Enhanced cellulase production by <Emphasis Type="Italic">Trichoderma harzianum</Emphasis> by cultivation on glycerol followed by induction on cellulosic substrates

The use of glycerol obtained as an intermediate of the biodiesel manufacturing process as carbon source for microbial growth is a potential alternative strategy for the production of enzymes and other high-value bioproducts. This work evaluates the production of cellulase enzymes using glycerol for high cell density growth of Trichoderma harzianum followed by induction with a cellulosic material. Firstly, the influence of the carbon source used in the pre-culture step was investigated in terms of total protein secretion and fungal morphology. Enzymatic productivity was then determined for cultivation strategies using different types and concentrations of carbon source, as well as different feeding procedures (batch and fed-batch). The best strategy for cellulase production was then further studied on a larger scale using a stirred tank bioreactor. The proposed strategy for cellulase production, using glycerol to achieve high cell density growth followed by induction with pretreated sugarcane bagasse, achieved enzymatic activities up to 2.27 ± 0.37 FPU/mL, 106.40 ± 8.87 IU/mL, and 9.04 ± 0.39 IU/mL of cellulase, xylanase, and β-glucosidase, respectively. These values were 2 times higher when compared to the control experiments using glucose instead of glycerol. This novel strategy proved to be a promising approach for improving cellulolytic enzymes production, and could potentially contribute to adding value to biomass within the biofuels sector.     

Glucose transport and utilization are altered in the brain of rats deficient in n-3 polyunsaturated fatty acids

Long-chain polyunsaturated (n-3) fatty acids have been reported to influence the efficiency of membrane receptors, transporters and enzymes. Because the brain is particularly rich in docosahexaenoic acid (DHA, 22:6 n-3), the present study addresses the question of whether the 22:6 n-3 fatty acid deficiency induces disorder in regulation of energy metabolism in the CNS. Three brain regions that share a high rate of energy metabolism were studied: fronto-parietal cortex, hippocampus and suprachiasmatic nucleus. The effect of the diet deficient in n-3 fatty acids resulted in a 30-50% decrease in DHA in membrane phospholipids. Moreover, a 30% decrease in glucose uptake and a 20-40% decrease in cytochrome oxidase activity were observed in the three brain regions. The n-3 deficient diet also altered the immunoreactivity of glucose transporters, namely GLUT1 in endothelial cells and GLUT3 in neurones. In n-3 fatty acid deficient rats, GLUT1-immunoreactivity readily detectable in microvessels became sparse, whereas the number of GLUT3 immunoreactive neurones was increased. However, western blot analysis showed no significant difference in GLUT1 and GLUT3 protein levels between rats deficient in n-3 fatty acids and control rats. The present results suggest that changes in energy metabolism induced by n-3 deficiency could result from functional alteration in glucose transporters.     

Naturally occurring radionuclides in food and drinking water from a thorium-rich area

This paper focuses on a survey of uranium and thorium decay chain radionuclides in food and drinking water from the thorium-rich (monazite-bearing) region of Buena, which is located in the state of Rio de Janeiro, Brazil. The radionuclide concentration values in the food and drinking water from Buena reached values higher than 100-fold the international reference values. The daily intake of radionuclides by the local population is similar to that of another high background radiation area in Brazil, but the intake is higher than that of residents from a normal background radiation area. Approximately 58?% of the food consumed by Buena inhabitants is produced locally. Based on that figure, locally produced food and the dilution of total radionuclides in the diet of residents caused by food importation are both highly relevant to a population’s intake of radionuclides. The concentration values for ²¹⁰Pb and the radium isotopes in drinking water from Buena are among the highest values to be reported in the literature. ²²⁸Ra is the most important radionuclide ingested with both food and water among the inhabitants of Buena.     

