oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2020 ( 1 )

2019 ( 41 )

2018 ( 71 )

2017 ( 49 )

Custom range...

Search Results: 1 - 10 of 32522 matches for " MACHADO SILVIA RODRIGUES "
All listed articles are free for downloading (OA Articles)
Page 1 /32522
Display every page Item
Anatomia comparada do pulvino primário de leguminosas com diferentes velocidades de movimento foliar
Rodrigues, Tatiane Maria;Machado, Silvia Rodrigues;
Brazilian Journal of Botany , 2006, DOI: 10.1590/S0100-84042006000400020
Abstract: the pulvinus, structure responsible for slow or fast leaf movements answering to outside or endogenous stimulus, constitutes a remarkable feature of leguminous species. the leaf position adjustments represent an efficient mechanism that allows the photosynthesis maximization under adverse conditions. in the available literature, the majority of the information about pulvinus structure refers to few leguminous species, especially those with fast movements. in this work the primary pulvinus anatomy of nine leguminous species from brazilian "cerrado" with different kinds and velocity of leaf movement is described, attempting to identify patterns and to point structural peculiarities. the primary pulvinus of the studied species show uniseriate epidermis recovered by thick cuticle, large parenchymatous cortex, central vascular system and reduced or absent pith. the outer cortex cells are wider and show phenolic compounds, except in zornia diphylla pers.; in the inner cortex, the cells are juxtaposed and do not have phenolic content. the collateral vascular bundles are surrounding by a septate fibers sheath. the general anatomy organization pattern is common to the pulvini of the studied species, independently of the subfamily they belong. the observed peculiarities are possible related to the kind and velocity of leaf movement.
Anatomia e ultra-estrutura foliar de Cyperus maritimus Poir. (Cyperaceae): estratégias adaptativas ao ambiente de dunas litoraneas
Martins, Shirley;Machado, Silvia Rodrigues;Alves, Marccus;
Acta Botanica Brasilica , 2008, DOI: 10.1590/S0102-33062008000200017
Abstract: anatomical and ultrastructural aspects of cyperus maritimus poir. were analyzed with the aim of identifying adaptive features for the dune environment. collections were made at pipa beach, rio grande do norte, brazil. leaves were submitted to different analyses: light microscopy, scanning and transmission electron microscopy. in frontal view, the epidermis has unicellular trichomes, silica bodies, a striate cuticle and wax deposits. in transverse section, the epidermis is uniseriate with thickened outer periclinal walls. the stomata are paracitic and the pore sometimes obstructed by wax. under the adaxial epidermis, there are several layers of aqueous parenchyma. the vascular bundles occur in multiple rows, the peripheral row having bundles with narrower diameters than the central row. characters related to kranz syndrome of the chlorocyperoid type were observed. ultrastructural features support a possible c4 pathway in this species. this work is the first citation of chloroplasts in the cells of the vascular system for the genus. in this study, it was possible to observe several important features of plants submitted to water and salt stress, such as: wax, thickened outer periclinal walls of the epidermal cells, aqueous parenchyma and kranz syndrome.
Submicroscopical Features of Leaves of Xyris Species
Sajo, Maria das Gra?as;Machado, Silvia Rodrigues;
Brazilian Archives of Biology and Technology , 2001, DOI: 10.1590/S1516-89132001000400011
Abstract: the leaf ultrastructure of five xyris species were examined using scanning electron microscope (sem), transmission electron microscope (tem) and histochemical methods. all studied leaves show some features in epidermis and mesophyll, which were of considerable adaptative significance to drought stress. such features included the occurrence of a pectic layer on the stomatal guard cells and the presence of a network of pectic compounds in the cuticle. pectic compunds were also in abundance in lamellated walls of the mesophyll cells and on the inner surface of the sclerified cell walls of the vascular bundle sheaths. there were also specialized chlorenchymatous "peg cells" in the mesophyll and drops of phenolic compounds inside the epidermal cells.
Coléteres dendróides em Alibertia sessilis (Vell.) K. Schum., uma espécie n?o-nodulada de Rubiaceae
Barreiro, Daniela Pacheco;Machado, Silvia Rodrigues;
Brazilian Journal of Botany , 2007, DOI: 10.1590/S0100-84042007000300005
