Anatomia de escapos, folhas e brácteas de Syngonanthus sect. Eulepis (Bong. ex Koern.) Ruhland (Eriocaulaceae)

Estudou-se a anatomia de escapos, folhas e brácteas de 24 espécimes de Syngonanthus sect. Eulepis, que ocorrem nos campos rupestres do Brasil. Os escapos apresentam número variado de costelas, epiderme unisseriada, com células de paredes totalmente espessadas; córtex com esclerênquima e parênquima clorofiliano alternados; endoderme contínua ou descontínua; periciclo estrelado; feixes vasculares colaterais; medula com células de paredes finas ou espessadas. As folhas e as brácteas apresentam epiderme com células de paredes total ou parcialmente espessadas, estômatos na face abaxial, margem com parênquima clorofiliano ou esclerênquima; mesofilo com hipoderme constituída de esclerênquima ou parênquima aqüífero, feixes vasculares colaterais envolvidos externamente pela endoderme e internamente pelo periciclo. Escapos, folhas e brácteas de Syngonanthus sect. Eulepis apresentam células com paredes espessadas e grande quantidade de esclerênquima, provavelmente como resposta adaptativa dessas plantas ao vento e à radiação excessiva comum nos campos rupestres. Epiderme com células de paredes espessadas, estômatos com câmara subestomática não especializada, presença de hipoderme, esclerênquima, e parênquima clorofiliano compacto, caracterizam anatomicamente escapos, folhas e brácteas de Syngonanthus sect. Eulepis. No geral, os caracteres anatômicos não são consistentes para separar os táxons dentro da seção.

Vascularização foliar e anatomia do pecíolo de Melastomataceae do cerrado do Estado de São Paulo, Brasil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Anatomia e ultra-estrutura foliar de Cyperus maritimus Poir. (Cyperaceae): estratégias adaptativas ao ambiente de dunas litorâneas

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Efeitos od laser CO2 na mandíbula de ratos: Estudo através da microscopia eletrônica de varredura

A face lateral do corpo da mandíbula de ratos foi irradiada pelo laser CO2 com disparos contínuos de 10watts de potência. Após três meses, o sulco formado pela irradiação apresentou, em uma grande extensão, material fundido com diversas fraturas. Após sete meses, o periósteo neoformado recobriu amplas áreas da incisão, que apresentou ainda material carbonizado. Um ano após a incisão, o periósteo neoformado estava composto por fibras colágenas, que formaram feixes espessos, transversais à incisão, ou malhas regulares, que recobriram a incisão. Ainda nessa fase, resquícios de material carbonizado foram verificados, caracterizando um retardo na regeneração óssea

Study of alternative schemes for the parameterization step of the continuation power flow method based on physical parameters, part II: Performance evaluation

New parameterization schemes have been proposed by the authors in Part I of this paper. In this part these new options for the parameterization of power flow equations are tested, namely, the total power losses (real and reactive), the power at the slack bus (real or reactive), the reactive power at generation buses, and the transmission line power losses (real and reactive). These different parameterization schemes can be used to obtain the maximum loading point without ill-conditioning problems, once the singularity of Jacobian matrix is avoided. The results obtained with the new approach for the IEEE test systems (14, 30, 57, and 118 buses) show that the characteristics of the conventional method are not only preserved but also improved. In addition, it is shown that the proposed method and the conventional one can be switched during the tracing of PV curves to determine, with few iterations, all points of the PV curve. Several tests were also carried out to compare the performance of the proposed parameterization schemes for the continuation power flow method with the use of both the secant and tangent predictors.