Kinetics of double-chain reversals bridging contiguous quartets in tetramolecular quadruplexes

Repetitive 5'GGXGG DNA segments abound in, or near, regulatory regions of the genome and may form unusual structures called G-quadruplexes. Using NMR spectroscopy, we demonstrate that a family of 5'GCGGXGGY sequences adopts a folding topology containing double-chain reversals. The topology is composed of two bistranded quadruplex monomeric units linked by formation of G:C:G:C tetrads. We provide a complete thermodynamic and kinetic analysis of 13 different sequences using absorbance spectroscopy and DSC, and compare their kinetics with a canonical tetrameric parallel-stranded quadruplex formed by TG4T. We demonstrate large differences (up to 10(5)-fold) in the association constants of these quadruplexes depending on primary sequence; the fastest samples exhibiting association rate equal or higher than the canonical TG4T quadruplex. In contrast, all sequences studied here unfold at a lower temperature than this quadruplex. Some sequences have thermodynamic stability comparable to the canonical TG4T tetramolecular quadruplex, but with faster association and dissociation. Sequence effects on the dissociation processes are discussed in light of structural data.     

Antioxidant activities of Ptychopetalum olacoides (“muirapuama”) in mice brain

Ptychopetalum olacoides (PO) roots are used by Amazonian peoples to prepare traditional remedies for treating various central nervous system conditions in which free radicals are likely to be implicated. Following the identification of PO ethanol extract (POEE) free-radical scavenging properties in vitro, the aim of this study was to verify the in vivo antioxidant effect of POEE. Aging mice (14 months) were treated (i.p.) with saline, DMSO (20%) or POEE (100mg/kg body wt.), and the hippocampi, cerebral cortex, striata, hypothalamus and cerebellum dissected out 60 min later to measure antioxidant enzyme activities, free-radical production and damage to macromolecules. POEE administration reduced free-radical production in the hypothalamus, lead to significant decrease in lipid peroxidation in the cerebral cortex, striatum and hypothalamus, as well as in the carbonyl content in cerebellum and striatum. In terms of antioxidant enzymes, catalase activity was increased in the cortex, striatum, cerebellum and hippocampus, while glutathione peroxidase activity was increased in the hippocampus. This study suggests that POEE contains compounds able to improve the cellular antioxidant network efficacy in the brain, ultimately reducing the damage caused by oxidative stress.     

Microquantification of proteins with low chromophore content

The advantages of the intrinsic fluorescence of the tryptophan and the absorbance of the methionine residues of the 18 kDa-hsp - a recombinant protein from Mycobacterium leprae - was exploited here to develop a sensitive and low costs method for protein assaying. They presented linearity between 3 and 1000 g of protein. The correlations between intrinsic fluorescence or absorbance at 230 nm and protein contents were both superiors to 0.99. These methods can be extended to others proteins with low aromatic residue contents.     

Possibility of reducing the luteolytic dose of cloprostenol in cyclic dairy cows

The administration of cloprostenol by intravulvosubmucous (i.v.s.m.) injection at 1 2 and 1 4 of the dose usually given by intramuscular (i.m.) injection, was tested in dairy cows for luteolysis and estrus synchronization. The i.m. injection was used in ten adult cows at the usual dose of 500 mug/animal. Eleven adult cows and 11 heifers were treated i.v.s.m. with a dose equivalent to 250 mug/animal and 125 mug/animal, respectively. Two injections of cloprostenol were administered 11 days apart to the cows not detected in oestrus after a single injection. Forty-three out of the total 46 animals were detected to be in dioestrus at the time of at least one of the injections, as reflected by the plasma progesterone concentrations at the time of treatments. Three out of the 43 animals injected during dioestrus were refractory to the luteolytic effect of cloprostenol; this appeared to be independent of the dosage and the route of administration (refractory cows were: one adult cow treated i.m. and two treated i.v.s.m. with 125 mug of cloprostenol). The mean time interval from injection to the onset of heat was 82.8 hours with a confidence limit for 95% of probability between 67.9 hours and 92.7 hours. The difference between treatments is not significant. The results suggest that in heifers and adult cows cloprostenol can be given i.v.s.m. route at a reduced dose of 1 4 of the usual 500 mug i.m. dosage without affecting the luteolytic effect of the drug or fertility.