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排序方式: 共有1610条查询结果,搜索用时 15 毫秒
91.
Dupuis-Williams P Fleury-Aubusson A de Loubresse NG Geoffroy H Vayssié L Galvani A Espigat A Rossier J 《The Journal of cell biology》2002,158(7):1183-1193
Centrioles and basal bodies fascinate by their spectacular architecture, featuring an arrangement of nine microtubule triplets into an axial symmetry, whose biogenesis relies on yet elusive mechanisms. However, the recent discovery of new tubulins, such as delta-, epsilon-, or eta-tubulin, could constitute a breakthrough for deciphering the assembly steps of this unconventional microtubule scaffold. Here, we report the functional analysis in vivo of epsilon-tubulin, based on gene silencing in Paramecium, which demonstrates that this protein, which localizes at the basal bodies, is essential for the assembly and anchorage of the centriolar microtubules. 相似文献
92.
We investigated the bacterial flora present in skin lesions of patients with chiclero's ulcer from the Yucatan peninsula of Mexico using conventional culture methods (11 patients), and an immunocolorimetric detection of pathogenic Streptococcus pyogenes (15 patients). Prevalence of bacteria isolated by culture methods was 90.9% (10/11). We cultured, from chiclero's ulcers (60%), pathogenic bacterial such as Staphylococcus aureus (20%), S. pyogenes (1.6%), Pseudomonas aeruginosa (1.6%), Morganella morganii (1.6%), and opportunist pathogenic bacteria such as Klebsiella spp. (20.0%), Enterobacter spp. (20%), and Enterococcus spp. (20%). We also cultured coagulase-negative staphylococci in 40% (4/10) of the remaining patients. Micrococcus spp. and coagulase-negative staphylococci constituted the bacterial genuses more frequently isolated in the normal skin of patients with chiclero's ulcer and healthy individuals used as controls. We also undertook another study to find out the presence of S. pyogenes by an immunocolorimetric assay. This study indicated that 60% (9/15) of the ulcerated lesions, but not normal controls, were contaminated with S. pyogenes. Importantly, individuals with purulent secretion and holding concomitant infections with S. pyogenes, S. aureus, P. aeruginosa, M. morganii, and E. durans took longer to heal Leishmania (L.) mexicana infections treated with antimonial drugs. Our results suggest the need to eliminate bacterial purulent infections, by antibiotic treatment, before starting antimonial administration to patients with chiclero's ulcer. 相似文献
93.
Kwaks TH Barnett P Hemrika W Siersma T Sewalt RG Satijn DP Brons JF van Blokland R Kwakman P Kruckeberg AL Kelder A Otte AP 《Nature biotechnology》2003,21(5):553-558
The expression of transgenic proteins is often low and unstable over time, a problem that may be due to integration of the transgene in repressed chromatin. We developed a screening technology to identify genetic elements that efficiently counteract chromatin-associated repression. When these elements were used to flank a transgene, we observed a substantial increase in the number of mammalian cell colonies that expressed the transgenic protein. Expression of the shielded transgene was, in a copy number-dependent fashion, substantially higher than the expression of unprotected transgenes. Also, protein production remained stable over an extended time period. The DNA elements are small, not exceeding 2,100 base pairs (bp), and they are highly conserved between human and mouse, at both the functional and sequence levels. Our results demonstrate the existence of a class of genetic elements that can readily be applied to more efficient transgenic protein production in mammalian cells. 相似文献
94.
Background
Cul1 is a core component of the evolutionarily conserved SCF-type ubiquitin ligases that target specific proteins for destruction. SCF action contributes to cell cycle progression but few of the key targets of its action have been identified. 相似文献95.
96.
Duim B Ang CW van Belkum A Rigter A van Leeuwen NW Endtz HP Wagenaar JA 《Applied and environmental microbiology》2000,66(9):3917-3923
The high-resolution genotyping method of amplified fragment length polymorphism (AFLP) analysis was used to study the genetic relationships between Campylobacter jejuni strains infecting chickens (n = 54) and those causing gastroenteritis in humans (n = 53). In addition, C. jejuni strains associated with the development of Guillain-Barré syndrome (GBS) (n = 14) and Miller Fisher syndrome (MFS) (n = 4), two related acute paralytic syndromes in human, were included. Strains were isolated between 1989 and 1998 in The Netherlands. The AFLP banding patterns were analyzed with correlation-based and band-based similarity coefficients and UPGMA (unweighted pair group method using average linkages) cluster analysis. All C. jejuni strains showed highly heterogeneous fingerprints, and no fingerprints exclusive for chicken strains or for human strains were obtained. All strains were separated in two distinct genetic groups. In group A the percentage of human strains was significantly higher and may be an indication that genotypes of this group are more frequently associated with human diseases. We conclude that C. jejuni from chickens cannot be distinguished from human strains and that GBS or MFS related strains do not belong to a distinct genetic group. 相似文献
97.
98.
Periplasmic or membrane-bound bacterial hydrogenases are generally composed of a small subunit and a large subunit. The small subunit contains a peculiar N-terminal twin-arginine signal peptide, whereas the large subunit lacks any known targeting signal for export. Genetic and biochemistry data support the assumption that the large subunit is cotranslocated with the small subunit across the cytoplasmic membrane. Indeed, the signal peptide carried by the small subunit directs both the small and the large subunits to the recently identified Mtt/Tat pathway, independently of the Sec machinery. In addition, the twin-arginine signal peptide of hydrogenase is capable of directing protein import into the thylakoidal lumen of chloroplasts via the homologous deltapH-driven pathway, which is independent of the Sec machinery. Therefore, the translocation of hydrogenase shares characteristics with the deltapH-driven import pathway in terms of Sec-independence and requirement for the twin-arginine signal peptide, and with protein import into peroxisomes in a "piggyback" fashion. 相似文献
99.
The human nucleus accumbens is highly susceptible to G protein down-regulation by methamphetamine and heroin 总被引:3,自引:0,他引:3
McLeman ER Warsh JJ Ang L Li PP Kalasinsky KS Ross BM Tong J Schmunk G Adams V Kish SJ 《Journal of neurochemistry》2000,74(5):2120-2126
Although the nucleus accumbens is assumed to be a critical brain "pleasure center," its function in humans is unknown. As animal data suggest that a unique feature of this small brain area is its high sensitivity to down-regulation of an inhibitory G protein by drugs of abuse, we compared G protein levels in postmortem nucleus accumbens with those in seven other brain regions of chronic users of cocaine, methamphetamine, and heroin, and of matched controls. Biochemical changes were restricted to the nucleus accumbens in which concentrations of G(alpha)1 and/or G(alpha)2 were reduced by 32-49% in the methamphetamine and heroin users. This selective responsiveness to these abused drugs implies a special role for the human nucleus accumbens in mechanisms of drug reinforcement and suggests that some features of the drug-dependent state (e.g., tolerance) might be related to inhibition of G(alpha)1-linked receptor activity. 相似文献
100.