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Say Anouhe, J. B., Adima, A. A., Niamké, B. F., Stien, D., Kassi Amian, B., Virieux, D., et al. (2016). Wood Natural durability study source of biomolecules: case of Dicorynia guianensis Amsh. Heartwood. In IRG/WP.
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Lopez, M. (2016). Les plantations forestières en Guyane : sont elles une solution durable à l'approvisionnement bois dans les prochaines années ? Cayenne - Guyane française: ONF.
Keywords: plantations forestières ; Guyane française ; filière bois ; carbone
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Fu, T., Touboul, D., Della-Negra, S., Houël, E., Amusant, N., Duplais, C., et al. (2016). Localization od bioactive metabolites in durable ? Tropical tree Sextonia rubra (Lauracaea) with argon and bismuth cluster dual beam depth profiliing and imaging. In Imaging mass spectrometry conference – Ustron – Pologne – Octobre 2016.
Abstract: Many tropical tree species generate natural decay resistance by producing bioactive metabolites. Among them, Sextonia rubra (Lauraceae) is a widely exploited species for construction in French Guiana. Rubrynolide and rubrenolide, which are secondary metabolites isolated from the stem wood of S. rubra, exhibit potent antifungal and termiticidal activities that result in the exceptional durability of the heartwood. Although the structure and total synthesis of these two biologically active compounds have been well described in literature, little is known about their cellular localization or biosynthesis process in living trees. Time-of-flight secondary ion mass spectrometry (TOF-SIMS) has been well known for its high lateral resolution imaging with a typical beam size of 0.4-2 µm, thus sufficient to image the wood surface at subcellular level.
Wood surfaces of sapwood, transition zone and heartwood from living trees of S. rubra were prepared with ultramicrotome using diamond knife. Each surface was mapped by Bi3+ cluster TOF-SIMS with high lateral resolution (~ 0.4 µm) which was achieved by employing burst alignment primary ion focusing mode with an extraction delay of the secondary ions to improve mass resolution. 3D imaging of a multi-structure wood sample was performed using dual beam depth profiling method, with 25 keV Bi3+ and 10 keV Ar1000+ as analysis and sputter beam, respectively. To examine the effect of life-history traits on the production of bioactive metabolites, the corresponding counterparts from a tree which had suffered stress during growth were investigated as well.
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Houël, E., Rodrigues, A. M. S., Jahn-Oyac, A., Bessière, J. - M., Odonne, G., Gonzales, G., et al. (2016). How can plant defences lead to valuable products? Inspiration from plant complexity in phytochemistry. Planta Medica, 81(S01), S1–S381.
Abstract: If plants are known for centuries as a valuable source of molecules, complexity remains and can open up numerous perspectives. Plants have indeed evolved a wide range of secondary metabolites as defense, competition or attraction compounds [1]. More particularly, the exceptional biodiversity encountered in the tropics, along with the presence of various pathogens and a strong herbivory especially linked to a rich entomofauna, leads to a promising chemodiversity, due to the constant and dynamic interactions between plants and their environment. Taking into account the role and “raison d'être”[2] of natural products, and the fact that all these molecules work together as complex mixtures can therefore lead to a new point of view, by shifting from the “magic bullet” classical approach to a “herbal shotgun” strategy[3]. We will illustrate the fact that, inspired by their ecological functions, and taking into account synergistic interactions, some therapeutic applications can be found for these versatile mixtures of compounds. In particular we examined whether the antidermatophytic activity of essential oils (EOs) obtained from particularly fragrant plant species from French Guiana could be used as an indicator for the discovery of active natural products against Leishmania amazonensis. A significant correlation was observed between antidermatophytic and antileishmanial activity, confirming the “alternative use” strategy in the case of EOs, and allowed us to highlight P. hispidum Sw. (Piperaceae) EO as a promising antileishmanial product [4]. We also illustrated the importance of synergistic effects through the example of the antifungal EO of Otacanthus azureus (Linden) Ronse (Plantaginaceae) [5] and the biomimetic design of optimized synergistic mixtures thanks to a full factorial experiment approach.
Keywords: Essential oils ; therapeutic switching ; antifungal agents ; antiparasitic agents ; biomimetic design
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Touré, S., Falkowski, M., Dusfour, I., Jahn-Oyac, A., Odonne, G., Stien, D., et al. (2016). Ae aegypti larvicidal sesquiterpene alkaloids from Maytenus oblongata Reissek (Celastraceae). Planta Medica, 81(S01), S1–S381.
