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981.
González AI Pérez de la Vega M Ruiz ML Polanco C 《Applied and environmental microbiology》2003,69(8):4979-4982
The analysis of 46 isolates obtained directly from different and distant common bean fields from the northwestern part of Spain revealed that they do not produce phaseolotoxin. The isolates were classified as race 5, and their analysis revealed that they do not carry the argK-tox gene cluster involved in the biosynthesis of the phaseolotoxin. 相似文献
982.
Pharmacovigilance is a health sciences discipline devoted to the data collection, data analysis and decision-making related to adverse drug reactions (ADR). It has played an expanded theoretical and practical role since the 1960's. However, few studies have made a careful analysis of the decision-making costs in evaluating ADRs. Herein, the relevant literature is reviewed concerning the costs generated due to the attention of the drug adverse events in medical practice. Examples are taken from international literature which offer by extrapolation of the potential future costs of ADR in Colombia. The objective is to sensitize and generate insights about the need for implementation and development of a national pharmacovigilance system. 相似文献
983.
Continuous cultures of two strains of Clostridium acetobutylicum were stable for over 70 d when grown on glucose/glycerol mixtures. Butanol was the major fermentation end-product, accounting for 43 to 62% (w/w) of total products. Low-grade glycerol [65% (w/v) purity] could replace commercial glycerol [87% (w/v) purity], leading to a similar fermentation pattern: a butanol yield of 0.34 (mol/mol), a butanol productivity of 0.42 g l–1 h–1 and a 84% (w/w) glycerol consumption were attained when cultures were grown at pH 6 and D = 0.05 h–1; butanol accounted for 94% (w/w) of total solvents. These values are among the highest reported in literature for C. acetobutylicum simple chemostats. 相似文献
984.
The induction of a Crassulacean acid like metabolism (CAM) was evidenced after 21–23 days of drought stress in the C4 succulent plant Portulaca oleracea L. by changes in the CO2 exchange pattern, in malic acid content and in titratable acidity during the day–night cycle. Light microscopy studies also
revealed differences in the leaf structure after the drought treatment. Following the induction of the CAM-like metabolism,
the regulatory properties of phosphoenolpyruvate carboxylase (PEPC, EC 4.1.1.31), the enzyme responsible for the diurnal fixation
of CO2 in C4 plants but nocturnal in CAM plants, were studied. The enzyme from stressed plants showed different kinetic properties with
respect to controls, notably its lack of cooperativity, higher sensitivity to L-malate inhibition, higher PEP affinity and
lower enzyme content on a protein basis. In both conditions, PEPC's subunit mass was 110 kDa, although changes in the isoelectric
point and electrophoretic mobility of the native enzyme were observed. In vivo phosphorylation and native isoelectrofocusing studies indicated variations in the phosphorylation status of the enzyme of
samples collected during the night and day, which was clearly different for the control and stressed groups of plants. The
results presented suggest that PEPC activity and regulation are modified upon drought stress treatment in a way that allows
P. oleracea to perform a CAM-like metabolism.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
985.
Trejo-Tapia Gabriela Arias-Castro Carlos Rodríguez-Mendiola Martha 《Plant Cell, Tissue and Organ Culture》2003,72(1):7-12
The effects of the concentration of PO4
3-, NO3
–, Fe 2+, sucrose and inoculum size on the accumulation of blue pigment and growth of suspension cultures of Lavandula spica D.C. (
L. latifolia Vill.), were studied. The combination of 2.5 mM PO4
3-, 14.1 mM NO3
–, 1 mM Fe 2+, 30 g l–1 sucrose and 10 g l–1fresh weight of inoculum, promoted a 7-fold enhancement on the productivity of blue pigment in comparison to the control medium. Among all the culture medium constituents tested, phosphate exerted the highest beneficial effect and Fe2+ showed to be essential for the accumulation of the pigment. High levels of sucrose (60 or 90 g l–1) did not stimulate the accumulation of blue pigment. In these conditions, cell growth and cell viability were drastically affected. 相似文献
986.
