A new species of <Emphasis Type=Italic>Pradosia</Emphasis> (Sapotaceae) from Central Amazonia

Pradosia lahoziana is here described as new. It is known from four collections from wet lowland and non-flooded terra firme forests near Manaus in Central Amazonia. Illustrations are provided together with a comparison of the morphological differences with similar species.     

Swimming performance of the freshwater neotropical fish: Pimelodus maculatus Lacepède, 1803

The present study used fixed and increasing velocity tests in an experimental apparatus based on Brett's respirometer to examine prolonged and sustained speeds of the "mandi-amarelo", Pimelodus maculatus. When comparing the curves of critical speed versus total length between the mandi and the sockeye salmon Oncorhynchus nerka, it is observed that for an equal total length, the mandi presents a greater speed, probably due to water temperature differences. The sustained speed for the species was estimated in 5 lengths per second and the percentage of fatigued fish within time in a certain velocity was established. The data raised for the mandi represents an important contribution to the improvement of the handling of the species, providing guidance and criteria for designing several structures, such as fishways, fish screens and guidance systems.     

Transporter protein genes are differentially expressed in <Emphasis Type="Italic">Acidithiobacillus</Emphasis><Emphasis Type="Italic">ferrooxidans</Emphasis> LR maintained in contact with covellite

Gene expression in response to the copper sulfide, covellite (CuS), in Acidithiobacillus ferrooxidans LR was investigated by using RNA arbitrarily primed polymerase chain reaction (RAP-PCR). Seven genes that encode for proteins involved with transport and binding were up-regulated in the presence of CuS. The differential expression of the seven genes was confirmed by real-time PCR. An atomic absorption analysis of the covellite samples showed that the quantity of copper(II) ions in solution changed from zero to approximately 1.11 g/l after 24 h, and the pH changed from 1.8 to 4.0, suggesting that the copper ions in solution and the pH alteration may be responsible, at least in part, for the up-regulation of the transporter genes in the presence of covellite. An in silico protein–protein interaction analysis of the proteins encoded by the seven transporter protein genes, as well as of proteins encoded by genes of the same functional category that are adjacent to the seven genes identified by RAP-PCR, showed that besides the correlated function, the transporter proteins may act in different steps of the bacterial response to covellite.     

Polymerization of lignin fragments contained in a model effluent by polyphenoloxidases and horseradish peroxidase/hydrogen peroxide system*

An effluent containing soluble lignin fragments was treated with potato-polyphenoloxidases (PPO) or horseradish peroxidase/hydrogen peroxide system (HRP/H(2)O(2)). In both cases the reaction was evidenced by the formation of a brown precipitate that was a consequence of the polymerization of lignin fragments. The effect of reaction time, pH, and amount of soluble lignin per unit of enzyme activity on the insolubilization yield was evaluated for PPO-initiated reactions. For HRP-initiated reactions, the amount of H(2)O(2) per unit of enzyme activity was also evaluated. Mathematical models were calculated to predict the insolubilization yield as a function of the significant variables. Based on these models, the insolubilization reaction was optimized and reached maximal values of ca. 50% in both reaction systems. Higher insolubilization yields were not achieved. Chemical characterization of the soluble lignin fragments indicated that the insolubilization yield could not be improved, because the lignin fragments had limited amounts of free phenolic substructures available for the initial steps of the polymerization reaction.     

Evolution of Chlorophyll Degradation: The Significance of RCC Reductase

Abstract: In angiosperms the key process of chlorophyll breakdown in senescing leaves is catalyzed by pheophorbide a oxygenase and RCC reductase which, in a metabolically channeled reaction, cleave the porphyrin macrocycle and produce a colourless primary catabolite, pFCC. RCC reductase is responsible for the reduction of the C20/C1 double bond of the intermediary catabolite, RCC. Depending on plant species, RCC reductase produces one of the two C1 stereoisomers, pFCC-1 or pFCC-2. Screening of a large number of taxa for the type of RCCR revealed that the isomer produced is uniform within families. It also revealed that type RCCR-2 is predominant; RCCR-1 seems to represent a recent derivation which in unrelated lineages has evolved independently from RCCR-2. A third type of pFCC was produced by RCCR from basal pteridophytes and some gymnosperms; its structure is unknown. Collectively, the data suggest that the pathway of chlorophyll breakdown is very conserved in vascular plants. RCCR appears to represent a decisive addition to the catabolic pathway: it allows terrestrial plants to metabolize the porphyrin part of the chlorophyll molecule to photodynamically inactive final products that are stored in the vacuoles of senescing mesophyll cells.     

