantic and Indo-Pacific, very little is known of the at-sea distribution of this species in the South Atlantic, where the world's largest population nests in Gabon (central Africa). This paucity of data is of marked concern given the pace of industrialization in fisheries with demonstrable marine turtle bycatch in African/Latin American waters. We tracked the movements of 25 adult female leatherback turtles obtaining a range of fundamental and applied insights, including indications for methodological advancement. Individuals could be assigned to one of three dispersal strategies, moving to (i) habitats of the equatorial Atlantic, (ii) temperate habitats off South America or (iii) temperate habitats off southern Africa. While occupying regions with high surface chlorophyll concentrations, these strategies exposed turtles to some of the world's highest levels of longline fishing effort, in addition to areas with coastal gillnet fisheries. Satellite tracking highlighted that at least 11 nations should be involved in the conservation of this species in addition to those with distant fishing fleets. The majority of tracking days were, however, spent in the high seas, where effective implementation of conservation efforts is complex to achieve

Total phenolic and lignin contents, phytochemical screening, antioxidant and fungal inhibition properties of the heartwood extractives of ten Congo Basin tree species

International audienceAbstract Key messageContent and type of extractives vary considerably among woody species in the Congo Basin tropical forest. They influence the natural durability of wood with respect to fungal and insect degradation. Species containing higher amounts of extractives and Klason lignin were generally less susceptible to fungal colonization. Phenolic extractives with large anti-fungal and high antioxidant activities were the main chemical family of compounds extracted from the tested species, which suggests a potential chemical valorization of these extractives.ContextSeveral woody species from the Congo Basin are known for their natural durability, but the causes of this natural durability are not always fully elucidated. This is particularly the case for the resistance to white rotting fungi decay.AimsThe chemical composition as well as the antioxidant activity of the heartwood extractives of several species were quantified and correlated to the ability of different fungi to colonize wood sawdusts in order to better understand their decay resistance.MethodsThe chemical screening of extracts was conducted using colorimetric methods. The quantity of lignin, extracts and total phenolic compounds, as well as antioxidant activities were determined. Extracted and unextracted heartwood sawdusts were exposed to two white rot fungi to assess the effect of extractives on their colonization.ResultsExtractives and lignin contents ranged from 2.7 to 16.0 % and from 26.5 to 35.9 %, respectively. Antioxidant activity was directly connected to total phenolic contents. The phytochemical screening revealed the presence of different chemical groups in all extracts. Resistance to fungi was correlated to the amount of extractives and in most cases to the lignin content.ConclusionPhenolic compounds associated with antioxidant activities influenced the natural resistance of heartwood

Tropical Soil Humus

In strongly weathered tropical soils, humus and humic substances (HSs) appear to play an important role in soil fertility because they represent the dominant reservoir and source of plant nutrients. As the refractory organic carbon form of soil, HSs play a vital role in the atmospheric CO2 sequestration. Detailed classification of humus forms in tropical ecosystems and the dynamics and function of humus are still poorly understood. Nevertheless, in tropical environment many studies indicated that it is very difficult to differentiate between tropical humus, at least in normally drained soil. Moders, mulls, and Amphimull are the dominant humus forms in the topsoil of tropical environment. Knowing the mechanisms of formation, the dynamics and the methods of characterization of humus in tropical zones are a scientific challenge. This chapter aims to share recent findings from a broad humus in tropical soil and research related to this theme

Myasthenie auto-immune: diagnostic et prise en charge. A propos de six cas au Benin et au Gabon

