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21.
Daniele Novarina Georges E. Janssens Koen Bokern Tim Schut Noor C. van Oerle Hinke G. Kazemier Liesbeth M. Veenhoff Michael Chang 《Aging cell》2020,19(2)
To ensure proper transmission of genetic information, cells need to preserve and faithfully replicate their genome, and failure to do so leads to genome instability, a hallmark of both cancer and aging. Defects in genes involved in guarding genome stability cause several human progeroid syndromes, and an age‐dependent accumulation of mutations has been observed in different organisms, from yeast to mammals. However, it is unclear whether the spontaneous mutation rate changes during aging and whether specific pathways are important for genome maintenance in old cells. We developed a high‐throughput replica‐pinning approach to screen for genes important to suppress the accumulation of spontaneous mutations during yeast replicative aging. We found 13 known mutation suppression genes, and 31 genes that had no previous link to spontaneous mutagenesis, and all acted independently of age. Importantly, we identified PEX19, encoding an evolutionarily conserved peroxisome biogenesis factor, as an age‐specific mutation suppression gene. While wild‐type and pex19Δ young cells have similar spontaneous mutation rates, aged cells lacking PEX19 display an elevated mutation rate. This finding suggests that functional peroxisomes may be important to preserve genome integrity specifically in old cells. 相似文献
22.
Microbial carbon limitation: The need for integrating microorganisms into our understanding of ecosystem carbon cycling 总被引:2,自引:0,他引:2
Jennifer L. Soong Lucia Fuchslueger Sara Maraon‐Jimenez Margaret S. Torn Ivan A. Janssens Josep Penuelas Andreas Richter 《Global Change Biology》2020,26(4):1953-1961
Numerous studies have demonstrated that fertilization with nutrients such as nitrogen, phosphorus, and potassium increases plant productivity in both natural and managed ecosystems, demonstrating that primary productivity is nutrient limited in most terrestrial ecosystems. In contrast, it has been demonstrated that heterotrophic microbial communities in soil are primarily limited by organic carbon or energy. While this concept of contrasting limitations, that is, microbial carbon and plant nutrient limitation, is based on strong evidence that we review in this paper, it is often ignored in discussions of ecosystem response to global environment changes. The plant‐centric perspective has equated plant nutrient limitations with those of whole ecosystems, thereby ignoring the important role of the heterotrophs responsible for soil decomposition in driving ecosystem carbon storage. To truly integrate carbon and nutrient cycles in ecosystem science, we must account for the fact that while plant productivity may be nutrient limited, the secondary productivity by heterotrophic communities is inherently carbon limited. Ecosystem carbon cycling integrates the independent physiological responses of its individual components, as well as tightly coupled exchanges between autotrophs and heterotrophs. To the extent that the interacting autotrophic and heterotrophic processes are controlled by organisms that are limited by nutrient versus carbon accessibility, respectively, we propose that ecosystems by definition cannot be ‘limited’ by nutrients or carbon alone. Here, we outline how models aimed at predicting non‐steady state ecosystem responses over time can benefit from dissecting ecosystems into the organismal components and their inherent limitations to better represent plant–microbe interactions in coupled carbon and nutrient models. 相似文献
23.
24.
Maud Martin Ilse Geudens Jonathan Bruyr Michael Potente Anouk Bleuart Marielle Lebrun Nicolas Simonis Christophe Deroanne Jean‐Claude Twizere Philippe Soubeyran Paul Peixoto Denis Mottet Veerle Janssens Wolf‐Karsten Hofmann Filip Claes Peter Carmeliet Richard Kettmann Holger Gerhardt Franck Dequiedt 《The EMBO journal》2013,32(18):2491-2503
25.