Abstract: this paper describes the distribution, structure and histochemistry of the colleters in vegetative and reproductive apices of alibertia sessilis (vell.) k. schum., a native rubiaceae species of the brazilian "cerrado". in this family, dendroid colleters have been associated with the presence of bacterial nodules in the leaves. samples were prepared according to common light and scanning electron microscopy techniques, and histochemical assays involved freshly collected material. colleters are dendroid and occur on the adaxial surface of stipules, bracts and sepals; they consist of a multicellular and multiseriate central axis of parenchymatous nature, covered by digitiform or sharply pointed epidermal cells of irregular sizes, joined together only in the proximal portion and separated from each other in the distal portion. the columnar cells are axially elongated, with thick cell walls, prominent nucleus and reduced cytoplasm, developed vacuole with lipid inclusions and phenolic compounds. the epidermal cells have thin walls, a conspicuous nucleus, abundant cytoplasm and a poorly developed vacuome. the colleters are devoid of cuticle. the secretion is more abundant in the vegetative apex, impregnating the leaf buds and the stipules, forming a spherical cap that is hard, bright, and hydrophobic. in all analyzed samples, the histochemical assays detected polysaccharides, proteins and lipids in the protoplast of both epidermal and columnar cells; phenolic compounds were detected solely in the columnar cells. the resinous nature of the exudate was confirmed with the use of the diethylic ether solvent. bacterial leaf nodules were not found.
Estrutura e desenvolvimento dos tricomas secretores em folhas de Piper regnellii (Miq.) C. DC. var. regnellii (Piperaceae)
SILVA, ELAINE MARIA J.;MACHADO, SILVIA RODRIGUES;
Brazilian Journal of Botany , 1999, DOI: 10.1590/S0100-84041999000200002
Abstract: piper regnellii has two types of trichomes: pearl glands and sac-like trichomes. both secretory trichomes originate from the protoderm of the leaf primordium and reach maturity in the young leaves found in the shoot apex. the pearl glands are more abundant on the abaxial surface, while the sac-like trichomes cover completely both young leaf blade. the density of both trichomes decreases during blade expansion, being scarce in the adult leaf. the pearl glands are composed of a basal cell and an apical cell whose shape ranges from semi-globular to spatula-like. secretion release occurs after rupture of the distended cuticle. the sac-like trichomes are composed of a basal cell, 1-2 stalked cells and an apical conical cell parallel to the leaf surface. the secretion is accumulated in minute subcuticular spaces. no cuticular ruptures have been observed.
Anatomy, ultrastructure and secretion of Hibiscus pernambucensis Arruda (Malvaceae) extrafloral nectary
Rocha, Joecildo Francisco;Machado, Silvia Rodrigues;
Brazilian Journal of Botany , 2009, DOI: 10.1590/S0100-84042009000300008
Abstract: this paper reports on the extrafloral nectary (efn) of hibiscus pernambucensis, a native shrub species occurring in mangrove and restinga along brazil's coastline. efns occur as furrows with a protuberant border on the abaxial surface veins of the leaf blade. each nectary consists of numerous secretory multicellular trichomes, epidermal cells in palisade-like arrangements and non-vascularized parenchyma tissue. nectar secretion is prolonged, since secretion starts in very young leaves and remains up to completely expanded leaves. reduced sugars, lipids, and proteins were histochemically detected in all the nectary cells; phenolic substances were detected in the vacuoles of the epidermal palisade cells and in some secretory trichome cells. the secretory cells that constitute the body of trichomes have large nuclei, dense cytoplasm with numerous mitochondria, dictyosomes, scattered lipid droplets and plastids with different inclusions: protein, lipid droplets or starch grains; vacuoles with different sizes have membranous material, phenolic and lipophilic substances. the palisade cells show thick periclinal walls, reduced cytoplasm with voluminous lipid drops and developed vacuoles. the nectary parenchyma cells contain abundant plasmodesmata and cytoplasm with scattered lipid droplets, mitochondria, plastids with starch grains and endoplasmic reticulum. mucilage idioblasts are common in the inner nectary parenchyma. protoderm and ground meristem participate in the formation of efn. our data indicate that all nectary regions are involved in nectar production and secretion, constituting a functional unit. longevity of the extrafloral nectaries is likely associated with the presence of mucilage idioblasts, which increases the capacity of the nectary parenchyma to store water.
Estrutura e desenvolvimento dos tricomas secretores em folhas de Piper regnellii (Miq.) C. DC. var. regnellii (Piperaceae)
SILVA ELAINE MARIA J.,MACHADO SILVIA RODRIGUES
Brazilian Journal of Botany , 1999,
