Germinação de sementes de Stryphnodendron Mart. osmocondicionadas

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Efeito da disponibilidade hídrica do substrato, da QUALIDADE FISIOLÓGICA E do teor de água inicial das sementes de soja no PROCESSO de germinação

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

COMPORTAMENTO DAS SEMENTES DE SOJA DURANTE A FASE INICIAL do PROCESSO DE GERMINAÇÃO

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Efeitos estéricos e eletrônicos de substituintes alquilas em catalisadores titanocênicos solúveis na polimerização sindioespecífica de estireno

Titanocenos são catalisadores solúveis conhecidos para a polimerisação estereoespecífica de olefinas pró-quirais como o estireno. Nesse trabalho descrevemos as relações entre as características do poliestireno e a estrutura do precursor do catalisador, de fato aqueles da família (RCp)2TiCl2 (R = H, etila, iso-propila, n-propila, sec-butila, n-butila, iso-amila e ciclohexila). Todos os catalisadores são ativos para a produção de poliestireno acima de zero graus centígrados. A sindiotaticidade dos polímeros são dependentes da cadeia lateral dos anéis aromáticos do titanoceno e da temperatura da polimerização. A relação entre os fatores estéricos e eletrônicos do precursor do catalisador e os produtos de polimerização são apresentados e discutidos.

Biorregulador e pré-condicionamento osmótico na germinação de sementes e no crescimento inicial da muda de carobinha (Jacaranda decurrens subsp. symmetrifoliolata Farias & Proença) - Bignoniaceae

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

INJECTION OF RAMIPRIL INTO THE LATERAL VENTRICLE INTERFERES WITH THE DRINKING RESPONSE INDUCED BY PHARMACOLOGICAL AND NATURAL THIRST STIMULI

We investigated the effects of ramipril, an angiotensin I-converting enzyme (ACE) inhibitor, on water intake by male Holtzman rats (250-300 g) with cannulae implanted into the lateral ventricle. Intracerebroventricular (icv) injection of ramipril (1 mu g/mu l) significantly reduced drinking in response to subcutaneous (sc) injection of isoprenaline (100 mu g/kg) from 8.49 +/- 0.69 to 2.96 +/- 0.36 ml/2 h, polyethyleneglycol (PEG) (30% w/v, 10 ml/kg) from 9.51 +/- 2.20 to 1.6 +/- 0.34 ml/2 h or water deprivation for 24 h from 12.61 +/- 0.83 to 5.10 +/- 1.37 ml/2 h. Ramipril had no effect on water intake induced by cellular dehydration produced by sc injection of hypertonic saline (2 M NaCl). These results are consistent with the hypothesis that ramipril acts as an ACE-blocking agent in the brain. The possibility that ramipril is transformed to ramiprilat, the active drug, by the brain is suggested.

Titi monkeys (Callicebus spp., Atelidae : Platyrrhini) in the Brazilian state of Rondonia

Five species of titi monkey (Callicebus brunneus, Callicebus caligatus, Callicebus cinerascens, Callicebus donacophilus, and Callicebus moloch) were recorded in surveys of primate populations at 26 sites throughout the Brazilian state of Rondonia. The distribution of the two species, C. cinerascens and C. donacophilus (recorded in the state for the first time), appeared to be related to that of non-forest ecosystems, the former in the cerrado woodlands, and the latter in gallery forests of the Guapore grasslands. The results of the surveys also indicate that C. brunneus has a more restricted distribution in southern Rondonia than was previously thought, whereas C. moloch is more widespread. However, the ecological factors that determine species distribution in the south of the state remain unclear on the basis of the available data. All species were observed in small social groups of no more than five individuals, which are typical of the genus, generally in the middle and lower forest strata.