Engineered control of cell morphology in vivo reveals distinct roles for yeast and filamentous forms of Candida albicans during infection 总被引:3,自引:0,他引:3 下载免费PDF全文
It is widely assumed that the ability of Candida albicans to switch between different morphologies is required for pathogenesis. However, most virulence studies have used mutants that are permanently locked into either the yeast or filamentous forms which are avirulent but unsuitable for discerning the role of morphogenetic conversions at the various stages of the infectious process. We have constructed a strain in which this developmental transition can be externally modulated both in vitro and in vivo. This was achieved by placing one copy of the NRG1 gene (a negative regulator of filamentation) under the control of a tetracycline-regulatable promoter. This modified strain was then tested in an animal model of hematogenously disseminated candidiasis. Mice injected with this strain under conditions permitting hyphal development succumbed to the infection, whereas all of the animals injected under conditions that inhibited this transition survived. Importantly, fungal burdens were almost identical in both sets of animals, indicating that, whereas filament formation appears to be required for the mortality resulting from a deep-seated infection, yeast cells play an important role early in the infectious process by extravasating and disseminating to the target organs. Moreover, these infecting Candida yeast cells still retained their pathogenic potential, as demonstrated by allowing this developmental transition to occur at various time points postinfection. We demonstrate here the importance of morphogenetic conversions in C. albicans pathogenesis. This engineered strain should provide a useful tool in unraveling the individual contributions of the yeast and filamentous forms at various stages of the infectious process. 相似文献
987.
988.
Ito LS Yamashita M Strüssmann CA 《Journal of experimental zoology. Part A, Comparative experimental biology》2003,297(2):169-179
Elevated temperature causes degeneration and disappearance of the germ cells in the males of scrotal mammals. It was recently shown that heat-induced germ cell degeneration occurs also in fish but, unlike in mammals, it occurs not only in males but also in females. The purpose of this study was to clarify the histological process and dynamics of heat-induced germ cell disappearance in pejerrey Odontesthes bonariensis larvae and juveniles. Monosex and mixed-sex fish produced by thermal manipulation of sex (temperature-dependent sex determination) were subjected to 29 degrees C for periods between 1 and 12 weeks, and used to analyze, by histological methods, the changes in gonadal size and the number of normal and degenerating germ cells. Groups exposed to 29 degrees C for 8-12 weeks were subsequently transferred to 24 degrees C to verify if any gonadal damage would be permanent. Germ cell degeneration, histologically characterized by nuclear pyknosis or eosinophilia and cytoplasmic eosinophilia, was observed with increasing frequency at higher temperatures (29>24> 17 degrees C) and more in males than in females. Clear degenerative changes in the germinal epithelium usually began within one week of exposure to 29 degrees C and appeared clearer in females than in males. Complete loss of germ cells was observed only in individuals exposed for periods of 8-12 weeks to 29 degrees C but no treatment produced 100% sterile fish. Germ cells that remained in the gonads after exposure to 29 degrees C retained the capacity to rapidly recolonize germ cell-depleted areas, suggesting that the associated somatic cells in the gonads are little or not affected by this temperature. 相似文献
989.
Rosa CA Lachance MA Silva JO Teixeira AC Marini MM Antonini Y Martins RP 《FEMS yeast research》2003,4(3):271-275
The yeast communities associated with the stingless bees Tetragonisca angustula, Melipona quadrifasciata and Frieseomelitta varia were studied. The bees T. angustula and F. varia showed a strong association with the yeast Starmerella meliponinorum. M. quadrifasciata more frequently carried a species related to Candida apicola, but also vectored low numbers of S. meliponinorum. Some of the yeasts isolated from adult bees were typical of species known to occur in flowers. Other yeast species found in adult bees were more typical of those found in the phylloplane. S. meliponinorum and the species in the C. apicola complex, also part of the Starmerella clade, may have a mutualistic relationship with the bees studied. Many yeasts in that group are often found in bees or substrates visited by bees, suggesting that a mutually beneficial interaction exists between them. 相似文献
990.
Decaestecker TN Coopman EM Van Peteghem CH Van Bocxlaer JF 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2003,789(1):19-25
An entire series of SPE sorbents, classified into three different categories (apolar, mixed-mode and polymeric) was evaluated for sample preparation of a data-dependent LC-MS-MS "general unknown" screening procedure. An extraction procedure was formulated for each individual column, in agreement with the enclosed instructions, according to the characteristics of each packing. For conciseness, only neutral and basic compounds were chosen for this sorbent suitability test. Thus, the goal of our research was to select the best sorbent with regard to extraction yield and cleanliness of the extracts, all with respect to data-dependent acquisition (DDA) mediated LC-MS-MS general unknown screening. We conclude that for that purpose an Isolute C(8) sorbent performs best in terms of extraction yield and clean-up potential. 相似文献