La myasthénie est une maladie auto-immune qui se caractérise par une faiblesse musculaire fluctuante, s’aggravant à l’effort et s’améliorant au repos, mettant en jeu le pronostic vital. Le polymorphisme clinique de cette affection rend souvent le diagnostic clinique difficile. Aussi le dosage des anticorps anti récepteur d’acétylcholine (AC anti Rach) et l’ENMG sont les principaux outils du diagnostic. Les auteurs rapportent 6 cas de myasthénie pour mettre en relief les difficultés de diagnostic et de prise en charge en Afrique subsaharienne.Mots clés: Ac anti-Rach, Myasthénie, électromyogramme, AfriqueEnglish Title: Myasthenia autoimmune: diagnosis and management. About six cases in Benin and GabonEnglish AbstractMyasthenia is a life threatening autoimmune disease presenting varying degrees of muscle weakness becoming worse during effort and released by rest. Its clinical polymorphism makes difficult the diagnosis. The anti-AChR antibodies testing and EMNG are the main diagnostic tools. The authors report 6 cases of myasthenia to underline the difficulties regarding diagnosis and management of this disease in sub-Saharan Africa.Keywords: Anti-AChR antibodies, Myasthenia, Electromyogram, Afric

La sclerose en plaques en milieu hospitalier a Libreville. A propos de deux cas et revue de la litterature

Introduction: La sclérose en plaques est une pathologie rarement diagnostiquée en Afrique noire. Description: Nous rapportons le cas de deux patientes, respectivement âgées de 23 ans et de 18 ans au début des troubles. La première patiente a été vue initialement pour des troubles visuels et présenta par la suite des signes encéphaliques cérébelleux et pyramidaux. Deux ans plus tard, survenait une seconde poussée marquée par l‘installation d‘un syndrome lésionnel. L‘imagerie par résonance magnétique cérébrale objectivait de nombreuses plaques de démyélinisation sus et sous-tentorielles. Ultérieurement, l‘imagerie médullaire réalisée mettait en évidence une plaque au niveau cervical. La deuxième patiente, rapportait également au début une baisse de l‘acuité visuelle puis plus tard un trouble sensitivo-moteur. L‘étude du LCR a objectivé une discrète augmentation de l‘index IgG.  L‘imagerie cérébrale concluait à des multiples hypersignaux flair et T2 disséminés de la substance blanche péri-ventriculaire, du tronc cérébral et de la moelle épinière cervicale. Au niveau médullaire, on notait la présence de plaques de démyélinisation médullaire cervicale en regard de C3. Le diagnostic de sclérose en plaques dans sa forme rémittente a été retenu dans les deux cas sur la dissémination spatio-temporelle apportée par les critères clinico-radiologiques. Le traitement prescrit était uniquement celui de la poussée inflammatoire vu l‘absence d‘immunomodulateurs. Conclusion: La sclérose en plaques au Gabon parait avoir les mêmes caractéristiques cliniques que dans les zones tempérées.   L‘avènement de l‘imagerie par résonance magnétique ces dernières années pourrait expliquer la fréquence des cas rapportés.   English title: Multiple sclerosis in Libreville, Gabon. about two cases and literature review   Introduction: Multiple sclerosis is a disease rarely diagnosed in Africa. We report the case of two patients, 23-years-old and 18- years-old, at the beginning of the disorders. Description: The first patient was seen initially for visual disturbances and presented cerebellar and pyramidal encephalic features. Two years later, there was a second surge marked by the installation of an injury  syndrome. Cerebral MRI revealed many additional demyelinated sustentorial and infratentorial plaques. Subsequently, the spinal cord imaging showed a cervical plaque. The second patient, also reported at first a decrease in visual acuity and later a sensory-motor disorder. The CSF study showed a slight increase in the IgG index. Brain imaging showed multiple FLAIR and T2 hyperintensities disseminated on the periventricular white matter, brainstem and cervical spinal cord. On the spinal cord, there were cervical demyelinating plaques opposite to the C3 vertebra. The diagnosis of multiple sclerosis in its relapsing form was retained in both cases on the spatio-temporal dissemination provided by clinico-radiological criteria. The treatment was only corticotherapy given the absence of immunomodulators. Multiple sclerosis in Gabon seems to have the same clinical features as in temperate zones. The advent of magnetic resonance imaging in recent years may explain the reported case frequency

