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 xylose transporter in Aspergillus nidulans

Abstract: Background The production of bioethanol from lignocellulosic feedstocks will only become economically feasible when the majority of cellulosic and hemicellulosic biopolymers can be efficiently converted into bioethanol. The main component of cellulose is glucose, whereas hemicelluloses mainly consist of pentose sugars such as D-xylose and L-arabinose. The genomes of filamentous fungi such as A. nidulans encode a multiplicity of sugar transporters with broad affinities for hexose and pentose sugars. Saccharomyces cerevisiae, which has a long history of use in industrial fermentation processes, is not able to efficiently transport or metabolize pentose sugars (e.g. xylose). Subsequently, the aim of this study was to identify xylose-transporters from A. nidulans, as potential candidates for introduction into S. cerevisiae in order to improve xylose utilization.

Simultaneous analysis of parabens in cosmetic products by stir bar sorptive extraction and liquid chromatography.

Abstract: A sensitive and precise stir bar sorptive extraction (SBSE) combined with LC (SBSE/LC) analysis is described for simultaneous determination of methyl, ethyl, propyl, and butyl parabens in commercial cosmetic products in agreement with the European Union Cosmetics Directive 76/768/EEC. Important factors in the optimization of SBSE efficiency are discussed, such as time and temperature of extraction, pH, and ionic strength of the sample, matrix effects, and liquid desorption conditions by different modes (magnetic stirring, ultrasonic). The LOQs of the SBSE/LC method ranged from 30 to 200 ng/mg, with linear response over a dynamic range, from the LOQ to 2.5 microg/mg, with a coefficient of determination higher than 0.993. The interday precision of the SBSE/LC method presented a coefficient of variation lower than 5%. The effectiveness of the proposed method was proven for analysis of commercial cosmetic products such as body creams, antiperspirant creams, and sunscreens.

Hyperosmoregulation in the red freshwater crab Dilocarcinus pagei (Brachyura, Trichodactylidae): structural and functional asymmetries of the posterior gills.

Abstract: SUMMARY The osmotic and ionic status of the haemolymph and the structural and ion-transport characteristics of the posterior gills of Dilocarcinus pagei, a hololimnetic crab, were investigated. Haemolymph osmolality was 386±18 mosmol kg–1, while [Na+] and [Cl–] were 190±13 and 206±12 mmol l–1, respectively; [K+], [Ca2+] and [Mg2+] were 9.7±0.7, 10.2±0.5 and 2.8±0.4 mmol l–1, respectively (means ± s.e.m., N=12–17). The gill lamellae possess a central, osmiophilic area, which exhibits a marked structural asymmetry. The thick (18–20 μm) proximal epithelium is characterised by basal invaginations and a few apical vesicles, while the thin (3–10 μm) distal epithelium consists of apical pillar cell flanges populated by vesicles and membrane invaginations. Isolated gills, bathed and perfused with NaCl saline, spontaneously generate a negative transbranchial potential difference (Vte), which stabilises at positive or negative values. Ouabain shifts Vte to more positive values. When mounted in an Ussing chamber, distal split lamellae generate a negative, Cl–-dependent short-circuit current (Isc). Na+ substitution leads to more negative values of Isc. Internal ouabain is without effect, while diphenylamine-2-carboxylate and acetazolamide abolish Isc. Proximal split lamellae show a positive, Na+-dependent Isc, which decreases after internal application of ouabain. These data suggest that the thin epithelium actively absorbs Cl–, while the thick epithelium actively absorbs Na+.