Collenchyma in Panicum maximum (Poaceae): localisation and possible role

This work relates the occurrence and distribution of collenchyma in Panicum maximum Jacq. P. maximum leaves were collected at different phases of development and sampled from both the base of the sheath and from the sheath-leaf blade transition area. For the stems, the study was made by using hand-cut sections of the internodal base. In the leaves, analyses of serial sections showed, at the base and sheath-leaf blade transition area, a sudden change of tissue at vascular bundle. The vascular bundles are surrounded by sclerenchyma, both in the sheath and the leaf blade, as well as by fibrous threads that occur on the adaxial side of the central bundles. However, at the base of the sheath and at the sheath-leaf blade transition area, sclerenchyma was substituted for collenchyma. In the stem, the substitution of sclerenchyma associated with vascular bundles for collenchyma occurs at the base of the internode, in the pulvinus region. The analyses from transmission electron microscopy showed the presence of lamellated cell wall and active protoplast in collenchyma cells.

Simultaneous effects of ferulic and vanillic acids on peroxidase and phenylalanine ammonia-lyase in soybean (Glycine max) roots

Simultaneous effects of ferulic (FA) and vanillic (VA) acids on peroxidase (POD, EC 1.11.1.7) and phenylalanine ammonia-lyase (PAL, EC 4.3.1.5) activities on soybean (Glycine max (L.) MERR.) root growth were analyzed. Three-day-old seedlings were cultivated in nutrient solution containing FA or VA (0.5 mM; 1.0 mM or equimolar mixtures) for 48 h. Acting alone, both compounds (at 0.5 or 1.0 mM) decreased root length (RL), fresh weight (FW), dry weight (DW) and increased soluble POD and cell wall (CW)-bound POD activities. At 1.0 mM, FA increased (but VA decreased) the PAL activity. Acting simultaneously, the effects of the allelochemical interaction were lower than the sum of the effects of each compound tested separately, suggesting antagonism.

Estrutura foliar de Loudetiopsis chrysothrix (Nees) Conert e Tristachya leiostachya Nees (Poaceae)

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

Microscopic evidence supports the hypothesis of high cellulose degradation capacity by the symbiotic fungus of leaf-cutting ants

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Stem protective tissue in Erythroxylum tortuosum (Erythroxylaceae), a fire tolerant species from cerrado

The origin and structure are described of the secondary protective tissue in the stem of Erythorxylum tortuosum Mart., a fire tolerant shrubby species common in Brazilian cerrado. The highly tortuous stems are covered with thick bark which is more developed at the base of the stem. After fire in the cerrado, rhytidome fragments of the burned stem flake off, revealing newly formed cork. The first periderm appears near of the terminal buds and is iniated by periclinal divisions in subepidermal cells giving rise to radial rows of cells. The first phellogen is discernible only after the differentiation of the several radial rows of cork cells. Other phellogens have their origin in successively deeper layers of the cortex. The sucessive periderms are discontinuous around the circumference. The collapsed cells with phenolic substances and the accumulated dead cells cause the formation of discontinuous blackish lines, which delimit the sucessive periderms in the rhytidome. The rhytidome contains large quantities of sclereids developed from cell wall thickening of cortex cells. The occurrence of periderm, in the young parts of the stem and of rhytidome in the older parts represents pyrophytic characteristics and may explain, in part, the fire tolerance of this species.

Down-modulation of lymphoproliferation and interferon-gamma production by beta-glucan derived from Saccharomyces cerevisiae

beta-glucan, one of the major cell wall components of Saccharomyces cerevisiae, has been found to enhance immune functions. This study investigated in vivo and in vitro effects of beta-glucan on lymphoproliferation and interferon-gamma (IFN-gamma) production by splenic cells from C57BL/6 female mice. All experiments were performed with particulate beta-glucan derived from S. cerevisiae. Data demonstrated that both, i.p administration of particulate beta-glucan (20 or 100 µg/animal) and in vitro stimulation of splenic cells (20 or 100 µg/ml of culture) decreased lymphoproliferation and IFN-gamma production induced by concanavalin A. These results suggest that beta-glucan can trigger a down-modulatory effect regulating a deleterious immune system hyperactivity in the presence of a strong stimulus.