Systematic consideration of petiole anatomy of species of Echinodorus Richard (Alismataceae) from north-eastern Brazil

Petiole anatomy of the north-eastern Brazilian species Echinodorus glandulosus, E. palaefolius, E. pubescens, E subalatus, E lanceolatus and E paniculatus were examined. All species had petioles with an epidermis composed of tabular cells with thin walls. The chlorenchyma just below the epidermis alternates with collateral vascular bundles. The interior of the petiole is filled by aerenchyma with ample open spaces or lacunas. The lacunas are bridged at intervals by plates, or by diaphragm-like linkages. There are lactiferous ducts and groups of fibres throughout the entire length of the petiole, but more frequently in the chlorenchyma. Important taxonomic characteristics for the genus Echinodorus include the shape and outline of the petiole in transversal section, the presence of winged extensions, and the number of vascular bundle arcs. Exceptions occur in E. lanceolatus and E. paniculatus, whose petioles have similar anatomic patterns. A comparative chart of the petiole anatomic characteristics analyzed is presented. (c) 2007 Elsevier GmbH. All rights reserved.

Peanut seed tegument is affected by liming and drying method

Calcium plays a fundamental role in cell division and growth, and is an important constituent of the cell wall. An increase in Ca concentration in the tegument of peanut (Arachis hypogea L.) seeds in response to lime application can affect its structure. The tegument structure can also be affected by the drying method of the seeds. The effects of lime application and drying methods as affecting the peanut seed tegument structure were studied in seeds from a field experiment conducted in Sao Manuel, São Paulo, Brazil. Peanut (cv. Botutatu, Valencia Type) was grown in presence or absence of 2.1 Mg ha(-1) of lime and dried in an oven, in shade and in the field. The tegument anatomical features were described and its structure was analysed. Pectic substances, lipidic reserves and starch accumulation were studied. The peanut tegument exhibited well differentiated exotesta, mesotesta and endotesta rich in pectates and covered by a cuticle. Tannin was not observed but there was lipid accumulation in mature teguments. Lignin was observed in the vascular bundles. Lime increased the tegument thickness and decreased the central cavity mainly in the exotesta cells when the period of seed drying was shortened. The effect of drying method upon the tegument was more noticeable in seeds grown without lime. It can be inferred that liming increased the resistance of the tegument.

Chondroitin sulfate proteoglycans are structural renewable constituents of the rabbit vitreous body

Purpose: To characterize the vitreous intrinsic proteoglycans, investigate their dynamics, and examine their role in the supramolecular organization of the vitreous. Methods: Vitreous from normal rabbits was collected and processed for observation with the transmission electron microscope after treatment with glycosidases. Also, rabbits were injected intravitreally with [S-35]-sodium sulfate and sacrificed at several time intervals after the injection. Proteoglycans (PGs) were assayed in the vitreous supernatant or in whole samples extracted with guanidine hydrochloride by polyacrylamide or agarose gel electrophoresis, followed respectively by fluorography or autoradiography, and ion-exchange chromatography and gel-filtration chromatography, combined with glycolytic treatment of the samples. The sulfated glycosaminoglycans (GAGs) were characterized by agarose gel electrophoresis after treating vitreous samples with protease and specific glycosidases. Results: the electron microscopic study revealed a network with hyaluronic acid ( HA) as thin threads coating and connecting collagen fibrils. The elimination of the HA coat showed chondroitin sulfate granules (8-25 nm) arranged at regular intervals on the fibril surface. The chondroitinase ABC digestion, besides removing the granules, also caused the formation of thicker bundles of the collagen fibrils. The PG and GAG analysis indicated that there are three renewable PGs in the vitreous ( e. g., one heparan-and two chondroitin-sulfate ones). Conclusions: At least one of the chondroitin sulfate PGs is involved in the interactions that occur in the vitreous structure, mainly by providing adequate spacing between the collagen fibrils, a condition that is probably required for the transparency of the vitreous.

