Résumé : Planta trepadora glabra, con tubérculos de forma irregular que se desarrollan en la axila de las hojas. Hojas alternas, ovadas a suborbiculares, de 7 a 19 cm, largo-acuminadas, acorazonadas en la base. Flores estaminadas solitarias, en espigas de hasta 10 cm, en ocasiones paniculadas; flores pistiladas fasciculadas, en espigas simples de hasta 25 cm. Cápsula oblonga, de 2.2 a 2.5 cm.
Plante grimpante glabre, avec des tubercules de forme irrégulière qui se développent dans l’axe des feuilles. Feuilles alternes, ovées à semi-arrondies, de 7 à 19 cm, longues-acuminées, en forme de cœur à la base. Fleurs à étamines solitaires, en épis pouvant atteindre 10 cm, parfois paniculées; fleurs avec pistil fasciculées, en épis simples pouvant atteindre 25 cm. Capsule oblongue, de 2,2 à 2,5 cm.
Herbaceous, dioecious, climber with glabrous stem, bearing in leaf axils, large, brown, tuberculate bulbils ca 15 cm in diameter; leaves alternate, simple, cordate at base, petioles 6-14 cm long, blades broadly ovate 15-25 cm x 7-20 cm; male flowers borne on clustered spikes up to 20 cm long; female flowers borne on simple spikes 10-15 cm long; fruit a capsule oblong 2.5 cm x1.5 cm.
Originaria de Asia tropical, cultivada en regiones tropicales.
Originaire d’Asie tropicale, cultivée dans les régions tropicales.
Native to tropical Asia, cultivated in tropical regions.

http://www.tramil.net/fototeca/plant159

Résumé : Arbusto aromático, 1 a 2 m de alto, ramas largas mimbreadas, decumbentes y arraigantes, densamente puberulentas o estrigosas. Hojas opuestas o ternadas, brevemente pecioladas, de 2-6 (raro 9) cm de longitud y 1.2-4.5 cm de ancho, oblongas, arrugadas, festonadas, cubiertas con pelillos cortos y nervaduras prominentes. Inflorescencias en cabezuelas axilares globosas, cilíndricas en la fructificación. Brácteas ovadas, acuminadas, las inferiores mucronadas. Flores zigomorfas, cáliz de 1.5-1.7 mm de largo y acrescente a la madurez; corola morada con fauces amarillas y blancas, rosada o blanca de 4 a 5 mm de largo. Fruto obovoide de 3 mm de ancho.
Arbuste aromatique, de 1 à 2 m de haut, aux branches longues et flexibles, décombantes et s’enracinant spontanément, très pubérulentes ou rugueuses. Feuilles opposées ou par groupes de trois, à pétiole court, de 2-6 (rarement 9) cm de longueur et de 1,2-4,5 cm de large, oblongues, rugueuses, festonnées, couvertes de petits poils courts et de nervures proéminentes. Inflorescences sous forme de petites têtes axillaires arrondies, cylindriques lors de la fructification. Bractées ovées, acuminées, les plus basses étant mucronées. Fleurs zygomorphes, calice de 1,5-1,7 mm de long continuant à croître une fois arrivé à maturité; corolle violette avec coeur jaune et blanc, rosée ou blanche de 4 à 5 mm de long. Fruit ovoïde de 3 mm de large.
Aromatic shrub, 1 to 2 m in height, branches long, slender and flexible like willow stems (osier-like), decumbent, lower basal branches can become long rooting suckers, densely puberulent or strigose.  Leaves opposite or ternate, briefly petiolate, 2-6 (rarely 9) cm long and 1.2-4.5 cm wide, oblong, corrugate, crenate, covered with short small hairs (pubescent) and prominent veins.  Inflorescences in globose axillary heads, cylindrical upon fructification.  Bracts ovate, acuminate, the inferior ones mucronate.  Flowers zygomorphic; calyx 1.5-1.7 mm in length and accrescent when ripe; corolla purple with yellow and white fauces (the throat of a gamopetalous corolla), pink or white, 4 to 5 mm in length.  Fruit obovoid, 3 mm in diameter.
América tropical y subtropical.
Amérique tropicale et subtropicale.
Tropical and subtropical America.

