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Search Results: 1 - 10 of 449766 matches for " Frans J. de Bruijn "
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“Biological Nitrogen Fixation” Book Summary  [PDF]
Frans J. de Bruijn
Advances in Microbiology (AiM) , 2016, DOI: 10.4236/aim.2016.66040
Abstract: Biological nitrogen fixation is a very valuable alternative to nitrogen fertilizer. This process will be discussed in the “Biological Nitrogen Fixation” book. A wide array of free-living and associative nitrogen fixing organisms (diazotrophs) will be covered. The most extensively studied and applied example of biological nitrogen fixation is the symbiotic interaction between nitrogen fixing “rhizobia” and legume plants. While legumes are important as major food and feed crops, cereals such as wheat, maize and rice are the primary food crops, but do not have this symbiotic nitrogen fixing interaction with rhizobia. It has thus been a “holy grail” to transfer the ability to fix nitrogen to the cereals and this topic will be also addressed in these books.
Desiccation induces viable but Non-Culturable cells in Sinorhizobium meliloti 1021
Jan AC Vriezen, Frans J de Bruijn, Klaus R Nüsslein
AMB Express , 2012, DOI: 10.1186/2191-0855-2-6
Abstract: The survival of S. meliloti 1021 was estimated during nine weeks at 22% relative humidity. We found that after an initial rapid decline of colony forming units, the decline slowed to a steady 10-fold reduction in colony forming units every 22 days. In spite of the reduction in colony forming units, the fraction of the population identified as viable (42-54%) based on the Baclight live/dead stain did not change significantly over time. This change in the ability of viable cells to form colonies shows (i) an underestimation of the survival of rhizobial cells using plating methods, and that (ii) in a part of the population desiccation induces a Viable But Non Culturable (VBNC)-like state, which has not been reported before. Resuscitation attempts did not lead to a higher recovery of colony forming units indicating the VBNC state is stable under the conditions tested. This observation has important consequences for the use of rhizobia. Finding methods to resuscitate this fraction may increase the quality of powder-based seed inocula.Rhizobia form root nodules in symbiosis with legumes in which they fix atmospheric nitrogen and supply the fixed nitrogen to the plants (Jones et al. 2007). This system can be used to replenish soils with biologically-fixed nitrogen, and reduces the need for chemical fertilizers and pollution. However, this process is affected by salinity, drought and desiccation stress (Zahran 1999; Vriezen et al. 2007). To make optimal use of this system, inoculants are employed which allow for close contact between the microorganisms and the germinating seed (Smith 1992; Kosanke et al. 1999; Deaker et al. 2004). Many inoculants are powder-based, and a drying step during production reduces their quality (Kosanke et al. 1992). According to Catroux et al. (2001) many inoculants remain unreliable because of the inability of bacterial cells to persist under adverse conditions, including desiccation.Many conditions have been identified that affect the survival
Genetic basis of transcriptome differences between the founder strains of the rat HXB/BXH recombinant inbred panel
Marieke Simonis, Santosh S Atanur, Sam Linsen, Victor Guryev, Frans-Paul Ruzius, Laurence Game, Nico Lansu, Ewart de Bruijn, Sebastiaan van Heesch, Steven JM Jones, Michal Pravenec, Tim J Aitman, Edwin Cuppen
Genome Biology , 2012, DOI: 10.1186/gb-2012-13-4-r31
Abstract: We generated a comprehensive inventory of genomic differences between the two founder strains of the rat HXB/BXH recombinant inbred panel: SHR/OlaIpcv and BN-Lx/Cub. We identified 3.2 million single nucleotide variants, 425,924 small insertions and deletions, 907 copy number changes and 1,094 large structural genetic variants. RNA-sequencing analyses on liver tissue of the two strains identified 532 differentially expressed genes and 40 alterations in transcript structure. We identified both coding and non-coding variants that correlate with differential expression and alternative splicing. Furthermore, structural variants, in particular gene duplications, show a strong correlation with transcriptome alterations.We show that the panel is a good model for assessing the genetic basis of phenotypic heterogeneity and for providing insights into possible underlying molecular mechanisms. Our results reveal a high diversity and complexity underlying quantitative and qualitative transcriptional differences.Thanks to technological developments in next generation DNA sequencing the amounts of genetic variants that are identified in healthy and diseased individuals are growing rapidly. This has increased the potential of personal genomics: the sequencing of complete genomes with the intention to guide prevention or treatment strategies. For personal genomics to become a reality, however, it is important not only to systematically make inventories of genome-wide genetic variation, but also to know which genetic alterations can affect gene function [1,2]. Studying the effects of genomic variation in human populations is difficult, due to the large number of variants in every individual. Moreover, alleles can be heterozygous and homozygous with both recessive and dominant effects.Here we have systematically studied the effects of genomic variants using two inbred rat strains, the spontaneously hypertensive rat (SHR/OlaIpcv) and a Brown Norway-derived strain, BN-Lx/Cub [3,4]. We r
Influence of heat treatment on the antioxidant properties of grifola gargal hydro-alcoholic extracts
J. De Bruijn,C. Loyola,P. Aqueveque,J. Ca?umir
Micología Aplicada Internacional , 2008,
Abstract: El hongo Gargal (Grifola gargal) se sometió a un tratamiento térmico con el propósito de determinar su efecto sobre el rendimiento de extracción, actividad antioxidante y polifenoles en el extracto. El hongo crudo se calentó a 100 C y 121 C, durante 20 min y 45 min. La capacidad antioxidante se midió mediante la captación de radicales libres de 2,2-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) y 1,1-diphenyl-2-picrylhydrazyl, poder reductor y poder secuestrador. Con el tratamiento térmico mejoró el rendimiento de extracción (hasta 1.3 veces, calentando a 121 C durante 45 min), mientras que en el extracto del hongo aumentó el contenido de polifenoles (hasta 1.3 veces, calentando a 121 C durante 20 min) y el contenido de fl avonoides (máximo 1.4 veces, calentando a 121 C durante 20 min), en comparación con la muestra cruda. Sin embargo, no se detectó un efecto del tratamiento térmico sobre la actividad antioxidante, debido probablemente a su gran capacidad de captar radicales libres [90.9 93.3 mg ácido ascórbico/L en el test de 2,2-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) y 84.0 90.0% en el test de 1,1-diphenyl-2-picrylhydrazyl] y su fuerte poder reductor (135.6 mg ácido ascórbico/L). Los resultados indicaron que el hongo G. gargal posee un potencial interesante como antioxidante natural para la industria alimentaria.
