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Odonne, G., Herbette, G., Eparvier, V., Bourdy, G., Rojas, R., Sauvain, M., et al. (2011). Antileishmanial sesquiterpene lactones from Pseudelephantopus spicatus, a traditional remedy from the Chayahuita Amerindians (Peru). Part III. J. Ethnopharmacol., 137(1), 875–879.
Abstract: Ethnopharmacological relevance: The study of traditional remedies used by the Chayahuita, an ethnic group from the Peruvian Amazonia, has prompted us to investigate in detail the ethanolic extract of Pseudelephantopus spicatus (Juss. ex Aubl.) C.F. Baker, which has demonstrated strong biological activity towards Leishmania amazonensis. Our goal was to discover the active compound of this plant-based remedy. Materials and methods: A bioguided fractionation of the crude extract was undertaken based on the biological activity recorded against Leishmania amazonensis axenic amastigotes in in vitro bioassays. Results: Three strongly to moderately active compounds were isolated: two hirsutinolides (the 8,13-diacetyl-piptocarphol and the 8-acetyl-13-O-ethyl-piptocarphol) and ursolic acid. IC50 against Leishmania amazonensis axenic amastigotes are respectively 0.2, 0.37 and 0.99 μM (while IC50 of amphotericin B is 0.41 μM). These compounds have never been isolated from this plant species, and germacranolides have never been identified as potential antileishmanial agents. Conclusions: The compounds isolated from Pseudelephantopus spicatus account for the antileishmanial activity of the plant, thus giving support to its use by the Chayahuita in Peru. © 2011 Elsevier Ireland Ltd All rights reserved.
Keywords: Asteraceae; Chayahuita; Hirsutinolides; Leishmaniasis; Peru; Pseudelephantopus spicatus; Traditional remedy; 8,13 diacetylpiptocarphol; acetyl 13 o ethylpiptocarphol; amphotericin B; antileishmanial agent; plant extract; Pseudelephantopus spicatus extract; sesquiterpene lactone derivative; unclassified drug; ursolic acid; amastigote; article; biological activity; Ic 50; in vitro study; Leishmania; leishmaniasis; medicinal plant; nonhuman; Peru; Pseudelephantopus spicatus; traditional medicine; Asteraceae; Leishmania amazonensis; Pseudelephantopus spicatus
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Vincent, G., Weissenbacher, E., Sabatier, D., Blanc, L., Proisy, C., & Couteron, P. (2010). Detection des variations de structure de peuplements en foret dense tropicale humide par lidar aeroporte. Rev. Fr. Photogramm. Teledetect., 191, 42–51.
Abstract: Characterisation of forest structure is a major stake for forestry, species conservation, carbon stock estimates and many forest ecology and management issues. At large scale natural forest structure tends to vary according to climate and geomorphomology (Paget, 1999; Steege et al., 2006) while soil characteristics (and notably water regime) and syMgenetic stage add some finer scale variation (Oldeman, 1989; Sabatier et al., 1997). Forest structure characterisation traditionally relies on field-based collection of individual tree dimensions such as stem diameter and stem height sampled across tracks of forest (Hall et al., 1998). However, such field intensive methods are costly, and of low accuracy regarding measures of tree heights. Airborne light detection and ranging (LiDAR) technology provides horizontal and vertical Information at high spatial resolutions and vertical accuracies (Lim et al., 2003; Hyyppä et al., 2004). It has the potential for gathering vegetation structure data over large areas rapidly at moderate cost and hence is of particular relevance for poorly sampled, difficult to access and largely unexplored tropical rainforests. In this study we examined the ability of airborne LiDAR to detect spatial changes in the structure of dense tropical rain forest and we probed this remote sensing approach against local statistics derived from stem diameters (i.e. classical field data information) mapped across a large track of forest at a long term experimental site in French Guyana. The large variability in forest structure occurring at the experimental site is du to natural variation of the soil cover (and notably drainage properties) combined with various logging intensities applied 15 years before the LiDAR data were acquired. On this basis ten different forest types were identified at the site (figure 1 and 3). Various stem based statistics were computed for a series of meshes with cells ranging from 30 by 30 m plots to 250 by 250 m plots. These statistics included basal area, stem density, quadratic mean diameter, and