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1.
F. Lavigne G. Martin Y. Anciaux J. Papaïx L. Roques 《Evolution; international journal of organic evolution》2020,74(1):29-42
The establishment of a population into a new empty habitat outside of its initial niche is a phenomenon akin to evolutionary rescue in the presence of immigration. It underlies a wide range of processes, such as biological invasions by alien organisms, host shifts in pathogens, or the emergence of resistance to pesticides or antibiotics from untreated areas. We derive an analytically tractable framework to describe the evolutionary and demographic dynamics of asexual populations in a source-sink system. We analyze the influence of several factors on the establishment success in the sink, and on the time until establishment. To this aim, we use a classic phenotype-fitness landscape (Fisher's geometrical model in n dimensions) where the source and sink habitats have different phenotypic optima. In case of successful establishment, the mean fitness in the sink follows a typical four-phases trajectory. The waiting time to establishment is independent of the immigration rate and has a “U-shaped” dependence on the mutation rate, until some threshold where lethal mutagenesis impedes establishment and the sink population remains so. We use these results to get some insight into possible effects of several management strategies. 相似文献
2.
Does an acute COPD crisis modify the cardiorespiratory and ventilatory adjustments to exercise in horses? 总被引:1,自引:0,他引:1
Art T.; Duvivier D. H.; Votion D.; Anciaux N.; Vandenput S.; Bayly W. M.; Lekeux P. 《Journal of applied physiology》1998,84(3):845-852
The present study was conducted to understandbetter the mechanisms leading to the decrease in exercise capacityobserved in horses suffering from chronic obstructive pulmonary disease (COPD). Five COPD horses were submitted to a standardized submaximal treadmill exercise test while they were in clinical remission or inacute crisis. Respiratory airflow,O2 andCO2 fractions in the respired gas,pleural pressure changes and heart rate were recorded, and arterial andmixed venous blood were analyzed for gas tensions, hemoglobin, andplasma lactate concentrations. O2 consumption, CO2 production,expired minute ventilation, tidal volume, alveolar ventilation, cardiacoutput, total pulmonary resistance, and mechanical work of breathingwere calculated. The results showed that, whensubmaximally exercised, COPD horses in crisis were significantly morehypoxemic and hypercapnic and that their total pulmonary resistance andmechanical work of breathing were significantly higher and theirexpired minute ventilation significantly lower than when they were inremission. However, their O2consumption remained unchanged, which was probably due to theoccurrence of compensatory mechanisms, i.e., higher heart rate, cardiacoutput, and hemoglobin concentration. Last, their net anaerobicmetabolism seemed to be more important. 相似文献
3.
Yoann Anciaux Amaury Lambert Ophlie Ronce Lionel Roques Guillaume Martin 《Evolution; international journal of organic evolution》2019,73(8):1517-1532
Populations may genetically adapt to severe stress that would otherwise cause their extirpation. Recent theoretical work, combining stochastic demography with Fisher's geometric model of adaptation, has shown how evolutionary rescue becomes unlikely beyond some critical intensity of stress. Increasing mutation rates may however allow adaptation to more intense stress, raising concerns about the effectiveness of treatments against pathogens. This previous work assumes that populations are rescued by the rise of a single resistance mutation. However, even in asexual organisms, rescue can also stem from the accumulation of multiple mutations in a single genome. Here, we extend previous work to study the rescue process in an asexual population where the mutation rate is sufficiently high so that such events may be common. We predict both the ultimate extinction probability of the population and the distribution of extinction times. We compare the accuracy of different approximations covering a large range of mutation rates. Moderate increase in mutation rates favors evolutionary rescue. However, larger increase leads to extinction by the accumulation of a large mutation load, a process called lethal mutagenesis. We discuss how these results could help design “evolution‐proof” antipathogen treatments that even highly mutable strains could not overcome. 相似文献
4.
Cécile Boland Sophie Bertrand Wesley Mattheus Katelijne Dierick Vicky Jasson Toon Rosseel Steven Van Borm Jacques Mahillon Pierre Wattiau 《Applied and environmental microbiology》2015,81(9):3169-3175
Fifty-nine monophasic Salmonella enterica serovar Typhimurium isolates, collected in Belgium during the period from 2008 to 2011, have been serotyped as 4,[5]:i:− and shown to harbor an fljB coding sequence. The genetic differences between these strains and phenotypically biphasic Salmonella Typhimurium were analyzed through PCR and DNA sequencing. Genetic alterations in the fljB promoter region affecting expression of the phase 2 flagellin were observed in 53 isolates. Other genetic events in the invertible region carrying the fljB promoter were observed in 2 isolates. For the remaining 4 isolates, no molecular differences with a reference biphasic Salmonella Typhimurium strain could be observed. Next-generation sequencing of one representative isolate affected in the fljB promoter region revealed a 26-kb IS26 composite transposon insertion along with a local genomic rearrangement. Several other IS26 element-mediated alterations of this genomic region were observed. This group of monophasic Salmonella Typhimurium isolates was genetically heterogeneous, as revealed by multilocus variable-number tandem-repeat analysis (MLVA), PCR, and sequencing. Pigs and pork represented a major source of such monophasic isolates in Belgium, as reported in other countries. Three out of 5 isolates of human origin presented genetic profiles identical to those of food isolates, demonstrating the pathogenic potential of the newly characterized variants and potential dissemination along the food chain. This study highlighted the key role played by IS26 insertions in the loss of phase 2 flagellin expression and the subsequent generation of multiple monophasic variant lineages from biphasic Salmonella Typhimurium ancestors. 相似文献
5.