Here today, here tomorrow: Beached timber in Gabon, a persistent threat to nesting sea turtles

notes:types: JOURThe African country of Gabon has seen decadal increases in commercial logging. An unforeseen consequence of this has been that many coastal areas, including several National Parks and Reserves, have suffered severe pollution from beached timber. This has the potential to adversely affect nesting sea turtles, particularly the leatherback turtle (Dermochelys coriacea) for which Gabon constitutes the world’s largest rookery. In this study, we analyse aerial survey data (2003, 2007 and 2011) to determine the temporal persistence and spatial extent of beached timber, and by integrating spatial data on nesting, ascertain regions where beached timber poses the greatest threat to nesting leatherback turtles. There was no marked difference in the number of beached logs recorded across the study area during the period, with 15,160, 13,528 and 17,262 logs recorded in the three years, respectively. There was, however, a significant difference in abundance of beached logs among geographical areas. Analysis highlighted two coastal areas where nesting leatherback turtles were likely to be at greatest risk from beached timber. At one such site, Kingere, within Pongara National Park, where both logs and turtle densities are high, monitoring in 2006/2007 and 2007/2008 suggested that between 1.6% and 4.4% of leatherback turtles could be entrapped at this site. Given the dynamic nature of Gabon’s coastal environment, and the potential limitations of aerial surveys, densities of beached timber could be greater than this analysis reveals. We also propose, that despite recent export restrictions of whole logs, their environmental persistence potentially represents a long-term problem

When ideology influences the process of comprehension : a study on the political ideology of the readers

Comprendre un texte, c’est élaborer un modèle de situation, une représentation cohérente qui est le résultat de l’interaction entre les informations textuelles et les connaissances du lecteur (van Dijk & Kintsch, 1983 ; Kintsch, 1988 ; Ehrlich et al., 1993). Cependant, les connaissances du lecteur ne sont toujours pas objectives et attestées (vraies). Ces connaissances peuvent également être des croyances voire des idéologies (van Dijk, 1998). Ce travail a pour objectif de montrer le rôle que peut jouer l’idéologie des lecteurs dans la compréhension de textes. Nous nous sommes intéressés à l’idéologie politique que nous avons mesurée à l’aide d’un test d’association implicite (IAT) que nous avons construit. Une première expérience a mis en évidence que la compréhension des textes est sensible à l’idéologie des lecteurs. En effet, les temps de lecture et les performances des lecteurs dépendent de l’appartenance politique des participants et de la cohérence entre cette appartenance et la nature idéologique des textes. Ensuite, à partir des simulations que permetle modèle Landscape (van den Brook et al., 1996, 1999), nous nous sommes intéressé à la dynamique de la compréhension à travers les inférences de type antécédent causal par rapport à l’idéologie des lecteurs. Les résultats obtenus à partir de trois expériences montrent que l’activation, le maintien et la récupération des inférences en mémoire est sensible à l’idéologie des lecteurs. En somme, ce travail complète les travaux sur la compréhension de texte enmettant en évidence l’importance des croyances des lecteurs, ici leur idéologie politique.To understand a text, it is to work out a model of situation, a coherent representation which is the result of the interaction between textual informations and knowledge of the reader (van Dijk & Kintsch, 1983 ; Kintsch, 1988 ; Ehrlich and al., 1993).However, the reader’s knowledge are not still objective and attested (true). This knowledge can also be beliefs even ideologies (van Dijk, 1998). This work aims to demonstrate the potential role of ideology readers in reading comprehension. We were interested in the political ideology which we measured using an implicit test of association (IAT) that we built. A first experiment showed that text comprehension is sensitive to the reader’s ideology. Indeed, the reading times and the performances of the readers depend on the political affiliation on the participants and consistency between this membership and ideological nature of texts. Then, starting from simulations which the model Landscape allows (van den Brook and al., 1996, 1999), we were interested in dynamics of comprehension through the bridging inferences compared to the ideology of the readers. The results obtained starting from three experiments show that activation, the maintenance and the retrieval of inferences in memory are sensitive to the ideology of the readers. To sum up, this work supplements work on text comprehension by highlighting the importance of the beliefs of the readers, heretheir political ideology