http://www.tramil.net/fototecaplant211

Résumé : Arbusto muy ramificado, erguido de 1 a 3 m, tallos teretes, estriados, puberulentos a glabros. Hojas opuestas, aovadas a aovado-lanceoladas, trinervadas desde la base, de hasta 15 cm, márgenes irregularmente dentados. Capítulos en corimbos terminales de hasta 10 cm de ancho; flores azules o blancas. Aquenios columnares acostillados.
Arbuste très ramifié, dressé, de 1 à 3 m, tiges charnues, striées, légèrement velues à glabres. Feuilles opposées, ovées à ovées-lancéolées, trinervées à partir de la base, pouvant atteindre 15 cm, bords irrégulièrement dentés. Capitules en corymbes terminaux pouvant atteindre 10 cm de large. Fleurs bleues ou blanches. Akènes en forme de colonnes à côtes.
Perennial shrub, erect or scrambling 1-3 m high. Stems round, pubescent; leaves opposite, 6-12 cm long, ovate to ovate-lanceolate, blades three-nerved from the base, pubescent above and below with copious yellow glands among the hairs beneath, margins irregularly dentate; capitula in terminal corymbs, up to 5-10 cm wide; florets 14-25 pale mauve or white; achenes ribbed 4-5mm long.
América tropical.
Amérique tropicale.
Tropical America.

http://www.tramil.net/fototeca/plant169

Résumé : Planta herbácea, arrosetada, de hasta 20 cm de longitud, a menudo formando grupos. Hojas, alternas, sésiles, densamente imbricadas, linear-lanceoladas, acuminadas, verdes en ambas superficies o purpúreas en el envés. Pedúnculos, a menudo ramificados arriba; brácteas cimbiformes, ovadas, opuestas, glabras y agudas; inflorescencia incluida en la bráctea; sépalos ovado-lanceolados; pétalos ovados, blancos. Cápsula ovoidea.
Plante herbacée, feuilles basilaires disposées en couronnes serrées, pouvant atteindre 20 cm de longueur, souvent en groupes. Feuilles alternes, sessiles, densément imbriquées, linéaires-lancéolées, acuminées, vertes sur les deux faces ou avec le dessous pourpre. Pédoncules à la partie supérieure souvent ramifiée; bractées naviculaires, ovées, opposées, glabres et aiguës; inflorescence incluse sur la bractée; sépales ovo-lancéolés; pétales ovés, blancs. Capsule ovoïde.
Herb 40-70 cm high, forming large colonies, stems thick and covered with withered leaves. Leaves alternate, sessile, densely imbricate, linear-lanceolate, 20-35 x 3-5 cm, dark green above, purple beneath and along the margins; inflorescence axillary,  umbelliform cyme enclosed by compressed spathe-like bracts, 3-4.5 cm broad and 2-3 high, petals white 5-8 mm long; capsule 3-angled 4.5 mm long.
México, Guatemala, Belice y las Antillas.
Mexique, Guatemala, Belize et Antilles.
Mexico, Guatemala, Belice and the Antilles.

http://www.tramil.net/fototeca/plant351

Éditeur(s) : Université des Antilles. Service commun de la documentation University of Virgin Islands, USA
Extrait de : 52e congrès annuel de la Société caribéenne des plantes alimentaires / 52nd annual meeting of the Caribbean food crops society (CFCS), du 10 au 16 juillet 2016. INRA, CFCS
Description : Limited work has focused on the nutritionally beneficial purple-fleshed sweetpotato in the Caribbean. Purple-fleshed sweetpotatoes are an excellent source of bioflavonoids and antioxidants. Cultivars of purple-fleshed sweetpotato are common in Asia but seldom grown in the west. These Asian cultivars set tuberous roots along the stem length where they root. The objective of this work was to introgress the purple-fleshed characteristic into highly productive early bearing (90-105 days) lines. The purple-fleshed line 'VIP' was used in reciprocal crosses with ?Bonita?, ?Liberty?, ?Mojave? and ?Ruddy?. From hand pollination of these hexaploid plants, 179 seedlings were obtained with a skin color ranging from white to deep burgundy. After the first field trial, 60 were selected for further evaluation based on early tuberous root shape and set, weevil tolerance and soluble sugar content. Continued evaluation will reduce selection down to 20 which further scrutiny to narrow selection to the top five. Le travail limité s'est concentré sur le sweetpotato pourpre-étoffé nutritionnellement salutaire dans les Caraïbe. Les sweetpotatoes Pourpre-étoffés sont une excellente source des bioflavonoïdes et des antioxydants. Les cultivateurs du sweetpotato pourpre-étoffé sont communs en Asie mais sont rarement développés dans l'ouest. Ces cultivateurs asiatiques placent les racines tubéreuses sur la longueur de tige où ils s'enracinent. L'objectif de ce travail était aux introgress que la caractéristique pourpre-étoffée dans la première incidence fortement productive (90-105 jours). La ligne pourpre-étoffée 'VIP' a été employée dans les croix réciproques avec « Bonita », « liberté », « Mojave » et « vermeil ». De la pollinisation de main de ces usines hexaploïdes, 179 jeunes plantes ont été obtenues avec une couleur de la peau s'étendant de blanc à Bourgogne profond. Après le premier essai pratique, 60 ont été sélectionnés pour davantage d'évaluation basée sur la forme tôt et l'ensemble de racine tubéreuse, la tolérance de charançon et le contenu soluble de sucre. L'évaluation continue ramènera la sélection pour avaler à 20 qui promeuvent l'examen minutieux pour rétrécir la sélection aux cinq principaux.
Siècle(s) traité(s) : 21
Droits : CC-BY-NC-ND - Attribution - Pas d'utilisation commerciale - Pas de modification
Permalien : http://www.manioc.org/fichiers/V16265
V16265

