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81.
Approximately 280 Escherichia coli isolates were isolated from a bovine feedlot at the University of Connecticut campus via enrichment in lauryl tryptose broth and random selection from MacConkey plates. The E. coli subspecies diversity was estimated by employing whole-cell BOX-PCR genomic fingerprints. A total of 89 distinct operational taxonomic units (OTUs) were identified by employing a criterion of 85% fingerprint similarity as a surrogate for an OTU, while the Chao1 index estimated the E. coli population richness at 128 OTUs. One genotype (at a similarity level of 60%) dominated the population at 66% regardless of sampling depth or location, while no significant vertical distribution pattern was observed in terms of genotype, mobility, antibiotic resistance profile, or biofilm-forming ability. Motility, measured by a soft agar assay, had a very broad range among the E. coli population and was positively correlated with biofilm-forming ability in minimal medium (Spearman's rank correlation coefficient r = 0.619, P < 10(-4)) but not in Luria broth. Only an estimated 48% of the population possessed gene agn43, which encodes Ag43, a phase-variable outer membrane protein that has been implicated in biofilm formation in minimal medium. We observed significantly more biofilm formation in both minimal medium and Luria broth for agn43(+) strains, with a larger effect in minimal medium. This study represents an exhaustive inventory of extant E. coli population diversity at a bovine feedlot and reveals significant subspecies heterogeneity in interfacial behavior. 相似文献
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A glycosylated type I membrane protein becomes cytosolic when peptide: N-glycanase is compromised 总被引:2,自引:0,他引:2 下载免费PDF全文
The human cytomegalovirus-encoded glycoprotein US2 catalyzes proteasomal degradation of Class I major histocompatibility complex (MHC) heavy chains (HCs) through dislocation of the latter from the endoplasmic reticulum (ER) to the cytosol. During this process, the Class I MHC HCs are deglycosylated by an N-glycanase-type activity. siRNA molecules designed to inhibit the expression of the light chain, beta(2)-microglobulin, block the dislocation of Class I MHC molecules, which implies that US2-dependent dislocation utilizes correctly folded Class I MHC molecules as a substrate. Here we demonstrate it is peptide: N-glycanase (PNGase or PNG1) that deglycosylates dislocated Class I MHC HCs. Reduction of PNGase activity by siRNA expression in US2-expressing cells inhibits deglycosylation of Class I MHC HC molecules. In PNGase siRNA-treated cells, glycosylated HCs appear in the cytosol, providing the first evidence for the presence of an intact N-linked type I membrane glycoprotein in the cytosol. N-glycanase activity is therefore not required for dislocation of glycosylated Class I MHC molecules from the ER. 相似文献
84.
A spectrocolorimetric study on the effect of ultraviolet irradiation of four tropical hardwoods 总被引:3,自引:0,他引:3
Colour modifications caused by exposure to artificial UV radiation (350 nm, UV-A) of four tropical hardwoods, jatobá, angelim vermelho, garapeira, and marupá, have been evaluated by diffuse reflectance spectroscopy and by the CIE-L*a*b* system. To obtain the absorption maxima of the chromophore species formed during UV irradiation, Kubelka-Munk (K-M) difference spectra (non-irradiated-irradiated) have been recorded as a function of exposure time. The K-M difference spectra have shown that the investigated species develop strong absorption bands in the visible region upon UV irradiation that were assigned to the formation of lignin and extractive photodegradation products. The K-M difference spectra and CIE-L*a*b* parameters ( DeltaL, Deltaa, and Deltab) have shown that marupá is the wood species that suffers the major changes upon UV irradiation while angelim vermelho was the least affected. 相似文献
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86.