Ignacio Gisbert Algaba Bavo Verhaegen Malgorzata Jennes Mizanur Rahman Wim Coucke Eric Cox Pierre Dorny Katelijne Dierick Stéphane De Craeye 《International journal for parasitology》2018,48(7):555-560
Toxoplasma gondii is an ubiquitous apicomplexan parasite which can infect any warm-blooded animal including humans. Humans and carnivores/omnivores can also become infected by consumption of raw or undercooked infected meat containing muscle cysts. This route of transmission is considered to account for at least 30% of human toxoplasmosis cases. To better assess the role of pork as a source of infection for humans, the parasite burden resulting from experimental infection with different parasite stages and different strains of T. gondii during the acute and chronic phases was studied. The parasite burden in different tissues was measured with a ISO 17025 validated Magnetic Capture-quantitative PCR. A high burden of infection was found in heart and lungs during the acute phase of infection and heart and brain were identified as the most parasitised tissues during the chronic phase of infection, independent of the parasite stage and the strain used. Remarkably, a higher parasite burden was measured in different tissues following infection with oocysts of a type II strain compared with a tissue cyst infection with three strains of either type II or a type I/II. However, these results could have been affected by the use of different strains and euthanasia time points. The parasite burden resulting from a tissue cyst infection was not significantly different between the two strains. 相似文献
6.
The effect of pressure (0.1 to 400 MPa) and solvent composition (methanol concentration of 5 to 30%) on the synthesis of beta-methylgalactoside was studied. Galactose was used as a reactant and the reaction was catalyzed by beta-galactosidase from Aspergillus oryzae. Under the applied conditions the enzyme was sufficiently stable and the reaction equilibrium was reached. Higher methanol concentrations obviously influenced the product yield positively due to an increase in reactant concentration but also due to a solvent effect. This solvent effect can be explained by measurement of the activities of galactose and methylgalactoside. These results may be generalized to other methylations in methanol-water systems, where methanol positively affects synthesis yields. Pressure had a small, negative effect on synthesis yields. 相似文献
7.
Katelijne De Nys Els Meyhi Guy P Mannaerts Marc Fransen Paul P Van Veldhoven 《Biochimica et Biophysica Acta (BBA)/Molecular and Cell Biology of Lipids》2001,1533(1):66-72
Based on the primary structure of the rat peroxisomal 2,4-dienoyl-CoA reductase (M. Fransen, P.P. Van Veldhoven, S. Subramani, Biochem. J. 340 (1999) 561–568), the cDNA of the human counterpart was cloned. It contained an open reading frame of 878 bases encoding a protein of 291 amino acids (calculated molecular mass 30?778 Da), being 83% identical to the rat reductase. The gene, encompassing nine exons, is located at chromosome 16p13. Bacterially expressed poly(His)-tagged reductase was active not only towards short and medium chain 2,4-dienoyl-CoAs, but also towards 2,4,7,10,13,16,19-docosaheptaenoyl-CoA. Hence, the reductase does not seem to constitute a rate limiting step in the peroxisomal degradation of docosahexaenoic acid. The reduction of docosaheptaenoyl-CoA, however, was severely decreased in the presence of albumin. 相似文献
8.
