Showing papers by "Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto published in 1991"
TL;DR: The production of pectinase was studied in Neurospora crassa, using the hyperproducer mutant exo-1, which synthesized and secreted five to six times more enzyme than the wild-type, and the purified enzyme was classified as an endopolygalacturonase.
Abstract: The production of pectinase was studied in Neurospora crassa, using the hyperproducer mutant exo-1, which synthesized and secreted five to six times more enzyme than the wild-type. Polygalacturonase, pectin lyase and pectate lyase were induced by pectin, and this induction was glucose-repressible. Polygalacturonase was induced by galactose four times more efficiently than by pectin; in contrast the activity of lyases was not affected by galactose. The inducing effect of galactose on polygalacturonase was not glucose-repressible. Extracellular pectinases were separated by ion exchange chromatography. Pectate and pectin lyases eluted into three main fractions containing both activities; polygalacturonase eluted as a single, symmetrical peak, apparently free of other protein contaminants, and was purified 56-fold. The purified polygalacturonase was a monomeric glycoprotein (38% carbohydrate content) of apparent molecular mass 36.6-37.0 kDa (Sephadex G-100 and urea-SDS-PAGE, respectively). The enzyme hydrolysed predominantly polypectate. Pectin was also hydrolysed, but at 7% of the rate for polypectate. K m and Vmax for polypectate hydrolysis were 5.0 mg ml-1 and 357 µmol min-1 (mg protein)-1, respectively. Temperature and pH optima were 45°C and 6°0, respectively. The purified polygalacturonase reduced the viscosity of a sodium polypectate solution by 50%, with an increase of 7% in reducing sugar groups. The products of hydrolysis at initial reaction times consisted of oligogalacturonates without detectable monomer. Thus, the purified Neurospora crassa enzyme was classified as an endopolygalacturonase [poly(1,4-α-D-galacturonide) glycanohydrolase; EC 3.2.1.15].
86 citations
85 citations
TL;DR: Facultative necrophagy in Trigona probably became obligate due to preadaptations including massive forager recruitment via pheromone trails; aggressive foraging on carrion exudates; rapid location of novel resources; beneficial microbes in bee glandular secretions that metabolize protein and produce antibiotics; and queen cells and food storage pots of the same size and close proximity.
Abstract: A systematic revision and biological account is given of the only apoid obligate necrophages, the Trigona hypogea group, along with descriptions of Trigona necrophaga sp. nov. and the male of Trigona crassipes. Trigona necrophaga is endemic to eastern Panama and possibly the Choco; T. hypogea and T. crassipes are sympatric throughout the Amazon Basin and the Guianas. The lack of a corbicula on the hind leg and reduction of giant setae on the labial palpi, workers foraging upon carrion, lack of stored pollen in nests, and complete absence of pollen grains in larval provisions demonstrate obligate necrophagy in all three social, stingless bee species. Evolution of T. hypogea and T. crassipes from a common ancestor in the Amazon Basin is postulated, and T. necrophaga is likely to be an offshoot of T. crassipes. Morphology links T. crassipes and T. hypogea, but nest architecture joins necrophaga and crassipes. Facultative necrophagy in Trigona probably became obligate due to preadaptations including (1) massive forager recruitment via pheromone trails; (2) aggressive foraging on carrion exudates; (3) apical mandibular teeth; (4) rapid location of novel resources; (5) beneficial microbes in bee glandular secretions that metabolize protein and produce antibiotics, and (6) queen cells and food storage pots of the same size and close proximity. Accidental placement of regurgitated, partly-digested carrion in queen cells may have promoted admixture of hypopharyngeal glandular secretions and microbes with harvested liquid carrion. The most derived species, T. necrophaga, may have additional mutualist microbes because only this species has distinctive grey-green protein, and five Bacillus species in food pots and brood cells. No unusual anatomical features were found in worker bees. All three species make sweet, clear honey that contains some pollen but is of unknown origin.
