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21.
Roselyne Ferrari Isabelle Lacaze Pauline Le Faouder Justine Bertrand-Michel Camille Oger Jean-Marie Galano Thierry Durand Stéphane Moularat Laetitia Chan Ho Tong Charlie Boucher Jaafar Kilani Yohann Petit Océane Vanparis César Trannoy Sylvain Brun Hervé Lalucque Fabienne Malagnac Philippe Silar 《Biochimica et Biophysica Acta (BBA)/General Subjects》2018,1862(10):2174-2182
Oxylipins are secondary messengers used universally in the living world for communication and defense. The paradigm is that they are produced enzymatically for the eicosanoids and non-enzymatically for the isoprostanoids. They are supposed to be degraded into volatile organic compounds (VOCs) and to participate in aroma production. Some such chemicals composed of eight carbons are also envisoned as alternatives to fossil fuels. In fungi, oxylipins have been mostly studied in Aspergilli and shown to be involved in signalling asexual versus sexual development, mycotoxin production and interaction with the host for pathogenic species. Through targeted gene deletions of genes encoding oxylipin-producing enzymes and chemical analysis of oxylipins and volatile organic compounds, we show that in the distantly-related ascomycete Podospora anserina, isoprostanoids are likely produced enzymatically. We show the disappearance in the mutants lacking lipoxygenases and cyclooxygenases of the production of 10-hydroxy-octadecadienoic acid and that of 1-octen-3-ol, a common volatile compound. Importantly, this was correlated with the inability of the mutants to repel nematodes as efficiently as the wild type. Overall, our data show that in this fungus, oxylipins are not involved in signalling development but may rather be used directly or as precursors in the production of odors against potential agressors.
Significance
We analyzse the role in inter-kingdom communication of lipoxygenase (lox) and cyclooxygenase (cox) genes in the model fungus Podospora anserina.Through chemical analysis we define the oxylipins and volatile organic compounds (VOCs)produce by wild type and mutants for cox and lox genes,We show that the COX and LOX genes are required for the production of some eight carbon VOCs.We show that COX and LOX genes are involved in the production of chemicals repelling nematodes.This role is very different from the ones previously evidenced in other fungi. 相似文献22.
1. The separation of the alpha-components of codfish-skin and calf-skin collagen from the higher-molecular-weight components was accomplished by gel filtration with Bio-Gel P-300 resin in 5m-lithium chloride and at pH7.4. 2. From this fraction three distinct alpha-components, corresponding to the alpha1-, alpha2- and alpha3- chains of collagen, were isolated by free-flow electrophoresis in 6m-urea at 4 degrees . At the temperatures and pH values used there was no detectable degradation of the alpha-chains. 相似文献
23.
24.
James Hansen Pushker Kharecha Makiko Sato Valerie Masson-Delmotte Frank Ackerman David J. Beerling Paul J. Hearty Ove Hoegh-Guldberg Shi-Ling Hsu Camille Parmesan Johan Rockstrom Eelco J. Rohling Jeffrey Sachs Pete Smith Konrad Steffen Lise Van Susteren Karina von Schuckmann James C. Zachos 《PloS one》2013,8(12)
We assess climate impacts of global warming using ongoing observations and paleoclimate data. We use Earth’s measured energy imbalance, paleoclimate data, and simple representations of the global carbon cycle and temperature to define emission reductions needed to stabilize climate and avoid potentially disastrous impacts on today’s young people, future generations, and nature. A cumulative industrial-era limit of ∼500 GtC fossil fuel emissions and 100 GtC storage in the biosphere and soil would keep climate close to the Holocene range to which humanity and other species are adapted. Cumulative emissions of ∼1000 GtC, sometimes associated with 2°C global warming, would spur “slow” feedbacks and eventual warming of 3–4°C with disastrous consequences. Rapid emissions reduction is required to restore Earth’s energy balance and avoid ocean heat uptake that would practically guarantee irreversible effects. Continuation of high fossil fuel emissions, given current knowledge of the consequences, would be an act of extraordinary witting intergenerational injustice. Responsible policymaking requires a rising price on carbon emissions that would preclude emissions from most remaining coal and unconventional fossil fuels and phase down emissions from conventional fossil fuels. 相似文献
25.
26.
