This work investigated the influence of temperature, pressure, exposure times and depressurization rate on the activity of a non-commercial immobilized lipase from Yarrowia lipolytica (YLL) submitted to compressed carbon dioxide, propane and n-butane. A high-pressure cell was employed in the experiments, in the pressure range of 10–280 bar, varying the temperature from 35 to 75 °C, exposure times from 1 to 6 h, and adopting distinct decompression rates. Results showed that significant activity losses were obtained when the treatment was conducted in carbon dioxide, while negligible losses were observed in both propane and n-butane. For the treatment with carbon dioxide, within the range studied, the decompression rate affected positively enzyme activity, while the exposure time and temperature presented an opposite effect on the non-commercial immobilized lipase from Y. lipolytica (YLL). Additionally, the performance of two commercial immobilized lipases (Lipozyme IM and Novozym 435) and the immobilized YLL in the three solvents was compared. Immobilized YLL has shown to be more suitable than Lipozyme IM for enzyme-catalyzed reactions using compressed propane and n-butane as solvents, but with inferior performance compared to Novozym 435 treated in these solvents. 相似文献
The composition of a metabolically active prokaryotic community thriving in hydrothermal mud fluids of the deep-sea hypersaline
anoxic Western Urania Basin was characterized using rRNA-based phylogenetic analysis of a clone library. The physiologically
active prokaryotic assemblage in this extreme environment showed a great genetic diversity. Most members of the microbial
community appeared to be affiliated to yet uncultured organisms from similar ecosystems, i.e., deep-sea hypersaline basins
and hydrothermal vents. The bacterial clone library was dominated by phylotypes affiliated with the epsilon-Proteobacteria subdivision recognized as an ecologically significant group of bacteria inhabiting deep-sea hydrothermal environments. Almost
18% of all bacterial clones were related to delta-Proteobacteria, suggesting that sulfate reduction is one of the dominant metabolic processes occurring in warm mud fluids. The remaining
bacterial phylotypes were related to alpha- and beta-Proteobacteria, Actinobacteria, Bacteroides, Deinococcus-Thermus, KB1 and OP-11 candidate divisions. Moreover, a novel monophyletic clade, deeply branched with unaffiliated 16S rDNA clones
was also retrieved from deep-sea sediments and halocline of Urania Basin. Archaeal diversity was much lower and detected phylotypes
included organisms affiliated exclusively with the Euryarchaeota. More than 96% of the archaeal clones belonged to the MSBL-1 candidate order recently found in hypersaline anoxic environments,
such as endoevaporitic microbial mats, Mediterranean deep-sea mud volcanoes and anoxic basins. Two phylotypes, represented
by single clones were related to uncultured groups DHVE-1 and ANME-1. Thus, the hydrothermal mud of hypersaline Urania Basin
seems to contain new microbial diversity. The prokaryotic community was significantly different from that occurring in the
upper layers of the Urania Basin since 60% of all bacterial and 40% of all archaeal phylotypes were obtained only from mud
fluids. The uniqueness of the composition of the active prokaryotic community could be explained by the complex environmental
conditions at the site. The interaction of oxygenated warm mud fluids with the cold hypersaline brine of the Urania Basin
seems to simultaneously select for various metabolic processes, such as aerobic and anaerobic heterotrophy, sulfide- and methane-dependent
chemotrophy along with anaerobic oxidation of methane, sulfate- and metal-reduction. 相似文献
A cation-sensing electrode can be used to monitor enzymatic reactions if their substrates and products differ in the ability to bind the cation. In the first method, the electrode potential vs time curve is recorded. The second, metal-stat method consists of measuring the rate at which substrate must be added to the reaction medium in order to keep the electrode potential at a constant level. These approaches have been used to assay inorganic pyrophosphatase, carboxypeptidase A, and hexokinase with the Mg2+ and Cu2+ ions as the indicators. 相似文献
Summary Computer simulations of tight epithelia under three experimental conditions have been carried out, using the rheogenic nonlinear model of Lew, Ferreira and Moura (Proc. Roy. Soc. London. B206:53–83, 1979) based largely on the formulation of Koefoed-Johnsen and Ussing (Acta Physiol. Scand.42:298–308, 1958). First, analysis of the transition between the short-circuited and open-circuited states has indicated that (i) apical Cl– permeability is a critical parameter requiring experimental definition in order to analyze cell volume regulation, and (ii) contrary to certain experimental reports, intracellular Na+ concentration (cNac
