Showing papers by "Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto published in 2003"

Expressed Sequence Tag Analysis of the Human Pathogen Paracoccidioides brasiliensis Yeast Phase: Identification of Putative Homologues of Candida albicans Virulence and Pathogenicity Genes

Abstract: Paracoccidioides brasiliensis, a thermodimorphic fungus, is the causative agent of the prevalent systemic mycosis in Latin America, paracoccidioidomycosis. We present here a survey of expressed genes in the yeast pathogenic phase of P. brasiliensis. We obtained 13,490 expressed sequence tags from both 5′ and 3′ ends. Clustering analysis yielded the partial sequences of 4,692 expressed genes that were functionally classified by similarity to known genes. We have identified several Candida albicans virulence and pathogenicity homologues in P. brasiliensis. Furthermore, we have analyzed the expression of some of these genes during the dimorphic yeast-mycelium-yeast transition by real-time quantitative reverse transcription-PCR. Clustering analysis of the mycelium-yeast transition revealed three groups: (i) RBT, hydrophobin, and isocitrate lyase; (ii) malate dehydrogenase, contigs Pb1067 and Pb1145, GPI, and alternative oxidase; and (iii) ubiquitin, delta-9-desaturase, HSP70, HSP82, and HSP104. The first two groups displayed high mRNA expression in the mycelial phase, whereas the third group showed higher mRNA expression in the yeast phase. Our results suggest the possible conservation of pathogenicity and virulence mechanisms among fungi, expand considerably gene identification in P. brasiliensis, and provide a broader basis for further progress in understanding its biological peculiarities.

Adaptive patterns of osmotic and ionic regulation, and the invasion of fresh water by the palaemonid shrimps.

Abstract: To evaluate trends in the osmoregulatory behavior of neotropical, palaemonid shrimps, we investigated osmotic and ionic regulatory patterns in five species of Palaemon or Macrobrachium. The species’ life histories depend on saline water to differing degrees, their habitats ranging from the marine/intertidal (P. northropi), through estuaries (P. pandaliformis) to coastal, freshwater streams (M. olfersii, M. potiuna) and inland, continental river systems (M. brasiliense). Hemolymph osmolality, chloride, sodium and magnesium concentrations were measured in shrimps exposed to experimental media ranging from fresh water (<0.5‰) to concentrated seawater (42‰) for up to 10 days. The marine and estuarine Palaemon species exhibit well-developed hyper/hypo-osmotic, sodium and chloride regulatory capabilities in mid-range salinities, tending to hyperconform in low salinities. The freshwater Macrobrachium species show variable hyperosmotic, sodium and chloride regulatory capacities, tending to hypoconform or unable to survive at higher salinities. All species hyper-regulate magnesium in fresh water, but hyporegulate strongly in saline media. Palaemonids from the saline habitats show the strongest osmoregulatory capabilities, and fresh water may have been gradually invaded by ancestral species with similar regulatory capacity. However, this regulatory plasticity has been lost to varying degrees in extant freshwater species.

Photoinduced NO release by visible light irradiation from pyrazine-bridged nitrosyl ruthenium complexes.

Abstract: The binuclear complex [RuII(NH3)5(pz)RuII(bpy)2(NO)](PF6)5 was prepared and characterized by elemental analysis, UV−vis, and IR spectroscopy. The complex UV−vis spectrum has presented bands at 242, 286, and 530 nm in acetate buffer solution at pH 4.5. The photochemical study by laser flash-photolysis at 532 nm showed the NO release account from the NO measured by a NO sensor. The quantum yield for NO release (0.025 ± 0.004 mol einsten-1) was determined with a laser flash-photolysis apparatus (Continuum Q-switched Nd:YAG laser). The major irradiation product of the [RuII(NH3)5(pz)RuII(bpy)2(NO)]5+ complex besides nitric oxide is [RuIII(NH3)5(pz)RuII(bpy)2(H2O)]5+.

