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991.
Anna Allué-Guardia Alexandre Martínez-Castillo Maite Muniesa 《Applied and environmental microbiology》2014,80(7):2142-2149
In Shiga toxin-producing Escherichia coli (STEC), induction of Shiga toxin-encoding bacteriophages (Stx phages) causes the release of free phages that can later be found in the environment. The ability of Stx phages to survive different inactivation conditions determines their prevalence in the environment, the risk of stx transduction, and the generation of new STEC strains. We evaluated the infectivity and genomes of two Stx phages (Φ534 and Φ557) under different conditions. Infectious Stx phages were stable at 4, 22, and 37°C and at pH 7 and 9 after 1 month of storage but were completely inactivated at pH 3. Infective Stx phages decreased moderately when treated with UV (2.2-log10 reduction for an estimated UV dose of 178.2 mJ/cm2) or after treatment at 60 and 68°C for 60 min (2.2- and 2.5-log10 reductions, respectively) and were highly inactivated (3 log10) by 10 ppm of chlorine in 1 min. Assays in a mesocosm showed lower inactivation of all microorganisms in winter than in summer. The number of Stx phage genomes did not decrease significantly in most cases, and STEC inactivation was higher than phage inactivation under all conditions. Moreover, Stx phages retained the ability to lysogenize E. coli after some of the treatments. 相似文献
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Recent studies have shown that lysine side-chain NH3 + groups are excellent probes for NMR investigations of dynamics involving hydrogen bonds and ion pairs relevant to protein function. However, due to rapid hydrogen exchange, observation of 1H-15N NMR cross peaks from lysine NH3 + groups often requires use of a relatively low temperature, which renders difficulty in resonance assignment. Here we present an effective strategy to assign 1H and 15N resonances of NH3 + groups at low temperatures. This strategy involves two new 1H/13C/15N triple-resonance experiments for lysine side chains. Application to a protein-DNA complex is demonstrated. 相似文献
994.
Nicolas Chenouard Alexandre Dufour Jean-Christophe Olivo-Marin Dr. 《Biotechnology journal》2009,4(6):838-845
Understanding subcellular dynamic processes governing pathogenic mechanisms is a necessary step towards the development of new drugs and strategies against infectious diseases. Subcellular pathogenic mechanisms, such as viral invasion processes involve highly dynamic nanometric-scale objects and rapid molecular interactions that require the study of individual particle paths. Single-particle tracking methods allow visualizing and characterizing the dynamics of biological objects, and provide a straightforward and accurate means to understand subcellular processes. This review describes a number of particle-tracking methods in time-lapse microscopy sequences and provides examples of using such techniques to investigate mechanisms of host-pathogen interactions. 相似文献
995.
Alexandre Roulin Amélie N. Dreiss Mathias Kölliker 《Ethology : formerly Zeitschrift fur Tierpsychologie》2010,116(9):787-796
Consistent inter‐individual variation in behaviour over time and across contexts has been reported for a wide variety of animals, a phenomenon commonly referred to as personality. As behavioural patterns develop inside families, rearing conditions could have lasting effects on the expression of adult personality. In species with parental care, conflicts among family members impose selection on parental and offspring behaviour through coadaptation. Here, we argue that the interplay between the evolution of personality traits (i.e. boldness, exploration, activity, aggressiveness and sociability) expressed outside the family context and the specialized behaviours expressed inside families (i.e. offspring begging behaviour and parental response to offspring solicitations) can have important evolutionary consequences. Personality differences between parents may relate to the typically observed variation in the way they respond to offspring demand, and dependent offspring may already express personality differences, which may relate to the way they communicate with their parents and siblings. However, there has been little research on how personality relates to parental and offspring behaviours. Future research should thus focus on how and why personality may be related to the specialized parent and offspring behaviour that evolved as adaptations to family life. 相似文献
996.
Alexandre M. J. J. Bonvin J. Antoon C. Rullmann Rolf M. J. N. Lamerichs Rolf Boelens Robert Kaptein 《Proteins》1993,15(4):385-400
The structure in solution of crambin, a small protein of 46 residues, has been determined from 2D NMR data using an iterative relaxation matrix approach (IRMA) together with distance geometry, distance bound driven dynamics, molecular dynamics, and energy minimization. A new protocol based on an “ensemble” approach is proposed and compared to the more standard initial rate analysis approach and a “single structure” relaxation matrix approach. The effects of fast local motions are included and R-factor calculations are performed on NOE build-ups to describe the quality of agreement between theory and experiment. A new method for stereospecific assignment of prochiral groups, based on a comparison of theoretical and experimental NOE intensities, has been applied. The solution structure of crambin could be determined with a precision (rmsd from the average structure) of 0.7 Å on backbone atoms and 1.1 Å on all heavy atoms and is largely similar to the crystal structure with a small difference observed in the position of the side chain of Tyr-29 which is determined in solution by both J-coupling and NOE data. Regions of higher structural variability (suggesting higher mobility) are found hi the solution structure, in particular for the loop between the two helices (Gly-20 to Pro-22). © 1993 Wiley-Liss, Inc. 相似文献
997.
Pierre Bize Aurélie Klopfenstein Caroline Jeanneret Alexandre Roulin 《Journal of Ornithology》2007,148(4):387-393
The Alpine swift (Apus melba) forages on insects caught exclusively on the wing, implying that dependent nestlings face acute food shortage in periods
of cold and rainy weather. Therefore, there should be strong selection on nestling swifts to evolve physiological strategies
to cope with periods of undernutrition. We have investigated intra-individual changes in nestling pectoral muscle and body
temperature in response to a 1-week period of inclement weather. The pectoral muscle is the largest reserves of proteins,
and nestlings have to devote a large amount of energy in the maintenance of body temperature. The results show that nestling
pectoral muscle size and body temperature were significantly reduced during the episode of inclement weather. Assuming that
these physiological changes are adaptive, our study suggests that nestling swifts spare energy by a pronounced reduction (up
to 18°C) in body temperature and use proteins from the pectoral muscle as a source of extra energy to survive prolonged periods
of fasting. 相似文献
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