Floral anatomy of Eriocaulon elichrysoides and Syngonanthus caulescens (Eriocaulaceae)

The floral anatomy of Eriocaulon elichrysoides Bong. and Syngonanthus caulescens (Poir.) Ruhland, from Brazilian mountain rock savannas (campos rupestres) was studied. The staminate flowers of E. elichrysoides present a diplostemonous androecium with six stamens, and those of S. caulescens present an isostemonous androecium with three stamens and three scalelike staminodes. Eriocaulon elichrysoides and S. caulescens have three nectariferous pistillodes located in the central portion of the receptacle. The pistillate flowers of E. elichrysoides present three simple styles while those of S. caulescens present three simple styles interspersed with three nectariferous appendices. Both the styles of E. elichrysoides and the nectariferous appendices of S. caulescens are vascularized by the dorsal vascular bundles of the carpels. The styles of S. caulescens lack vascularization. At the base of the gynoecium of E. elichrysoides there are six staminodes and there are three in the S. caulescens. Entomophily is suggested as the pollination syndrome in E. elichrysoides and S. caulescens as they present staminate and pistillate flowers with nectariferous structures. The ancestral character in Eriocaulon is probably given by the presence of the two staminal whorls. The staminate flowers of S. caulescens are probably derived from the reduction of a diplostemonous ancestral androecium. It remains open whether the pistillate flowers with nectariferous, appendices present an ancestral character or a derived one.

Stem anatomy of Pennisetum purpureum schum. (Poaceae) cultivars

Elephant-grass is known like a great feed to dairy and beef cattle al tropical regions. Its agricultural aspects have been very observed. However, its botanical, mainly anatomical characteristics are few studied. The objective of this work was to investigate the anatomical changes occurred in stems of three elephant-grass cultivars (ROXO, EMPASC 307 TESTO and EMPASC 309 AREIA) at three stages of plant development (4, 8 and 16 weeks after sprouting). The anatomical features were similar among cultivars. When stems were young (4 weeks), a disorganization of vascular bundles were detected. However, at 8 weeks stage the were organized as a definitive form. Was observed a magnified of lignification as the stems age, mainly caused by the increased of bundles sheaths that surrounds all vascular bundles.

Collagen-hydroxyapatite films: piezoelectric properties

In this paper we report a study of the physicochemical, dielectric and piezoelectric properties of anionic collagen and collagen-hydroxyapatite (HA) composites, considering the development of new biomaterials which have potential applications in support for cellular growth and in systems for bone regeneration. The piezoelectric strain tensor element d(14), the elastic constant s(55) and the dielectric permittivity 8(11), were measured for the anionic collagen and collagen-HA films. The thermal analysis shows that the denaturation endotherm is at 59.47 degreesC for the collagen sample. The collagen-HA composite film shows two transitions, at 48.9 and 80.65 degreesC. The X-ray diffraction pattern of the collagen film shows a broad band characteristic of an amorphous material. The main peaks associated to the crystalline HA is present in the sample of collagen-HA. In the collagen-HA composite, one can also notice the presence of other peaks with low intensities which is an indication of the formation of other crystalline phases of apatite. The scanning electron photomicrograph of anionic collagen membranes shows very thin bundles of collagen. The scanning electron photomicrography of collagen-HA film also show deposits of hydroxyapatite on the collagen fibers forming larger bundles and suggesting that a collagenous structure of reconstituted collagen fibers could act as nucleators for the formation of apatite crystal similar to those of bone. The piezoelectric strain tensor element d(14) was measured for the anionic collagen, with a value of 0.062 pC N-1, which is in good agreement compared with values reported in the literature obtained with other techniques. For the collagen-HA composite membranes, a slight decrease of the value of the piezoelectricity (0.041 pC N-1) was observed. The anionic collagen membranes present the highest density, dielectric permittivity and lowest frequency constant f.L. (C) 2001 Elsevier B.V. B.V. All rights reserved.

Roots, leaves and scapes anatomy of species of Paepalanthus subgenus Platycaulon (Eriocaulaceae)

The anatomical features of roots, leaves and scapes of the subgenus Platycaulon, genus Paepalanthus (Eriocaulaceae) that grow in the Brasilian rupestrian fields of Serra do Cipo - MG - Brazil were studied. The following main anatomical features were found: epidermis cells of varied thicknesses, chlorenchyma with compact or spread organization and leaf margin shape in the leaves; the scapes with continuous or discontinuous endodermis, divided or undivided pericycle, vascular bundles absent in the cortex and in the pith. These anatomical characteristics of the leaves and scapes occur in different species and can be used to separate them into Divise or Conferti sections. It was possible to confirm the proposed taxonomy based only on the morphological characteristics. Other anatomical features such as: presence or absence of air in the cortex roots and hypodermis which originate water parenchyma reserves in the mesophyll, can be an adaptative response that plants towards produce the environmental factors in this ecosystem.