diameter distribution percentiles. Similarly local statistics were extracted either from the Canopy Height Model (e.g. median height, mean height, standard height deviation, height coefficient of variation, height percentiles, frequency of hits below 5 m above ground level). Additionally a wetness index (Böhner et al., 2002) was computed at each node of a 5 by 5 m grid from the Digital Terrain Model also extracted from the LiDAR data set. We used both types of cell statistics to discriminate the various forest types. Comparison between the two approaches for a range of spatial resolution is available from in table 1. Results indicate that LiDAR based statistics are essentially as powerful as field based statistics to discriminate forest types at coarse scale. This reflects the very strong correlation between the CHM and the field based stem diameter data. For example (figure 5) the Pearson correlation coefficient between median height and quadratic mean diameter for cells of 125 by 125 m is 0.945 (n=0.72). When a finer resolution is required however as for the detection of seasonally flooded bottomland forest along thalwegs, then LiDAR technology proves more efficient than field based inventories as it combines information from the DTM and the CHM. The wetness index alone correctly retrieves about 2 thirds of the seasonally flooded areas. All in all, discriminant analysis performance of the LiDAR derived information approaches 80% when classifying forests cover at the finest scale of 5 by 5m into 10 different types and reaches 87% when a coarser classification Into 6 forest types is considered (figure 4).
Keywords: Above-ground biomass estimation; Canopy height model; Stem diameter distribution; Tropical moist forest; Above ground biomass; Above ground level; Airborne LiDAR; Basal area; Canopy Height Models; Carbon stocks; Characterisation; Classical fields; Coefficient of variation; Diameter distributions; Digital terrain model; Flooded areas; Forest ecology; Forest structure; Forest type; High spatial resolution; Individual tree; LIDAR data; Light detection and ranging; Local statistics; Long term; Management issues; Natural forests; Natural variation; Pearson correlation coefficients; Quadratic mean diameter; Soil characteristics; Soil cover; Spatial changes; Spatial resolution; Stem density; Stem diameter; Stem height; Strong correlation; Tree height; Tropical moist forest; Tropical rain forest; Vegetation structure; Vertical accuracy; Water regime; Discriminant analysis; Ecology; Optical radar; Remote sensing; Soils; Statistics; Stem cells; Temperature control; Tropics; Vegetation; Forestry; Biomass; Discriminant Analysis; Ecology; Forest Canopy; Forestry; Radar; Remote Sensing; Stems; Temperature Control; Tropical Atmospheres
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Christensen-Dalsgaard, K. K., Ennos, A. R., & Fournier, M. (2007). Changes in hydraulic conductivity, mechanical properties, and density reflecting the fall in strain along the lateral roots of two species of tropical trees. J. Exp. Bot., 58(15-16), 4095–4105.
Abstract: Roots have been described as having larger vessels and so greater hydraulic efficiency than the stem. Differences in the strength and stiffness of the tissue within the root system itself are thought to be an adaptation to the loading conditions experienced by the roots and to be related to differences in density. It is not known how potential mechanical adaptations may affect the hydraulic properties of the roots. The change in strength, stiffness, conductivity, density, sapwood area, and second moment of area distally along the lateral roots of two tropical tree species in which the strain is known to decrease rapidly was studied and the values were compared with those of the trunk. It was found that as the strain fell distally along the roots, so did the strength and stiffness of the tissue, whereas the conductivity increased exponentially. These changes appeared to be related to differences in density. In contrast to the distal-most roots, the tissue of the proximal roots had a lower conductivity and higher strength than that of the trunk. This suggests that mechanical requirements on the structure rather than the water potential gradient from roots to branches are responsible for the general pattern that roots have larger vessels than the stem. In spite of their increased transectional area, the buttressed proximal roots were subjected to higher levels of stress and had a lower total conductivity than the rest of the root system. © 2007 The Author(s).