68 citations
TL;DR: Experiments with the cyclic AMP‐deficient cr‐1 mutant suggested that the effects of temperature shifts on trehalose level were independent of cAMP metabolism, and cells exposed at 45°C under conditions permissive fortrehalose accumulation also acquired thermotolerance.
66 citations
TL;DR: A study conducted on rats using classical clearance techniques and arterial pressure measurements showed that stevioside from Stevia rebaudiana leaves produced a fall in systemic blood pressure, as well as diuresis and natriuresis per milliliter of glomerular filtration rate, consistent with the possibility that st Stevioside may act as a calcium antagonist, as is the case for verapamil.
56 citations
TL;DR: A soluble form of an alkaline phosphatase obtained from rat osseous plates was purified and showed a broad substrate specificity, however, ATP, bis(p-nitrophenyl) phosphate and pyrophosphate were among the less hydrolyzed substrates assayed.
48 citations
TL;DR: The antihypertensive drug methyldopa (Aldomet) was tested for possible clastogenic activity on normal and hypertensive rats and on human lymphocyte cultures and for its influence on the cell cycle of Allium cepa and showed a toxic effect on A. cepA root tip cells.
Abstract: The antihypertensive drug methyldopa (Aldomet) was tested for possible clastogenic activity on normal and hypertensive rats and on human lymphocyte cultures and for its influence on the cell cycle of Allium cepa. The drug had no clastogenic effect on rat bone marrow cells but showed a toxic effect on A. cepa root tip cells and significantly increased the frequency of sister-chromatid exchanges in lymphocyte cultures, without any effect on the frequency of chromosome aberrations.
15 citations
TL;DR: In this paper, the reaction system of an organic substrate by iodosylbenzene in organic solvents was studied by UV-Vis and EPR spectroscopic techniques at low temperature and the following intermediate species were detected: (i) oxo iron(IV) porphyrin π-cation radical supposed to be present in the oxidation reaction was not detected in our experimental conditions.
13 citations
Journal Article•
TL;DR: The results indicate that different levels of activity have different effects on the cardiac function of Megalobulimus sanctipauli, and the lowest heart rate was associated with the animal retracted into the shell and the highest rates were related to locomotion and feeding behaviors.
Abstract: Adult specimens (N = 20) of the pulmonate land snail Megalobulimus sanctipauli were observed systematically in the laboratory and four behavioral patterns reflecting different degrees of activity are described. The changes in heart rate associated with different behavioral patterns were monitored using three silver chloride electrodes chronically implanted in the visceral mass of the animals (N = 13). Continuous heart rate recordings were performed at room temperature (25 degrees C) with a Nihon Kohden polygraph model RM-45. Analysis of the results by the Multiple Comparisons Test based on Friedman rank sums revealed significant differences in heart rate, reported as median, between the following behaviors: retracted into the shell and locomotion, 25 vs 35 (P less than 0.008), retracted and eating, 25 vs 38 (P less than 0.008), still with local activity and eating, 33 vs 38 (P = 0.021). These results indicate that different levels of activity have different effects on the cardiac function of Megalobulimus sanctipauli. The lowest heart rate was associated with the animal retracted into the shell. The highest rates were related to locomotion and feeding behaviors.
11 citations
Journal Article•
TL;DR: The mussel Anodontites trapesialis (Lam, 1819) was used as an indicator of organochloride pollutants in the Canoas River, located in the municipality of Mococa, State of São Paulo, Brazil, and found to have been exposed to DDT, Lindane and Heptachlor.
Abstract: The mussel Anodontites trapesialis (Lam, 1819) was used as an indicator of organochloride pollutants in the Canoas River, located in the municipality of Mococa (21 degrees 25'08''S and 47 degrees W), State of Sao Paulo, Brazil. Biological monitoring was performed for one year at the site of an orange grove on the left bank of the river. Forty-five animals were placed in aluminum enclosures on the river bottom at this site and 4 animals were sacrificed for pesticide analysis at 3-month intervals, each corresponding to one season of the year. Pesticides were extracted by the method of Bedford et al., (1968), modified, and the analyses were performed by gas phase chromatography equipped with an electron capture detector. The animals were found to have been exposed to DDT, Lindane and Heptachlor. Variation in Aldrin and Dieldrin levels was not significant enough to permit inferences. Endrin was not detected in any of the analyses.