Studies on a thermostable α-amylase from the thermophilic fungus Scytalidium thermophilum

Abstract: An α-amylase produced by Scytalidium thermophilum was purified using DEAE-cellulose and CM-cellulose ion exchange chromatography and Sepharose 6B gel filtration. The purified protein migrated as a single band in 6% PAGE and 7% SDS-PAGE. The estimated molecular mass was 36 kDa (SDS-PAGE) and 49 kDa (Sepharose 6B). Optima of pH and temperature were 6.0 and 60°C, respectively. In the absence of substrate the purified α-amylase was stable for 1 h at 50°C and had a half-life of 12 min at 60°C, but was fully stable in the presence of starch. The enzyme was not activated by several metal ions tested, including Ca2+ (up to 10 mM), but HgCl2 and CuCl2 inhibited its activity. The α-amylase produced by S. thermophilum preferentially hydrolyzed starch, and to a lesser extent amylopectin, maltose, amylose and glycogen in that order. The products of starch hydrolysis (up to 6 h of reaction) analyzed by thin layer chromatography, showed oligosaccharides such as maltotrioses, maltotetraoses and maltopentaoses. Maltose and traces of glucose were formed only after 3 h of reaction. These results confirm the character of the enzyme studied to be an α-amylase (1,4-α-glucan glucanohydrolase).

Synthesis, Electrochemical, Spectral, and Antioxidant Properties of Complexes of Flavonoids with Metal Ions

Abstract: Complexes of metal ions with the flavonoids quercetin (H2L1), rutin (H2L2) and 3‐hydroxyflavone (HL3) have been synthesized. From the data obtained by elemental analyses, molar conductance, atomic absorption, thermal analyses, 1H NMR, IR, UV‐Vis and EPR spectroscopies one can propose the compositions: [Cu2(L1)(H2O)4]Cl2 (1), [Cu3(L2)2(H2O)6]Cl2 (2), [Cu(L3)(H2O)2]Cl (3), [Fe2(L1)(H2O)8]Cl2 (4), [Fe3(L2)2(H2O)12]Cl2 (5) and [Fe(L3)(H2O)4]Cl (6). We have used the assumption that the electrochemical oxidation can be used as a model for antioxidant activities for the flavonoids. The cyclic voltammograms show irreversible oxidation processes at + 0.58 V and + 0.91 V for (1), + 0.82 V for (2), + 0.89 V for (3), + 0.58 V and + 0.90 V for (4), + 0.78 V for (5) and + 0.86 V for (6) versus Ag/AgCl. These values are lower than those for the free flavonoids indicating a more favorable antioxidant activity. Furthermore, these complexes were also more effective than the uncomplexed flavonoids scavenging superoxide radi...

Atividade antimicrobiana de flavonóides e esteróides isolados de duas espécies de Chromolaena

Abstract: The crude extracts (dichloromethanic and ethanolic) and some compounds (8 flavonoids and 5 steroids) isolated from Chromolaena squalida (leaves and stems) and Chromolaena hirsuta (leaves and flowers) have been evaluated against 22 strains of microorganisms including bacteria (Gram-positive and Gram-negative) and yeasts. All crude extracts, flavonoids and steroids evaluated have been shown actives, mainly against Gram-positive bacteria.

Rhizopus microsporus var. rhizopodiformis : a thermotolerant fungus with potential for production of thermostable amylases

Abstract: The effect of several nutritional and environmental parameters on growth and amylase production from Rhizopus microsporus var. rhizopodiformis was analysed. This fungus was isolated from soil of the Brazilian "cerrado" and produced high levels of amylolytic activity at 45°C in liquid medium supplemented with starch, sugar cane bagasse, oat meal or cassava flour. Glucose in the culture medium drastically repressed the amylolytic activity. The products of hydrolysis were analysed by thin layer chromatography, and glucose was detected as the main component. The amylolytic activity hydrolysed several substrates, such as amylopectin, amylase, glycogen, pullulan, starch, and maltose. Glucose was always the main end product detected by high-pressure liquid chromatography analysis. These results indicated that the amylolytic activity studied is a glucoamylase, but there were also low levels of α-amylase. As compared to other fungi, R. microsporus var. rhizopodiformis can be considered an efficient producer of thermostable amylases, using raw residues of low cost as substrates. This information is of technological value, considering the importance of amylases for industrial hydrolysis.

Occurrence and characterization of entomogen galls in plants from natural vegetation areas in Delfinópolis, MG, Brazil.