Keywords: Buttress roots; Density; Hydraulic conductivity; Hydraulic-mechanical trade-offs; Modulus of elasticity; Tropical trees; Wood; Elastic moduli; Hydraulic conductivity; Wood; Buttress roots; Hydraulic-mechanical trade-offs; Tropical trees; Forestry; water; article; biomechanics; histology; legume; physiology; plant root; plant stem; tree; wood; Xylopia; Biomechanics; Fabaceae; Plant Roots; Plant Stems; Trees; Water; Wood; Xylopia; Conductivity; Elastic Strength; Forestry; Wood
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Dejean, A., Moreau, C. S., Uzac, P., Le Breton, J., & Kenne, M. (2007). The predatory behavior of Pheidole megacephala. C. R. Biol., 330(9), 701–709.
Abstract: We studied the foraging and predatory behaviors of the invasive African myrmicine ant, Pheidole megacephala (F.) in its native range. Workers can singly capture a wide range of insects, including relatively large prey items. For still larger prey, they recruit at short range those nestmates situated within reach of an alarm pheromone and together spread-eagle the insect. These behaviors are complimented by a long-range recruitment (of nestmates remaining in the nest) based on prey size. P. megacephala scouts also use long-range recruitment when they detect the landmarks of termites and competing ant species, thus permitting them to avoid confronting these termites and ants solitarily.
Keywords: Invasive ants; Landmarks; Pheidole megacephala; Predatory behavior; Recruitment; pheromone; ant; behavioral ecology; foraging behavior; invasive species; nest predation; pheromone; predator-prey interaction; animal experiment; ant; article; competitor species; controlled study; foraging behavior; host range; Isoptera; nest predation; nonhuman; predation; predator prey interaction; prey selection; species invasion; worker (insect); Animals; Ants; Feeding Behavior; Female; Isoptera; Predatory Behavior; Social Behavior; Formicidae; Hexapoda; Isoptera; Pheidole megacephala
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Dejean, A., Delabie, J. H. C., Cerdan, P., Gibernau, M., & Corbara, B. (2006). Are myrmecophytes always better protected against herbivores than other plants? Biol. J. Linn. Soc., 89(1), 91–98.
Abstract: The present field study compared the degree of defoliation of three Guianian melastome, two myrmecophytes (i.e. plants sheltering ants in hollow structures) and Clidemia sp., a nonmyrmecophytic plant serving as a control. Maieta guianensis Aubl. hosted mostly Pheidole minutula Mayr whatever the area, whereas Tococa guianensis Aubl. hosted mostly Azteca bequaerti Wheeler along streams and Crematogaster laevis Mayr or Azteca sp. 1 in the understory where it never blossomed. Only Tococa, when sheltering A. bequaerti in what can be considered as a truly mutualistic relationship, showed significantly less defoliation than control plants. In the other associations, the difference was not significant, but P. minutula is mutualistic with Maieta because it furnishes some protection (exclusion experiments) plus nutrients (previous studies). When devoid of ants, Tococa showed significantly greater defoliation than control plants; therefore, it was deduced that Tococa probably lacks certain antidefoliator metabolites that control plants possess (both Tococa and control plants are protected by ground-nesting, plant-foraging ants, which is termed 'general myrmecological protection'). Consequently, plant-ants other than A. bequaerti probably also protect Tococa slightly, thus compensating for this deficiency and permitting it to live in the understory until treefall gaps provide the conditions necessary for seed production. © 2006 The Linnean Society of London.