Enzymes in juice processing: a review

P>The use of enzymes in juice industry has contributed in increasing the yield and production of various types of juices. The addition pectinases aims in particular to degrade the pectic substances, in the cell wall and middle lamella of the cells of plants, aiming to minimise the impacts of these compounds on the characteristics of the final product, such as colour, turbidity and viscosity. Enzymes able to remove bitterness of citrus juice, extract pigments, among other applications, have also had great interest in the juice industry.

Functional characterization and target discovery of glycoside hydrolases from the digestome of the lower termite Coptotermes gestroi

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Use of weathered diesel oil as a low-cost raw material for biosurfactant production

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

Purification and characterization of the exopolygalacturonase produced by Aspergillus giganteus in submerged cultures

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

Intracellular papillae of Actinocephalus (Eriocaulaceae-Poales) roots and their interaction with fungi: A light and transmission electron microscopy study

The genus Actinocephalus comprises 25 species and is restricted to Brazil, occurring mainly in the Espinhaco Mountains of Minas Gerais and Bahia States. Previous anatomical studies have reported the occurrence of intracellular papillae in the Actinocephalus roots, without dealing with their ultrastructure and function. The purpose of this paper is to investigate the structure, the composition and the probable function of the intracellular papillae of Actinocephalus roots, based on light microscopy, transmission electron microscopy and histochemical tests. The intracellular papillae occurred in all root tissues, from the rhizodermis to the vascular cylinder; they presented different forms and sizes and, ultrastructurally, they corresponded to material deposited between the cell wall and the plasma membrane. The histochemical tests carried out were positive for cellulose, pectin and callose. The intracellular papillae are responses of the plant cells to the interaction with fungi. They work as a physical barrier restricting fungal penetration, and they may also favor the supply of water and nutrients to the plant, since they increase root absorption surface. This might explain why the species of Actinocephalus are among the tallest Eriocaulaceae despite their reduced radicular system and the nutritional deficiency of the soil in which they grow. (C) 2006 Elsevier Ltd. All rights reserved.

Anatomia de raízes de nove espécies de Bromeliaceae (Poales) da região amazônica do estado de Mato Grosso, Brasil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Effects of Dimerization on the Structure and Biological Activity of Antimicrobial Peptide Ctx-Ha

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Structural variations among monocot emergent and amphibious species from lakes of the semi-arid region of Bahia, Brazil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Bromatological characteristics and in vitro digestibility of four sugarcane varieties subjected or not to the application of quicklime

O experimento foi conduzido para avaliar as características bromatológicas e a digestibilidade in vitro de quatro variedades de cana-de-açúcar submetidas ou não à hidrólise com cal virgem. Utilizou-se delineamento inteiramente casualizado com três repetições, arranjadas em esquema fatorial 4 × 2, com quatro variedades de cana-de-açúcar (SP 52454, RB 867515, RB 855536 e IAC 862480), hidrolisadas ou não. Houve efeito significativo para as características brix (p < 0,05) e fibra industrial (p < 0,05), sendo a variedade IAC 862480 a que apresentou os menores teores de fibra industrial. Não foram observadas diferenças significativas (p > 0,05) nos teores de fibra em detergente neutro, fibra em detergente ácido e lignina entre as variedades de cana-de-açúcar estudadas, bem como para cana-de-açúcar hidrolisada ou não. O uso da hidrólise da cana-de-açúcar com 1% de cal virgem melhora a digestibilidade in vitro da FDN e FDA independente da variedade estudada. A hidrólise com 1% de cal virgem não modificou a composição químico-bromatológica da cana-de-açúcar.