Abstract: In the present work we aimed to register the occurrence of galls, inductors, inquilines, and parasitoids in plants of three natural vegetation areas in Delfinopolis, MG, Brazil Results obtained showed 22 types of galls collected from leaf, vein leaf, petioles, stem, and inflorescence of nineteen species belonging to fifteen distinct families Concerning gall morphology, the following were collected: globoid, conicle, discoidal, fusiform, shell-shape, indefinite, and one substituition of an ovary by an immature As principal inducers were found insects of the families Cecidomyiidae (Diptera), Psyllidae, and Diaspididae (Sternorrhyncha/Hemiptera) As parasitoids the most common are of the Chalcidoidea superfamily (Hymenoptera) and, as occasional inquilines, Polyxenidae (Diplopoda) and Psocodea (Psocoptera) The results of this study contribute to existing of knowledge host-plant diversity and gall-associated insects in rocky fields, cerrado, and gallery forests

Active NaCl absorption across posterior gills of hyperosmoregulating Chasmagnathus granulatus.

Abstract: Split lamellae of posterior gills of Chasmagnathus granulatus adapted to 2.5 per thousand salinity were mounted in a modified Ussing chamber. With NaCl-saline on both sides of the preparation a transepithelial voltage (V(te)) of 4.1+/-0.5 mV (outside positive) was measured. After voltage-clamping, the negative short-circuit current (I(sc)) amounted to -142+/-21 micro A cm(-2) at a conductance (G(te)) of 44+/-5 mS cm(-2). Substitution of either chloride (by nitrate) or sodium (by choline) on both sides of split gill lamellae significantly reduced I(sc) (by 70-80%) and G(te) (by 30-50%). External CsCl (but not BaCl(2) or furosemide) inhibited the negative I(sc) without affecting G(te). Addition of ouabain, BaCl(2) or diphenylamine-2-carboxylate to the internal bath inhibited I(sc) at unchanged G(te). Internal acetazolamide did not affect I(sc) or G(te) across split gill lamellae. Unidirectional Na(+) influx across isolated and perfused posterior gills, however, was reduced by internal acetazolamide by approximately 20% at constant V(te). The results suggest that posterior gills of hyperosmoregulating C. granulatus display a high conductance epithelium that actively absorbs NaCl in a coupled way by an electrogenic mechanism similar to that seen in the thick ascending limb of Henle's loop and, to a minor degree, by an electroneutral mechanism, presumably via apical Na(+)/H(+)- and Cl(-)/HCO(3)(-)-antiports.

The reactivity of nitrosyl ruthenium complexes containing polypyridyl ligands

Abstract: A series of cis nitrosyl complexes containing polypyridyl ligands were prepared and characterized as cis-[RuL(bpy)2(NO)](PF6)3 (L = pyridine, 4-picoline, or 4-acetylpyridine), by elemental analysis, u.v.–vis. and i.r. spectroscopy, and by electrochemical techniques such as cyclic voltammetry, differential pulse voltammetry, spectroelectrochemistry, and coulometry. The complexes exhibit stretching frequencies ν(NO) at ca. 1950 cm−1 indicating that nitrosyl group has a sufficiently high degree of nitrosonium ion (NO+) character. In non-aqueous solution, the reduction of these complexes induce nitrosyl to nitro conversion. In aqueous solution the reduction product is cis-[RuL(bpy)2(NH3)]2+ formed by a six electron mechanism. The nitrosyl compounds are susceptible to nucleophilic attack by hydroxide ion. The equilibrium constants were determined.

Sesquiterpene lactones from Lychnophora ericoides.

Abstract: Two new sesquiterpene lactones, (4S,6R,7S,8S,10R,11S,16R)-1-oxo-3(10),8(16)-diepoxy-16-methylprop-1Z-enyl-16-methoxygermacra-2-en-6(12)-olide (1) and (4S,6R,7S,8S,10R,11S)-1-oxo-3,10-epoxy-8-angeloyloxygermacra-2-en-6(12)-olide (2), were isolated from Lychnophora ericoides. Their structures, including absolute configuration, were established by spectroscopic methods, including single-crystal X-ray analysis. Monitoring the furanoheliangolide metabolism of L. ericoides revealed an increase in biosynthesis during the plant flowering period.