Fixed vs. Random Temporal Predictability of Predation Risk: An Extension of the Risk Allocation Hypothesis 总被引:1,自引:0,他引:1
Maud C. O. Ferrari Alix C. Rive† Camille J. MacNaughton† Grant E. Brown† & Douglas P. Chivers 《Ethology : formerly Zeitschrift fur Tierpsychologie》2008,114(3):238-244
Predation is a strong selective force acting on prey animals. Predation is by nature highly variable in time; however, this aspect of predation risk has traditionally been overlooked by behavioural ecologists. Lima and Bednekoff proposed the predation risk allocation hypothesis (RAH), predicting how temporal variation in predation risk drives prey antipredator behaviours. This model is based on the concept that prey adaptively allocate their foraging and antipredator efforts across high‐ and low‐risk situations, depending on the duration of high‐ vs. low‐risk situations and the relative risk associated with each of them. An unstudied extension of the RAH is the effect of predictability of predation risk. A predictable risk should lead to prey displaying minimal vigilance behaviours during predictable low‐risk periods and the strongest antipredator behaviours during risky periods. Conversely, an unpredictable predation risk should result in prey displaying constant vigilance behaviour, with suboptimal foraging rates during periods of safety but antipredator behaviours of lower intensity during periods of risk. We tested this extension of the RAH using convict cichlids exposed to high‐risk alarm cues at two frequencies of risk (1× vs. 3×) per day, on either a fixed or random schedule for 5 d. We then tested the fish for a response to high‐risk cues (alarm cues) and to low‐risk cues (disturbance resulting from the introduction of distilled water). Our study supports previous results on the effects of risk frequency and cue intensity on cichlid behaviour. We failed to show an effect of risk predictability on the behavioural responses of cichlids to high‐risk alarm cues, but predictability did influence responses to low‐risk cues. We encourage further studies to test the effect of predictability in other systems. 相似文献
27.
Grégory Dubar Elie Azria Antoine Tesnière Hervé Dupont Camille Le Ray Thomas Baugnon Sophie Matheron Dominique Luton Jean-Christophe Richard Odile Launay Vassilis Tsatsaris Fran?ois Goffinet Alexandre Mignon for the French Registry on A/HNv during pregnancy 《PloS one》2010,5(10)
Background
The first reports on the pandemic influenza 2009 A/H1N1v from the USA, Mexico, and Australia indicated that this disease was associated with a high mortality in pregnant women. The aim of this study was to describe and compare the characteristics of severe critically ill and non-severe pregnant women with 2009 A/H1N1v-related illness in France.Methodology/Principal Findings
A national registry was created to screen pregnant women with laboratory-confirmed 2009 A/H1N1v influenza. Three hundred and fifteen patients from 46 French hospitals were included: 40 patients were admitted to intensive care units (severe outcomes), 111 were hospitalized in obstetric or medical wards (moderate outcomes), and 164 were outpatients (mild outcomes). The 2009 A/H1N1v influenza illness occurred during all pregnancy trimesters, but most women (54%), notably the severe patients (70%), were in the third trimester. Among the severe patients, twenty (50%) underwent mechanical ventilation, and eleven (28%) were treated with extracorporeal membrane oxygenation. Three women died from A/H1N1v influenza. We found a strong association between the development of a severe outcome and both co-existing illnesses (adjusted odds ratio [OR], 5.1; 95% confidence interval [CI], 2.2–11.8) and a delay in oseltamivir treatment after the onset of symptoms (>3 or 5 days) (adjusted OR, 4.8; 95% CI, 1.9–12.1 and 61.2, 95% CI; 14.4–261.3, respectively). Among the 140 deliveries after 22 weeks of gestation known to date, 19 neonates (14%) were admitted to a neonatal intensive care unit, mainly for preterm delivery, and two neonates died. None of these neonates developed 2009 A/H1N1v infection.Conclusions
This series confirms the high incidence of complications in pregnant women infected with pandemic A/H1N1v observed in other countries but depicts a lower overall maternal and neonatal mortality and morbidity than indicated in the USA or Australia. Moreover, our data demonstrate the benefit of early oseltamivir treatment in this specific population. 相似文献28.
29.
