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951.
Neudörffer A Desvergne JP Bonnefont-Rousselot D Legrand A Fleury MB Largeron M 《Journal of agricultural and food chemistry》2006,54(5):1898-1905
4-Hydroxycinnamate derivatives are known to be potent protectors against oxidation of low-density lipoproteins (LDL), via a combination of free radical scavenging and transition metal chelation. Through a series of 4-hydroxycinnamic ethyl ester derivatives and related 8-8 dehydrodimers, we have tried to bring out the structural requirements for radical scavenging and cupric ion chelation. We found that the monomeric compounds, except for highly lipophilic tert-butyl derivative 3, exhibited rather low radical scavenging properties. Furthermore, they did not chelate copper but, in contrast, reduced cupric ion to cuprous ion, affording the related 8-8 dehydrodimers, for which they could be considered as precursors in vitro. In the copper-dependent human LDL oxidation in vitro, the cyclic 8-8 dehydrodimer forms behaved essentially as efficient copper chelators, while related noncyclic 8-8 forms, which were found to be the best protectors, mainly acted as radical scavengers. 相似文献
952.
Paul Tixier Mary‐Anne Lea Mark A. Hindell Dirk Welsford Camille Maz Sophie Gourguet John P. Y. Arnould 《Fish and Fisheries》2021,22(1):31-53
The sustainable mitigation of human–wildlife conflicts has become a major societal and environmental challenge globally. Among these conflicts, large marine predators feeding on fisheries catches, a behaviour termed “depredation,” has emerged concomitantly with the expansion of the world’s fisheries. Depredation poses threats to both the socio‐economic viability of fisheries and species conservation, stressing the need for mitigation. This review synthesizes the extent and socio‐ecological impacts of depredation by sharks and marine mammals across the world, and the various approaches used to minimize it. Depredation was reported in 214 fisheries between 1979 and 2019 (70% post‐2000) and affected fleets from 44 countries, in all sectors (commercial, artisanal and recreational), and in all major fishing techniques (nets, traps and hook‐and‐lines). A total of 68 predator species were involved in depredation (20 odontocetes, 21 pinnipeds and 27 sharks), and most (73%) were subject to either by‐catch and/or retaliatory killing from fishers when interacting with gear. Impacts on fishers were primarily associated with catch losses and gear damage but often lacked assessments. Deterrence was a major mitigation approach but also the least effective. Gear modifications or behavioural adaptation by fishers were more promising. This review highlights the need for improved monitoring, and interdisciplinary and integrated research to quantify the determinants and impacts of depredation in the socio‐ecological dimension. More importantly, as the conflict is likely to escalate, efforts directed towards changing perceptions and integrating knowledge through adaptive co‐management are raised as key directions towards coexistence between fisheries and large marine predators. 相似文献
953.
Tillage with a spring tine harrow has become a recommended mechanical weeding technique for cereal crops. In this study, the impact of its use on soil mineral N content, soil aggregation and spring wheat (Triticum aestivum L.) production was investigated. The experiment was performed during 2 successive years (2005–2006) on a clay loam and on a silty loam. The two-main plot treatments consisted of a wheat crop subjected or not to intensive harrow use in a weed-free production system. Two N fertilizer treatments (mineral fertilizer and dry granular poultry manure) were also included as subplots within these main treatments and compared to a non-fertilized control. Harrowing had significant and variable effects on soil NO3− contents in the 0–5 cm soil layer. Slightly higher NO3− contents (average difference of 3.2 kg NO3− ha−1) were measured in the harrowed treatments than in the undisturbed plots in the clay loam soil in 2006. However, significantly lower mineral N contents were observed in the harrowed treatments than in the undisturbed plots in the clay loam soil in 2005 and in the silty loam soil in 2006. This apparent N immobilization amounted to 19 kg NO3− ha−1 in the clay loam soil in 2005 (for both fertilizers) and 30 kg NO3− ha−1 in the silty loam soil in 2006 (only in mineral fertilizer plots) after the successive harrowing treatments. In all cases, data of the last sampling dates in the fall indicated that residual NO3− content was not affected by the treatments. Overall harrowing had a minor decreasing and transient effect on the mean weight diameter (MWD) of soil aggregates while the dry poultry manure tended to increase MWD. The harrowing treatment had no significant effect on wheat, grain N uptake and yield. In conclusion, harrow use had variable impacts on soil NO3− content and a minor decreasing effect on the MWD of soil aggregates. Of note, significant apparent mineral N immobilization was observed on a few sampling dates following the harrow treatments. 相似文献
954.