Antioxidant properties of extracts obtained from Grifola gargal mushrooms
J. de Bruijn,C. Loyola,P. Aqueveque,J. Ca?umir
Micología Aplicada Internacional , 2009,
Abstract: Se investigó el efecto de diferentes solventes en el rendimiento de extracción, actividad antioxidante y contenido de polifenoles y flavonoides en extractos de los cuerpos fructíferos de Grifola gargal. Se utilizaron los siguientes disolventes en la extracción: acetona, etanol, acetato de etilo, n-hexano, agua, y mezclas de agua y etanol. La capacidad antioxidante se midió mediante la captación de radicales libres de ácido 2,2-azino-bis-(3-etilbenzotiazol-6-sulfónico) y 2,2-difenil-1-picrilhidracilo, poder reductor y poder secuestrador. Los extractos de acetona presentaron la mayor actividad de captación de radicales libres, equivalente a 96,0 mg ácido ascórbico/L en el test de 2,2-azino-bis-(3-etilbenzotiazol-6-sulfónico) y 92,9% en el test de 2,2-difenil-1-picrilhidracilo. Los extractos de agua y etanol presentaron un fuerte poder reductor (135,6 mg ácido ascórbico/L), mientras que los extractos de acetato de etilo tenían un poder secuestrador de 19,8%. Los extractos acuosos presentaron el mayor contenido de flavonoides (6,1 mg/100 g), mientras que los extractos de agua y etanol (20:80, v/v) tenían el mayor contenido de polifenoles (63,8 mg/100 g). La actividad antioxidante [tanto la captación de radicales libres de 2,2-azino-bis-(3-etilbenzotiazol-6-sulfónico), como poder reductor] correlacionó bien (R<0,93) con el contenido de polifenoles y flavonoides en los extractos. Los atributos específicos de antioxidantes de los extractos del hongo Gargal dependieron del tipo de disolvente utilizado en la extracción.
Overdiagnosis and overtreatment of breast cancer: Microsimulation modelling estimates based on observed screen and clinical data
Harry J de Koning, Gerrit Draisma, Jacques Fracheboud, Arry de Bruijn
Breast Cancer Research , 2005, DOI: 10.1186/bcr1369
Abstract: Breast cancer screening has been effective in reducing breast cancer mortality. Both randomised controlled trials and nation-wide screening programmes have shown a roughly 25% reduction in disease-specific mortality for women aged 50 years and over invited to screening [1-4]. This benefit applies to the group as a whole, but at the individual level it is impossible to determine who will actually benefit or who will receive more harm than benefit from such a programme: there is a delicate balance between the favourable and unfavourable side-effects of screening in general [5]. For example, detecting breast cancers by screening that would otherwise never have been clinically diagnosed, but are now treated, is such an unfavourable side effect. Because of lead time and length-biased sampling, the screening test will generally detect more early lesions with possibly different biological behaviour and also more slowly growing tumours, especially ductal carcinoma in situ (DCIS). Screening at older ages will, due to existing co-morbidity, lead to the detection of clinically relevant diseases; however, women may not necessarily benefit because they more often die due to other diseases.This paper presents quantitative estimates of overdiagnosis in breast cancer screening based on microsimulation modelling, with special emphasis on DCIS. In this study, overdiagnosis is defined as diagnosing cancers that would not have been diagnosed clinically if there were no screening programme.Starting to screen a population systematically for breast cancer will lead to the detection of cancers about three to four years earlier than without such an approach [6]; therefore, the number of detected cancers at the population level is expected to increase. Because screening is continued every consecutive year, this number is higher, and remains so, than if there were no systematic screening. Figure 1 shows the Dutch national data since 1989, when screening was gradually being implemented [7,8].