Keywords: Ant-plant mutualism; Azteca; Maieta; Myrmecophytes; Plant protection; Tococa; ant; defoliation; field method; mutualism; myrmecophyte; plant-herbivore interaction; Azteca; Azteca bequaerti; Clidemia; Crematogaster laevis; Formicidae; Maieta; Maieta guianensis; Pheidole minutula; Tococa; Tococa guianensis
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Gibernau, M., Orivel, J., Delabie, J. H. C., Barabe, D., & Dejean, A. (2007). An asymmetrical relationship between an arboreal ponerine ant and a trash-basket epiphyte (Araceae) RID D-4390-2009 RID C-4034-2011. Biol. J. Linnean Soc., 91(3), 341–346.
Abstract: The relationship between ants and Philodendron insigne, a trash-basket epiphyte abundant along streams, was studied in French Guiana. Only a few (3%) of the young plants sheltered ants, whereas 90% of the mature individuals did. The most frequent associate was Odontomachus hastatus (Fabricius), an arboreal ponerine ant, and its nests were almost entirely (94.4%) located in P. insigne root clusters. Experimental choice tests conducted on O. hastatus workers confirmed their preference for P. insigne. We propose that the interactions between P. insigne and ants may be intermediate between non-obligatory, reward-based interactions and obligatory, specific ant-myrmecophyte interactions because (1) almost all mature P. insigne individuals are associated with ants; (2) O. hastatus is the most frequent when diverse ants nest in its root clusters; (3) ants colonize mature P. insigne, but rarely young individuals; (4) ants, particularly O. hastatus, protect the foliage of their host; and (5) at least one ant species, O. hastatus, prefers P. insigne over other host plants. The latter relationship is asymmetrical because P. insigne is inhabited by diverse ants whereas O. hastatus nests almost exclusively in P. insigne. (c) 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 91, 341-346.
Keywords: hanging soil; mutualism; nest site selection; plant protection
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Porth, I., Scotti-Saintagne, C., Barreneche, T., Kremer, A., & Burg, K. (2005). Linkage mapping of osmotic stress induced genes of oak. Tree Genet. Genomes, 1(1), 31–40.
Abstract: Water stress affecting long-lived trees is an important challenge in forestry. Due to global climate change, forest trees will be threatened by extreme conditions like flooding or drought. It is necessary to understand differences in stress tolerance within certain species and to investigate putative relations on genomic level. In this study, osmotic stress induced genes of Quercus ssp. were positioned on two genetic linkage maps of oak. An intra-specific cross 3P*A4 of Quercus robur consisting of 88 offspring and an inter-specific cross 11P*QS29 of Q. robur and Q. petraea comprising 72 full-sibs were analyzed for the inheritance of 14 loci represented by 34 individual single nucleotide polymorphisms. Seven genes in the intra-cross, as well as other six genes in the inter-cross could be mapped and one gene could not be localised due to the severe distortion of the segregation. The collection of expressed sequences involved ribosomal proteins, members of the oxylase/oxygenase gene family, betaine aldehyde dehydrogenase, Dc3 promoter-binding factor, a putative member of the nodulin family, glutathione-S-transferase and proteins with unknown functions. In the inter-cross, two linked markers exhibited 89% deficiency of heterozygosity. Thirteen genes were positioned on ten different oak chromosomes and can serve as orthologous markers in comparative mapping studies within Fagaceae. © Springer-Verlag 2005.
Keywords: Est; Linkage map; Oak; Osmotic stress; Quercus ssp.; Fagaceae; Quercus; Quercus petraea; Quercus robur
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Latouche-Hallé, C., Ramboer, A., Bandou, E., Caron, H., & Kremer, A. (2003). Nuclear and chloroplast genetic structure indicate fine-scale spatial dynamics in a neotropical tree population. Heredity, 91(2), 181–190.