11 citations
TL;DR: No significant increase in frequency of chromosomal aberrations in bone marrow cells or of micronuclei in peripheral blood cells was detected in the animals acutely or chronically exposed to Rochagan in vivo.
Abstract: Benznidazole (bz) is the active component of the antichagasic drug Rochagan. Tests were carried out to detect the induction of chromosomal aberrations and micronuclei in rodent bone marrow cells and peripheral blood cells, respectively. Rats were exposed to acute treatment with Rochagan by gavage at total doses of 150, 300, 1500, 2000 and 3000 mg bz/kg body weight and killed at different times. In the chronic treatments, healthy and chagasic Balb/c mice were treated with Rochagan by gavage at a dose of 100 mg bz/kg/day for 10 and 25 days. No significant increase in frequency of chromosomal aberrations in bone marrow cells or of micronuclei in peripheral blood cells was detected in the animals acutely or chronically exposed to Rochagan in vivo.
TL;DR: In this paper, the reduction of benzenesulfonyl derivatives of n-butylamine and N,N -di-n-butyl-4- and N -n- butyl-2-nitrobenzenes sulfonamides is reported.
TL;DR: Cytological observations of the nuclei of 250 spores of the wild strain indicated that the most frequent class contained 12 nuclei, which may permit the occurrence of heterokaryosis and account at least in part for the variability observed.
Journal Article•
TL;DR: Microinjection of morphine into the periaqueductal grey area (PAG) of C57BL/6 (C57) and DBA/2 (DBA) mice increased the pain threshold in the tail-flick test and confirmed that these two strains of mice present genotype-dependent differences in sensitivity to opioids as determined after injections of morphine.
Abstract: 1. Microinjection of morphine (0.31, 1.25 and 5.0 micrograms) into the periaqueductal grey area (PAG) of C57BL/6 (C57) and DBA/2 (DBA) mice increased the pain threshold in the tail-flick test. The highest dose also caused a behavioral reaction in both strains characterized by periods of immobility alternating with explosive motor behavior. 2. In the DBA strain, the analgesic effect was demonstrated with all doses of morphine, while in the C57 strain only the highest dose induced analgesia. 3. DBA mice presented a decrease in activity with the lowest dose of morphine, whereas in the C57 strain, this effect was obtained only with the highest dose of morphine. 4. These data corroborate at the PAG level the results of other studies which have shown that central and peripheral injections of morphine produce analgesia and alter motor activity in C57 and DBA strains. They also confirm that these two strains of mice present genotype-dependent differences in sensitivity to opioids as determined after injections of morphine into the PAG.
01 Jan 1991
TL;DR: In this article, a soluble form of an alkaline phosphatase obtained from rat osseous plates was purified 204-fold with a yield of 24.3% and showed a single protein band of Mr 80 000 on SDS-PAGE and an apparent molecular weight of 163 000 by gel filtration on Sephacryl S-300.
Abstract: A soluble form of an alkaline phosphatase obtained from rat osseous plates was purified 204-fold with a yield of 24.3%. The purified enzyme showed a single protein band of Mr 80 000 on SDS-PAGE and an apparent molecular weight of 163 000 by gel filtration on Sephacryl S-300 suggesting a dimeric structure for the soluble enzyme. The specific activity of the enzyme at pH 9.4 in the presence of 2 mM MgCl2 was 19 027 U/mg and the hydrolysis of p-nitrophenyl phosphate (K0.5 = 92 μM) showed positive cooperativity (n = 1.5). The purified enzyme showed a broad substrate specificity, however, ATP, bis(p-nitrophenyl) phosphate and pyrophosphate were among the less hydrolyzed substrates assayed. Surprisingly the enzyme was not stimulated by cobalt and manganese ions, in contrast with a 20–25% stimulation observed for magnesium and calcium ions. Zinc ions exerted a strong inhibition on p-nitrophenylphosphatase activity of the enzyme. This paper provides a simple experimental procedure for the isolation of a soluble form of alkaline phosphatase which is induced by demineralized bone matrix during endochondral ossification.