EFFET DE LA CULTURE, DES SOUS-CULTURES DU GABON SUR LA COMPRÉHENSION DE TEXTES

Déterminante dans les activités cognitives (Boudechiche et Hana, 2015; Retschitzki, 2011); cette étude teste l’effet de la culture, les sous-cultures Fang et Punu du Gabon; sur le processus de compréhension. Deux contes : « les trois fils d’Ada » et « Didi et Yibingitibingiti » culturellement Fang et Punu, ont été présentés aux participants sélectionnés selon leur rapport à ces cultures. La lecture est suivie de trois épreuves de compréhension. Les résultats montrent un effet des sous-cultures sur les performances en compréhension. L’origine culturelle et de la cohérence entre cette dernière, et le conte, module l’investissement cognitif.A determining factor in cognitive activities (Boudechiche et Hana, 2015; Retschitzki, 2011), this study tests the effect of culture; Fang and Punu subcultures; on the comprehension process. Two tales « les trois fils d’Ada » and « Didi et Yibingitibingiti » culturally Fang and Punu were presented to the participants according tho their relationship to these cultures. Reading is followed by three comprehension tasks. The results show an effect of subcultures on comprehension performances. The cognitive investment depends on the cultural origin of the reader and the coherence between that one and the tales

HPLC characterization of markers allowing evaluation of some wood macroscopic properties during various degradation processes

L’identification de marqueurs susceptibles de mettre en évidence et quantifier l’altération du bois par différents agents de dégradation peut présenter un grand intérêt dans la mise au point de méthodes de contrôle du matériau. Dans la première partie de ce travail, la caractérisation et le dosage des composés extractibles de deux essences non durables, le hêtre et le chêne soyeux, exposées à différents champignons de pourritures blanches ou brunes préalablement traitées ou non avec du propiconazole a été effectué. L’évolution de la quantité et de la nature des extractibles dépend directement de la présence du biocide et permet de différencier clairement les éprouvettes en fonction du taux de dégradation de ces dernières. C’est le cas notamment de la catéchine présente dans les extraits de hêtre, qui disparaît rapidement lorsque le bois est exposé à un agent de pourriture et qui peut à ce titre constituer un marqueur de l’attaque du bois. Dans la seconde partie de ce travail, l’évolution de la composition chimique du bois traité par pyrolyse douce à 240°C sous azote a été étudiée. Bien que les résultats obtenus confirment en grande partie ceux décrits précédemment dans la littérature, le dosage des différentes fractions du bois (lignine et holocellulose) et l’analyse des monosaccharides constitutifs de la fraction holocellulose du bois ont permis de mettre en évidence un important phénomène de carbonisation rapporté jusqu’à présent pour des températures plus élevées. Ce phénomène confirmé par RMN13C peut être à l’origine de certaines des nouvelles propriétés du matériau.The identification of markers able to highlight and quantify wood deterioration by different degradation agents can be of great interest in the development of material control methods. In the first part of this work, the characterization and the quantification of the two non durable wood species extractives, beech and silky oak, treated or not with propiconazole and exposed to various white rot or brown rot fungi were carried out. The evolution of the quantity and the nature of extractives depend directly on the presence of biocide and allowed to clearly differentiate degraded and non-degraded samples. This is particularly true in the case of catechin identified in the extracts of beech, which is rapidly degraded by rotting fungi constituting therefore a valuable marker of wood degradation. In the second part of this work, the evolution of the chemical composition of wood treated by mild pyrolysis at 240°C under nitrogen was investigated. Although the results mainly confirm those described previously in the literature, isolation of lignin and holocellulose fractions and analysis of monosaccharides constitutive of holocellulose fraction highlighted an important carbonization of wood reported up to now for higher temperatures. This phenomenon is confirmed by 13C NMR and could be at the origin of some of the new properties of the material