Cell-Based Bone Tissue Engineering
Gert J Meijer ,Joost D de Bruijn,Ron Koole,Clemens A van Blitterswijk
PLOS Medicine , 2007, DOI: 10.1371/journal.pmed.0040009
Abstract:
Complex Odor from Plants under Attack: Herbivore's Enemies React to the Whole, Not Its Parts
Michiel van Wijk, Paulien J. A. de Bruijn, Maurice W. Sabelis
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0021742
Abstract: Background Insect herbivory induces plant odors that attract herbivores' natural enemies. Assuming this attraction emerges from individual compounds, genetic control over odor emission of crops may provide a rationale for manipulating the distribution of predators used for pest control. However, studies on odor perception in vertebrates and invertebrates suggest that olfactory information processing of mixtures results in odor percepts that are a synthetic whole and not a set of components that could function as recognizable individual attractants. Here, we ask if predators respond to herbivore-induced attractants in odor mixtures or to odor mixture as a whole. Methodology/Principal Findings We studied a system consisting of Lima bean, the herbivorous mite Tetranychus urticae and the predatory mite Phytoseiulus persimilis. We found that four herbivore-induced bean volatiles are not attractive in pure form while a fifth, methyl salicylate (MeSA), is. Several reduced mixtures deficient in one component compared to the full spider-mite induced blend were not attractive despite the presence of MeSA indicating that the predators cannot detect this component in these odor mixtures. A mixture of all five HIPV is most attractive, when offered together with the non-induced odor of Lima bean. Odors that elicit no response in their pure form were essential components of the attractive mixture. Conclusions/Significance We conclude that the predatory mites perceive odors as a synthetic whole and that the hypothesis that predatory mites recognize attractive HIPV in odor mixtures is unsupported.
Differential long-term effects of climate change and management on stocks and distribution of soil organic carbon in productive grasslands
A. M. G. De Bruijn, P. Calanca, C. Ammann,J. Fuhrer
Biogeosciences (BG) & Discussions (BGD) , 2012,
Abstract: We studied the impact of climate change on the dynamics of soil organic carbon (SOC) stocks in productive grassland systems undergoing two types of management, an intensive type with frequent harvests and fertilizer applications and an extensive system without fertilization and fewer harvests. Simulations were conducted with a dedicated newly developed model, the Oensingen Grassland Model. It was calibrated using measurements taken in a recently established permanent sward in Central Switzerland, and run to simulate SOC dynamics over 2001–2100 under various climate change scenarios assuming different elements of IPCC A2 emission scenarios. We found that: (1) management intensity dominates SOC until approximately 20 years after grassland establishment. Differences in SOC between climate scenarios become significant after 20 years and climate effects dominate SOC dynamics from approximately 50 years after establishment. (2) Carbon supplied through manure contributes about 60 % to measured organic C increase in fertilized grassland. (3) Soil C accumulates particularly in the top 10 cm of the soil until 5 years after establishment. In the long-term, C accumulation takes place in the top 15 cm of the soil profile, while C content decreases below this depth. The transitional depth between gains and losses of C mainly depends on the vertical distribution of root senescence and root biomass. We discuss the importance of previous land use on carbon sequestration potentials that are much lower at the Oensingen site under ley-arable rotation with much higher SOC stocks than most soils under arable crops. We further discuss the importance of biomass senescence rates, because C balance estimations indicate that these may differ considerably between the two management systems.
Differential long-term effects of climate change and management on stocks and distribution of soil organic carbon in productive grasslands
A. M. G. De Bruijn,P. Calanca,C. Ammann,J. Fuhrer
Biogeosciences Discussions , 2012, DOI: 10.5194/bgd-9-1055-2012
Abstract: We studied the impact of climate change on the dynamics of soil organic carbon (SOC) stocks in productive grassland systems undergoing two types of management, an intensive type with frequent harvests and fertilizer applications and an extensive system where fertilization is omitted and harvests are fewer. The Oensingen Grassland Model was explicitly developed for this study. It was calibrated using measurements taken in a recently established permanent sward in Central Switzerland, and run to simulate SOC dynamics over 2001–2100 under three climate change scenarios assuming different elements of IPCC A2 emission scenarios. We found that: (1) management intensity dominates SOC until approximately 20 yr after grassland establishment. Differences in SOC between climate scenarios become significant after 20 yr and climate effects dominate SOC dynamics from approximately 50 yr after establishment, (2) carbon supplied through manure contributes about 60% to measured organic C increase in fertilized grassland. (3) Soil C accumulates particularly in the top 10 cm soil until 5 yr after establishment. In the long-term, C accumulation takes place in the top 15 cm of the soil profile, while C content decreases below this depth. The transitional depth between gains and losses of C mainly depends on the vertical distribution of root senescence and root biomass. We discuss the importance of previous land use on carbon sequestration potentials that are much lower at the Oensingen site under ley-arable rotation and with much higher SOC stocks than most soils under arable crops. We further discuss the importance of biomass senescence rates, because C balance estimations indicate that these may differ considerably between the two management systems.
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