Éditeur(s) : HAL CCSD Linnean Society of London
Résumé : International audience
The circumscription of Salicaceae has recently been enlarged to include a majority of the species formerly placed in the polyphyletic tropical family Flacourtiaceae. Several studies have reported a peculiar and infrequently formed multilayered structure of tension wood in four of the tropical genera. Tension wood is a tissue produced by trees to restore their vertical orientation, and most studies have focused on trees developing tension wood by means of cellulose-rich, gelatinous fibres, as is known in Populus L. and Salix L. (Salicaceae s.s.). This study aims to determine if the multilayered structure of tension wood is an anatomical characteristic common in other Salicaceae, and if so, how its distribution correlates to phylogenetic relationships. Therefore, we studied the tension wood of 14 genera of Salicaceae as well as two genera of Achariaceae, one genus of Goupiaceae, and one genus of Lacistemataceae, families closely related to Salicaceae or formerly placed in Flacourtiaceae. Opposite wood and tension wood were compared with light microscopy and 3D Laser Scanning Confocal Microscopy. The results indicate that a multilayered structure of tension wood is common in the family except in Salix, Populus, and one of their closest relatives, Idesia polycarpa Maxim. We suggest that tension wood may be a useful anatomical character in understanding phylogenetic relationships in Salicaceae. Further investigation is still needed on the tension wood of several other putatively close relatives of Salix and Populus, in particular Bennettiodendron Merr., Macrohasseltia L.O.Williams and Itoa Hemsl.
ISSN: 0024-4074

hal-01392845
https://hal.archives-ouvertes.fr/hal-01392845
https://hal.archives-ouvertes.fr/hal-01392845/document
https://hal.archives-ouvertes.fr/hal-01392845/file/GhislainEtAl2016_MultylayerTWSalicaceae_Bot_Jsur the_Lin_Soc_HALssfig.pdf
DOI : 10.1111/boj.12471

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
Tension wood of Laetia procera (Poepp.) Eichl. (Flacourtiaceae), a neo-tropical forest species, shows a peculiar secondary wall structure, with an alternance of thick and thin layers, while opposite wood of this species has a typical secondary wall structure (S1 + S2 + S3). Samples for the study of microstructural properties were collected upon the estimation of growth stresses in the living tree, in order to analyze the correlation of the former with the latter. Investigation using optical microscopy, scanning electron microscopy and UV microspectrophotometry allowed the description of the anatomy, ultra-structure and chemistry of this peculiar polylaminate secondary wall. In the thick layers, cellulose microfibril angle is very low (i.e., microfibril orientation is close to fibre axis) and cellulose microfibrils are well organized and parallel to each other. In the thin layers, microfibrils (only observable in the inner layer) are less organized and are oriented with a large angle relative to the axis of the cell. Thick layers are lightly lignified although thin layers show a higher content of lignin, close to that of opposite wood secondary wall. The more the wood was under tensile stress, the less the secondary wall was lignified, and lower the syringyl on guaiacyl lignin units' ratio was. The innermost layer of the secondary wall looks like a typical S3 layer with large microfibril angle and lignin occurrence. The interest of this kind of structure for the understanding of stress generation is discussed.
ISSN: 0931-1890

hal-00194923
https://hal.archives-ouvertes.fr/hal-00194923
https://hal.archives-ouvertes.fr/hal-00194923/document
https://hal.archives-ouvertes.fr/hal-00194923/file/Trees_RuelleYoshidaClairThibaut_submitted2006.pdf
DOI : 10.1007/s00468-007-0128-0

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : Increasing interest in understanding tension stress generation in tension wood with fibres having a gelatinous layer (G-layer) has focused attention on the specific role of this layer. To distinguish its contribution from those of other wall layers, the G-layer of wood sections was isolated by ultrasonication. The aim of this study was to assess the effect of sectioning and of the ultrasonic treatment on the mesoporosity of tension wood using nitrogen adsorption-desorption analysis. The results showed that the process of isolating the G-layer using ultrasonication strongly affects its mesoporosity. Most damage was found to occur during sectioning rather than as a result of the 15-min ultrasonic treatment.
ISSN: 0043-7719

hal-01601127
https://hal.archives-ouvertes.fr/hal-01601127
DOI : 10.1007/s00226-017-0890-0
PRODINRA : 401888