Résumé : Herbácea de hasta 1 m de alto; tallos jóvenes pilosos. Hojas en pares o solitarias, de diferentes tamaños pero similares en forma, enteras o sinuado-dentadas, ovadas a ovado-lanceoladas, ápice acuminado, base atenuada. Inflorescencia internodal, racemosa o subumbelifera; corola blanca o lila, con una mancha obscura en la base de cada lóbulo. Fruto globoso de 4 a 7 mm de diámetro.
Herbacée pouvant atteindre 1 m de haut; tiges jeunes pileuses. Feuilles par paires ou solitaires, de différentes tailles mais de forme semblable, entières ou sinuo-dentées, ovées à ovo-lancéolées, à pointe acuminée et à base atténuée. Inflorescence internodale, en grappe ou subombellifère; corolle blanche ou couleur lilas, avec une tache sombre à la base de chaque lobe. Fruit arrondi de 4 à 7 mm de diamètre.
Anthers 1.7 mm or more in length; dull black or green mature fruit; calyx adhering to fruit; fruiting pedicels noticably deflexed; plants of highlands. Herb, up to 1 m high; young stems pilose.  Leaves in pairs or solitary, of different sizes but similar appearance, entire or sinuate-dentate, ovate to ovate-lanceolate; apex acuminate, base attenuate.  Inflorescences internodal, racemose or subumbellate; corolla white or lilac, with a dark spot at the base of each lobe.  Fruit globose, 4-7 mm in diameter.
Nativa de Centroamérica, crece en todo el trópico americano.
Originaire de l’Amérique centrale, présente dans l’ensemble de la zone tropicale américaine, mais jamais signalé aux Petites Antilles.
Native to Central America; grows

http://www.tramil.net/fototeca/plant328

Éditeur(s) : HAL CCSD Wiley-Blackwell Wiley
Résumé : The Late Early-to-Early Middle Eocene Zegdoumyidae are the oldest representatives of the order Rodentia to be known in Africa thus far. Despite the fragmentary nature of their fossil record, these early African rodents have been central in discussions surrounding the early evolutionary history of the Anomaluroidea clade (the living forms of which are the ‘scaly-tailed squirrels’, i.e. Anomaluridae). Here, we describe new dental remains attributable to Zegdoumys sbeitlai, a zegdoumyid from Tunisia (Djebel Chambi, CBI-1) dated at ca 50–45 Ma. The original material referred to this taxon was limited to four teeth documenting few dental loci. The new gathered material comprises practically all dental loci (except P4), thereby allowing a better description and characterization of this taxon. This Tunisian species is clearly distinct from its roughly coeval Algerian counterpart (Z. lavocati) or from the younger species recorded from Namibia (Z. namibiensis). We investigated the phylogenetic positions of Z. sbeitlai and the Zegdoumyidae in a high-level rodent phylogeny with a cladistic assessment of the dental evidence. Our results show that zegdoumyids represent the earliest offshoots (pectinately arranged) of a large clade that also encompasses the more advanced Eocene anomaluroids (here named Nementchamyidae), the Miocene Nonanomaluridae, and the stem and crown Anomaluridae. In this phylogenetic context, the species of Zegdoumys are the basalmost members of this large Anomaluroidea clade. Zegdoumyid taxa are therefore the oldest stem anomaluroid candidates, a statement which strengthens support for the hypothesis of the great antiquity of the Anomaluroidea clade in Africa. From a historical biogeography perspective, this assumption suggests that anomaluroids invaded Asia from Afro-Arabia sometime during the Middle Eocene, a dispersal event which was likely concomitant but opposite to the dispersals envisaged for the hystricognathous rodents and anthropoid primates from Asia to Afro-Arabia.
ISSN: 0300-3256

hal-01172007
https://hal.archives-ouvertes.fr/hal-01172007
DOI : 10.1111/zsc.12095