Abstract: Vector-borne diseases account for 17% of the estimated global burden of all infectious diseases [1]. For most of these, vector control remains the sole method to circumvent transmission and eventually epidemics in the absence of vaccine and/or specific arbovirose treatments. Furthermore, the efficacy of existing insecticides is decreasing due to the development of resistances [2, 3]. The situation urges to find novel insecticide or alternative method for controlling mosquito vectors. Taking into account these elements, in a constantly evolving epidemiological and regulatory context, the need to discover alternative, environmentally friendly, and safer biopesticides appears as crucial. Plants are a source of inspiration for new insecticides discovery as coevolution with phytophagous insects promoted the occurrence of a unique chemical diversity devoted to herbivory resistance at least in part [4, 5]. The insecticidal activity of 160 extracts from 87 species collected in French Guiana were evaluated on Ae. aegypti mosquitoes larvae. It was discovered that Maytenus oblongata Reissek (Celastraceae) stem ethyl acetate extract exhibited promising insecticidal properties, i.e., larvicidal and adulticidal activity against Ae. aegypti under laboratory conditions, without ecotoxicity (essay on Chironomus riparius and Daphnia magna) or cytotoxicity (Test on Ae. albopictus C6/36 cells and two human cell lines: KB and MCR5). Four β-dihydroagrofurane sesquiterpene alkaloids (1-4) and one steroid (5) were isolated from this extract. Compounds 2 (1-benzoyl,4-deoxy-alatamine) and 3 (1,2-dibenzoyl,4-deoxy-alatamine) showed LD50 of 7.75 µg/ml (95% confidence interval: 6.46 – 10.00 µg/ml) and 2.38 µg/ml (95% CI: 1.91 – 2.87 µg/ml), respectively, against Ae. aegypti larvae.
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Keywords: Maytenus oblongata ; Aedes aegypti ; larvicidal ; sesquiterpenes alkaloids
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Leponce, M., Novotny, V., Pascal, O., Robillard, T., Legendre, F., Villemant, C., et al. (2016). Land module of our planet reviewed – Papua New Guinea: aims, methods and first taxonomical results. In Insects of Mount Wilhelm, Papua New Guinea (pp. 11–48). Paris - France: Muséum national d'Histoire naturelle.
Abstract: Until now the altitudinal factor has not been taken into account to estimate tropical arthropod diversity. The ultimate aim of the terrestrial biodiversity
survey “Our Planet Reviewed – Papua New Guinea” was to estimate biological diversity generated by altitudinal turnover of arthropod species. It took place on Mount Wilhelm, Papua New Guinea highest peak (4509 m a.s.l.), and one of the few equatorial mountains outside the Andes left with a continuous undisturbed forest from the sea level all the way to the timber line limit. An unprecedented sampling effort was concentrated over 16 days in 2012 with a semi-simultaneous sampling at eight different elevations (every 500 m from 200 m to 3700 m a.s.l.). Arthropods were collected with various methods: flight interception traps (targeting Coleoptera), Malaise traps (targeting Hymenoptera, Diptera and Hemiptera), Steiner traps (targeting tephritid flies), beating of the understorey vegetation, and insecticide spraying on tree barks (various groups targeted). A botany survey was conducted at each elevation to characterize vegetation. An additional site, Wanang, was sampled according to the same protocol, as replicated lowland site. Our team combined international experts with local postgraduate students, para-ecologists and villagers. Arthropod samples collected during the biotic survey were pre-sorted in Papua New Guinea and forwarded to taxonomists worldwide. The current book presents the first taxonomic results of the biotic survey. Project outputs included not only species discovery, but also direct financial benefits to landowner communities, raised profile of conservation areas, training of paraecologists and postgraduate students, education programmes and, finally, crucial biodiversity information needed for ecological analyses and conservation management.
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Cortesero, A. - M., Proffit, M., Duplais, C., & Viard, V. (2016). Chemical Ecology: An Integrative and Experimental Science. In Chemical Ecology: New Advances (pp. 23–46).