Anatomy of Brazilian Eriocaulaceae: correlation with taxonomy and habitat using multivariate analyses

In this study we present a survey on vegetative anatomy in species of Actinocephalus, Blastocaulon, Eriocaulon, Leiothrix, Paepalanthus, Philodice, Syngonanthus, and Tonina (Eriocaulaceae). Multivariate analyses were used to correlate anatomical characters to taxa and the habitats where the species occur. Root and stem anatomical characters seem to be more affected by environmental factors where these species occur, and seem of little value for delimiting major taxonomic groups within the family. Other characters in the leaves, such as epidermis with thickened wall cells, compartmented substomatal chambers, mesophyll with hypodermis, compact chlorenchyma, collenchymatous bundle sheath extensions, and numerous vascular bundles, were shown to be important for defining species clusters in Leiothrix, Syngonanthus, and Paepalanthus subg. Platycaulon. Similarly, loosely aggregated chlorenchyma caused Blastocaulon, Eriocaulon, Philodice, Syngonanthus sect. Carpocephalus, S. sect. Syngonanthus, and Tonina, genera from humid environments, to cluster. Scape characters appear to be more informative in discriminating groups. This situation probably reflects lower selection pressures determining anatomical characters of this organ.

MICROFIBRILS - NEGLECTED COMPONENTS OF PRESSURE-BEARING TENDONS

Some tendons wrap around joints and receive compressive forces besides transferring the tension forces from muscle to bone. These tendons develop a fibrocartilaginous structure which enables them to withstand pressure. This article describes the existence and distribution of microfibrils (or preelastic fibers) in the pressure-bearing tendons of rabbits and dogs by the application of histochemical assays and transmission electron microscopy. Rabbit and dog tendons possess no mature elastic fibers. The rabbit tendon exhibits some response to Weigert's method prior to oxidation which indicates the existence of the so-called elaunin fibers, especially in the pressure zone. Oxidation with peracetic acid or oxone discloses intricate aspects of the oxytalan fiber distribution in both tension and pressure zones of the dog and rabbit tendons. Bundles of 12 nm microfibrils were demonstrated in the rabbit tendon by electron microscopy after fixation in the presence of tannic acid. The existence of preelastic fibers in the pressure-bearing tendons has been neglected and they are assumed to have importance in the microarchitecture of the tissue and in the ability of the tendon to support tension and compression forces.

Non-linear boundary element analysis of floor slabs reinforced with rectangular beams

In this work, a numerical model to perform non-linear analysis of building floor structures is proposed. The presented model is derived from the Kirchhoff-s plate bending formulation of the boundary element method (BENI) for zoned domains, in which the plate stiffness is modified by the presence of membrane effects. In this model, no approximation of the generalized forces along the interface is required and the compatibility and equilibrium conditions along interfaces are imposed at the integral equation level. In order to reduce the number of degrees of freedom, the Navier Bernoulli hypothesis is assumed to simplify the strain field for the thin sub-regions (rectangular beams). The non-linear formulation is obtained from the linear formulation by incorporating initial internal force fields, which are approximated by using the well-known cell sub-division. Then, the non-linear solution of algebraic equations is obtained by using the concept of the consistent tangent operator. The Von Mises criterion is adopted to govern the elasto-plastic material behaviour checked at points along the plate thickness and along the rectangular beam element axes. The numerical representations are accurately obtained by either computing analytically the element integrals or performing the numerical integration accurately using an appropriate sub-elementation scheme. (C) 2007 Elsevier Ltd. All rights reserved.