Protein content and pattern during mucus gland maturation and its ecdysteroid control in honey bee drones

Abstract: We analyzed mucus gland protein content and pattern for drones of Africanized honey bees. The effect of exogenous ecdysteroids on mucus gland maturation was judged against the endogenous ecdysteroid titer. During the first 5 days of adult life, the mucus protein content increases steeply, whereas the protein pattern becomes reduced in complexity. Subsequently, the protein content decreases, reaching a plateau level at day 8. The protein pattern of mature glands is characterized by three dominant polypeptides. Injection of 20-hydroxyecdysone into newly emerged drones abolished the normal increase in protein content and prolonged the persistence of the protein pattern typical for immature glands. Ecdysteroids thus appear to act as negative regulators in the maturation process of drone mucus glands. This hypothesis received support from analyses of the hemolymph ecdysteroid titer, which was found to rapidly decline soon after emergence. male accessory gland / ecdysone / radioimmunoassay / Apis mellifera / mucus protein

Translocation analysis by the FISH-painting method for retrospective dose reconstruction in individuals exposed to ionizing radiation 10 years after exposure.

Abstract: Fluorescence in situ hybridization (FISH) is a powerful method largely used for detecting chromosomal rearrangements, translocations in particular, which are important biomarkers for dose assessment in case of human exposure to ionizing radiation. To test the possibility of using the translocation analysis by FISH-painting method in retrospective dose assessment, we carried out in vitro experiments in irradiated human lymphocytes, in parallel with the analysis of translocations in lymphocytes from 10 individuals, who were exposed to 137 cesium in the Goiânia (Brazil) accident (samples collected 10 years after exposure). The in vitro dose–response curve for the genomic translocation frequencies (FGs) fits a linear quadratic model, according to the equation: Y =0.0243 X 2 +0.0556 X . The FG values were also calculated for the individuals exposed to 137 cesium , ranging from 0.58 to 5.91 per 100 cells, and the doses were estimated and compared with the results obtained by dicentric analysis soon after the accident, taking the opportunity to test the validity of translocation analysis in retrospective biodosimetry. A tentative of retrospective dosimetry was performed, indicating that the method is feasible only for low level exposure (below 0.5 Gy), while for higher doses there is a need to apply appropriate correction factors, which take into consideration mainly the persistence of chromosomal translocations along with time, and the influence of endogenous and exogenous factors determining the inter-individual variability in the cellular responses to radiation.

Effects of essential fatty acids and N and P-limited algae on the growth rate of tropical cladocerans

Abstract: SUMMARY 1. In this study, the effects of nutrient (N and P) deficiency and the importance of essential polyunsaturated fatty acids (PUFA) [eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)] to tropical cladocerans, growth and reproduction were determined in a growth bioassay. 2. The animals were fed N/P-sufficient, N-deficient and P-deficient algae, and also N and P-deficient algae supplemented with fish oil emulsions rich in EPA and DHA. 3. Cladocerans showed different responses to nutrient-deficient algae and also to supplements of fish oil emulsions. Moina micrura was most sensitive to P-deficient alga and, surprisingly, grew better and produced more eggs in N-deficient alga than in N/P sufficient alga. Ceriodaphnia cornuta was less sensitive, growing well in both N and P-deficient algae. This species, however, had a lower clutch size in N-deficient alga. On the other hand, Daphnia gessneri was the most sensitive to mineral limitation, showing decreased growth and clutch size in both nutrient-deficient algae. 4. The PUFA supplements to nutrient-deficient algae increased growth rates only for M. micrura and C. cornuta, suggesting that these fatty acids are important food requirements for these species.

Effects of septal cholinergic lesion on rat exploratory behavior in an open-field.

