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排序方式: 共有198条查询结果,搜索用时 375 毫秒
61.
Peter W. Inglis Rubia B. C. Sarmento Camila F. C. Gavião Heloisa Frazão M. Cléria Valadares-Inglis 《World journal of microbiology & biotechnology》2006,22(10):1083-1085
Summary An insertional mutant of Metarhizium anisopliae is described with enhanced submerged conidiation. In a 500 ml submerged culture, this mutant produces a mean of 4.05 × 108 propagules ml−1 from an inoculum of 1 × 106 conidia, where the parental strain accumulates only 3.75 × 104 propagules ml−1. 相似文献
62.
The influence of the hydraulic retention time (HRT) and organic loading rate (OLR) on the performance of the hydrolytic–acidogenic step of a two-stage anaerobic digestion process of sunflower oil cake (SuOC) were assessed. The experiments were performed in laboratory-scale completely stirred tank reactors at mesophilic (35 °C) temperature. Six OLR (ranging from 4 to 9 g VS L−1 d−1) for four HRTs (8, 10, 12 and 15 days) were tested to check the effect of each operational variable. Based on the results obtained, it can be concluded that the hydrolysis yields obtained for all HRTs and OLRs assayed were in the range of 20.5–30.1%. In addition, the acidification degree of the substrate was mainly influenced by the OLR but not by the HRTs, the highest value (83.8%) being achieved for an HRT of 10 days and an OLR of 6 g VS L−1 d−1. 相似文献
63.
Ghezzi P Casagrande S Massignan T Basso M Bellacchio E Mollica L Biasini E Tonelli R Eberini I Gianazza E Dai WW Fratelli M Salmona M Sherry B Bonetto V 《Proteomics》2006,6(3):817-825
Using redox proteomics techniques to characterize the thiol status of proteins in human T lymphocytes, we identified cyclophilin A (CypA) as a specifically oxidized protein early after mitogen activation. CypA is an abundantly expressed cytosolic protein, target of the immunosuppressive drug cyclosporin A (CsA), for which a variety of functions has been described. In this study, we could identify CypA as a protein undergoing glutathionylation in vivo. Using MALDI-MS we identified Cys52 and Cys62 as targets of glutathionylation in T lymphocytes, and, using bioinformatic tools, we defined the reasons for the susceptibility of these residues to the modification. In addition, we found by circular dichroism spectroscopy that glutathionylation has an important impact on the secondary structure of CypA. Finally, we suggest that glutathionylation of CypA may have biological implications and that CypA may play a key role in redox regulation of immunity. 相似文献
64.
Casagrande R Georgetti SR Verri WA Jabor JR Santos AC Fonseca MJ 《AAPS PharmSciTech》2006,7(1):E64-E71
The present study evaluates the antioxidant activity of the flavonol quercetin, and its functional stability as a raw material
and when added in formulations. The iron-chelating activity was determined using the bathophenanthroline assay, and the functional
stability was evaluated with the antilipoperoxidative assay. Raw material presented concentration-dependent antilipoperoxidative
and iron-chelating activities. The initial antilipoperoxidative activity of the raw material, cream and gel-cream were 63%,
78%, and 69%, respectively. There was no detectable loss of activity during 182 days (6 months) of storage at all tested temperatures
(4°C, room temperature [RT], 37°C, and 45°C) for the raw material. Considering the method variability of 10%, activity loss
greater than 10% for nonionic cream was detected after 126 days at 4°C (20.1%), decreasing thereafter to 22.2% after 182 days.
At 45°C, the loss of activity started after 182 days (13.2%). For the anionic gel-cream, activity loss started after 84 days
(28.4%, 45°C), decreasing after 182 days to 40.3% at 45°C. At 37°C, activity loss was detected after 182 days (12%). In conclusion,
the results suggest that the activity of quercetin depends on iron chelation, and its posible usefulness as a topical antioxidant
to prevent oxidative stress-induced skin damage depends on maintaining its antilipoperoxidative activity stored at RT, which
avoids special storage conditions.
Published: February 3, 2006 相似文献
65.
Inhibition of mitochondrial creatine kinase activity by D-2-hydroxyglutaric acid in cerebellum of young rats 总被引:2,自引:0,他引:2
da Silva CG Bueno AR Rosa RB Dutra Filho CS Wannmacher CM Wyse AT Wajner M 《Neurochemical research》2003,28(9):1329-1337
D-2-Hydroxyglutaric aciduria (DHGA) is a neurometabolic disorder biochemically characterized by tissue accumulation and excretion of high amounts of D-2-hydroxyglutaric acid (DGA). Although the affected patients have predominantly severe neurological findings, the underlying mechanisms of brain injury are virtually unknown. In previous studies we have demonstrated that DGA, at concentrations as low as 0.25 mM, significantly decreased creatine kinase activity and other parameters of energy metabolism in cerebral cortex of young rats. In the present study, we investigated the effect of DGA (0.25-5 mM) on total creatine kinase (tCK) activity, as well as on CK activity in cytosolic (Cy-CK) and mitochondrial (Mi-CK) preparations from cerebellum of 30-day-old Wistar rats in order to test whether the inhibitory effect of DGA on CK was tissue specific. We verified that tCK (22% inhibition) and Mi-CK (40% inhibition) activities were moderately inhibited by DGA at concentrations of 2.5 mM and higher, in contrast to Cy-CK, which was not affected by the acid. Kinetic studies revealed that the inhibitory effect of DGA was non-competitive in relation to phosphocreatine. We also observed that this inhibition was fully prevented by preincubation of the homogenates with reduced glutathione, suggesting that the inhibition of CK activity by DGA is possibly mediated by modification of essential thiol groups of the enzyme. Our present results therefore demonstrate a relatively weak inhibitory effect of DGA on cerebellum Mi-CK activity, as compared to that provoked in cerebral cortex, and may possibly be related to the neuropathology of DHGA, characterized by cerebral cortex abnormalities. 相似文献
66.
