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51.
Root and microbial involvement in the kinetics of 14C-partitioning to rhizosphere respiration after a pulse labelling of maize assimilates 总被引:1,自引:0,他引:1
In a previous study, we examined the kinetics of radioactivity evolution from rhizosphere respiration after the pulse labelling of maize shoots with 14CO2 (Nguyen et al., 1999). The specific activity of rhizosphere respiration demonstrated two peaks of 14CO2 production. The first one occurred a few hours after the pulse of 14CO2 and was followed by a second peak, which took place during the night following the labelling. In the present work, we demonstrate that the second phase of activity occurred in both sterile and non sterile plant–soil systems. This was inconsistent with the results obtained for wheat by Warembourg and Billès (1979) who observed the second peak solely in the case of non-sterile cultures. These authors suggested that this second phase of 14CO2 production was related to microbial mineralisation of labelled complex compounds. Their synthesis and breakdown into smaller molecules delayed their utilisation by micro-organisms. However, in the present work, we also demonstrate that the second phase of activity was closely related to photoperiod. When plants were transferred from a 16 h to 20 h photoperiod, the second mineralisation of labelled rhizosphere compounds occurred sooner after the initiation of the dark period and it was strongly attenuated. Therefore, we suggest that the second phase of activity resulted from the utilisation by roots and by micro-organisms of stored 14C-compounds, which accumulated during the previous light period. 相似文献
52.
A total of 27 maize-based products destined for human consumption were collected from retail outlets within the city of Glasgow
in the UK and were analysed for the presence of aflatoxins using immunoaftinity column chromatography with fluorescence detection
and for fumonisins by competitive ELISA. Aflatoxins were detected at a trace level below 4 in eight (30%) of the 27 samples
tested, no sample contained aflatoxins at a high level although one sample of sweetcorn did contain aflatoxins at a level
of 5-10 Fumonisins were detected in eight (30%) of the samples at levels from 1 to 8mgkg-1 and a further eight samples contained fumonisin at a level below 1 mgkg-1 but above the detectable level. The highest concentration of fumonisins was found in a sample of fine corn meal at 8-12mgkg-1. 相似文献
53.
Connecting viral with cellular interactomes 总被引:1,自引:0,他引:1
54.
Célia M. Silveira Pedro O. Quintas Isabel Moura José J. G. Moura Peter Hildebrandt M. Gabriela Almeida Smilja Todorovic 《PloS one》2015,10(6)
Cytochrome cd1 nitrite reductases (cd
1NiRs) catalyze the one-electron reduction of nitrite to nitric oxide. Due to their catalytic reaction, cd
1NiRs are regarded as promising components for biosensing, bioremediation and biotechnological applications. Motivated by earlier findings that catalytic activity of cd
1NiR from Marinobacter hydrocarbonoclasticus (Mhcd
1) depends on the presence of its physiological redox partner, cytochrome c
552 (cyt c
552), we show here a detailed surface enhanced resonance Raman characterization of Mhcd
1 and cyt c
552 attached to biocompatible electrodes in conditions which allow direct electron transfer between the conducting support and immobilized proteins. Mhcd
1 and cyt c552 are co-immobilized on silver electrodes coated with self-assembled monolayers (SAMs) and the electrocatalytic activity of Ag // SAM // Mhcd
1 // cyt c
552 and Ag // SAM // cyt c
552 // Mhcd
1 constructs is tested in the presence of nitrite. Simultaneous evaluation of structural and thermodynamic properties of the immobilized proteins reveals that cyt c
552 retains its native properties, while the redox potential of apparently intact Mhcd
1 undergoes a ~150 mV negative shift upon adsorption. Neither of the immobilization strategies results in an active Mhcd
1, reinforcing the idea that subtle and very specific interactions between Mhcd
1 and cyt c
552 govern efficient intermolecular electron transfer and catalytic activity of Mhcd
1. 相似文献
55.
J Yanci C Granados M Otero A Badiola J Olasagasti I Bidaurrazaga-Letona A Iturricastillo SM Gil 《Biology of sport / Institute of Sport》2015,32(1):71-78
The aims of the present study were, firstly, to determine the reliability and reproducibility of an agility T-test and Yo-Yo 10 m recovery test; and secondly, to analyse the physical characteristics measured by sprint, agility, strength and endurance field tests in wheelchair basketball (WB) players. 16 WB players (33.06 ± 7.36 years, 71.89 ± 21.71 kg and sitting body height 86.07 ± 6.82 cm) belonging to the national WB league participated in this study. Wheelchair sprint (5 and 20 m without ball, and 5 and 20 m with ball) agility (T-test and pick-up test) strength (handgrip and maximal pass) and endurance (Yo-Yo 10 m recovery test) were performed. T-test and Yo-Yo 10 m recovery test showed good reproducibility values (intraclass correlation coefficient, ICC = 0.74-0.94). The WB players’ results in 5 and 20 m sprints without a ball were 1.87 ± 0.21 s and 5.70 ± 0.43 s and with a ball 2.10 ± 0.30 s and 6.59 ± 0.61 s, being better than those reported in the literature. Regarding the pick-up test results (16.05 ± 0.52 s) and maximal pass (8.39 ± 1.77 m), players showed worse values than those obtained in elite players. The main contribution of the present study is the characterization of the physical performance profile of WB players using a field test battery. Furthermore, we demonstrated that the agility T-test and the aerobic Yo-Yo 10 m recovery test are reliable; consequently they may be appropriate instruments for measuring physical fitness in WB. 相似文献
56.