Aims
Tree roots are spatially highly heterogeneous and it thus requires large numbers of samples to detect statistically significant changes in root biomass. The objectives of this study were to understand and quantify the sources of error in the assessment of fine root biomass (<2 mm) during the second year of a high-density Populus plantation.Methods
Soil cores were collected in winter (n?=?35) and in summer (n?=?20), and fine roots were picked by hand for varying lengths of time: 1, 2, 5, 20, 40, and 60 min. The root biomass data were used to identify the best combination of the time spent for root picking and the number of samples collected, that minimizes the overall uncertainty (i.e. the combination of the spatial error due to the incomplete sampling and the temporal error due to the incomplete core processing).Results
On average, 25 min was enough time to pick 90 % of the fine root biomass in winter, while in summer only 10 min were needed. In winter fewer samples were needed, but more time for picking was necessary as compared to summer when root biomass was higher.Conclusions
Fine root sampling can be optimized by minimizing the uncertainty of the biomass estimates and simultaneously decreasing root sampling time investment. 相似文献26.
Pilou L. H. R. Janssens Rick Hursel Eveline A. P. Martens Margriet S. Westerterp-Plantenga 《PloS one》2013,8(7)
Background
Addition of capsaicin (CAPS) to the diet has been shown to increase energy expenditure; therefore capsaicin is an interesting target for anti-obesity therapy.Aim
We investigated the 24 h effects of CAPS on energy expenditure, substrate oxidation and blood pressure during 25% negative energy balance.Methods
Subjects underwent four 36 h sessions in a respiration chamber for measurements of energy expenditure, substrate oxidation and blood pressure. They received 100% or 75% of their daily energy requirements in the conditions ‘100%CAPS’, ‘100%Control’, ‘75%CAPS’ and ‘75%Control’. CAPS was given at a dose of 2.56 mg (1.03 g of red chili pepper, 39,050 Scoville heat units (SHU)) with every meal.Results
An induced negative energy balance of 25% was effectively a 20.5% negative energy balance due to adapting mechanisms. Diet-induced thermogenesis (DIT) and resting energy expenditure (REE) at 75%CAPS did not differ from DIT and REE at 100%Control, while at 75%Control these tended to be or were lower than at 100%Control (p = 0.05 and p = 0.02 respectively). Sleeping metabolic rate (SMR) at 75%CAPS did not differ from SMR at 100%CAPS, while SMR at 75%Control was lower than at 100%CAPS (p = 0.04). Fat oxidation at 75%CAPS was higher than at 100%Control (p = 0.03), while with 75%Control it did not differ from 100%Control. Respiratory quotient (RQ) was more decreased at 75%CAPS (p = 0.04) than at 75%Control (p = 0.05) when compared with 100%Control. Blood pressure did not differ between the four conditions.Conclusion
In an effectively 20.5% negative energy balance, consumption of 2.56 mg capsaicin per meal supports negative energy balance by counteracting the unfavorable negative energy balance effect of decrease in components of energy expenditure. Moreover, consumption of 2.56 mg capsaicin per meal promotes fat oxidation in negative energy balance and does not increase blood pressure significantly.Trial Registration
Nederlands Trial Register; registration number NTR2944 相似文献27.
Sara Vandenwijngaert Peter Pokreisz Hadewich Hermans Hilde Gillijns Marijke Pellens Noortje A. M. Bax Giulia Coppiello Wouter Oosterlinck Agnes Balogh Zoltan Papp Carlijn V. C. Bouten Jozef Bartunek Jan D'hooge Aernout Luttun Erik Verbeken Marie Christine Herregods Paul Herijgers Kenneth D. Bloch Stefan Janssens 《PloS one》2013,8(3)
Background
The intracellular second messenger cGMP protects the heart under pathological conditions. We examined expression of phosphodiesterase 5 (PDE5), an enzyme that hydrolyzes cGMP, in human and mouse hearts subjected to sustained left ventricular (LV) pressure overload. We also determined the role of cardiac myocyte-specific PDE5 expression in adverse LV remodeling in mice after transverse aortic constriction (TAC).Methodology/Principal Findings
In patients with severe aortic stenosis (AS) undergoing valve replacement, we detected greater myocardial PDE5 expression than in control hearts. We observed robust expression in scattered cardiac myocytes of those AS patients with higher LV filling pressures and BNP serum levels. Following TAC, we detected similar, focal PDE5 expression in cardiac myocytes of C57BL/6NTac mice exhibiting the most pronounced LV remodeling. To examine the effect of cell-specific PDE5 expression, we subjected transgenic mice with cardiac myocyte-specific PDE5 overexpression (PDE5-TG) to TAC. LV hypertrophy and fibrosis were similar as in WT, but PDE5-TG had increased cardiac dimensions, and decreased dP/dtmax and dP/dtmin with prolonged tau (P<0.05 for all). Greater cardiac dysfunction in PDE5-TG was associated with reduced myocardial cGMP and SERCA2 levels, and higher passive force in cardiac myocytes in vitro.Conclusions/Significance
Myocardial PDE5 expression is increased in the hearts of humans and mice with chronic pressure overload. Increased cardiac myocyte-specific PDE5 expression is a molecular hallmark in hypertrophic hearts with contractile failure, and represents an important therapeutic target. 相似文献28.
