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71.
A microtitration plate, antibody capture, enzyme-linked immunosorbent assay was developed for the detection of Aeromonas hydrophila serotype O : 11 (highly virulent strains). The assay utilizes a detector antibody which shows no cross-reactions with Aeromonas strains other than serotype O : 11 or non- Aeromonas competing organisms. The detector antibody is mixed with the sample and incubated for 1 h, microcentrifuged and the supernatant fluid (unadsorbed antibody) titred in a microtitre plate coated with A. hydrophila cells from serotype O : 11. All the A. hydrophila strains from serotype O : 11 tested reacted strongly with the detector antibody. Also by culturing and performing the immunoassay with the detector antibody we established and quantified the presence of A. hydrophila O : 11 in different foods. 相似文献
72.
73.
Choonkeun Kim Catarina Milheiri?o Susana Gardete Mark A. Holmes Matt T. G. Holden Hermínia de Lencastre Alexander Tomasz 《The Journal of biological chemistry》2012,287(44):36854-36863
Methicillin-resistant Staphylococcus aureus (MRSA) strains show strain-to-strain variation in resistance level, in genetic background, and also in the structure of the chromosomal cassette (SCCmec) that carries the resistance gene mecA. In contrast, strain-to-strain variation in the sequence of the mecA determinant was found to be much more limited among MRSA isolates examined so far. The first exception to this came with the recent identification of MRSA strain LGA251, which carries a new homolog of this gene together with regulatory elements mecI/mecR that also have novel, highly divergent structures. After cloning and purification in Escherichia coli, PBP2ALGA, the protein product of the new mecA homolog, showed aberrant mobility in SDS-PAGE, structural instability and loss of activity at 37 °C, and a higher relative affinity for oxacillin as compared with cefoxitin. The mecA homolog free of its regulatory elements was cloned into a plasmid and introduced into the background of the β-lactam-susceptible S. aureus strain COL-S. In this background, the mecA homolog expressed a high-level resistance to cefoxitin (MIC = 400 μg/ml) and a somewhat lower resistance to oxacillin (minimal inhibitory concentration = 200 μg/ml). Similar to PBP2A, the protein homolog PBP2ALGA was able to replace the essential function of the S. aureus PBP2 for growth. In contrast to PBP2A, PBP2ALGA did not depend on the transglycosylase activity of the native PBP2 for expression of high level resistance to oxacillin, suggesting that the PBP2A homolog may preferentially cooperate with a monofunctional transglycosylase as the alternative source of transglycosylase activity. 相似文献
74.
Peluc SI Reed WL McGraw KJ Gibbs P 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2012,182(5):687-702
Androgens and carotenoids circulating in plasma affect the physiology and behavior of vertebrates. Much is known about control mechanisms and functions of each of these substances, yet their interactive effects are not well understood. Here we examine possible additive, multiplicative, and interactive effects of testosterone and carotenoids on female endocrine physiology, immunocompetence, and investment in eggs by simultaneously manipulating levels of testosterone [via gonadotropin releasing hormone (GnRH) challenges] and carotenoids (via diet supplementation) in captive female Japanese quail (Coturnix japonica). Females were randomly assigned to one of four treatments: carotenoid supplementation, GnRH challenge, GnRH challenge?+?carotenoid supplementation, or control. Carotenoid supplementation significantly increased circulating plasma carotenoid levels and acquired immune system performance, but not innate immunity. GnRH challenges elevated circulating testosterone and carotenoid levels, and induced immunosuppression in females. However, females in the GnRH challenge?+?carotenoid supplementation treatment had higher cell-mediated immune responses than control females and similar responses to those of carotenoid-supplemented females. Hence, availability of carotenoids in female quail seemed to counteract immunosuppressive effects of GnRH challenges. Our results provide further evidence for synergistic effects of carotenoids and testosterone on endocrine physiology and immune function in female birds. Elevated plasma testosterone or carotenoids levels resulted in increased deposition of those compounds to eggs, respectively. Furthermore, because we found that concentrations of testosterone and carotenoids in yolks were correlated within each treatment group, differential deposition of hormones and carotenoids in eggs may not only respond to surrounding social and environmental conditions, but also to other components of the egg. 相似文献
75.