Jennyfer Miot Karim Benzerara Martin Obst Andreas Kappler Florian Hegler Sebastian Sch?dler Camille Bouchez Fran?ois Guyot Guillaume Morin 《Applied and environmental microbiology》2009,75(17):5586-5591
Iron oxidation at neutral pH by the phototrophic anaerobic iron-oxidizing bacterium Rhodobacter sp. strain SW2 leads to the formation of iron-rich minerals. These minerals consist mainly of nano-goethite (α-FeOOH), which precipitates exclusively outside cells, mostly on polymer fibers emerging from the cells. Scanning transmission X-ray microscopy analyses performed at the C K-edge suggest that these fibers are composed of a mixture of lipids and polysaccharides or of lipopolysaccharides. The iron and the organic carbon contents of these fibers are linearly correlated at the 25-nm scale, which in addition to their texture suggests that these fibers act as a template for mineral precipitation, followed by limited crystal growth. Moreover, we evidence a gradient of the iron oxidation state along the mineralized fibers at the submicrometer scale. Fe minerals on these fibers contain a higher proportion of Fe(III) at cell contact, and the proportion of Fe(II) increases at a distance from the cells. All together, these results demonstrate the primordial role of organic polymers in iron biomineralization and provide first evidence for the existence of a redox gradient around these nonencrusting, Fe-oxidizing bacteria.Fe(II) can serve as a source of electrons for phylogenetically diverse microorganisms that precipitate iron minerals as products of their metabolism (see, e.g., references 3, 5, 25, and 30). For example, mixotrophic or autotrophic bacteria can couple the oxidation of Fe(II) to the reduction of nitrate in anoxic and neutral-pH environments. With Fe(III) being highly insoluble at neutral pH, this metabolism leads to the formation of poorly to well-crystallized iron minerals (3, 18, 26, 27) that precipitate partly within the cell periplasm for some strains (22). Similar Fe minerals are also synthesized by autotrophic bacteria that perform anoxygenic photosynthesis, using Fe(II) as an electron donor and light as a source of energy for CO2 fixation (8, 12, 30), according to the equation HCO3− + 4 Fe2+ + 10 H2O ⇆ <CH2O> + 4 Fe(OH)3 + 7 H+.However, the biological mechanisms of iron oxidation in these bacteria and in particular the way they cope with the formation of minerals within their ultrastructures are still not fully understood. Indeed, iron minerals are potentially lethal since their precipitation may alter cellular ultrastructures but also catalyze the production of free radicals (2). Recent genetic studies of the phototrophic, iron-oxidizing bacteria Rhodobacter sp. strain SW2 (6) and Rhodopseudomonas palustris strain TIE-1 (16) have identified genes (fox and pio operons, respectively) encoding proteins specific for iron oxidation. Interestingly, Jiao and Newman (16) suggested that one of these proteins could have a periplasmic localization. However, in contrast to what has been observed in some other phototrophic iron oxidizers (25) and in some nitrate-reducing, iron-oxidizing bacteria (22), no iron-mineral precipitation occurs within the periplasm of the purple nonsulfur iron-oxidizing bacterium Rhodobacter sp. strain SW2 (3). Similarly to some other anaerobic neutrophilic (22, 25) and microaerobic iron-oxidizing bacteria (5, 10), this strain seems indeed to have the ability to localize iron biomineralization at a distance from the cells, leaving large areas of the cells free of precipitates (17, 25). While it has been shown that the Gallionella and Leptothrix genera, for example, produce extracellular polymers that facilitate the nucleation of iron minerals outside cells (see, e.g., references 5 and 9), only a little is known about the existence and function of such polymers in anaerobic, neutrophilic iron-oxidizing bacteria and particularly in the phototrophic strain SW2. In the present study, we investigate iron biomineralization by the photoautotrophic iron-oxidizing bacterium Rhodobacter sp. strain SW2. We use scanning transmission X-ray microscopy (STXM) to map and identify organic polymers produced by the cells as well as the redox state of iron at the 25-nanometer scale regularly during a 2 week-period. These results demonstrate the primordial role of organic polymers in iron biomineralization and provide the first evidence for the existence of a redox gradient around SW2 cells. 相似文献
30.
QTL mapping of Fusarium head blight resistance in three related durum wheat populations 总被引:2,自引:0,他引:2
Noemie Prat Camille Guilbert Ursa Prah Elisabeth Wachter Barbara Steiner Thierry Langin Olivier Robert Hermann Buerstmayr 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2017,130(1):13-27