Co-cultivation of plant cells as a technique for the elicitation of secondary metabolite production

Cells of Mikania glomerata, Cephaelis ipecacuanha and Maytenus aquifolia were co-cultured in a two-phase system using filter paper as a solid support. The species were co-cultured in all possible paired combinations. Interaction between Mikania and Maytenus cells resulted in increased biomass production of Maytenus cells, but the friedelin content was reduced. Co-cultivation of Cephaelis and Mikania cells enhanced coumarin content, but inhibited the growth of Mikania cells. However, yield of emetine as well as Cephaelis biomass accumulation were positively stimulated by the co-cultivation. Results indicate a possible occurrence of allelopathy in such a system.

Overexpression of plant uncoupling mitochondrial protein in transgenic tobacco increases tolerance to oxidative stress

An Arabidopsis thaliana cDNA clone encoding a plant uncoupling mitochondrial protein (AtPUMP1) was overexpressed in transgenic tobacco plants. Analysis of the AtPUMP1 mRNA content in the transgenic lines, determined by Northern blot, revealed variable levels of transgene expression. Antibody probing of Western blots of mitochondrial proteins from three independent transgenic lines showed significant accumulation of AtPUMP1 in this organelle. Overproduction of AtPUMP1 in transgenic tobacco plants led to a significant increase in tolerance to oxidative stress promoted by exogenous hydrogen peroxide as compared to wild-type control plants. These results provide the first biological evidence for a role of PUMP in protection of plant cells against oxidative stress damage.

Evaluation of the genotoxicity of cellulose nanofibers

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.

Putative pyrophosphate phosphofructose 1-kinase genes identified in sugarcane may be getting energy from pyrophosphate

Pyrophosphate-dependent phosphofructokinase (PPi-PFK) has been detected in several types of plant cells, but the gene has not been reported in sugar cane. Using Citrux paradixi PPi-PFK gene (AF095520 and AF095521) sequences to search the sugar cane EST database, we have identified both the α and β subunits of this enzyme. The deduced amino acid sequences showed 76 and 80% similarity with the corresponding α and β subunits of C. paradisi. A high degree of similarity was also observed among the PFK β subunits when the alignment of the sugar cane sequences was compared to those of Ricinus communis and Solanum tuberosum, it appears that α and β are two distinct subunits; they were found at different concentrations in several sugar cane tissues. It remains to be determined if the different gene expression levels have some physiological importance and how they affect sucrose synthesis, export, and storage in vacuoles. A comparison between the amino acid sequences of β PFKs from a variety of organisms allowed us to identify the two critical Asp residues typical of this enzyme's activity site and the other binding sites; these residues are tightly conserved in all members of this protein family. Apparently, there are catalytic residues on the β subunit of the pyrophosphate-dependent enzyme.

Mentha piperita cultivada com variação de cálcio. Trocas gasosas e óleo essencial

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Identicação e caracterização de dois promotores de eucalipto: com padrão de expressão ubíquo e específico de câmbio

Pós-graduação em Ciências Biológicas (Genética) - IBB

Differential effect of plant lectins on mast cells of different origins

Histamine release induced by plant lectins was studied with emphasis on the carbohydrate specificity, external calcium requirement, metal binding sites, and mast cell heterogeneity and on the importance of antibodies bound to the mast cell membrane to the lectin effect. Peritoneal mast cells were obtained by direct lavage of the rat peritoneal cavity and guinea pig intestine and hamster cheek pouch mast cells were obtained by dispersion with collagenase type IA. Histamine release was induced with concanavalin A (Con A), lectins from Canavalia brasiliensis, mannose-specific Cymbosema roseum, Maackia amurensis, Parkia platycephala, Triticum vulgaris (WGA), and demetallized Con A and C. brasiliensis, using 1-300 µg/ml lectin concentrations applied to Wistar rat peritoneal mast cells, peaking on 26.9, 21.0, 29.1, 24.9, 17.2, 10.7, 19.9, and 41.5%, respectively. This effect was inhibited in the absence of extracellular calcium. The lectins were also active on hamster cheek pouch mast cells (except demetallized Con A) and on Rowett nude rat (animal free of immunoglobulins) peritoneal mast cells (except for mannose-specific C. roseum, P. platycephala and WGA). No effect was observed in guinea pig intestine mast cells. Glucose-saturated Con A and C. brasiliensis also released histamine from Wistar rat peritoneal mast cells. These results suggest that histamine release induced by lectins is influenced by the heterogeneity of mast cells and depends on extracellular calcium. The results also suggest that this histamine release might occur by alternative mechanisms, because the usual mechanism of lectins is related to their binding properties to metals from which depend the binding to sugars, which would be their sites to bind to immunoglobulins. In the present study, we show that the histamine release by lectins was also induced by demetallized lectins and by sugar-saturated lectins (which would avoid their binding to other sugars). Additionally, the lectins also released histamine from Rowett nude mast cells that are free of immunoglobulins.