Éditeur(s) : HAL CCSD Lavoisier
Résumé : International audience
Influence des constituants de la fibre de bagasse sur la prise du matériau composite bagasse/ciment
ISSN: 1169-7954

hal-00808663
https://hal.univ-antilles.fr/hal-00808663

Éditeur(s) : HAL CCSD Montpellier : CIRAD
Résumé :  
Influence de la température sur le comportement mécanique du bois vert: application à l'étuvage d'essences guyanaises en vue du déroulage. Des essais mécaniques dans les directions orthogonales à la fibre et des essais de déroulage ont été menés en parallèle sur 10 essences guyanaises, de densité variant de 0,27 à 1,18, et à 12 températures croissant de 25 à 80 °C. L'influence de la densité et de la température sont très fortes et souvent couplées. Les essais mécaniques peuvent être utilisés pour expliquer les variations des efforts de coupe. Les ratios entre descripteurs mécaniques apparaissent comme des prédicteurs intéressants de l'aptitude au déroulage des bois homogènes.
ISSN: 0006-579X

hal-01032179
https://hal.archives-ouvertes.fr/hal-01032179

Résumé : Dans les régions tropicales. Il existe une multitude de systèmes alternatifs avec une grande diversité de pratiques. Ces systèmes sont souvent basés sur une utilisation optimale des ressources animales et végétales locales présentes sur l'exploitation. L'objectif de ce travail est de mieux connaître certaines de ces ressources tropicales disponibles et pouvant potentiellement être intéressantes à utiliser en alimentation porcine dans le cadre de ces systèmes alternatifs de type polyculture - élevage. Les résultats montrent que la capacité d'Ingestion des feuilles de manioc et de patate douce est la même quel que soit la forme de présentation (feuilles fraîches ou en farine). La capacité d'ingestion des feuilles de madère est plus élevée lorsqu'elles sont distribuées en farine (95 vs.40SgIj), inversement, les feuilles fraîches d'érythrine sont mieux ingérées (246 vs. 488 g/j). Les résultats sur la valeur nutritionnelle des feuillages tropicaux montrent qu'ils ont une faible densité énergétique comprise entre 6.5 et 8.2 MJ/kg de MS. La détermination du profil en acides aminés des feuilles montrent que les acides aminés des feuilles de madère et de patate douce sont plus digestibles que ceux des feuilles d'érythrine et de manioc.Au final les teneurs en lysine digestible sont de 5,3 g/kg MS pour la patate et 6,3 g/kg MS pour le madère. En conclusion, l'ingestion, ainsi que la teneur énergétique et protéique des feuilles d'une feuille à l'autre varie en fonction de sa teneur en fibres mais également en fonction de leur concentration en tanins. En pratique, les feuilles de patate douce et de madère sont les plus intéressantes pour la réalisation de ration.
In the troples, there are a multitude of alternative systems with wide variety of practices. These systems are often based on an optimal use of local plantand animal on the farm. The objective of this work is to better understand some of these tropical resources avaibable and can potentially be interesting to use in pig feed in the context of these mixed farming system.The results show that the feed intake capacity of cassava and sweet potato leaves is the same whatever the processing form (fresh leaves or meal).The intake capacity of cocoyam leaves18 higher when distributed Into meal (95 vs.408g1d). In opposite the Erythrina fresh leaves are best Ingested (246 va, 488 g 1dl. Results on the nutrltlonal value of tropical foliage show they have low energy density between 6.5 and 8.2 MJ1kg DM. The determlnation of amino acid profile show that the amina acids of cocoyam and sweet potato leaves are more dlgestible than the erythrina and cassava leaves. Ultlmately digestible lysine contents were 5.3 g/kg DM for potato and 6.3 g / kg DM for the cocoyam. ln conclusion, ingestion, and energy and protein content of leaves from one sheet to another depends on its fiber content but aIso according to their tannin. In practice,the leaves of sweet potato and cocoyam are the most Interesting for the realization of diet

http://www.theses.fr/2011AGUY0398/document

Éditeur(s) : HAL CCSD
Résumé : International audience
BACKGROUND: Worrying trends regarding human reproductive endpoints (e.g. semen quality, reproductive cancers) have been reported and there is growing circumstantial evidence for a possible causal link between these trends and exposure to endocrine disrupting chemicals (EDCs). However, there is a striking lack of human data to fill the current knowledge gaps. To answer the crucial questions raised on human reproductive health, there is an urgent need for a reproductive surveillance system to be shared across countries. METHODS: A multidisciplinary network named HUman Reproductive health and Global ENvironment Network (HURGENT) was created aiming at designing a European monitoring system for reproductive health indicators. Collaborative work allowed setting up the available knowledge to design such a system. Furthermore we conducted an overview of 23 potential indicators, based upon a weight of evidence (WoE) approach according to their potential relation with EDC exposure. RESULTS: The framework and purposes of the surveillance system are settled as well as the approach to select suitable reproductive indicators. The indicators found with the highest scores according to the WoE approach are prostate and breast cancer incidence, sex ratio, endometriosis and uterine fibroid incidence, indicators related to the testicular dysgenesis syndrome, precocious puberty incidence and reproductive hormone levels. CONCLUSION: Not only sentinel health endpoints, but also diseases with high burdens in public health are highlighted as prior indicators in the context of EDC exposure. Our work can serve as a basis to construct, as soon as possible, the first multi-country reproductive monitoring system
European Journal of Public Health

hal-01197348
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01197348
DOI : 10.1093/eurpub/ckv153
PUBMED : 26330492