Background
The transglutaminase activated factor XIII (FXIIIa) acts to strengthen pathological fibrin clots and to slow their dissolution, in part by crosslinking active α2-antiplasmin (α2AP) to fibrin. We previously reported that a yeast-derived recombinant fusion protein comprising α2AP residues 13-42 linked to human serum albumin (HSA) weakened in vitro clots but failed to become specifically incorporated into in vivo clots. In this study, our aims were to improve both the stability and clot localization of the HSA fusion protein by replacing α2AP residues 13-42 with shorter sequences recognized more effectively by FXIIIa.Results
Expression plasmids were prepared encoding recombinant HSA with the following N-terminal 23 residue extensions: H6NQEQVSPLTLLAG4Y (designated XL1); H6DQMMLPWAVTLG4Y (XL2); H6WQHKIDLPYNGAG4Y (XL3); and their 17 residue non-His-tagged equivalents (XL4, XL5, and XL6). The HSA moiety of XL4- to XL6-HSA proteins was C-terminally His-tagged. All chimerae were efficiently secreted from transformed Pichia pastoris yeast except XL3-HSA, and following nickel chelate affinity purification were found to be intact by amino acid sequencing, as was an N-terminally His-tagged version of α2AP(13-42)-HSA. Of the proteins tested, XL5-HSA was cross-linked to biotin pentylamine (BPA) most rapidly by FXIIIa, and was the most effective competitor of α2AP crosslinking not only to BPA but also to plasma fibrin clots. In the mouse ferric chloride vena cava thrombosis model, radiolabeled XL5-HSA was retained in the clot to a greater extent than recombinant HSA. In the rabbit jugular vein stasis thrombosis model, XL5-HSA was also retained in the clot, in a urea-insensitive manner indicative of crosslinking to fibrin, to a greater extent than recombinant HSA.Conclusions
Fusion protein XL5-HSA (DQMMLPWAVTLG4Y-HSAH6) was found to be more active as a substrate for FXIIIa-mediated transamidation than seven other candidate fusion proteins in vitro. The improved stability and reactivity of this chimeric protein was further evidenced by its incorporation into in vivo clots formed in thrombosis models in both mice and rabbits. 相似文献57.
Aldair JW Pinto Maria M Figueiredo Fabiana L Silva Trycia Martins Marilene SM Michalick Washington L Tafuri Wagner L Tafuri 《Acta veterinaria Scandinavica》2011,53(1):1-8
Background
A nationwide survey on the microbial etiology of cases of subclinical mastitis in dairy cows was carried out on dairy farms in Sweden. The aim was to investigate the microbial panorama and the occurrence of antimicrobial resistance. Moreover, differences between newly infected cows and chronically infected cows were investigated.Methods
In total, 583 quarter milk samples were collected from 583 dairy cows at 226 dairy farms from February 2008 to February 2009. The quarter milk samples were bacteriological investigated and scored using the California Mastitis Test. Staphylococci were tested for betalactamase production and presence of resistance was evaluated in all specific udder pathogens. Differences between newly infected cows and chronically infected cows were statistically investigated using logistic regression analysis.Results
The most common isolates of 590 bacteriological diagnoses were Staphylococcus (S) aureus (19%) and coagulase-negative staphylococci (CNS; 16%) followed by Streptococcus (Str) dysgalactiae (9%), Str. uberis (8%), Escherichia (E.) coli (2.9%), and Streptococcus spp. (1.9%). Samples with no growth or contamination constituted 22% and 18% of the diagnoses, respectively. The distribution of the most commonly isolated bacteria considering only bacteriological positive samples were: S. aureus - 31%, CNS - 27%, Str. dysgalactiae - 15%, Str. uberis - 14%, E. coli - 4.8%, and Streptococcus spp. - 3.1%. There was an increased risk of finding S. aureus, Str. uberis or Str. dysgalactiae in milk samples from chronically infected cows compared to findings in milk samples from newly infected cows. Four percent of the S. aureus isolates and 35% of the CNS isolates were resistant to penicillin G. Overall, resistance to other antimicrobials than penicillin G was uncommon.Conclusions
Staphylococcus aureus and CNS were the most frequently isolated pathogens and resistance to antimicrobials was rare. 相似文献58.