Abstract: All living organisms, whether plants, animals or microorganisms, interact through chemical compounds. Chemical ecology seeks to identify the compounds that are involved in these interactions, the structures that allow their biosynthesis, emission and perception. It deciphers their implication in the functioning and the evolution of the living organisms whether at a molecular, individual, population or ecosystemic scale. Semiochemicals are involved in the interactions of organisms among themselves and with their environment. Involved in numerous interactions, semiochemicals play an essential role in the structuring of trophic networks and the evolution of the species. Chemical ecology also sheds light on certain large ecological problems like biological invasions and helps envision new methods for managing invasive species. The chemical signals emitted in the environment by local species play a role from the beginning of the introduction process, notably for the detection of habitats favorable to the establishment of non-indigenous species. © ISTE Ltd 2016.
Keywords: Biological invasions; Chemical ecology; Non-indigenous species; Semiochemicals; Trophic network
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Maillard, B. (2016). Variations interspécifiques de traits fonctionnels liés à l'acquisition et au stockage des ressources chez les broméliacées.
Abstract: Les broméliacées, présentant différentes écologies et adaptations, ont été classées en 5 types écophysiologiques en fonction de la forme de vie (épiphyte, terrestre ou lithophyte), la morphologie de la rosette (avec ou sans réservoir d’eau), le métabolisme photosynthétique (C3 ou CAM) ou encore le caractère absorbant ou non des trichomes et racines. L’objectif du stage était de caractériser si certains traits foliaires et racinaires pouvaient discriminer les types écophysiologiques représentés par 14 espèces. Les résultats montrent que les parties apicales et basales des feuilles se spécialisent différemment en fonction de l’exposition lumière. La taille du disque central des trichomes augmente avec la sécheresse. La densité de trichome de la partie apicale supérieure résulte d’un trade-off entre l’acquisition de l’eau et l’exposition à la lumière. Aussi, le genre A echmea présente un grand nombre de stomates, les T illandsia atmosphériques un plus grand recouvrement de la surface foliaire par les trichomes et les C3 ont un LMA plus
petit. Enfin, les associations fongiques permettent de différencier le genre T illandsia des autres genres. Pour conclure, certains traits permettent de discriminer les types écophysiologiques mais ce sont avant tout la disponibilité en eau et l’exposition à la lumière qui façonnent les traits fonctionnels.
Keywords: broméliacées ; endophytes racinaires ; feuilles ; traits fonctionnels ; trichonnes foliaires ; types écophysiologiques
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Ribaud, M. (2016). Comment améliorer la cartographie de la biodiversité de la forêt amazonienne ?.
Keywords: cartographie ; biodiversité ; forêt amazonienne
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Bonhomme, C. (2016). Les prédateurs aux interfaces eau-air accélèrent-ils le recyclage des nutriments ? Master's thesis, Université de Guyane, Cayenne.
Abstract: Étant donné le risque d'extinction accru des niveaux trophiques supérieurs en réponse aux changements environnementaux, la compréhension des mécanismes qui déterminent l’importance des prédateurs dans les fonctions clés de l’écosystème est essentielle. Les broméliacées à réservoirs sont des plantes capables d’absorber une partie de l’azote recyclé par les communautés de micro et macro-organismes aquatiques qu’elles hébergent dans les réservoirs d’eau entre leurs feuilles. Ces plantes ont été utilisées comme habitat dans lesquelles nous avons recréé différentes configurations de communautés aquatiques. En serres, l’apport de proies terrestres enrichies en 15N a permis de déterminer quelle configuration de communauté permet le recyclage le plus rapide de l’azote, en utilisant les broméliacées comme « intégrateurs ». Au laboratoire, nous avons testé l’influence d’un prédateur chassant à l’interface eau-air sur la quantité de proies terrestres entrant dans l’ «écosystème broméliacée ». Nos résultats montrent que (i) les prédateurs chassant à l’interface eau-air ont permis une augmentation de l’entrée de nutriments allochtones, (ii) les micro-organismes ont joué un rôle essentiel dans le recyclage de cet l’azote, et (iii) les prédateurs ont permis d’accélérer ce recyclage, d’autant plus qu’ils sont restés longtemps dans la plante. Nos résultats donnent un aperçu des mécanismes qui peuvent déterminer l’importance des effets « top-down » et « bottom-up » sur le cycle des nutriments dans d’autres systèmes.
Keywords: broméliacées à réservoirs ; aquatic communities ; nitrogen cycling ; predation ; digestive mutualism
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