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951.
Identification of Tn4430, a transposon of Bacillus thuringiensis functional in Escherichia coli 总被引:3,自引:0,他引:3
Didier Lereclus Jacques Mahillon Ghislaine Menou Marguerite-M. Lecadet 《Molecular & general genetics : MGG》1986,204(1):52-57
Summary The mobile genetic element Tn4430, originating from the gram-positive bacterium, Bacillus thuringiensis, and previously described as the Th-sequence, is the first transposon isolated from the genus Bacillus. In the present work a gene (APH-III) conferring resistance to kanamycin was inserted into this 4.2 kb transposon. Transposition experiments showed that Tn4430APH-III could transpose in the gram-negative host Escherichia coli when its insertion functions were supplied by an intact copy of Tn4430. By transposing Tn4430APH-III directly onto pBR322, it was possible to determine the nucleotide sequence of the terminal inverted repeats of Tn4430 and of the target DNA site. Identical 38 bp in inverted orientation are situated at each end of the transposon and there is a direct duplication of 5 bp at the insertion site. Thus, it is clear that Tn4430 is closely related to the transposons belonging to the Tn3 family (class II elements). 相似文献
952.
Gauthier JY Black WC Courchesne I Cromlish W Desmarais S Houle R Lamontagne S Li CS Massé F McKay DJ Ouellet M Robichaud J Truchon JF Truong VL Wang Q Percival MD 《Bioorganic & medicinal chemistry letters》2007,17(17):4929-4933
Highly potent, selective, and bioavailable inhibitors of human, mouse, or rat cathepsin S are described. The key structural features combine a sulfonyl moiety attached to a large group in P2 and a small substituent in P3. 相似文献
953.
Human susceptibility and resistance to Norwalk virus infection 总被引:27,自引:0,他引:27
Lindesmith L Moe C Marionneau S Ruvoen N Jiang X Lindblad L Stewart P LePendu J Baric R 《Nature medicine》2003,9(5):548-553
Infectious diseases have influenced population genetics and the evolution of the structure of the human genome in part by selecting for host susceptibility alleles that modify pathogenesis. Norovirus infection is associated with approximately 90% of epidemic non-bacterial acute gastroenteritis worldwide. Here, we show that resistance to Norwalk virus infection is multifactorial. Using a human challenge model, we showed that 29% of our study population was homozygous recessive for the alpha(1,2)fucosyltransferase gene (FUT2) in the ABH histo-blood group family and did not express the H type-1 oligosaccharide ligand required for Norwalk virus binding. The FUT2 susceptibility allele was fully penetrant against Norwalk virus infection as none of these individuals developed an infection after challenge, regardless of dose. Of the susceptible population that encoded a functional FUT2 gene, a portion was resistant to infection, suggesting that a memory immune response or some other unidentified factor also affords protection from Norwalk virus infection. 相似文献
954.
Alain Rabi Maryse Selme-Matrat Marie-Claude Clavel Jean Clos Jacques Legrand 《Developmental neurobiology》1977,8(4):337-354
Newborn rats were treated at different stages of their development with low doses of methylazoxymethanol acetate. The postnatal increase of the DNA content of the cerebrum did not differ from that of controls. In the cerebellum, the DNA content was transitorily reduced, but later, the external granular layer became thicker and DNA deposition increased in comparison with controls; finally, the cerebellar DNA returned to a normal value. Morphological abnormalities of the cerebellum, abnormal orientation of migrating cells, scattering of Purkinje cell bodies within the internal granule cells and specially striking abnormalities of the morphology and orientation of Purkinje cell dendrites were noted in rats treated with MAM from birth to day 3. The effects on the Purkinje cell morphogenesis persisted but were much less marked when MAM was given from 4 to 7 or from 8 to 11 days. Neonatal thyroid deficiency, as MAM-treatment between days 0 and 3, leads to an abnormal position of Purkinje cell bodies within the cerebellar cortex; it also leads to morphological abnormalities of their dendritic arborization which closely resemble those observed after MAM-treatment during the second postnatal week. It also alters the cell formation in the cerebellum. Thyroid deficiency probably exerts its effect on cell formation earlier than previous biochemical studies have shown. On another hand, the morphological abnormalities of Purkinje cell arborizations in the thyroid-deficient animals may be partly due to the perturbations of cell formation which persist later in the cerebellum. 相似文献
955.
Abstract: Quantification of the size of epiphytic bacterial populations and characterization of their composition involves definition of a sampling strategy in time and space, the choice of methods for liberating the bacteria from the leaf surface and for recovering them for subsequent determination of the number of viable or culturable cells. This literature review focuses on some of the issues related to these choices. After briefly reviewing the different types of epiphytic colonizers we consider the biological, methodological, and statistical consequences of the choice of the sampling unit and of the spatial and temporal variability of population size and composition for epiphytic bacteria. The different methods available for the detection and enumeration of naturally occurring microorganisms in the phyllosphere are discussed. Advantages and drawbacks of each are described in this review designed as a 'hands-on' guide. 相似文献
956.