Abstract: Dicorynia guianensis is a canopy tree, endemic to the tropical rain forest of French Guiana. We compared generational and spatial genetic structure for maternally and biparentally inherited markers in two cohorts (adult and seedling) in order to infer processes shaping the distribution of genetic diversity. The study was conducted on a 40 ha study plot located at Paracou near Kourou, where 172 adults trees and 375 saplings were sampled. Aggregation of trees was therefore suggested at different distances, ranging from 100 to 400 m. There was a strong link between demographic and genetic spatial structures at small distances (less than 100 m) that is likely to be the consequence of restricted seed dispersal. Genetic differentiation was more pronounced between spatial aggregates than between cohorts. Despite the spatial differentiation, the species was able to maintain high levels of diversity for maternal genomes, suggesting rapid turnover of aggregates. Spatial autocorrelation was larger for chloroplast than nuclear markers indicating a strong asymmetry between pollen and seed flow. Fixation indices indicated a lower heterozygote deficiency for the adults, maybe because of gradual elimination of selfed trees. Genetic relatedness at lower distances was higher in adult trees than in saplings, as a result of generation overlapping in the adult cohort. Overall, our results confirm earlier biological knowledge about the dispersion mechanisms of the species, and lead to an enhanced role of spatial processes in the dynamics of genetic diversity of D. guianensis.
Keywords: Dicorynia guianensis; Gene flow; Genetic differentiation; Microsatellites; Spatial analysis; Tropical tree; gene flow; genetic structure; population genetics; spatial analysis; tree; tropical forest; Cell Nucleus; Chloroplasts; Cohort Studies; DNA, Plant; French Guiana; Genetic Markers; Pollen; Population Dynamics; Seeds; Trees; Variation (Genetics); French Guiana; Dicorynia guianensis; Embryophyta
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Groc, S., Delabie, J. H. C., Cereghino, R., Orivel, J., Jaladeau, F., Grangier, J., et al. (2007). Ant species diversity in the 'Grands Causses' (Aveyron, France): In search of sampling methods adapted to temperate climates RID C-4034-2011. C. R. Biol., 330(12), 913–922.
Abstract: This study aimed at showing the applicability of using a combination of four sampling methods (i.e., Winkler extractors, pitfall traps, baiting and manual collection), something most often conducted in the tropics, to create an inventory of ant species diversity in temperate environments. We recorded a total of 33 ant species in the Grands Causses by comparing three vegetal formations: a steppic lawn ('causse' sensu stricto), which was the most species-rich (29 species), followed by an oak grove (22 species) and a pine forest (17 species). No sampling method alone is efficient enough to provide an adequate sampling, but their combination permits one to make a suitable inventory of the myrmecofauna and to obtain information on the ecology of these ant species.
Keywords: ant diversity; Grands Causses; sampling methods; temperate climate
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Sharma, K., Degen, B., Von Wuehlisch, G., & Singh, N. B. (2002). Allozyme variation in eight natural populations of Pinus roxburghii Sarg. in India. Silvae Genet., 51(5-6), 246–253.
Abstract: Seeds collected from eight populations of Chir pine (Pinus roxburghii SARG.) from the natural distribution range of the species in Himachal Himalayas in India were analysed isozymatically at 11 enzyme systems. For the enzyme systems studied, 25 gene loci were identified out of which 18 were polymorphic. The observed mean values for genetic variation were slightly lower than mean values reported for Pinus species (number of alleles: 1.65 compared to 2.36; effective number of alleles: 1.13 compared to 1.26; observed heterozygosity: 0.153 compared to 0.179). A small differentiation among populations and large variation within populations were reflected by small value of GST (0.04): Considering the different genetic parameters three populations seem favourable for gene conservation measures.
Keywords: Allozymes; Differentiation; Genetic distance; Multilocus diversity; Pinus roxburghii; Variation; Enzymes; Forestry; Genes; Allozyme variations; Genetic engineering; Enzymes; Genes; Genetic Engineering; Pinus Roxburghii; Embryophyta; Pinus roxburghii
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