Stefania Casagrande Davide Csermely Elena Pini Vittorio Bertacche James Tagliavini 《Journal of avian biology》2006,37(2):190-196
In the context of sexual selection carotenoid based signals are candidates for indicator traits: they have to be taken up in the diet by animals, they can indicate the ability of the bearer to accumulate a limited resource, and they help in maintaining the health status. We investigated the yellow-orange colouration of the tarsi of the kestrel Falco tinnunculus in relation to sex, diet and to different aspects of male reproductive behaviour. The colouration of the tarsi (estimated as hue) was more intense in males than in females. Among males, the tarsi hue was associated with the intake of invertebrates; this was true also if the population diet was based mainly on voles. Carotenoid based colouration was positively associated with the number of vertebrate preys delivered to the nest per time unit and with territory quality (calculated on the basis of home-range size, habitat extension and prey availability). These results are consistent with predictions derived from good-parent models of sexual selection, suggesting that in the common kestrel carotenoid based colouration is important as an indicator of male quality. 相似文献
67.
68.
Vianello Brondani RP Zucchi MI Brondani C Nakano Rangel PH De Oliveira Borba TC Rangel PN Magalhães MR Vencovsky R 《Genetica》2005,125(2-3):115-123
The existence of Oryza glumaepatula is threatened by devastation and, thus, the implementation of conservation strategies is extremely relevant. This study aimed
to characterize the genetic variability and estimate population parameters of 30 O. glumaepatula populations from three Brazilian biomes using 10 microsatellite markers. The levels of allelic variability for the SSR loci
presented a mean of 10.3 alleles per locus and a value of 0.10 for the average allelic frequency value. The expected total
heterozygosity (He) ranged from 0.63 to 0.86. For the 30 populations tested, the mean observed (Ho) and expected heterozygosities (He) were 0.03 and 0.11within population, respectively, indicating an excess of homozygotes resulting from the preferentially
self-pollinating reproduction habit. The estimated fixation index ( IS ) was 0.79 that differed significantly from zero, indicating high inbreeding within each O. glumaepatula population. The total inbreeding of the species (IT ) was 0.98 and the genetic diversity indexes among populations, ST and ST, were 0.85 and 0.90, respectively, indicating high genetic variability among them. Thus, especially for populations located
in regions threatened with devastation, it is urgent that in situ preservation conditions should be created or that collections be made for ex situ preservation to prevent loss of the species genetic variability. 相似文献
69.
p21CIP1 is dispensable for the G2 arrest caused by genistein in human melanoma cells 总被引:1,自引:0,他引:1
We have investigated the effect of genistein on cell cycle distribution of the human choroidal melanoma cell line OCM-1. We report that this isoflavonoid arrested cells in G2. This effect was correlated with the induction of the CDK inhibitor p21CIP1. However, while CDK1 activity was markedly reduced following genistein treatment, CDK2 activity was not affected. This was in agreement with the absence of G1 arrest that we observed but caused some doubt about the functionality of p21CIP1. Attempts to demonstrate mutation or post-translational modification of p21CIP1 from OCM-1 cells were unsuccessful. In fact, the level of p21CIP1 induced by genistein was shown to be insufficient to cause CDK2 inhibition. The role of p21CIP1 in the inhibition of CDK1 was questionable, as we demonstrated that genistein impaired Tyr15 dephosphorylation of CDK1 and because CDK1-cyclin B1 complexes from treated cells could be reactivated upon exposure to CDC25 phosphatase. Finally, we report that p21CIP1 was not absolutely required for the genistein-induced G2 arrest, as the isoflavone caused at least partial G2 arrest in p21-deficient Rat-1 fibroblasts as well as in p21-/- mouse embryo fibroblasts. 相似文献
70.
Dantzer F de La Rubia G Ménissier-De Murcia J Hostomsky Z de Murcia G Schreiber V 《Biochemistry》2000,39(25):7559-7569
In mammalian cells, damaged bases in DNA are corrected by the base excision repair pathway which is divided into two distinct pathways depending on the length of the resynthesized patch, replacement of one nucleotide for short-patch repair, and resynthesis of several nucleotides for long-patch repair. The involvement of poly(ADP-ribose) polymerase-1 (PARP-1) in both pathways has been investigated by using PARP-1-deficient cell extracts to repair single abasic sites derived from uracil or 8-oxoguanine located in a double-stranded circular plasmid. For both lesions, PARP-1-deficient cell extracts were about half as efficient as wild-type cells at the polymerization step of the short-patch repair synthesis, but were highly inefficient at the long-patch repair. We provided evidence that PARP-1 constitutively interacts with DNA polymerase beta. Using cell-free extracts from mouse embryonic cells deficient in DNA polymerase beta, we demonstrated that DNA polymerase beta is involved in the repair of uracil-derived AP sites via both the short and the long-patch repair pathways. When both PARP-1 and DNA polymerase beta were absent, the two repair pathways were dramatically affected, indicating that base excision repair was highly inefficient. These results show that PARP-1 is an active player in DNA base excision repair. 相似文献