Anne Van Dommelen Anja Croonenborghs Stijn Spaepen Jos Vanderleyden 《Biology and Fertility of Soils》2009,45(5):549-553
Azospirillum brasilense is a diazotrophic bacterium and one of the best studied plant-growth-promoting bacterium living in close association with
several agronomically important crops. The production of plant-growth-regulating substances is a main mechanism of plant growth
stimulation, although other mechanisms have also been proposed. Nitrogen transfer from the bacterium to the plant is one among
the other possible mechanisms of plant growth stimulation. In this study, we investigated, by means of a greenhouse trial
with winter wheat inoculation, the effect of a point mutation in the ammonium binding site of the A. brasilense glutamine synthetase. The glutamine synthetase is one of the main ammonium-assimilating enzymes and mutations in this enzyme
generally result in the release of ammonium from the bacterium to its environment. The ammonium-excreting mutant used in this
study was shown to perform better than the wild-type A. brasilense strain with respect to wheat growth parameters and yield. In the greenhouse conditions used, this effect was independent
of the way fertilizer was applied.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
955.
Manuela Hirz Henrike A. Gregersen Johannes Sander Dominique M. Votion Anne Schnzer Kernt Khler Christiane Herden 《Journal of veterinary diagnostic investigation》2021,33(5):961
Atypical myopathy (AM) is an acute seasonal rhabdomyolysis seen primarily in equids, caused by the ingestion of sycamore maple samaras containing hypoglycin A (HGA) and methylenecyclopropyl-glycine (MCPG). Toxic metabolites inhibit acyl-CoA dehydrogenases and enoyl-CoA hydratases, causing selective hyaline degeneration of type I muscle fibers. Two zoo-kept Bactrian camels (Camelus bactrianus) with a fatal course of AM had sudden onset of muscle pain and weakness, recumbency, and dysphagia, accompanied by increased serum creatine kinase activity and detection in serum of HGA, MCPG, and metabolites. Medical treatment was ineffective. At postmortem examination, sycamore maple tree material was found within the first gastric compartment of the 2-y-old gelding. Although musculature was macroscopically normal, histologically, monophasic hyaline degeneration was marked within type I fibers of intercostal and hypoglossal muscles of the gelding, and in neck, tongue, and masticatory muscles of the cow. The ingestion of sycamore maple material can cause AM in Bactrian camels, and trees of the Sapindaceae family should be avoided in enclosures. 相似文献
956.
Garand E Kamrath MZ Jordan PA Wolk AB Leavitt CM McCoy AB Miller SJ Johnson MA 《Science (New York, N.Y.)》2012,335(6069):694-698
Multidentate, noncovalent interactions between small molecules and biopolymer fragments are central to processes ranging from drug action to selective catalysis. We present a versatile and sensitive spectroscopic probe of functional groups engaged in hydrogen bonding in such contexts. This involves measurement of the frequency changes in specific covalent bonds upon complex formation, information drawn from otherwise transient complexes that have been extracted from solution and conformationally frozen near 10 kelvin in gas-phase clusters. Resonances closely associated with individual oscillators are easily identified through site-specific isotopic labeling, as demonstrated by application of the method to an archetypal system involving a synthetic tripeptide known to bind biaryl substrates through tailored hydrogen bonding to catalyze their asymmetric bromination. With such data, calculations readily converge on the plausible operative structures in otherwise computationally prohibitive, high-dimensionality landscapes. 相似文献
957.
958.
Messerschmidt DM de Vries W Ito M Solter D Ferguson-Smith A Knowles BB 《Science (New York, N.Y.)》2012,335(6075):1499-1502
Phenotypic variability in genetic disease is usually attributed to genetic background variation or environmental influence. Here, we show that deletion of a single gene, Trim28 (Kap1 or Tif1β), from the maternal germ line alone, on an otherwise identical genetic background, results in severe phenotypic and epigenetic variability that leads to embryonic lethality. We identify early and minute epigenetic variations in blastomeres of the preimplantation embryo of these animals, suggesting that the embryonic lethality may result from the misregulation of genomic imprinting in mice lacking maternal Trim28. Our results reveal the long-range effects of a maternal gene deletion on epigenetic memory and illustrate the delicate equilibrium of maternal and zygotic factors during nuclear reprogramming. 相似文献
959.
960.
M Oldenburg A Krüger R Ferstl A Kaufmann G Nees A Sigmund B Bathke H Lauterbach M Suter S Dreher U Koedel S Akira T Kawai J Buer H Wagner S Bauer H Hochrein CJ Kirschning 《Science (New York, N.Y.)》2012,337(6098):1111-1115
Host protection from infection relies on the recognition of pathogens by innate pattern-recognition receptors such as Toll-like receptors (TLRs). Here, we show that the orphan receptor TLR13 in mice recognizes a conserved 23S ribosomal RNA (rRNA) sequence that is the binding site of macrolide, lincosamide, and streptogramin group (MLS) antibiotics (including erythromycin) in bacteria. Notably, 23S rRNA from clinical isolates of erythromycin-resistant Staphylococcus aureus and synthetic oligoribonucleotides carrying methylated adenosine or a guanosine mimicking a MLS resistance-causing modification failed to stimulate TLR13. Thus, our results reveal both a natural TLR13 ligand and specific mechanisms of antibiotic resistance as potent bacterial immune evasion strategy, avoiding recognition via TLR13. 相似文献