Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto

About: Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto is a based out in . It is known for research contribution in the topics: Population & Genus. The organization has 2143 authors who have published 3674 publications receiving 71071 citations. The organization is also known as: FFCLRP & FFCLRP-USP.

Functional characterization of a lytic polysaccharide monooxygenase from the thermophilic fungus Myceliophthora thermophila

Abstract: Thermophilic fungi are a promising source of thermostable enzymes able to hydrolytically or oxidatively degrade plant cell wall components. Among these enzymes are lytic polysaccharide monooxygenases (LPMOs), enzymes capable of enhancing biomass hydrolysis through an oxidative mechanism. Myceliophthora thermophila (synonym Sporotrichum thermophile), an Ascomycete fungus, expresses and secretes over a dozen different LPMOs. In this study, we report the overexpression and biochemical study of a previously uncharacterized LPMO (MtLPMO9J) from M. thermophila M77 in Aspergillus nidulans. MtLPMO9J is a single-domain LPMO and has 63% sequence similarity with the catalytic domain of NcLPMO9C from Neurospora crassa. Biochemical characterization of MtLPMO9J revealed that it performs C4-oxidation and is active against cellulose, soluble cello-oligosaccharides and xyloglucan. Moreover, biophysical studies showed that MtLPMO9J is structurally stable at pH above 5 and at temperatures up to 50°C. Importantly, LC-MS analysis of the peptides after tryptic digestion of the recombinantly produced protein revealed not only the correct processing of the signal peptide and methylation of the N-terminal histidine, but also partial autoxidation of the catalytic center. This shows that redox conditions need to be controlled, not only during LPMO reactions but also during protein production, to protect LPMOs from oxidative damage.

Characterization of natural carious lesions by fluorescence spectroscopy at 405-nm excitation wavelength

Abstract: We aim to characterize natural caries enamel lesions by fluorescence spectroscopy. Sixty human samples with natural non- cavitated caries lesions on smooth surfaces were selected and classi- fied into three groups: dull, shiny, and brown lesions. All the samples were analyzed externally at the natural surface and after hemisec- tionig internally at the center of the lesion. The lesions were excited with a 405-nm InGaN diode laser and the fluorescence was collected with a single grating spectrometer. Four emission bands 455, 500, 582, and 622 nm are identified in both sound and carious regions. The area under each emission band is correlated with the total area of the four bands for the sound and carious regions. The detected fluo- rescence from natural and cut surfaces through the caries lesions is not statistically different for the shiny and dull lesion, but is different analysis of variance ANOVA p0.05 for brown lesion at all emission bands. At the 405-nm excitation wavelength, the area of the fluorescence bands at 455 and 500 nm differ statistically for natural carious lesions and sound tissue. © 2007 Society of Photo-Optical Instrumentation

A Novel Dimeric Melampolide and Further Terpenoids from Smallanthus sonchifolius (Asteraceae) and the Inhibition of the Transcription Factor NF-κB:

Abstract: A novel dimeric melampolide was isolated from the leaf rinse extract of Smallanthus sonchifolius (Poepp. & Endl.) H. Robinson (Asteraceae), an Andean medicinal plant popularly known as yacon. Dimer...

Photodynamic inactivation of conidia of the fungus Colletotrichum abscissum on Citrus sinensis plants with methylene blue under solar radiation.

Abstract: Antimicrobial photodynamic treatment (APDT) is a promising light based approach to control diseases caused by plant-pathogenic fungi. In the present study, we evaluated the effects of APDT with the phenothiazinium photosensitizer methylene blue (MB) under solar radiation on the germination and viability of conidia of the pathogenic fungus Colletotricum abscissum (former Colletotrichum acutatum sensu lato). Experiments were performed both on petals and leaves of sweet orange (Citrus sinensis) in different seasons and weather conditions. Conidial suspensions were deposited on the leaves and petals surface, treated with the PS (25 or 50μM) and exposed to solar radiation for only 30min. The effects of APDT on conidia were evaluated by counting the colony forming units recovered from leaves and petals and by direct evaluating conidial germination on the surface of these plant organs after the treatment. To better understand the mechanistic of conidial photodynamic inactivation, the effect of APDT on the permeability of the conidial plasma membrane was assessed using the fluorescent probe propidium iodide (PI) together with flow cytometry and fluorescence microscopy. APDT with MB and solar exposure killed C. abscissum conidia and prevented their germination on both leaves and petals of citrus. Reduction of conidial viability was up to three orders of magnitude and a complete photodynamic inactivation was achieved in some of the treatments. APDT damaged the conidial plasma membrane and increased its permeability to PI. No damage to sweet orange flowers or leaves was observed after APDT. The demonstration of the efficacy of APDT on the plant host represents a further step towards the use of the method for control phytopathogens in the field.