Abstract: Nesta espécie ocorrem dois tipos de tricomas secretores: glandula perolada e tricoma saculiforme. Ambos originam-se na protoderme do primórdio foliar e atingem sua maturidade nas folhas jovens presentes no ápice caulinar. A densidade dos dois tipos de tricomas diminui durante a expans o do limbo, sendo raros na folha adulta. As glandulas peroladas s o constituídas por uma célula basal e por uma célula apical grande cuja forma varia de semi-globóide a espatulada. A libera o da secre o ocorre após a ruptura da cutícula distendida. Os tricomas saculiformes s o constituídos por uma célula basal, 1-2 células colares e uma célula apical c nica, de posi o inclinada à superfície foliar. A secre o acumula-se em espa os subcuticulares diminutos, n o tendo sido observada ruptura da cutícula.
Submicroscopical Features of Leaves of Xyris Species
Sajo Maria das Gra?as,Machado Silvia Rodrigues
Brazilian Archives of Biology and Technology , 2001,
Abstract: The leaf ultrastructure of five Xyris species were examined using scanning electron microscope (SEM), transmission electron microscope (TEM) and histochemical methods. All studied leaves show some features in epidermis and mesophyll, which were of considerable adaptative significance to drought stress. Such features included the occurrence of a pectic layer on the stomatal guard cells and the presence of a network of pectic compounds in the cuticle. Pectic compunds were also in abundance in lamellated walls of the mesophyll cells and on the inner surface of the sclerified cell walls of the vascular bundle sheaths. There were also specialized chlorenchymatous "peg cells" in the mesophyll and drops of phenolic compounds inside the epidermal cells.
Ontogênese, anatomia e ultra-estrutura dos nectários extraflorais de Hymenaea stigonocarpa Mart. ex Hayne (Fabaceae - Caesalpinioideae)
Paiva, élder Ant?nio Sousa;Machado, Silvia Rodrigues;
Acta Botanica Brasilica , 2006, DOI: 10.1590/S0102-33062006000200022
Abstract: hymenaea stigonocarpa mart. ex hayne, known as "jatobá-do-cerrado" has extrafloral nectaries (efns), which are reported for the first time in hymenaea genus. in this research the origin, distribution, structure, and ultrastructure of the efns were studied. samples of leaflets at different developmental stages were collected, fixed and processed by standard methods for analyses at light and electronic microscopes; histochemical tests were employed to determine the nature of secretion products. efns are distributed all over leaf blade, more concentrated on the basal and medial thirds of each leaflet. these nectaries are embedded in the mesophyll, show secretory tissue surrounded by an endodermis, and are vascularized by xylem and phloem. efn secretory activity was exclusively observed in young leaves. the protoderm origins the efn secretory tissue, the ground meristem originates the endodermis and the procambium originates the vascular tissues. secretory cells of functional efns showed dense cytoplasm, large nucleus, mitochondria, plastids with a poorly developed membrane system, oil drops scattered in the cytosol, dictyosome, and smooth endoplasmic reticulum segments. secretion was released by cuticle rupture and contains polysaccharides and lipids.
Estruturas secretoras de mucilagem em Hibiscus pernambucensis Arruda (Malvaceae): distribui??o, caracteriza??o morfoanat?mica e histoquímica
Rocha, Joecildo Francisco;Pimentel, Rafael Ribeiro;Machado, Silvia Rodrigues;
Acta Botanica Brasilica , 2011, DOI: 10.1590/S0102-33062011000400003
Abstract: this work studied the mucilage-secreting structures of hibiscus pernambucensis using light and scanning electron microscopy. known as guaxima-do-mangue, algod?o-do-brejo and embira-do-mangue, this species is a native shrub that occurs in mangrove and restinga along the brazilian coast, and is important in the production of textile fibers and cellulose, provides abundant mucilage that is used medicinally like other malvaceae species, and has tannins. the results of this work found colleters, pearl glands, long-stalked secretory trichomes, ducts, cavities and idioblasts. the colleters occur on the shoot apices, stipules, leaf primordia, leaves, young sepals and petals. the pearl glands are present in the adaxial and abaxial surface of the leaf primordia. the ducts and the cavities occur in the vegetative and reproductive shoot apices. the idioblasts occur in the roots, both in primary and secondary stages of development, and in the leaf mesophyll. the secretion of the different secretory structures is made predominantly of acids and neutral polysaccharides, proteins, lipids and phenolic substances. the presence of external and internal mucilage-secreting structures in all plant organs, at different stages of development, represents an important adaptive mechanism to restinga and mangrove environments.
Page 1 /32522
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.