Intensive nitrogen loss over the Omani Shelf due to anammox coupled with dissimilatory nitrite reduction to ammonium 总被引:1,自引:0,他引:1
Marlene M Jensen Phyllis Lam Niels Peter Revsbech Birgit Nagel Birgit Gaye Mike SM Jetten Marcel MM Kuypers 《The ISME journal》2011,5(10):1660-1670
A combination of stable isotopes (15N) and molecular ecological approaches was used to investigate the vertical distribution and mechanisms of biological N2 production along a transect from the Omani coast to the central–northeastern (NE) Arabian Sea. The Arabian Sea harbors the thickest oxygen minimum zone (OMZ) in the world''s oceans, and is considered to be a major site of oceanic nitrogen (N) loss. Short (<48 h) anoxic incubations with 15N-labeled substrates and functional gene expression analyses showed that the anammox process was highly active, whereas denitrification was hardly detectable in the OMZ over the Omani shelf at least at the time of our sampling. Anammox was coupled with dissimilatory nitrite reduction to ammonium (DNRA), resulting in the production of double-15N-labeled N2 from 15NO2−, a signal often taken as the lone evidence for denitrification in the past. Although the central–NE Arabian Sea has conventionally been regarded as the primary N-loss region, low potential N-loss rates at sporadic depths were detected at best. N-loss activities in this region likely experience high spatiotemporal variabilities as linked to the availability of organic matter. Our finding of greater N-loss associated with the more productive Omani upwelling region is consistent with results from other major OMZs. The close reliance of anammox on DNRA also highlights the need to take into account the effects of coupling N-transformations on oceanic N-loss and subsequent N-balance estimates. 相似文献
59.
Guibing Zhu Shanyun Wang Yu Wang Chaoxu Wang Nils Risgaard-Petersen Mike SM Jetten Chengqing Yin 《The ISME journal》2011,5(12):1905-1912
Evidence for anaerobic ammonium oxidation in a paddy field was obtained in Southern China using an isotope-pairing technique, quantitative PCR assays and 16S rRNA gene clone libraries, along with nutrient profiles of soil cores. A paddy field with a high load of slurry manure as fertilizer was selected for this study and was shown to contain a high amount of ammonium (6.2–178.8 mg kg−1). The anaerobic oxidation of ammonium (anammox) rates in this paddy soil ranged between 0.5 and 2.9 nmolN per gram of soil per hour in different depths of the soil core, and the specific cellular anammox activity observed in batch tests ranged from 2.9 to 21 fmol per cell per day. Anammox contributed 4–37% to soil N2 production, the remainder being due to denitrification. The 16S rRNA gene sequences of surface soil were closely related to the anammox bacteria ‘Kuenenia'', ‘Anammoxoglobus'' and ‘Jettenia''. Most of the anammox 16S rRNA genes retrieved from the deeper soil were affiliated to ‘Brocadia''. The retrieval of mainly bacterial amoA sequences in the upper part of the paddy soil indicated that nitrifying bacteria may be the major source of nitrite for anammox bacteria in the cultivated horizon. In the deeper oxygen-limited parts, only archaeal amoA sequences were found, indicating that archaea may produce nitrite in this part of the soil. It is estimated that a total loss of 76 g N m−2 per year is linked to anammox in the paddy field. 相似文献
60.
Muhammad Toyabur Rahman SM Sohel Rana Md Salauddin Pukar Maharjan Trilochan Bhatta Jae Yeong Park 《Liver Transplantation》2020,10(12)
The fast growth of smart electronics requires novel solutions to power them sustainably. Portable power sources capable of harvesting biomechanical energy are a promising modern approach to reduce battery dependency. Herein, a novel elastic impact‐based nonresonant hybridized generator (EINR‐HG) is reported to effectively harvest biomechanical energy from diverse human activities outdoors. Through the rational integration of a nonlinear electromagnetic generator with two contact‐mode triboelectric nanogenerators, the proposed EINR‐HG generates hybrid electrical output simultaneously under the same mechanical excitations. By introducing a flux‐concentrator with a nanowire‐nanofiber surface modification, significant improvement in the energy harvesting efficiency of the EINR‐HG is achieved. After optimizing using simulations and vibration tests, the as‐fabricated EINR‐HG delivers an outstanding normalized power density of 3.13 mW cm?3 g?2 across a matching resistance of 1.5 kΩ at 6 Hz under 1 g acceleration. Under human motion testing, the EINR‐HG generates an optimal output power of 131.4 mW with horizontal handshaking. With a customized power management circuit, the EINR‐HG serves as a universal power source that successfully drives commercial smart electronics, including smart bands and smartphones. This work shows the massive potential of biomechanical energy‐driven hybridized generators for powering personal electronics and portable healthcare monitoring devices. 相似文献