Alkene epoxidation with iodosylbenzene catalysed by polyionic manganese porphyrins electrostatically bound to counter-charged supports

Manganese(III) complexes of tetra-anionic and tetra-cationic porphyrins have been immobilised on counter-charged, surface-modified silica supports and on organic ion-exchange resins. The reactions of these supported manganese(III) porphyrin systems and analogous uncharged homogeneous systems have been examined using cyclooctene and (E)- and (Z)-4- methylpent-2-ene epoxidations, with iodosylbenzene (PhIO) as the oxygen donor.Comparisons using the manganese porphyrin systems as catalysts for the epoxidation of cyclooctene in acetonitrile reveal that, in low turnover reactions (maximum 136 turnovers), they all give an essentially quantitative yield of epoxide although the heterogeneous reactions are significantly slower than the homogeneous analogues. In large scale repeat-use experiments, however, the supported catalysts are clearly superior, giving markedly better yields.The epoxidations of (E)- and (Z)-4- methylpent-2-ene with all the catalysts show a very high stereoretention, with the (Z)-alkene reacting faster than the (E)-isomer. The sterically hindered manganese(III) 5,10,15,20-tetrakis(2,6-dichloro-3-sulfonatophenyl)porphyrin (MnTDCSPP) shows the highest selectivity for the (Z)-isomer; by contrast the supported manganese(III) 5,10,15,20-tetrakis[2,3,5,6-tetrafluoro-4-(trimethylammonio)phenyl]porphyrin on Dowex (MnTF(4)TMAPP-Dowex) reacts with the two alkenes at effectively the same rate.The mechanism of the epoxidations and the influence of the porphyrin ligand and support on the substrate selectivity are discussed.

Effect of temperature on the interaction between the nonionic surfactant C(12)E(5) and poly(ethylene oxide) investigated by dynamic light scattering and fluorescence methods

The interaction between the nonionic surfactant C(12)E(5) and a high molar mass (M = 5.94 x 10(5)) poly(ethylene oxide) (PEG) in aqueous solution has been examined as a function of temperature by dynamic light scattering and fluorescence methods over a broad concentration range. Clusters of small surfactant micelles form within the PEO coil, leading to its extension. The hydrodynamic radius of the complex increases strongly with temperature as well as with the concentrations of surfactant and polymer. At high concentrations of the surfactant, the coil/micellar cluster complex coexists with free C(12)E(5) micelles in the solution. Fluorescence quenching measurements show a moderate micellar growth from 155 to 203 monomers in PEO-free solutions of C(12)E(5) over a wide concentration range (0.02-2.5%) at 8 degrees C. Below 0.25% C(12)E(5), the average aggregation number (N) of the micelles is smaller in the presence of PEO than in its absence. However, N increases with increasing surfactant concentration up to a plateau value of about 270 at about 1.2% (ca. 30 mM) C(12)E(5). At high surfactant concentrations, N is larger in the presence of polymer than in its absence, a finding which is connected to a significant lowering of the clouding temperature due to the PEO at these compositions. Similar results of increasing aggregation number followed by a plateau were also found at a fixed concentration of surfactant (2.5%) and varied PEO.

Characterization and catalytic activity of iron(III) mono(4-N-methyl pyridyl)-tris(halophenyl) porphyrins in homogeneous and heterogeneous systems