Résumé : Arbusto de 1 a 4 m de alto. Hojas alternas, aovadas, agudas a acuminadas en el ápice, aserradas. Bractéolas 5 a 7, lineales. Cáliz campanulado; corola blanca, roja purpúrea, amarilla o anaranjada, de tamaño variable, muy vistosa; tubo estaminal más largo que los pétalos. Cápsula oblonga de casi 3 cm de diámetro.
Arbuste de 1 à 4 m de haut. Feuilles alternes, ovées, pointues à acuminées à l’extrémité, denticulées. 5 à 7 petites bractées linéaires. Calice en forme de cloche; corolle blanche, rouge pourpre, jaune ou orangée, de taille variable, aux couleurs éclatantes; filet staminal plus long que les pétales. Capsule oblongue de presque 3 cm de diamètre.
Shrub, 1-4 m high.  Leaves 15cm x 10cm, spiraling around the stem,ovate, acute to acuminate at the tip, marginsserrate; flowers solitary, born on long stalks, in the axils of the upper leaves, epicalyx of 5-7 bractioles about 1 cm long, calyx cup-shaped 2.5cm long, corolla short-lived, showy, mainly red, but other varieties range frompurplish-red, yellow or orangeto white,variable in size,from 6-10cm,staminal tube longer than petals; capsules, rarely produced are oblong ca. 3 cm long, seeds globose ca.3 mm in diameter.
Originaria de Asia y cultivada en las zonas tropicales de todo el mundo.
Originaire d’Asie et cultivée dans les zones tropicales du monde entier.
Native to Asia and cultivated in tropical regions around the world.

http://www.tramil.net/fototeca/plant188

Éditeur(s) : HAL CCSD Oxford University Press (OUP)
Résumé : Architectural analyses of temperate tree species using a chronological approach suggest that the expression of epicormic branches is closely related to low growth rates in the axes that make up the branching system. Therefore, sole consideration of epicormic criteria may be sufficient to identify trees with low secondary growth levels or with both low primary and secondary growth levels. In a tropical tree such as Dicorynia guianensis (basralocus), where chronological studies are difficult, this relationship could be very useful as an easily accessible indicator of growth potentials. A simple method of architectural tree description was used to characterize the global structure of more than 1650 basralocus trees and to evaluate their growth level. Measurements of simple growth characters [height, basal diameter, internode length of submittal part (top of the main axis of the tree)] and the observation of four structural binary descriptors on the main stem (presence of sequential branches and young epicormic branches, state of the submittal part, global orientation), indicated that epicormic branch formation is clearly related to a decrease in length of the successive growth units of the main stem. Analysis of height vs. diameter ratios among different tree subgroups, with and without epicormic branching, suggested that trees with epicormic branches generally have a low level of secondary growth compared with primary growth.
ISSN: 0305-7364

hal-01032037
https://hal.archives-ouvertes.fr/hal-01032037
DOI : 10.1093/aob/mcg119

Éditeur(s) : HAL CCSD
Résumé : International audience
The main biological function of reaction wood is to act as “muscle” for trees, enabling them to control their posture and right stems when they are permanently disturbed from their set-point inclination by gravity or winds. The key property to achieve this function is the development of high mechanical stress during the formation of reaction wood cells, called “maturation strains”. Moreover, this function is basically performed through the asymmetric formation of wood (in quantity or quality) around the tree circumference. This asymmetry enables stems to bend upward or to compensate for the downward bending induced by gravity, as an asymmetric force associated to maturation strains creates a bending moment (i.e. one side of the stem “pulls” the other one). We will discuss the traits (cross sectional size and shape, wood features as G fibers or microfibril angle, eccentric growth even in usual or extreme cases as buttresses, total biomass growth and height of center of mass, stem lean and set-point angle) involved to understand how the posture control works. We will give simple formulas to estimate a “muscle efficiency” from biomechanical modeling. We will give practical methods to estimate all the involved traits, especially maturation strains from direct and indirect measurements, in peripheral functional wood or by retrospective dendrochronological analysis. Then, we will illustrate how tree stem tropisms and especially gravitropism, widely studied by physiologists, are key processes in natural ecosystems, through practical examples from tropical rainforest tree communities and regeneration of European mixed beech forests. Using the previous definition of postural control efficiency, we will show that the cross section size is rapidly a limiting factor, opposing the extreme strategies of flexible small stems, which bend easily but also right themselves quickly, to stiff big stems. Lastly, as wood in living trees ensures general storage, defence, vascular and skeletal functions, we will ask general questions about synergies and trade-offs between posture control and other functions.
Botany 2014 : new frontiers in botany
Boise, United States