Abstract: The medial septum participates in the modulation of exploratory behavior triggered by novelty. Also, selective lesions of the cholinergic component of the septohippocampal system alter the habituation of rats to an elevated plus-maze without modifying anxiety indices. We investigated the effects of the intraseptal injection of the cholinergic immunotoxin 192 IgG-saporin (SAP) on the behavior of rats in an open-field. Thirty-nine male Wistar rats (weight: 194-230 g) were divided into three groups, non-injected controls and rats injected with either saline (0.5 µl) or SAP (237.5 ng/0.5 µl). Twelve days after surgery, the animals were placed in a square open-field (120 cm) and allowed to freely explore for 5 min. After the test, the rats were killed by decapitation and the septum, hippocampus and frontal cortex were removed and assayed for acetylcholinesterase activity. SAP increased acetylcholinesterase activity in the septum, hippocampus and frontal cortex and decreased the total distance run (9.15 ± 1.51 m) in comparison to controls (13.49 ± 0.91 m). The time spent in the center and at the periphery was not altered by SAP but the distance run was reduced during the first and second minutes (2.43 ± 0.36 and 1.75 ± 0.34 m) compared to controls (4.18 ± 0.26 and 3.14 ± 0.25 m). SAP-treated rats showed decreased but persistent exploration throughout the session. These results suggest that septohippocampal cholinergic mechanisms contribute to at least two critical processes, one related to the motivation to explore new environments and the other to the acquisition and storage of spatial information (i.e., spatial memory).

Characterization of hydrogen bonds in the interactions between the hydroperoxyl radical and organic acids.

Abstract: The hydrogen bonds formed between the hydroperoxyl radical and formic, acetic, and trifluoroacetic acids were characterized using geometric, energetic, and electronic parameters through calculations done with the UB3LYP/6-311++G (3df,3pd) and UB3LYP/EPR-III methods. The wave functions were analyzed through the natural bond orbital, natural steric analysis, natural resonance theory, and atoms in molecules methods. The energy decomposition method proposed by Xantheas was used. The vibrational frequencies and the intensity of the O-H stretching bands, as well as the spin densities, were compared with experimental evidence. The results allowed the characterization of the hydrogen bonds formed in the complexation of the acids with the hydroperoxyl radical. Complexation led to significant alterations in the equilibrium geometry of the monomers. Energetic analysis proved that the studied complexes are stable and allowed the understanding of the effect of the electron-donating and electron-withdrawing groups in their stabilization. The alterations in the electronic structure of the monomers after complexation led to an increase in the resonance of the carboxyl group, which can be partially attributed to the hydrogen bond.

Molecular simulation of LiCl aqueous solutions

Abstract: Non-primitive LiCl aqueous electrolyte solutions were studied at 1.0, 5.0 and 10.0 M concentrations by molecular dynamics simulations. It was observed that the ion hydration structure is progressively lost with increasing concentration. The ions are aggregated in small clusters at C = 1.0 M. However, at this concentration, two large clusters were detected that are an initial step in an aggregation process. At C = 5.0 M, the highly unstable ion clustering seems to correspond to an intermediary state between low concentration states with poor aggregation and states where the ions are highly aggregated, as observed at C = 10.0 M where almost all the ions are clustered in one cluster. This cluster does not present a crystal-like structure. The high solubility of LiCl in aqueous solutions can consequently be explained as a result of the large radii difference between the anion and the cation that results in the instability of the ionic aggregates, which makes the formation of crystal seeds difficult.

Removal of Benzoate Anions from Aqueous Solution Using Mg-Al Layered Double Hydroxides

Abstract: The uptake of benzoate anions from aqueous solutions by calcined and uncalcined layered double hydroxides (LDHs) is reported. Adsorption (or sorption) isotherms have been determined at 25°C in the 0 to 100 mmol dm m 3 concentration range. The results showed that the calcined LDH sorbs 40 to 85% of the benzoate in solution in the concentration range usually found in industrial wastewater, and that the sorption capacity of this material is about 4 times greater than that observed for the parent LDH. The study of the sorption kinetics for the calcined material showed that it is a relatively slow process, which can be attributed to the fast regeneration of the calcined LDH with intercalated hydroxyl anions, followed by a slow process of anion exchange by benzoate. Collected solids after sorption present basal spacing close to 7.6 A, characteristic of intercalated hydroxyl anions or carbonate, suggesting a horizontal arrangement of benzoate in the interlayer.

