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171.
F. Aboagye-Nuamah S.K. Offei E.W. Cornelius & R.D. Bancroft 《The Annals of applied biology》2005,147(2):183-190
Severity of storage rots in different sections of white yam tubers (Dioscorea rotundata Poir.) was investigated. Yam samples with rots were collected from a yam barn and from selected markets in Accra, Ghana, to identify the most predominant pathogens associated with the rots. Nine fungal spoilage microorganisms, including Aspergillus flavus, Aspergillus niger, Botryodiplodia theobromae, Fusarium culmorum, Fusarium oxysporium, Fusarium sp., Penicillium brevi‐compactum, Penicillium sp. and Rhizopus stolonifer and a bacterium species Erwinia carotovora were identified. The mean incidence of occurrence of the organisms on rotten tissues ranged from 1.2% to 28.5%. Of the 10 microorganisms isolated, B. theobromae, F. oxysporium and R. stolonifer were the most frequently encountered spoilage microorganisms in the markets. E. carotovora, Fusarium solani and Penicillium sp. were relatively sparse (incidence not exceeding 3%) compared to the other yam spoilage microorganisms. The surface area and weight of necrotic tissue induced by the spoilage fungi in the various zones of the tubers over a 28‐day storage period were assessed. All the spoilage microorganisms produced rots in the yams, although to different degrees. The severity of the rots increased in weight and area over the period when the tubers were in store but were normally not significantly different in the zones of tubers. There was, however, a linear progression of rots in the various zones of the yam tubers. Although there was generally no significant (P ≥ 0.05) difference in the severity of rots induced by the different microorganisms in the tubers, R. stolonifer commonly induced more rot in the zones of the tubers compared to B. theobromae and F. oxysporium. 相似文献
172.
173.
The flavonoid glycosides of both varieties of Elmera racemosa were isolated and identified. The compounds were the monoglucosides of kaempferol, quercetin and myricetin, the rutinosides of the same aglycones, and the rhamnosylrutinosides of kaempferol and quercetin. All glycosides were linked at position-3 of the flavonols. The two varieties (var. racemosa and var. puberulenta C. L. Hitchcock) were identical. A comparison of the flavonoid chemistry of Elmera, Heuchera, and Tellima supports the existence of Elmera as a genus. A survey of several collections of Tellima grandiflora, Heuchera micrantha, and H. cylindrica showed only minor quantitative differences in the two-dimensional thin layer chromatograms from collection to collection. The possible origin of Tellima and Elmera from ancestral stock having Heuchera-like flavonoid chemistry is discussed. 相似文献
174.
Phosphoglycerate mutase-derived polypeptide inhibits glycolytic flux and induces cell growth arrest in tumor cell lines 总被引:3,自引:0,他引:3
Engel M Mazurek S Eigenbrodt E Welter C 《The Journal of biological chemistry》2004,279(34):35803-35812
The putative tumor metastasis suppressor protein Nm23-H1 is a nucleoside diphosphate kinase that exhibits a novel protein kinase activity when bound to glyceraldehyde-3-phosphate dehydrogenase (GAPDH). In this study we show that the glycolytic enzyme phosphoglycerate mutase B (PGM) becomes phosphorylated in the presence of the Nm23-H1.GAPDH complex in vitro. Mutation of His-10 in PGM abolishes the Nm23-H1.GAPDH complex-induced phosphorylation. Nm23-H1, GAPDH, and PGM are known to co-localize as shown by free flow isoelectric focusing. In association with Nm23-H1 and GAPDH, PGM could be activated by dCTP, which is a substrate of Nm23-H1, in addition to the well known PGM activator 2,3-bisphosphoglycerate. A synthetic cell-penetrating peptide (PGMtide) encompassing the phosphorylated histidine and several residues from PGM (LIRHGE) promoted growth arrest of several tumor cell lines, whereas proliferation of tested non-tumor cells was not influenced. Analysis of metabolic activity of one of the tumor cell lines, MCF-7, indicated that PGMtide inhibited glycolytic flux, consistent with in vivo inhibition of PGM. The specificity of the observed effect was further determined experimentally by testing the effect of PGMtide on cells growing in the presence of pyruvate, which helps to compensate PGM inhibition in the glycolytic pathway. Thus, growth of MCF-7 cells was not arrested by PGMtide in the presence of pyruvate. The data presented here provide evidence that inhibition of PGM activity can be achieved by exogenous addition of a polypeptide, resulting in inhibition of glycolysis and cell growth arrest in cell culture. 相似文献
175.
Background
For many applications one wishes to decide whether a certain set of numbers originates from an equiprobability distribution or whether they are unequally distributed. Distributions of relative frequencies may deviate significantly from the corresponding probability distributions due to finite sample effects. Hence, it is not trivial to discriminate between an equiprobability distribution and non-equally distributed probabilities when knowing only frequencies. 相似文献176.