hal-01627031
https://hal.archives-ouvertes.fr/hal-01627031

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
Domestication can influence many functional traits in plants, from overall life-history and growth form to wood density and cell wall ultrastructure. Such changes can increase fitness of the domesticate in agricultural environments but may negatively affect survival in the wild. We studied effects of domestication on stem biomechanics in manioc by comparing domesticated and ancestral wild taxa from two different regions of greater Amazonia. We compared mechanical properties, tissue organisation and wood characteristics including microfibril angles in both wild and domesticated plants, each growing in two different habitats (forest or savannah) and varying in growth form (shrub or liana). Wild taxa grew as shrubs in open savannah but as lianas in overgrown and forested habitats. Growth form plasticity was retained in domesticated manioc. However, stems of the domesticate showed brittle failure. Wild plants differed in mechanical architecture between shrub and liana phenotypes, a difference that diminished between shrubs and lianas of the domesticate. Stems of wild plants were generally stiffer, failed at higher bending stresses and were less prone to brittle fracture compared with shrub and liana phenotypes of the domesticate. Biomechanical differences between stems of wild and domesticated plants were mainly due to changes in wood density and cellulose microfibril angle rather than changes in secondary growth or tissue geometry. Domestication did not significantly modify "large-scale" trait development or growth form plasticity, since both wild and domesticated manioc can develop as shrubs or lianas. However, "finer-scale" developmental traits crucial to mechanical stability and thus ecological success of the plant were significantly modified. This profoundly influenced the likelihood of brittle failure, particularly in long climbing stems, thereby also influencing the survival of the domesticate in natural situations vulnerable to mechanical perturbation. We discuss the different selective pressures that could explain evolutionary modifications of stem biomechanical properties under domestication in manioc.
PLoS ONE

halsde-00917926
https://hal.archives-ouvertes.fr/halsde-00917926
https://hal.archives-ouvertes.fr/halsde-00917926/document
DOI : 10.1371/journal.pone.0074727

Éditeur(s) : HAL CCSD Elsevier
Résumé : Primary arc melts may form through fluxed or adiabatic decompression melting in the mantle wedge, or via a combination of both processes. Major limitations to our understanding of the formation of primary arc melts stem from the fact that most arc lavas are aggregated blends of individual magma batches, further modified by differentiation processes in the sub-arc mantle lithosphere and overlying crust. Primary melt generation is thus masked by these types of second-stage processes. Magma-hosted peridotites sampled as xenoliths in subduction zone magmas are possible remnants of sub-arc mantle and magma generation processes, but are rarely sampled in active arcs. Published studies have emphasised the predominantly harzburgitic lithologies with particularly high modal orthopyroxene in these xenoliths; the former characteristic reflects the refractory nature of these materials consequent to extensive melt depletion of a lherzolitic protolith whereas the latter feature requires additional explanation.Here we present major and minor element data for pristine, mantle-derived, lava-hosted spinel-bearing harzburgite and dunite xenoliths and associated primitive melts from the active Kamchatka and Bismarck arcs. We show that these peridotite suites, and other mantle xenoliths sampled in circum-Pacific arcs, are a distinctive peridotite type not found in other tectonic settings, and are melting residues from hydrous melting of silica-enriched mantle sources. We explore the ability of experimental studies allied with mantle melting parameterisations (pMELTS, Petrolog3) to reproduce the compositions of these arc peridotites, and present a protolith (‘hybrid mantle wedge’) composition that satisfies the available constraints. The composition of peridotite xenoliths recovered from erupted arc magmas plausibly requires their formation initially via interaction of slab-derived components with refractory mantle prior to or during the formation of primary arc melts. The liquid compositions extracted from these hybrid sources are higher in normative quartz and hypersthene (i.e., they have a more silica-saturated character) in comparison with basalts derived from prior melt-depleted asthenospheric mantle beneath ridges. These primary arc melts range from silica-rich picrite to boninite and high-Mg basaltic andesite along a residual spinel harzburgite cotectic. Silica enrichment in the mantle sources of arc-related, subalkaline picrite-boninite-andesite suites coupled with the amount of water and depth of melting, are important for the formation of medium-Fe (‘calc-alkaline’) andesite-dacite-rhyolite suites, key lithologies forming the continental crust.
ISSN: 0016-7037

hal-01553520
https://hal.archives-ouvertes.fr/hal-01553520
DOI : 10.1016/j.gca.2016.09.030