Nitric oxide release from the S-nitrosothiol zinc phthalocyanine complex by flash photolysis

Abstract: The photogeneration of nitric oxide (NO) using laser flash photolysis was investigated for S-nitroso-glutathione (GSNO) and S-nitroso-N-acetylcysteine (NacySNO) at pH 6.4 (PBS/HCl) and 7.4 (PBS). Irradiation of S-nitrosothiol with light (lambda = 355 nm followed by absorption spectroscopy) resulted in the homolytic decomposition of NacySNO and GSNO to generate radicals (GS and NacyS ) and NO. The release of NO from donor compounds measured with an ISO-Nometer apparatus was larger at pH 7.4 than pH 6.4. NacySNO was also incorporated into dipalmitoyl-phosphatidylcholine liposomes in the presence and absence of zinc phthalocyanine (ZnPC), a well-known photosensitizer useful for photodynamic therapy. Liposomes are usually used as carriers for hydrophobic compounds such as ZnPC. Inclusion of ZnPC resulted in a decrease in NO liberation in liposomal medium. However, there was a synergistic action of both photosensitizers and S-nitrosothiols resulting in the formation of other reactive species such as peroxynitrite, which is a potent oxidizing agent. These data show that NO release depends on pH and the medium, as well as on the laser energy applied to the system. Changes in the absorption spectrum were monitored as a function of light exposure.

Parasites and Symbionts of Crabs from Ubatuba Bay, São Paulo State, Brazil

Abstract: During July 1999, 172 crabs from Ubatuba Bay, Sao Paulo, Brazil, were examined from 4 families as follows: Portunidae, Arenaeus cribrarius, Callinectes danae, Callinectes ornatus, Charybdis hellerii, Portunus spinimanus, and Portunus spinicarpus; Calappidae, Hepatus pudibundus; Majidae, Libinia ferreirae; Leucosiidae, Persephona mediterranea and Persephona lichtensteinii. One cephaline gregarine symbiont was found in the hindgut of a specimen of Cal. ornatus, and no positively identified, internal and multicelled symbionts were detected. Twenty-one specimens (14.3%) from 7 of the 10 species (all except H. pudibundus, P. mediterranea, and P. lichtensteinii) carried the nemertean worm, Carcinonemertes carcinophila ct. imminuta in either their egg masses or gills. This is the first report of this epibiont from the Ubatuba region. Two specimens of an undescribed polychaete worm were found in the gill of a specimen of L. ferreirae. A stalked barnacle, Octolasmis lowei, was found on the gills of 11 crabs (7.5%). Only 3 crab species (36.6% of Cal. danae, 9.0% of Cal. ornatus, and 7.7% of Po. spinimanus) carried the typical barnacle, Chelonibia patula, on their dorsal carapaces. The percentage of individuals of Cal. danae and Cal. ornatus hosting barnacles (prevalence) as well as the number of barnacles on individual crabs was positively correlated with crab size.

A short and efficient synthesis of crocetin-dimethylester and crocetindial.

Abstract: In this paper we describe an efficient six-step synthesis of crocetin-dimethylester that could be further reduced to a “four-step” synthesis through the use of in situ procedures. The simplicity of the whole process, the ready availability of starting materials, and the high overall yield render this strategy a very attractive synthesis of this very important compound, which is the key intermediate for the synthesis of several carotenoids and other polyene natural products.

Escaping from cycles through a glass transition

Abstract: A random walk is performed over a disordered media composed of N sites random and uniformly distributed inside a d-dimensional hypercube. The walker cannot remain in the same site and hops to one of its n neighboring sites with a transition probability that depends on the distance D between sites according to a cost function E(D). The stochasticity level is parametrized by a formal temperature T. In the case T=0, the walk is deterministic and ergodicity is broken: the phase space is divided in a O(N) number of attractor basins of two-cycles that trap the walker. For d=1, analytic results indicate the existence of a glass transition at T(1)=1/2 as N--> infinity. Below T1, the average trapping time in two-cycles diverges and an out-of-equilibrium behavior appears. Similar glass transitions occur in higher dimensions when the right cost function is chosen. We also present some results for the statistics of distances for Poisson spatial point processes.

Short-time critical dynamics of the Baxter-Wu model.

Abstract: We study the early time behavior of the Baxter-Wu model, an Ising model with three-spin interactions on a triangular lattice. Our estimates for the dynamic exponent z are compatible with results recently obtained for two models which belong to the same universality class of the Baxter-Wu model: the two-dimensional four-state Potts model and the Ising model with three-spin interactions in one direction. However, our estimates for the dynamic exponent $\ensuremath{\theta}$ of the Baxter-Wu model are completely different from the values obtained for those models. This discrepancy could be related to the absence of a marginal operator in the Baxter-Wu model.