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41.
Cristina Elena Canteros Laura Rodero Maria Cristina Rivas Graciela Davel 《Mycopathologia》1996,136(1):21-23
A rapid method to evidence urease activity is described. Urea hydrolysis and consequent production ammonia are detected by a chemical reaction producing a blue phenol compound (indophenol blue). Three hundred and three yeast were tested. Out of 107 urease-positive organisms detected by Christensen's Urea Agar Test (CUAT) 102 were positive by our method. No false negatives were observed by this method when testing 87 Cryptococcus strains. Ths practical screening test for presumptive identification of Cryptococcus neoformans is simple, unaffected by pH changes and requires 15 minutes to be performed. 相似文献
42.
Jose Pontón Fernando L. Hernando Maria Dolores Moragues Pedro L. Barea Mara Gerloni Stefania Conti Paola Fisicaro Cristina Cantelli Luciano Polonelli 《Mycopathologia》1996,133(2):89-94
The presence of heat shock mannoproteins (HSMPs) reactive with sIgA was demonstrated in several C. albicans strains. The subculture of the C. albicans isolated from mucosal surfaces on Sabouraud's dextrose agar at 25 °C switched off the HSMP expression. A re-expression of the HSMPs was obtained in the same medium by shifting the temperature of incubation to 37 °C. However, expression of HSMPs in two strains isolated from deep infections was maintained during several subcultures on Sabouraud's dextrose agar at 25 °C. A glycoprotein of 200 kDa seemed to be the main HSMP reacting with vaginal sIgA. The data presented in this study suggest that factors other than temperature can influence the expression of C. albicans HSMPs and therefore these antigens should be referred as stress mannoproteins.Abbreviations HSMPs
heat shock mannoproteins
- MAb
monoclonal antibody
- sIgA
secretory IgA 相似文献
43.
Eitel Pastor Cristina Otero Antonio Ballesteros 《Biocatalysis and Biotransformation》1995,12(2):147-157
Mixtures of 1(3)-monostearin and distearin were prepared by direct esterification of glycerol with stearic acid or transesterification using ethyl stearate as acyl donor in the presence of Candida antarctica lipase (Novozym 435) using a variety of solvents of differing polarity. In all cases, the transesterification resulted in higher product yields. In n-heptane as reaction medium the addition of water (3%) was essential for high product yields, with mono- and distearin being produced in almost equal amounts. Using more polar solvents as reaction media, such as acetonitrile or acetone, again the highest yields were obtained in the transesterification mode; employing these solvents the reactions were much more selective towards the formation of monostearin. 相似文献
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46.
Marco Vinceti Sergio Rovesti Cristina Marchesi Margherita Bergomi Gianfranco Vivoli 《Biological trace element research》1994,40(3):267-275
In a part of the municipal territory of Reggio Emilia, northern Italy, selenium in drinking water decreased from 7 μg/L to
less than 1 μg/L. In a cohort of 4419 individuals, previously exposed for at least 5 yr to the drinking water with higher
selenium content, the 7-yr temporal distribution of deaths for coronary disease and for stroke was analyzed to examine a possible
relationship with changes in drinking water selenium. From January 1986 until August 1988, when tap water selenium was 7 μg/L,
deaths for coronary disease were one in males and two in females. After the decrease in drinking water selenium, 21 and 10
coronary deaths were observed, respectively, in males and in females from September 1988 to December 1992. No significant
difference in the temporal distribution of stroke deaths was observed both in males and in females. Even if an effect of chance
and aging in the temporal distribution of coronary deaths may not be excluded, findings of the study seem to be consistent
with the hypothesis of a beneficial effect of selenium on coronary disease mortality. 相似文献
47.
48.
Summary Thirty-three insertions of transposon Tn10l6l7 into genes involved in the control of rod cell shape were isolated in Salmonella typhimurium by the characteristic glossy appearance of colonies composed of spherical cells. Genetic tests demonstrated that 25 (76%) were insertions in the rodA gene, 7 (21 %) were mre mutants, and 1 (3%) was a divD mutant. No insertion in the pbpA gene were found. Insertions in cell shape genes only appeared when strains displaying resistance to mecillinam (not caused by -lactamase production) were employed. Neither rodA nor mre insertions could be transduced to wild-type strains but they were normally accepted by mecillinam-resistant derivatives and by cya and crp mutants, which, unlike the corresponding Escherichia coli strains, did not display resistance to mecillinam. On the other hand, the divD insertion could be efficiently transduced to any strain. It is concluded that the rodA, mre, and divD genes are involved in the control of rod cell shape but, in addition, the RodA and Mre products perform some function(s) that is essential for wild-type cells but dispensable for some mecillinam-resistant strains, and for cya and crp mutants. 相似文献
49.
Seedlings of carob ( Ceratonia siliqua L. cv. Mulata) were used in two sets of experiments in order to evaluate; (1) the reciprocal effects of each nitrogen form on net uptake of nitrate and ammonium, and (2) the effect of earlier nitrogen nutrition on ammonium versus nitrate uptake. In the former group of experiments we studied the kinetics of nitrate and ammonium uptake as well as the interference of each of the two forms with net uptake of ammonium and nitrate by both nitrogen depleted and nitrogen fed carob seedlings. On the whole, nitrogen depletion led to increase in both affinity and Vmax of the system for both forms of nitrogen, at the same time as the effects of nitrate on uptake of ammonium and vice versa were concentration dependent. In the second group of experiments the effects of earlier nitrogen nutrition on nitrate and ammonium uptake were characterized, and in this case we observed that: (a) if only one form of N was supplied, ammonium was taken up in greater amounts than nitrate; (b) the presence of ammonium enhanced nitrate uptake; (c) ammonium uptake was inhibited by nitrate; (d) there was a significant effect of the earlier nitrogen nutrition on the response of the plants to a different nitrogen source. The latter was evident mainly as regards ammonium uptake by plants grown in ammonium nitrate. The interactions between nitrate and ammonium uptake systems are discussed on the basis of the adaptation to the nitrogen source during early growth. 相似文献
50.
The metabolism of sugar and malic acid by Leuconostoc oenos: effect of malic acid, pH and aeration conditions 总被引:1,自引:1,他引:0
M. Paula Firme M. Cristina Leitão M. Vitória San Romão 《Journal of applied microbiology》1994,76(2):173-181
The co-metabolism of sugars by Leuconostoc oenos was studied under different environmental conditions. Under aerobic conditions, growth and sugar metabolism were poorer than under CO2 or N2 atmosphere and acetic acid accumulated to a larger extent. Glycerol was found in the aerobic cultures while erythritol was detected under N2 or CO2 . When medium conditions make growth difficult (low pH, aerobic conditions, low nutrients), sugars were only slightly metabolized and growth was very slow while malic acid was rapidly and completely degraded, leading to an increase in the y ATP . Aeration effects on the malic acid degradation rate depended on the nutrients and carbon source in the medium. Malic acid clearly stimulated bacterial growth, allowing an increase in the molar growth yields and ATP production. The results suggest that under adverse conditions cells are not able to grow and malic degradation supplies additional energy production. 相似文献