Éditeur(s) : Université des Antilles Études caribéennes
Résumé : Au cours des vingt dernières années, l'industrie des croisières au Mexique a apporté des changements importants qui découlent des tendances mondiales actuelles, d'un meilleur positionnement sur le marché, pour l'adoption généralisée de politiques nationales de promotion du tourisme croisière et pour la réforme radicale du système portuaire national qui a permis l'entrée de la participation privée dans les investissements des infrastructures, de gestion et d'exploitation des ports. Dans ce contexte, on a redéfini l´organisation spatiale du tourisme de croisière avec de nouveaux ports d´arrivée, des itinéraires variés à partir de différents ports d´origine et d’escales plaçant le Mexique en tête des destinations mondiales de l’industrie des croisières. Ainsi, l'objectif de cet article est d'examiner les conditions qui ont conduit à la dynamique spatio-temporelle du tourisme de croisière dans le pays à travers un examen critique de la nouvelle géographie régionale du tourisme de croisière au Mexique.
The cruise industry in Mexico has had significant changes stemming from current global trends during the last two decades. This has been due to its favorable and strategic geographical position in the market, its warm climate and proximity to the United States. Hence there has been a major relevance towards adopting national tourism policies as well as reforming the national port system allowing the entrance of private investment infrastructure, cruise terminal management and operation. The spatial organization of cruise tourism destination ports in Mexico has been redefined in this context. That is to say, there are new home ports, new routes and ports of call that have placed the country as a world’s leading destination for cruise ship arrivals. Therefore, the aim of this paper is to examine the conditions which have led the spatio-temporal dynamics into a critical review of the new regional geography of cruise tourism in Mexico.
En las dos últimas décadas el sector de los cruceros turísticos en México ha presentado profundos cambios, derivados de las tendencias globales, de un mayor aprovechamiento de su favorable condición geográfica dentro del mercado, por una mayor incorporación de la actividad en las políticas turísticas nacionales y por la profunda reforma del sistema portuario nacional que posibilitó el ingreso de la participación privada en la inversión de infraestructura, gestión y operación de terminales de cruceros. En este contexto se ha redefinido la organización espacial del turismo de cruceros con nuevas rutas que articulan diferentes puertos de origen y escalas que han posicionado a México como destino líder mundial en arribo de cruceros. De esta forma, el objetivo del presente artículo es examinar las condiciones que han propiciado la dinámica espacio-temporal del turismo de cruceros en el país, que conduzca a una revisión crítica de la nueva geografía regional de los cruceros turísticos en México.
Mexique

Droits : info:eu-repo/semantics/openAccess
urn:doi:10.4000/etudescaribeennes.5077
http://journals.openedition.org/etudescaribeennes/5077

Éditeur(s) : HAL CCSD Springer-Verlag Berlin Heidelberg
Résumé : International audience
The main biological function of reaction wood is to act as " muscle " for trees, enabling them to control their posture. The key property to achieve this function is the development of high mechanical stress during the formation of reaction wood cells, called " maturation strains ". Actually, reaction wood formation is basically the asymmetric formation of wood around the tree circumference, with higher maturation strains on the side where reaction wood is formed than on the opposite side. This asymmetry enables stems to bend upward or to compensate for the downward bending induced by gravity. At the cross section level, the performance in this biological function is linked not only to the magnitude of this asymmetry but also to an effect of the cross-sectional size (diameter) of the stem. Eccentric growth and variations in wood mechanical stiffness are second order effects that can modify this performance. Differences in maturation strains between reaction and non-reaction woods are related to their specific cell wall structure and composition. The swelling of the cell wall matrix during maturation and the effect of microfibril angle explain the differences in maturation strains between normal and compression wood. However, this mechanism fails in explaining the high maturation shrinkage of tension wood, and several hypotheses at the molecular levels are still under debate. How trees perceive their gravitational disequilibrium is also an open question for physiologists. Integrative biomechanical modelling (from the polymer level to the cell wall, cross section and whole tree levels) enables defining key variables that explain the performance of reaction wood as a system that insures the stem motricity. Maturation strains can be precisely measured only in recently formed wood at the tree surface, but their changes during the whole tree life can also be estimated by retrospective dendrochronological analysis through structural markers of reaction wood. Lastly, wood in living trees ensures general storage, defence, vascular and skeletal functions, that ask general questions about synergies and trade-offs as the structural characteristics of reaction wood can affect all these functions.
The Biology of Reaction Wood

ISBN : 978-3-642-10813-6
hal-01452085
https://hal.archives-ouvertes.fr/hal-01452085
https://hal.archives-ouvertes.fr/hal-01452085/document
https://hal.archives-ouvertes.fr/hal-01452085/file/Chap_Gril_al_Biomechanical_action_biological_functions_2014.pdf