Postiglione L Di Domenico G Ramaglia L di Lauro AE Di Meglio F Montagnani S 《European journal of histochemistry : EJH》2004,48(3):213-222
Commercially pure titanium implants presenting a relatively smooth, machined surface or a roughened endosseous surface show a large percentage of clinical success. Surface properties of dental implants seem to affect bone cells response. Implant topography appears to modulate cell growth and differentiation of osteoblasts affecting the bone healing around the titanium implant. The aim of the present study was to examine the effects of 1cm diameter and 1mm thick titanium disks on cellular morphology, adhesion and bone phenotypic expression of human osteoblast-like cells, SaOS-2. SaOS-2 cells were cultured on commercially 1 cm pure titanium disks with three different surface roughness: smooth (S), sandblasted (SB) and titanium plasma sprayed (TPS). Differences in the cellular morphology were found when they were grown on the three different surfaces. An uniform monolayer of cells recovered the S surface, while clusters of multilayered irregularly shaped cells were distributed on the rough SB and TPS surfaces. The adhesion of SaOS-2 cells, as measured after 3h of culture, was not affected by surface roughness. ECM components such as Collagen I (CoI), Fibronectin (FN), Vitronectin (VN) and Tenascin (TN) were secreted and organized only on the SB and TPS surfaces while they remained into the cytoplasm on the S surfaces. Osteopontin and BSP-II were largely detected on the SB and TPS surfaces, while only minimal production was observed on the S ones. These data show that titanium surface roughness affects bone differentiation of osteoblast like-cells, SaOS-2, indicating that surface properties may be able to modulate the osteoblast phenotype. These observations also suggest that the bone healing response around dental implants can be affected by surface topography. 相似文献
87.
Specchia G Pastore D Montagna MT Carluccio P Ciuffreda L Rizzi R Liso A 《The new microbiologica》2004,27(4):407-410
A retrospective study was conducted in 22 episodes of candidemia in 445 patients with acute leukemia (AL) (incidence 4.9%) observed at our Institution between February 1996 and November 2003 to evaluate the variables related to the onset and outcome of infection. Of 22 patients, 20 (90.9%) had refractory/relapsed AL. C. albicans was responsible for 7/22 of the fungemia cases (32%) and C. non albicans for 15/22 (68%). The median absolute neutrophil count was 0.1 x10(9)/L (range 0.04-0.3) at the time of the candidemia diagnosis. The fungemia responded to antifungal therapy in 15/22 (68.1%) patients; among patients with a positive outcome of the fungemia, in 14/15 (93.3%) the neutrophil count recovered within 7 days after the diagnosis of candidemia (p < 0.05). The mortality rate due to candidemia was 31.9% (1/7: 14.2% and 6/15: 40% in the C. albicans and C. non albicans groups, respectively). In our experience the determinants of a positive outcome of fungemia were infection by the C. albicans species and recovery of the neutrophil count. 相似文献
88.
Pier Giorgio?Biancogibianco@unina.it" title="PGB gibianco@unina.it" itemprop="email" data-track="click" data-track-action="Email author" data-track-label="">Email author Gennaro?Aprea Emilio?Balletto Teresa?Capriglione Domenico?Fulgione Gaetano?Odierna 《Ichthyological Research》2004,51(3):274-278
The chromosomes of eight species of Rutilus and Scardinius, mostly endemic to the Italian and the Balkan peninsula, were analyzed by conventional and other banding techniques. Parallel analyses were conducted also on two leuciscine species, Alburnus albidus, for which we provide the first karyological analysis, and Leuciscus cephalus. All species examined displayed the same karyotype (2n=50 chromosomes, 8 metacentric+13 submetacentric+4 subtelo/acrocentric pairs) with nucleolus organizer regions (NORs) on the ends of the shorter arms of a medium-sized submetacentric pair. In contrast, interspecific variation was observed in the distribution of constitutive heterochromatin. The variation observed in this genomic material proved to be systematically and phylogenetically informative. Indeed, a peritelomeric C-band on the first telocentric pair characterizes species of Rutilus and Scardinius. In both genera heterochromatin differentiation appears to be directed to a centromere–telomere direction, particularly evident along the metacentric elements of their karyotypes.An erratum to this article can be found at 相似文献
89.
90.
Magliani W Conti S Salati A Vaccari S Ravanetti L Maffei DL Polonelli L 《FEMS yeast research》2004,5(1):11-18
This review focuses on the potential of yeast killer toxin (KT)-like antibodies (KTAbs), that mimic a wide-spectrum KT through interaction with specific cell wall receptors (KTR) and their molecular derivatives (killer mimotopes), as putative new tools for transdisease anti-infective therapy. KTAbs are produced during the course of experimental and natural infections caused by KTR-bearing micro-organisms. They have been produced by idiotypic vaccination with a KT-neutralizing mAb, also in their monoclonal and recombinant formats. KTAbs and KTAbs-derived mimotopes may exert a strong therapeutic activity against mucosal and systemic infections caused by eukaryotic and prokaryotic pathogenic agents, thus representing new potential wide-spectrum antibiotics. 相似文献