The synthesis, characterization and catalytic activity of the cationic iron porphyrins Fe[M(4-N-MePy)TDCPP]Cl-2 and Fe[M(4-N-MePy)TFPP]Cl-2 in the epoxidation of (Z)-cyclooctene by PhIO in homogeneous solution and supported on silica gel (SG), imidazole propyl gel (IPG) or SG modified with 2-(4-sulfonatophenyl)ethyl groups (SiSO3) have been accomplished. When supported on IPG, both cationic FeP bind to the support via Fe-imidazole coordination. Fe[M(4-N-MePy)TDCPP]IPG contains a mixture of low-spin bis-coordinated (FeP)-P-III and high-spin mono-coordinated (FeP)-P-III species, whereas Fe[M(4-N-MePy)TFPP]IPG only contains high-spin mono-coordinated (FeP)-P-III. These FePIPG catalysts also contain (FeP)-P-II species, whose presence was confirmed by EPR spectroscopy using NO as a paramagnetic probe. Both cationic FePs coordinate to SG through Fe-O ligation and they are present as high-spin (FeP)-P-III species. The cationic FePs supported on SiSO3- are also high-spin (FeP)-P-III species and they bind to the support via electrostatic interaction between the 4-N-methylpyridyl groups and the SO3- groups present on the matrix. In homogeneous solution, both Fe[M(4-N-MePy)TDCPP]Cl-2 and Fe[M(4-N-MePy)TFPP]Cl-2 have similar catalytic activity to Fe(TDCPP)Cl and Fe(TFPP)Cl, leading to cis-epoxycyclooctane yields of 92%. When supported on inorganic matrices,both FePs lead to epoxide yields comparable to their homogeneous analogues and their anchoring enables catalyst recovery and re-use. Recycling of Fe[M(4-N-MePy)TDCPP]SiSO3- shows that this FeP maintains its activity in a second reaction. (C) 1999 Elsevier B.V. B.V. All rights reserved.

Purification, partial characterization and preliminary X-ray diffraction analysis of a mannose-specific lectin from Cymbosema roseum seeds

A lectin from Cymbosema roseum seeds (CRL) was purified, characterized and crystallized. The best crystals grew in a month and were obtained by the vapour-diffusion method using a precipitant solution consisting of 0.1 M Tris-HCl pH 7.8, 8% (w/v) PEG 3350 and 0.2 M proline at a constant temperature of 293 K. A data set was collected to 1.77 angstrom resolution at a synchrotron-radiation source. CRL crystals are orthorhombic, belonging to space group P2(1)2(1)2(1). Crystallographic refinement and full amino-acid sequence determination are in progress.

Using pegylated interferon alfa-2b and ribavirin to treat chronic hepatitis patients infected with hepatitis C virus genotype 1: Are nonresponders and relapsers different populations?

The combination of pegylated interferon (PEG-INF) and ribavirin is currently the best treatment for chronic hepatitis C, providing a sustained virological response (SVR) in 54%-63% of patients. In patients infected with hepatitis C virus (HCV) genotype 1, the SVR rate is 42%-52%. To evaluate the treatment efficacy of this drug combination, we conducted an open, prospective study of 58 consecutive treatment-naive patients infected with HCV genotype 1 and treated at a university hospital, comparing those presenting an SVR (SVRs), nonresponders (NRs), and relapsers (RELs). Among the intent-to-treat patients, an end-of-treatment virological response was achieved in 69 % of the sample as a whole and in 52 % of the SVRs. We found that being an SVR was significantly associated with mild fibrosis (p = 0.04) and with undetectable HCV RNA at weeks 12 and 24 of treatment (p < 0.0001). Comparing the SVR and REL groups, we observed that being older than 40 was significantly associated with being a REL (p = 0.04). Being an NR was found to be associated with severe fibrosis and moderate inflammatory infiltrates (portal or periportal). In the polytomous logistic regression, no independent factors were associated with the REL group when compared with the SVR group. We conclude that RELs and NRs differ in comparison with SVRs. The RELs accounted for 17% of the sample. The HCV RNA test results at weeks 12 and 24 of treatment, although independent predictors of non-response (OR: 4.8 and 8.2, respectively), did not differ between SVRs and RELs.

Crystallization and preliminary X-ray diffraction analysis of prephenate dehydratase from Mycobacterium tuberculosis H37Rv

Tuberculosis remains the leading cause of mortality arising from a bacterial pathogen ( Mycobacterium tuberculosis). There is an urgent need for the development of new antimycobacterial agents. The aromatic amino-acid pathway is essential for the survival of this pathogen and represents a target for structure-based drug design. Accordingly, the M. tuberculosis prephenate dehydratase has been cloned, expressed, purified and crystallized by the hanging-drop vapour-diffusion method using PEG 400 as a precipitant. The crystal belongs to the orthorhombic space group I222 or I2(1)2(1)2(1), with unit-cell parameters a = 98.26, b = 133.22, c = 225.01 angstrom, and contains four molecules in the asymmetric unit. A complete data set was collected to 3.2 angstrom resolution using a synchrotron-radiation source.