Éditeur(s) : HAL CCSD BioMed Central
Résumé : International audience
Background: Myosin II (or Myosin Heavy Chain II, MHCII) is a family of molecular motors involved in the contractile activity of animal muscle cells but also in various other cellular processes in non-muscle cells. Previous phylogenetic analyses of bilaterian MHCII genes identified two main clades associated respectively with smooth/non-muscle cells (MHCIIa) and striated muscle cells (MHCIIb). Muscle cells are generally thought to have originated only once in ancient animal history, and decisive insights about their early evolution are expected to come from expression studies of Myosin II genes in the two non-bilaterian phyla that possess muscles, the Cnidaria and Ctenophora. Results: We have uncovered three MHCII paralogues in the ctenophore species Pleurobrachia pileus. Phylogenetic analyses indicate that the MHCIIa /MHCIIb duplication is more ancient than the divergence between extant metazoan lineages. The ctenophore MHCIIa gene (PpiMHCIIa) has an expression pattern akin to that of ``stem cell markers'' (Piwi, Vasa...) and is expressed in proliferating cells. We identified two MHCIIb genes that originated from a ctenophore-specific duplication. PpiMHCIIb1 represents the exclusively muscular form of myosin II in ctenophore, while PpiMHCIIb2 is expressed in non-muscle cells of various types. In parallel, our phalloidin staining and TEM observations highlight the structural complexity of ctenophore musculature and emphasize the experimental interest of the ctenophore tentacle root, in which myogenesis is spatially ordered and strikingly similar to striated muscle formation in vertebrates. Conclusion: MHCIIa expression in putative stem cells/proliferating cells probably represents an ancestral trait, while specific involvement of some MHCIIa genes in smooth muscle fibres is a uniquely derived feature of the vertebrates. That one ctenophore MHCIIb paralogue (PpiMHCIIb2) has retained MHCIIa-like expression features furthermore suggests that muscular expression of the other paralogue, PpiMHCIIb1, was the result of neofunctionalisation within the ctenophore lineage, making independent origin of ctenophore muscle cells a likely option.
ISSN: 1471-2148

hal-01544486
https://hal.archives-ouvertes.fr/hal-01544486
DOI : 10.1186/1471-2148-12-107

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The separation of the germ line from the soma is a classic concept in animal biology, and depending on species is thought to involve fate determination either by maternally localized germ plasm (''preformation'' or ``maternal inheritance'') or by inductive signaling (classically termed ``epigenesis'' or ``zygotic induction''). The latter mechanism is generally considered to operate in non-bilaterian organisms such as cnidarians and sponges, in which germ cell fate is determined at adult stages from multipotent stem cells. We have found in the hydrozoan cnidarian Clytia hemisphaerica that the multipotent ``interstitial'' cells (i-cells) in larvae and adult medusae, from which germ cells derive, express a set of conserved germ cell markers: Vasa, Nanos1, Piwi and PL10. In situ hybridization analyses unexpectedly revealed maternal mRNAs for all these genes highly concentrated in a germ plasm-like region at the egg animal pole and inherited by the i-cell lineage, strongly suggesting i-cell fate determination by inheritance of animal-localized factors. On the other hand, experimental tests showed that i-cells can form by epigenetic mechanisms in Clytia, since larvae derived from both animal and vegetal blastomeres separated during cleavage stages developed equivalent i-cell populations. Thus Clytia embryos appear to have maternal germ plasm inherited by i-cells but also the potential to form these cells by zygotic induction. Reassessment of available data indicates that maternally localized germ plasm molecular components were plausibly present in the common cnidarian/bilaterian ancestor, but that their role may not have been strictly deterministic.
ISSN: 0012-1606

hal-01544487
https://hal.archives-ouvertes.fr/hal-01544487
DOI : 10.1016/j.ydbio.2012.01.018

Résumé : Arbol pequeño con tallo único raras veces ramificado, frondoso en la parte superior. Hojas grandes de 20 a 60 cm, usualmente palmado 7-lobuladas. Flores macho estaminadas en panículas de 10 cm o más; flores hembras con corola amarilla, pétalos en espiral. Fruto globoso o subgloboso de hasta 30 cm de diámetro, amarillo o anaranjado, con zumo lechoso; numerosas semillas negras.
Petit arbre à tige unique rarement ramifiée, terminée par un bouquet de grandes feuilles de 20 à 60 cm, habituellement digitées. Fleurs mâles garnies d';étamines formant des panicules de 10 cm ou davantage, fleurs femelles à corolle jaune avec pétales en spirale. Fruit sphérique ou formant un globe légèrement allongé dont le diamètre peut atteindre 30 cm, jaune ou orangé, avec un suc laiteux; nombreuses graines noires.
Small tree, short-lived, soft-wooded, single-stem with milky sap, rarely with branches; Leaves alternate, palmate, seven-lobed, bunched at the top with petioles, 20-60 cm long; male flowers born on long pendant racemes or panicles ca.10 cm long; female flowers 1-3 in short cyme with greenish-yellow corolla, petals in spiral; fruit globose or subglobose ca 30 cm in diameter, yellow to orange, with milky sap numerous black seeds with a pulpy coat.
Originaria de América Tropical, ampliamente cultivada en los trópicos.
Originaire d';Amérique tropicale, très cultivée sous les tropiques.
Native to tropical America, cultivated in tropical regions around the world.