In proteomic analysis of complex samples at the peptide level (termed shotgun proteomics), an effective prefractionation is crucial to decrease the complexity of the peptide mixture for further analysis. In this perspective, the high-resolving power of the IEF fractionation step is a determining parameter, in order to obtain well-defined fractions and correct information on peptide isoelectric points, to provide an additional filter for protein identification. Here, we explore the resolving power of OFFGEL IEF as a prefractionation tool to separate peptides. By modeling the peak width evolution versus the peptide charge gradient at pI, we demonstrate that for the three proteomes considered in silico (Deinococcus radiodurans, Saccharomyces cerevisiae, and Homo sapiens), 90% of the peptides should be correctly focused and recovered in two wells at most. This result strongly suggests OFFGEL to be used as a powerful fractionation tool in shotgun proteomics. The influence of the height and shape of the compartments is also investigated, to give the optimal cell dimensions for an enhanced peptide recovery and fast focusing time. 相似文献
957.
958.
Minor histocompatibility antigen-specific MHC-restricted CD8 T cell responses elicited by heat shock proteins 总被引:6,自引:0,他引:6
Robert J Gantress J Rau L Bell A Cohen N 《Journal of immunology (Baltimore, Md. : 1950)》2002,168(4):1697-1703
In mammals, the heat shock proteins (HSP) gp96 and hsp70 elicit potent specific MHC class I-restricted CD8(+) T cell (CTL) response to exogenous peptides they chaperone. We show in this study that in the adult frog Xenopus, a species whose common ancestors with mammals date back 300 million years, both hsp70 and gp96 generate an adaptive specific cellular immune response against chaperoned minor histocompatibility antigenic peptides that effects an accelerated rejection of minor histocompatibility-locus disparate skin grafts in vivo and an MHC-specific CD8(+) cytotoxic T cell response in vitro. In naturally class I-deficient but immunocompetent Xenopus larvae, gp96 also generates an antitumor immune response that is independent of chaperoned peptides (i.e., gp96 purified from normal tissue also generates a significant antitumor response); this suggests a prominent contribution of an innate type of response in the absence of MHC class I Ags. 相似文献
959.
Marsollier L Sévérin T Aubry J Merritt RW Saint André JP Legras P Manceau AL Chauty A Carbonnelle B Cole ST 《Applied and environmental microbiology》2004,70(10):6296-6298
Accumulative indirect evidence of the epidemiology of Mycobacterium ulcerans infections causing chronic skin ulcers (i.e., Buruli ulcer disease) suggests that the development of this pathogen and its transmission to humans are related predominantly to aquatic environments. We report that snails could transitorily harbor M. ulcerans without offering favorable conditions for its growth and replication. A novel intermediate link in the transmission chain of M. ulcerans becomes likely with predator aquatic insects in addition to phytophage insects. Water bugs, such as Naucoris cimicoides, a potential vector of M. ulcerans, were shown to be infected specifically by this bacterium after feeding on snails experimentally exposed to M. ulcerans. 相似文献
960.
Growth hormone (GH) may stimulate water loss during exercise by activating sweating. This study investigated GH secretion and water loss during sequential cycling and running, taking postural changes into account. The two exercise segments had similar durations and were performed at the same relative intensity to determine their respective contributions to water loss and the plasma volume variation noted in such trials. Eight elite triathletes first performed an incremental cycle test to assess maximal oxygen consumption. Then, the triathletes performed one of two trials in randomized order: constant submaximal cycling followed by treadmill running (C1-R2) or an inversed succession of running followed by cycling (R1-C2). Each segment of both trials was performed for 20 minutes at ∼75% of maximal oxygen consumption. The second trial, reversing the segment order of the first trial, took place two weeks later. During cycling, the triathletes used their own bicycles equipped with a profiled handlebar. Blood sampling (for GH concentrations, plasma viscosity and plasma volume variation) was conducted at rest and after each segment while water loss was estimated from the post- and pre-measures. GH increases were significantly lower in R2 than C2 (72.2±50.1 vs. 164.0±157 ng.ml−1.min−1, respectively; P<0.05). Water loss was significantly lower after C1-R2 than R1-C2 (1105±163 and 1235±153 ml, respectively; P<0.05). Plasma volume variation was significantly negative in C1 and R1 (−6.15±2.0 and −3.16±5.0%, respectively; P<0.05), not significant in C2, and significantly positive for seven subjects in R2 (4.05±3.1%). We concluded that the lower GH increases in R2 may have contributed to the smaller reduction in plasma volume by reducing sweating. Moreover, this lower GH response could be explained by the postural change during the transition from cycling to running. We recommend to pay particular attention to their hydration status during R1 which could limit a potential dehydration during C2. 相似文献