) is expected to be a strong function of transepithelial clamping voltage. Second, analysis of the effects of lowering serosal K+ concentration (cKs
) indicates that the basic model cannot simulate several well-documented observations; these defects can be overcome, at least qualitatively, by modifying the model to take account of the negative feedback interaction likely to exist between the apical Na+ permeability andcNac
. Third, analysis of the effects induced by lowering mucosal Na+ concentration (cNam
) strongly supports the concept that osmotically induced permeability changes in the apical intercellular junctions play a physiological role in conserving the body's stores of NaCl. The analyses also demonstrate that the importance of Na+ entry across the basolateral membrane is strongly dependent upon transepithelial potential,cNam
andcKs
; under certain conditions, net Na+ entry could be appreciably greater across the basolateral than across the apical membrane. 相似文献
The mechanism of how bone adapts to every day demands needs to be better understood to gain insight into situations in which the musculoskeletal system is perturbed. This paper offers a novel multi-factorial mathematical model of bone density adaptation which combines previous single-factor models in a single adaptation system as a means of gaining this insight. Unique aspects of the model include provision for interaction between factors and an estimation of the relative contribution of each factor. This interacting system is considered analogous to a Newtonian mechanical system and the governing response equation is derived as a linear version of the adaptation process. The transient solution to sudden environmental change is found to be exponential or oscillatory depending on the balance between cellular activation and deactivation frequencies. 相似文献
The endothelial type (NOS-3) of three isoforms of nitric oxide (NO) synthase occurs in porcine oocytes and granulosa cells, but the regulation of NO synthesis in oocytes remains unknown. The present study was designed to evaluate steroid control in the process of oocyte NO synthesis. Cumulus-oocyte complexes (COCs), obtained from small-sized antral follicles of immature porcine ovaries, were cultured in estrogen-deprived medium, and the effect of steroids or steroid-free porcine follicular fluids on the NO release from oocytes was investigated. Oocytes that were isolated from cultured COCs were incubated with 1 M ionomycin. The NO metabolites were identified using a NO detector-high-pressure liquid chromatography system. Oocytes from COCs cultured with 10 nM 17-estradiol (E2) released NO in response to ionomycin, whereas progesterone and testosterone had little effect on the synthesis of NO. An inhibitor of NOS suppressed the synthesis of NO. The maximal synthesis was observed after a 15 h-culture with E2. However, oocytes freshly obtained from antral follicles did not response to ionomycin, and the E2 action was suppressed by the addition of steroid-free follicular fluids. Analyses of RT-PCR and Western blotting showed that E2 did not increase NOS-3 expression. In addition, estrogen receptor was detected in oocytes and cumulus cells, and estrogen receptor was detected only in cumulus cells. These findings suggest that oocyte NOS-3 is promoted for the synthesis of NO by E2 without increases in NOS-3 expression, but the synthesis of NO is suppressed, at least in the oocytes of early antral follicles. 相似文献
Introduction: The development of precision medicine requires advanced technologies to address the multifactorial disease stratification and to support personalized treatments. Among omics techniques, proteomics based on Mass Spectrometry (MS) is becoming increasingly relevant in clinical practice allowing a phenotypic characterization of the dynamic functional status of the organism. From this perspective, Matrix Assisted Laser Desorption Ionization Time of Flight (MALDI-TOF) MS is a suitable platform for providing a high-throughput support to clinics.
Areas covered: This review aims to provide an updated overview of MALDI-TOF MS applications in clinical proteomics. The most relevant features of this analysis have been discussed, highlighting both pre-analytical and analytical factors that are crucial in proteomics studies. Particular emphasis is placed on biofluids proteomics for biomarkers discovery and on recent progresses in clinical microbiology, drug monitoring, and minimal residual disease (MRD).
Expert commentary: Despite some analytical limitations, the latest technological advances together with the easiness of use, the low time and low cost consuming and the high throughput are making MALDI-TOF MS instruments very attractive for the clinical practice. These features offer a significant potential for the routine of the clinical laboratory and ultimately for personalized medicine. 相似文献