http://www.tramil.net/fototeca/plant110

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
Heartwood/sapwood profile and the tradeoff between trunk and crown increment in a natural forest: the case study of a tropical tree (Dicorynia guianensis Amsh., Fabaceae) Key message Sapwood area and the radial growth rate of the trunk follow the same pattern at breast height, with an initial increase and subsequent constant value, resulting from the increasing growth allocation toward the crown rather than tree decline. Heartwood area and heartwood volume in the trunk increase more rapidly after this shift occurs. Abstract Sapwood (SW) and heartwood (HW) are two functionally distinct classifications of wood in perennial stems for which quantities can vary greatly in tropical trees. Numerous positive correlations have been found between the radial growth rate (RGR) and SW quantity; however, variations in the SW/HW quantities have not been studied in light of the ontogenetic variation of RGR. Wood core sampling, intensive measurements of tree structure (number of branches, stem volumes), and radial growth monitoring were performed on an abundant and highly exploited tree species in French Guiana (Dicorynia guianensis) to investigate the relationship between RGR, SW/HW quantity, tree structure, and their variations on the course of a tree's ontogeny. SW area and RGR followed the same pattern of variation throughout tree development, both increasing first and reaching a steady state after 50 cm DBH (diameter at breast height). After this value, we observed a strong increase in both the HW area and HW volume increment, concomitant with a more rapid increase in crown volume. The stabilization of RGR for trees with DBH >50 cm was related not to a tree's decline but rather to an increasing wood allocation to the crown, confirming that RGR at breast height is a poor indicator of whole-tree growth for bigger individuals. We also confirmed that HW formation is an ontogenetic process managing SW quantity that is continuously and increasingly produced within the crown as the tree grows. This study highlights the effect of growth-mediated ontogenetic changes on the localization of water and carbohydrate storage within a tree, resulting from SW and HW dynamics throughout tree ontogeny.
ISSN: 0931-1890

hal-01654003
https://hal.archives-ouvertes.fr/hal-01654003
https://hal.archives-ouvertes.fr/hal-01654003/document
https://hal.archives-ouvertes.fr/hal-01654003/file/Lehnebach%20et%20al.%E2%80%94Trees%202016-%20Own%20version.pdf
DOI : 10.1007/s00468-016-1473-7

Éditeur(s) : HAL CCSD Botanical Society of America
Résumé :  
Tree buckling risk (actual height/critical buckling height) is an important biomechanical trait of plant growth strategies, and one that contributes to species coexistence. To estimate the diversity of this trait among wide samples, a method that minimizes damage to the plants is necessary. On the basis of the rarely used, complete version of Greenhill's model (1881, Proceedings of the Cambridge Philosophical Society 4(2): 65-73), we precisely measured all the necessary parameters on a sample of 236 saplings of 16 species. Then, using sensitivity (variance) analysis, regressions between successive models for risk factors and species ranks and the use of these models on samples of self- and nonself-supporting saplings, we tested different degrees of simplification up to the most simple and widely used formula that assumes that the tree is a cylindrical homogeneous pole. The size factor had the greatest effect on buckling risk, followed by the form factor and the modulus of elasticity of the wood. Therefore, estimates of buckling risk must consider not only the wood properties but especially the form factor. Finally, we proposed a simple but accurate method of assessing tree buckling risk that is applicable to a wide range of samples and that requires mostly nondestructive measurements.
ISSN: 0002-9122

hal-01032059
https://hal.archives-ouvertes.fr/hal-01032059

Résumé : Herbácea bienal. Raíz típicamente globosa o elongada, de color exterior blanco, blanco con púrpura o amarillento. Casi sin tallo antes de florecer. Hojas de hasta 30 cm de largo, glaucas, a veces liradas. Tallo de inflorescencia con hojas lobuladas. Flores con 4 pétalos amarillos, dispuestas en racimos corimbosos.
Herbacée bisannuelle. Racine typiquement renflée ou allongée, extérieurement de couleur blanche, blanc mêlé de pourpre ou jaunâtre. Presque dépourvue de tige avant la floraison. Feuilles pouvant atteindre 30 cm de long, glauques, parfois en forme de lyre. Tige à inflorescence avec feuilles lobulées. Fleurs à 4 pétales jaunes, disposées en grappes ombelliformes.
Biennial herb, almost without stem before flowering.  Leaves pinnatifid, up to 60 cm long, with terminal lobe larger and rounded and the lower lobes smaller; inflorescence a raceme, flowers with four yellow petals; fruit dry, dehiscent; roots globose or elongated, skin white, white and purple, green or yellowish, the flesh white or yellow.
Originaria de Eurasia. Ampliamente cultivada en regiones templadas.
Originaire d';Eurasie. Largement cultivée dans les régions tempérées.
Native to Eurasia.  Widely cultivated in regions with moderate climate.

http://www.tramil.net/fototeca/plant107