Katelijne O De Swert Ken R Bracke Tine Demoor Guy G Brusselle Guy F Joos 《Respiratory research》2009,10(1):37
Background
The tachykinins, substance P and neurokinin A, present in sensory nerves and inflammatory cells such as macrophages and dendritic cells, are considered as pro-inflammatory agents. Inflammation of the airways and lung parenchyma plays a major role in the pathogenesis of chronic obstructive pulmonary disease (COPD) and increased tachykinin levels are recovered from the airways of COPD patients. The aim of our study was to clarify the involvement of the tachykinin NK1 receptor, the preferential receptor for substance P, in cigarette smoke (CS)-induced pulmonary inflammation and emphysema in a mouse model of COPD.Methods
Tachykinin NK1 receptor knockout (NK1-R-/-) mice and their wild type controls (all in a mixed 129/sv-C57BL/6 background) were subjected to sub acute (4 weeks) or chronic (24 weeks) exposure to air or CS. 24 hours after the last exposure, pulmonary inflammation and development of emphysema were evaluated.Results
Sub acute and chronic exposure to CS resulted in a substantial accumulation of inflammatory cells in the airways of both WT and NK1-R-/- mice. However, the CS-induced increase in macrophages and dendritic cells was significantly impaired in NK1-R-/- mice, compared to WT controls, and correlated with an attenuated release of MIP-3α/CCL20 and TGF-β1. Chronic exposure to CS resulted in development of pulmonary emphysema in WT mice. NK1-R-/- mice showed already enlarged airspaces upon air-exposure. Upon CS-exposure, the NK1-R-/- mice did not develop additional destruction of the lung parenchyma. Moreover, an impaired production of MMP-12 by alveolar macrophages upon CS-exposure was observed in these KO mice. In a pharmacological validation experiment using the NK1 receptor antagonist RP 67580, we confirmed the protective effect of absence of the NK1 receptor on CS-induced pulmonary inflammation.Conclusion
These data suggest that the tachykinin NK1 receptor is involved in the accumulation of macrophages and dendritic cells in the airways upon CS-exposure and in the development of smoking-induced emphysema. As both inflammation of the airways and parenchymal destruction are important characteristics of COPD, these findings may have implications in the future treatment of this devastating disease. 相似文献9.
Bram Laukens Pieter P. Jacobs Katelijne Geysens Jose Martins Charlot De Wachter Paul Ameloot Willy Morelle Jurgen Haustraete Jean-Christophe Renauld Bart Samyn Roland Contreras Simon Devos Nico Callewaert 《Biotechnology and bioengineering》2020,117(8):2479-2488
The glycosylation pathways of several eukaryotic protein expression hosts are being engineered to enable the production of therapeutic glycoproteins with humanized application-customized glycan structures. In several expression hosts, this has been quite successful, but one caveat is that the new N-glycan structures inadvertently might be substrates for one or more of the multitude of endogenous glycosyltransferases in such heterologous background. This then results in the formation of novel, undesired glycan structures, which often remain insufficiently characterized. When expressing mouse interleukin-22 in a Pichia pastoris (syn. Komagataella phaffii) GlycoSwitchM5 strain, which had been optimized to produce Man5GlcNAc2N-glycans, glycan profiling revealed two major species: Man5GlcNAc2 and an unexpected, partially α-mannosidase-resistant structure. A detailed structural analysis using exoglycosidase sequencing, mass spectrometry, linkage analysis, and nuclear magnetic resonance revealed that this novel glycan was Man5GlcNAc2 modified with a Glcα-1,2-Manβ-1,2-Manβ-1,3-Glcα-1,3-R tetrasaccharide. Expression of a Golgi-targeted GlcNAc transferase-I strongly inhibited the formation of this novel modification, resulting in more homogeneous modification with the targeted GlcNAcMan5GlcNAc2 structure. Our findings reinforce accumulating evidence that robustly customizing the N-glycosylation pathway in P. pastoris to produce particular human-type structures is still an incompletely solved synthetic biology challenge, which will require further innovation to enable safe glycoprotein pharmaceutical production. 相似文献
10.
Benjamin P. Colman Christina L. Arnaout Sarah Anciaux Claudia K. Gunsch Michael F. Hochella Jr Bojeong Kim Gregory V. Lowry Bonnie M. McGill Brian C. Reinsch Curtis J. Richardson Jason M. Unrine Justin P. Wright Liyan Yin Emily S. Bernhardt 《PloS one》2013,8(2)
A large fraction of engineered nanomaterials in consumer and commercial products will reach natural ecosystems. To date, research on the biological impacts of environmental nanomaterial exposures has largely focused on high-concentration exposures in mechanistic lab studies with single strains of model organisms. These results are difficult to extrapolate to ecosystems, where exposures will likely be at low-concentrations and which are inhabited by a diversity of organisms. Here we show adverse responses of plants and microorganisms in a replicated long-term terrestrial mesocosm field experiment following a single low dose of silver nanoparticles (0.14 mg Ag kg−1 soil) applied via a likely route of exposure, sewage biosolid application. While total aboveground plant biomass did not differ between treatments receiving biosolids, one plant species, Microstegium vimeneum, had 32 % less biomass in the Slurry+AgNP treatment relative to the Slurry only treatment. Microorganisms were also affected by AgNP treatment, which gave a significantly different community composition of bacteria in the Slurry+AgNPs as opposed to the Slurry treatment one day after addition as analyzed by T-RFLP analysis of 16S-rRNA genes. After eight days, N2O flux was 4.5 fold higher in the Slurry+AgNPs treatment than the Slurry treatment. After fifty days, community composition and N2O flux of the Slurry+AgNPs treatment converged with the Slurry. However, the soil microbial extracellular enzymes leucine amino peptidase and phosphatase had 52 and 27% lower activities, respectively, while microbial biomass was 35% lower than the Slurry. We also show that the magnitude of these responses was in all cases as large as or larger than the positive control, AgNO3, added at 4-fold the Ag concentration of the silver nanoparticles. 相似文献