Xavier Janssens Saskia Decuman Filip De Keyser Belgian Rheumatoid Arthritis Disability Assessment study group 《PloS one》2016,11(1)
Objective
Scores on the Health Assessment Questionnaire (HAQ) predict the need for support measures in patients with rheumatoid arthritis (RA). In this study we compare the performance of the HAQ in this context with that of the more disease-specific Belgian Rheumatoid Arthritis Disability Assessment (BRADA) questionnaire.Methods
In this multicenter observational study, patients with RA and disease duration of at least one year who consulted their rheumatologist for a routine follow-up visit filled out the HAQ, and BRADA questionnaires. The performance of HAQ and BRADA to predict the need for support measures available to patients with RA was evaluated using Receiver Operator Characteristic (ROC) curves, with the expert opinion of the rheumatologist as a reference.Results
The study analyzed data of 301 patients with RA (70.8% females) with mean age 59.8±12.8, disease duration 11.4±9.3 years, and DAS28 values of 2.84±1.18. HAQ scores averaged 0.97±0.73 and BRADA scores were 3.92±3.49 over the last week and 3.89±3.50 over the last 3 months. The area under the ROC curves for the BRADA scores for the support measures investigated ranged from 0.702 to 0.862 and did not differ significantly from those of the HAQ (range 0.725–0.860).Conclusion
The disease-specific BRADA questionnaire is equivalent to the HAQ in predicting the need for support measures in patients with stable RA. 相似文献29.
Phylogeny of Impatiens (Balsaminaceae): integrating molecular and morphological evidence into a new classification
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Sheng‐Xiang Yu Steven B. Janssens Xiang‐Yun Zhu Magnus Lidén Tian‐Gang Gao Wei Wang 《Cladistics : the international journal of the Willi Hennig Society》2016,32(2):179-197
Impatiens L. is one of the largest angiosperm genera, containing over 1000 species, and is notorious for its taxonomic difficulty. Here, we present, to our knowledge, the most comprehensive phylogenetic analysis of the genus to date based on a total evidence approach. Forty‐six morphological characters, mainly obtained from our own investigations, are combined with sequence data from three genetic regions, including nuclear ribosomal ITS and plastid atpB‐rbcL and trnL‐F. We include 150 Impatiens species representing all clades recovered by previous phylogenetic analyses as well as three outgroups. Maximum‐parsimony and Bayesian inference methods were used to infer phylogenetic relationships. Our analyses concur with previous studies, but in most cases provide stronger support. Impatiens splits into two major clades. For the first time, we report that species with three‐colpate pollen and four carpels form a monophyletic group (clade I). Within clade II, seven well‐supported subclades are recognized. Within this phylogenetic framework, character evolution is reconstructed, and diagnostic morphological characters for different clades and subclades are identified and discussed. Based on both morphological and molecular evidence, a new classification outline is presented, in which Impatiens is divided into two subgenera, subgen. Clavicarpa and subgen. Impatiens; the latter is further subdivided into seven sections. 相似文献
30.
Marcos Fernández-Martínez Sara Vicca Ivan A. Janssens Matteo Campioli Josep Peñuelas 《Trees - Structure and Function》2016,30(3):775-783