Journal Article•
TL;DR: The results provide additional evidence for the participation of the DPAG in the physiopathology of anxiety and suggest that it may be a site for the anxiolytic effect of systemically injected benzodiazepines.
Abstract: In order to investigate the role of the dorsal periaqueductal grey (DPAG) area in the anxiolytic effect of benzodiazepines male Wistar rats (N = 10), weighing 200-250 g at the time of surgery, were microinjected into this structure with midazolam (80 nmol) and submitted to the elevated plus-maze, an ethologically based model of anxiety. Midazolam significantly increased the percentage of open arm entries from 32.4 +/- 4.6 (control) to 49.5 +/- 3.0 and of time spent in the open arms from 21.0 +/- 4.5 (control) to 35.6 +/- 4.8 without affecting the total number of entries into either open or enclosed arms. This effect typifies an anxiolytic effect in the test and was antagonized by the benzodiazepine receptor antagonist flumazenil (80 nmol) microinjected into the same site 10 min before the midazolam (80 nmol) microinjection. Microinjection of flumazenil alone had no effect. These results provide additional evidence for the participation of the DPAG in the physiopathology of anxiety and suggest that it may be a site for the anxiolytic effect of systemically injected benzodiazepines.
TL;DR: O estudo serviu de subsidio para o replanejamento da unidade de ensino, no qual foram levadas em consideracao as expectativas e necessidades dos alunos para melhor aproveitamento, atraves de situacoes de aprendizagem planejadas.
Abstract: Por meio de um pre-teste, foram identificados os conhecimentos previos sobre terapia intensiva, paciente critico e as expectativas quanto a unidade de ensino "Assistencia de Enfermagem ao Paciente de Terapia Intensiva", entre os alunos do 7o semestre do Curso de Graduacao em Enfermagem. A analise dos dados mostrou que os conhecimentos e as expectativas dos alunos estao impregnadas de preconceitos devido a estigmas sobre os temas. O estudo, serviu de subsidio para o replanejamento da unidade de ensino, no qual foram levadas em consideracao as expectativas e necessidades dos alunos para melhor aproveitamento, atraves de situacoes de aprendizagem planejadas.
Journal Article•
TL;DR: The results indicate that the neocorticate, and the hippocampus in the absence of the neocortex, is not essential for spatial localization using a cue-learning strategy.
Abstract: Experiments were carried out in order to determine whether groups of rats with unilateral or bilateral ablation of the neocortex or with removal of the neocortex plus the hippocampus of either hemisphere could learn to escape from a tank of water by climbing a visible platform when trained for 6 consecutive days
TL;DR: In this paper, the free energy of transfer of Sn(II) from acetonitrile to N,N-dimethylformamide and to their mixtures was obtained using the theory of Cox et al.
01 Aug 1991
TL;DR: In this article, a programa desenvolvido junto a criancas iniciantes no ciclo basico and algumas caracteristicas comportamentais destas crianca nesta fase de transicao ecologica is described.
Abstract: Este e um estudo exploratorio que descreve: um programa desenvolvido junto a criancas iniciantes no ciclo basico e algumas caracteristicas comportamentais destas criancas nesta fase de transicao ecologica. O programa envolveu uma atuacao sobre o contexto ambiental visando a facilitacao da ambientacao das criancas a escola. Os resultados mostram dados favoraveis a proposta apresentada e novos estudos sao sugeridos para maiores consideracoes.