Quantitative analysis of sugar constituents of glycoproteins by capillary electrophoresis

A method for quantitative analysis of monosaccharides including N- acetylneuraminic acid derived from sialic acid-containing oligosaccharides and glycoproteins is presented. The analysis is based on the combination of chemical and enzymatic methods coupled with capillary electrophoretic (CE) separation and laser-induced fluorescence (LIF) detection. The present method utilizes a simplified acid hydrolysis procedure consisting of mild hydrolysis (0.1 M TFA) to release sialic acid and strong acid hydrolysis (2.0 N TFA) to produce amino and neutral sugars. Amino sugars released from strong acid hydrolysis of oligosaccharides and glycoproteins were reacetylated and derivatized with 8-aminopyrene-1,3,6-trisulfonate (APTS) along with neutral sugars in the presence of sodium cyanoborohydride to yield quantitatively the highly stable fluorescent APTS adducts. N- acetylneuraminic acid (Neu5Ac), a major component of most mammalian glycoproteins, was converted in a fast specific reaction by the action of neuraminic acid aldolase (N-acylneuraminate pyruvate-lyase EC 4.1.3.3) to N-acetylmannosamine (ManNAc) and pyruvate. ManNAc was then derivatized with APTS in the same manner as the other monosaccharides. This method was demonstrated for the quantitation of pure Neu5Ac and the species derived from mild acid hydrolysis of 6'-sialyl-N- acetyllactosamine and bovine fetuin glycan. Quantitative recovery of the N-acetylmannosamine was obtained from a known amount of Neu5Ac in a mixture of seven other monosaccharides or from the sialylated oligosaccharides occurring in glycoproteins. The sequence of procedures consists of acid hydrolysis, enzymatic conversion and APTS derivatization which produced quantitative recovery of APTS- monosaccharide adducts. The detection limits for sugars derivatized with APTS and detected by CE-LIF are 100 pmol for Neu5Ac and 50 pmol for the other sugars.      

Serological Diagnosis of Paracoccidioidomycosis: High Rate of Inter-laboratorial Variability among Medical Mycology Reference Centers

Background

Serological tests have long been established as rapid, simple and inexpensive tools for the diagnosis and follow-up of PCM. However, different protocols and antigen preparations are used and the few attempts to standardize the routine serological methods have not succeeded.

Methodology/Principal findings

We compared the performance of six Brazilian reference centers for serological diagnosis of PCM. Each center provided 30 sera of PCM patients, with positive high, intermediate and low titers, which were defined as the “reference” titers. Each center then applied its own antigen preparation and serological routine test, either semiquantitative double immunodifusion or counterimmmunoelectrophoresis, in the 150 sera from the other five centers blindly as regard to the “reference” titers. Titers were transformed into scores: 0 (negative), 1 (healing titers), 2 (active disease, low titers) and 3 (active disease, high titers) according to each center''s criteria. Major discordances were considered between scores indicating active disease and scores indicating negative or healing titers; such discordance when associated with proper clinical and other laboratorial data, may correspond to different approaches to the patient''s treatment. Surprisingly, all centers exhibited a high rate of “major” discordances with a mean of 31 (20%) discordant scores. Alternatively, when the scores given by one center to their own sera were compared with the scores given to their sera by the remaining five other centers, a high rate of major discordances was also found, with a mean number of 14.8 sera in 30 presenting a discordance with at least one other center. The data also suggest that centers that used CIE and pool of isolates for antigen preparation performed better.

Conclusion

There are inconsistencies among the laboratories that are strong enough to result in conflicting information regarding the patients'' treatment. Renewed efforts should be promoted to improve standardization of the serological diagnosis of PCM.     

Bombesin-dependent pro-MMP-9 activation in prostatic cancer cells requires beta1 integrin engagement

In Con8 rat mammary epithelial tumor cells, the synthetic glucocorticoid dexamethasone stimulates transepithelial electrical resistance (TER), promotes the remodeling of apical junctions, and down-regulates the level of fascin, an actin-bundling protein that can bind to beta-catenin. We have previously shown that ectopic expression of fascin prevented the glucocorticoid-mediated recruitment of tight junction and adherens junction proteins to the site of cell-cell contact. Here we demonstrate that exogenous treatment or constitutive production of transforming growth factor-alpha (TGF-alpha) ablated the dexamethasone down-regulation of the fascin protein level and disrupted the dexamethasone-induced remodeling of the apical junction and stimulation of the monolayer TER. The response to TGF-alpha was polarized in that basolateral, but not apical, exposure to this growth factor coordinately reversed the steroid control of fascin production and tight junction formation. Expression of dominant negative RasN17 or treatment with the PD098059 MEK inhibitor abolished or attenuated the TGF-alpha disruptive effects on TER, junction remodeling, and fascin protein levels. Our results implicate the regulation of fascin protein levels as a target of cross-talk between the Ras-dependent growth factor signaling and glucocorticoid signaling pathways that controls tight junction dynamics in mammary epithelial tumor cells. We propose that reversing the down-regulation of fascin is critical for the ability of TGF-alpha to disrupt the glucocorticoid-induced remodeling of the apical junction that leads to tight junction formation.