Do all tannins have similar nutritional effects? A comparison of three Brazilian fodder legumes

Three tropical legumes, namely Leucaena leucocephala, Sesbania sesban and Cajanus cajan, were subjected to chemical analysis plus in vitro, in situ and in vivo evaluations. Three different assays were used to determine total tannins: adsorption to polyvinyl pyrrolidine (PVPP-tannins), radial diffusion (RD-tannins) and protein precipitation capacity (BSA-tannins). Total phenols, total tannins and condensed tannins were highest for Sesbania. RD-tannins were correlated with total phenols (r(2) = 0.93), PVPP-tannins (r(2) = 0.92) and condensed tannins (r(2) = 0.99). The protein precipitation capacity of Sesbania, Leucaena and Cajanus were 25.9, 6.13 and 4.05 mu g BSA/g DM, respectively.Gas production at 24h was negatively correlated with total phenols (r(2) = 0.99), PVPP-tannins (r(2) = 0.99) and condensed tannins (r(2) = 0.91). The RD-, PVPP-tannins and the response to polyethylene glycol (PEG) in the gas production assay appeared to be useful as a first screen for tannins.In situ degradability did not reflect any adverse effects of tannins. However, in vivo experiments showed that the apparent DM digestibility of Sesbania and Leucaena was lower than the basal diet. The apparent protein digestibility was lower for all legumes compared to the basal diet. Most treatments caused a negative nitrogen balance. The problems associated with browse feeding were not only related to tannin contents, other factors such as inherently poor digestibility and low energy intake may also have lead to the poor animal performance on these diets. We propose, given the limitations of current tannin assays, that it is not possible to predict beneficial or harmful nutritional effects from total tannin concentrations per se. (C) 2004 Elsevier B.V. All rights reserved.

Influence of condensed tannins from Brazilian semi-arid legumes on ruminal degradability, microbial colonization and ruminal enzymatic activity in Saanen goats

The present study aimed at determining the influence of condensed tannins present in the Brazilian legume species Mimosa hostilis, Mimosa caesalpinifolia and Bauhinia cheilantha on ruminal degradability, microbial colonization and enzymatic activity. Polyethylene glycol (PEG) was used to reduce the astringency and concentration of soluble condensed tannins. Four ruminally-cannulated Saanen goats (60 +/- 8 kg BW) were fed, in two experimental periods, with a hay diet based on the studied legumes treated or non-treated with PEG. Voluntary intake, microbial colonization, DM, CP, NDF, and ruminal degradability of PEG treated and non-treated forage leaves, as well as pH, ammonia and 1,4 P-endoglucanase activity of the rumen content were evaluated. Astringency and soluble tannin concentration of the studied legumes were reduced by approximately 70% and 50%, respectively, with PEG treatment. Average DM intake was higher for the treated diet (16.76 g DM/kg BW/day against 13.06 g DM/kg BW/day). Percentile values for degradation parameters and for potential and effective degradabilities of DM, CP and NDF were also affected by the tannins, but at different intensities. Electron microscopic observations of ruminally-incubated legume leaves showed a more effective microbial colonization of PEG-treated leaves for all legume species. A decrease in pH and an increase in ammonia concentration and in endoglucanase activity in the ruminal content was also observed for PEG-treated diets at all sampling periods. Condensed tannins of the studied legume species have influenced the adhesion conditions, colonization and enzymatic activity of the microbial ecosystem, and consequently the ruminal degradation of the different dietary fractions. For this reason, the reduction in condensed tannin would be of great importance to improve the nutrition of ruminant feeding of these species. (c) 2005 Elsevier B.V. All rights reserved.