Copper resistance of biofilm cells of the plant pathogen Xylella fastidiosa

Xylella fastidiosa is a phytopathogen that causes diseases in different plant species. The development of disease symptoms is associated to the blockage of the xylem vessels caused by biofilm formation. In this study, we evaluated the sensitivity of biofilm and planktonic cells to copper, one of the most important antimicrobial agents used in agriculture. We measured the exopolysaccharides (EPS) content in biofilm and planktonic cells and used real-time reverse transcription polymerase chain reaction to evaluate the expression of the genes encoding proteins involved in cation/multidrug extrusion (acrA/B, mexE/czcA, and metI) and others associated with different copper resistance mechanisms (copB, cutA1, cutA2, and cutC) in the X. fastidiosa biofilm formed in two different media. We confirmed that biofilms are less susceptible to copper than planktonic cells. The amount of EPS seems to be directly related to the resistance and it varies according to the media where the cells are grown. The same was observed for gene expression. Nevertheless, some genes seem to have a greater importance in biofilm cells resistance to copper. Our results suggest a synergistic effect between diffusion barriers and other mechanisms associated with bacterial resistance in this phytopathogen. These mechanisms are important for a bacterium that is constantly under stress conditions in the host.

Genotoxicity of the medicinal plant Maytenus robusta in mammalian cells in vivo.

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

Cytotoxic and mutagenic evaluation of extracts from plant species of the Miconia genus and their influence on doxorubicin-induced mutagenicity: An in vitro analysis

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

Mutagenicity induced by the hydroalcoholic extract of the medicinal plant Plathymenia reticulata Benth

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Genotoxicity of Brosimum gaudichaudii measured by the Salmonella/microsome assay and chromosomal aberrations in CHO cells

The root bark of Brosimum gaudichaudii Trecul (Moraceae) is popularly used for treatment of vitiligo. In the present study the mutagenic activity of the aqueous and methanolic extract as well as of the n-butanolic fraction of this medicinal plant were evaluated using Salmonella typhimurium assays, TA100, TA98, TA102 and TA97a strains, while the clastogenic effect in Chinese hamster ovary (CHO) cells in the G(1)/S, S and G(2)/S phases of the cell cycle. The results showed mutagenic activity of the aqueous extract against TA102 in the presence of S9, and of methanolic extract, with and without metabolic activation. TA100 mutagenicity was only observed for the methanolic extract in the absence of S9. The n-butanolic fraction did not present mutagenic activity. In CHO cells only the methanolic extract induced a significant increase of chromosomal aberrations in the G(1)/S and S phases, whereas a decrease in the mitotic index was observed in the G(1)/S and G(2)/S phases. No clastogenicity was observed for the aqueous extract. The furocoumarins (psoralen and bergapten) presented in the extracts might contribute to the mutagenicity. The lower activity of the aqueous extract was probably due to the presence of smaller amount of furocoumarins compared to the methanolic extract. (C) 2002 Elsevier B.V. Ireland Ltd. All rights reserved.

Genotoxic effects of (-)-cubebin in somatic cells of mice

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Evaluation of the in vivo mutagenic potential of hydroalcoholic extracts of the northern highbush blueberry (Vaccinium corymbosum L. Ericales, Ericaceae) on peripheral blood cells of Swiss mice (Mus musculus Rodentia, Muridae)

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