Although numerous reactions have been performed using lipases and related enzymes (e.g. esterases and phospholipases), it is still a challenge to identify the most suitable biocatalyst and best reaction conditions for an efficient application. Frequently used methods such as immobilization and optimization of the reaction medium cannot be transferred from one reaction system or substrate to another. However, in the past few years, rational protein design and directed evolution have emerged as efficient alternative methods to optimize biocatalytic reactions. 相似文献
177.
Cornelius Hammer Axel Temming Hans-Joachim Schubert 《International Review of Hydrobiology》1994,79(3):385-396
Measurements of the swimming activity of a group of roach (12–19 cm TL, average) in a circular swimming chamber revealed two distinct activity patterns: a diurnal and a nocturnal one. The experiments showed that, having the choice, two factors stimulated the rhythmicity of the swimming behaviour of the fish, i.e. light intensity and the presence of a current field in the proximity of the fish. During daytime (bright light conditions) the fish moved into the current field and swam on average at 0.4 BL/s (resting swimming). The roach remained swimming at this speed even if no current field was established, however, then distributed evenly in the basin. By contrast, during night (dim light conditions) the fish predominantly chose the still water section but swam on average with a cruising speed of 1.6 BL/s (night swimming). Accordingly, they did not seek the still water section for night swimming if the light was kept on. Then again, the fish distributed more or less evenly in the basin. The results support the hypothesis that the fish migrate during night-time and do this preferably in still water. 相似文献
178.
Biomass, chemical composition, growth rates and the photosynthetic response of natural populations of sea ice algae in McMurdo Sound, Antarctica were followed over most of the spring bloom to examine temporal variability under a relatively constant incident irradiance (ca. 1500–1700 μE · m-2· s-1 at solar noon). Collection were restricted to bottom 20 cm of the ice sheet in an area with little or no snow (0–5 cm). At low temperature and irradiance these algae normally exhibited low assimilation numbers (ca. 0.1–0.4 mg C · mg Chl-1· h-1). Average growth rates (0.02–0.45 d-1), based on changes in standing stocks, were also low. Biomass, biochemical composition, growth rates, assimilation numbers and photosynthetic efficiencies (mg C · mg Chl-1· h-1 (μE · m-2· s-1)-1) displayed large fluctuations over periods of several days during the growth season. On the other hand, Ik which is an index of photoadaptation, and Im, the optimal irradiance for photosynthesis, were relatively constant with less than twofold variation throughout our study. Substantial nutrient fluxes (3.3–8.0 mmol Si or N · m-2· d-1) were necessary to satisfy the minimum nutrient demand for the observed biomass levels and population growth rates; over the 41 days of our study, integrated nutrient demand represented 69–150 mmol N or Si · m-2, Only 5–25% of this total demand could be met by all of the nutrients in the ice sheet, if they were readily available. However, adequate amounts were present in the top few meters of the water column. With small nutrient gradients in surface waters below the sea ice, vertical eddy diffusivities on the order of 3.8–9.3 cm2· s- should supply sufficient nutrients to meet algal demand. 相似文献
179.
Christian I. Schwer Cornelius Lehane Timo Guelzow Simone Zenker Karl M. Strosing Sashko Spassov Anika Erxleben Bernd Heimrich Hartmut Buerkle Matjaz Humar 《PloS one》2013,8(10)
Ischemic and traumatic brain injury is associated with increased risk for death and disability. The inhibition of penumbral tissue damage has been recognized as a target for therapeutic intervention, because cellular injury evolves progressively upon ATP-depletion and loss of ion homeostasis. In patients, thiopental is used to treat refractory intracranial hypertension by reducing intracranial pressure and cerebral metabolic demands; however, therapeutic benefits of thiopental-treatment are controversially discussed. In the present study we identified fundamental neuroprotective molecular mechanisms mediated by thiopental. Here we show that thiopental inhibits global protein synthesis, which preserves the intracellular energy metabolite content in oxygen-deprived human neuronal SK-N-SH cells or primary mouse cortical neurons and thus ameliorates hypoxic cell damage. Sensitivity to hypoxic damage was restored by pharmacologic repression of eukaryotic elongation factor 2 kinase. Translational inhibition was mediated by calcium influx, activation of the AMP-activated protein kinase, and inhibitory phosphorylation of eukaryotic elongation factor 2. Our results explain the reduction of cerebral metabolic demands during thiopental treatment. Cycloheximide also protected neurons from hypoxic cell death, indicating that translational inhibitors may generally reduce secondary brain injury. In conclusion our study demonstrates that therapeutic inhibition of global protein synthesis protects neurons from hypoxic damage by preserving energy balance in oxygen-deprived cells. Molecular evidence for thiopental-mediated neuroprotection favours a positive clinical evaluation of barbiturate treatment. The chemical structure of thiopental could represent a pharmacologically relevant scaffold for the development of new organ-protective compounds to ameliorate tissue damage when oxygen availability is limited. 相似文献
180.
Cuong Q Nguyen Janet G Cornelius Lauren Cooper Jonathan Neff Joann Tao Byung Ha Lee Ammon B Peck 《Arthritis research & therapy》2008,10(6):R137