Susana M.?GallegoEmail author Marcelo J.?Kogan Claudia E.?Azpilicueta Clara?Pe?a María L.?Tomaro 《Plant Growth Regulation》2005,46(3):267-276
Cadmium (Cd) homeostasis and detoxification in sunflower (Helianthus annuus L.) cells differing in Cd sensitivity/tolerance were studied by analyzing the glutathione-mediated antioxidant mechanism
vis-à-vis phytochelatin biosynthesis in vitro. Calluses exposed to Cd-shock/-acclimatization (150μM) were assayed for oxidative stress, reduced glutathione (GSH), glutathione
disulfide (GSSG), phytochelatins (PCs) and reactive oxygen species (ROS). Although Cd did not induce any oxidative stress
in Cd-tolerant callus (TCd), it generated oxidative stress in Cd-shock callus (SCd) both in terms of lipid peroxidation and
protein oxidation. GSH/GSSG ratio remained similar to control values in the cadmium-acclimatized calluses. However, after
acute treatment, there was a decline in both GSH and GSSG levels in SCd with concomitant reduction in the GSH/GSSG ratio.
Analysis of PCs was performed using HPLC and mass spectrometry methods. PC concentration in TCd were approximately twice those
that in SCd, showing in both cases a 1:2:1 relative proportion for PC n = 2 (PC2): PC n = 3 (PC3): PC n = 4 (PC4). Calluses growing in the presence of Cd developed an increased resistance to paraquat oxidative stress generation.
These results indicated that PCs synthesis was an important mechanism for Cd detoxification in sunflower calluses, but the
capacity to grow in the presence of Cd is related to the tissues ability to maintain high intracellular levels of GSH. 相似文献
76.
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78.
Effect of ice melting on bacterial carbon fluxes channelled by viruses and protists in the Arctic Ocean 总被引:1,自引:0,他引:1
Julia A. Boras M. Montserrat Sala Jesus M. Arrieta Elisabet L. Sà Jorge Felipe Susana Agustí Carlos M. Duarte Dolors Vaqué 《Polar Biology》2010,33(12):1695-1707
During the last few years, extensive sea ice melting in the Arctic due to climate change has been detected, which could potentially
modify the organic carbon fluxes in these waters. In this study, the effect of sea ice melting on bacterial carbon channelling
by phages and protists has been evaluated in the northern Greenland Sea and Arctic Ocean. Grazing on bacteria by protists
was evaluated using the FLB disappearance method. Lysis of bacteria due to viral infections was measured using the virus reduction
approach. Losses of bacterial production caused by protists (PMMBP) dominated losses caused by viruses (VMMBP) throughout the study. Lysogenic viral production was detected in 7 out of 21 measurements and constituted from 33.9 to 100.0%
of the total viral production. Significantly higher PMMBP and lower VMMBP were detected in waters affected by ice melting compared with unaffected waters. Consequently, significantly more bacterial
carbon was channelled to the higher trophic levels in affected waters (13.05 ± 5.98 μgC l−1 day−1) than in unaffected waters (8.91 ± 8.33 μgC l−1 day−1). Viruses channelled 2.63 ± 2.45 μgC l−1 day−1 in affected waters and 4.27 ± 5.54 μgC l−1 day−1 in unaffected waters. We conclude that sea ice melting in the Arctic could modify the carbon flow through the microbial food
web. This process may be especially important in the case of massive sea ice melting due to climate change. 相似文献
79.
Expression of the complete ORF2 of human astrovirus serotype 1 (HAstV-1) in the baculovirus system led to the formation of virus-like particles (VLPs) of around 38 nm. The same kind of VLPs were also obtained either with the expression of a truncated form of ORF2 lacking the first 70 amino acids (aa), or with the same truncated form in which those 70 aa were replaced by the green fluorescent protein. All three kinds of VLPs were equally recognized by an anti-HAstV-1 polyclonal antibody and by two monoclonal antibodies (MAbs; 8E7 and 5B7), indicating a nonessential role of those amino acids neither in the capsid assembly nor in the antigen structure. A second type of structure consisting of 16-nm ring-like units was observed in all of the cases, mostly after disassembling the 38-nm VLPs through the addition of EDTA. The removal of the EDTA and the addition of Mg(2+) ions promoted the reassembly of the 38-nm VLPs. The nature of these 16-nm ring-like structures, capsomers or T = 1 VLPs, still remains unclear. Biochemical analysis revealed no differences between the 38-nm VLPs and the 16-nm structures, whereas antigenically, they shared the 8E7 MAb epitope but differed in the 5B7 MAb epitope, with the latter structures being more readily recognized. 相似文献
80.
Stacey Llewellyn Tawin Inpankaew Susana Vaz Nery Darren J. Gray Jaco J. Verweij Archie C. A. Clements Santina J. Gomes Rebecca Traub James S. McCarthy 《PLoS neglected tropical diseases》2016,10(1)