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排序方式: 共有493条查询结果,搜索用时 15 毫秒
61.
Jelluma N Brenkman AB van den Broek NJ Cruijsen CW van Osch MH Lens SM Medema RH Kops GJ 《Cell》2008,132(2):233-246
Maintenance of chromosomal stability relies on coordination between various processes that are critical for proper chromosome segregation in mitosis. Here we show that monopolar spindle 1 (Mps1) kinase, which is essential for the mitotic checkpoint, also controls correction of improper chromosome attachments. We report that Borealin/DasraB, a member of the complex that regulates the Aurora B kinase, is directly phosphorylated by Mps1 on residues that are crucial for Aurora B activity and chromosome alignment. As a result, cells lacking Mps1 kinase activity fail to efficiently align chromosomes due to impaired Aurora B function at centromeres, leaving improper attachments uncorrected. Strikingly, Borealin/DasraB bearing phosphomimetic mutations restores Aurora B activity and alignment in Mps1-depleted cells. Mps1 thus coordinates attachment error correction and checkpoint signaling, two crucial responses to unproductive chromosome attachments. 相似文献
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Background
Small populations are thought to be adaptively handicapped, not only because they suffer more from deleterious mutations but also because they have limited access to new beneficial mutations, particularly those conferring large benefits.Methodology/Principal Findings
Here, we test this widely held conjecture using both simulations and experiments with small and large bacterial populations evolving in either a simple or a complex nutrient environment. Consistent with expectations, we find that small populations are adaptively constrained in the simple environment; however, in the complex environment small populations not only follow more heterogeneous adaptive trajectories, but can also attain higher fitness than the large populations. Large populations are constrained to near deterministic fixation of rare large-benefit mutations. While such determinism speeds adaptation on the smooth adaptive landscape represented by the simple environment, it can limit the ability of large populations from effectively exploring the underlying topography of rugged adaptive landscapes characterized by complex environments.Conclusions
Our results show that adaptive constraints often faced by small populations can be circumvented during evolution on rugged adaptive landscapes. 相似文献64.
Gutsche I Vujicić-Zagar A Siebert X Servant P Vannier F Castaing B Gallet B Heulin T de Groot A Sommer S Serre L 《Biochimica et biophysica acta》2008,1784(7-8):1050-1058
In order to preserve their genome integrity, organisms have developed elaborate tactics for genome protection and repair. The Deinococcus radiodurans bacteria famous for their extraordinary tolerance toward high doses of radiations or long period of desiccation, possess some specific genes with unknown function which are related to their survival in such extreme conditions. Among them, ddrA is an orphan gene specific of Deinococcus genomes. DdrA, the product of this gene was suggested to be a component of the DNA end protection system. Here we provide a three-dimensional reconstruction of the Deinococcus deserti DdrA((1-160)) by electron microscopy. Although not functional in vivo, this truncated protein keeps its DNA binding ability at the wild-type level. DdrA((1-160)) has a complex three-dimensional structure based on a heptameric ring that can self-associate to form a larger molecular weight assembly. We suggest that the complex architecture of DdrA plays a role in the substrate specificity and favors an efficient DNA repair. 相似文献
65.
Guinée Jeroen B. Koning Arjan de Pennington David W. Rosenbaum Ralph Hauschild Michael Olsen Stig I. Molander Sverker Bachmann Till M. Pant Rana 《The International Journal of Life Cycle Assessment》2004,9(5):320-326
Goal, Scope and Background The EU 5th framework project OMNIITOX will develop models calculating characterisation factors for assessing the potential toxic impacts
of chemicals within the framework of LCA. These models will become accessible through a web-based information system. The
key objective of the OMNIITOX project is to increase the coverage of substances by such models. In order to reach this objective,
simpler models which need less but available data, will have to be developed while maintaining scientific quality. Methods.
Experience within the OMNIITOX project has taught that data availability and quality are crucial issues for calculating characterisation
factors. Data availability determines whether calculating characterisation factors is possible at all, whereas data quality
determines to what extent the resulting characterisation factors are reliable. Today, there is insufficient knowledge and/or
resources to have high data availability as well as high data quality and high model quality at the same time.
Results The OMNIITOX project is developing two inter-related models in order to be able to provide LCA impact assessment characterisation
factors for toxic releases for as broad a range of chemicals as possible: 1) A base model representing a state-of-the-art
multimedia model and 2) a simple model derived from the base model using statistical tools. Discussion. A preliminary decision
tree for using the OMNIITOX information system (IS) is presented. The decision tree aims to illustrate how the OMNIITOX IS
can assist an LCA practitioner in finding or deriving characterisation factors for use in life cycle impact assessment of
toxic releases.
Conclusions and Outlook Data availability and quality are crucial issues when calculating characterisation factors for the toxicity impact categories.
The OMNIITOX project is developing a tiered model approach for this. It is foreseen that a first version of the base model
will be ready in late summer of 2004, whereas a first version of the simple base model is expected a few months later. 相似文献
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Glycine accomplishes several functions as a transmitter in the central nervous system(CNS). As an inhibitory neurotransmitter, it participates in the processing of motor and sensory information that permits movement, vision, and audition. This action of glycine is mediated by the strychnine-sensitive glycine receptor, whose activation produces inhibitory post-synaptic potentials. In some areas of the CNS, glycine seems to be co-released with GABA, the main inhibitory amino acid neurotransmitter. In addition, glycine modulates excitatory neurotransmission by potentiating the action of glutamate at N-methyl-D-aspartate (NMDA) receptors. It is believed that the termination of the different synaptic actions of glycine is produced by rapid reuptake through two sodium-and-chloride-coupled transporters, GLYT1 and GLYT2, located in the plasma membrane of glial cells or pre-synaptic terminals, respectively. Glycine transporters may become major targets for therapeutic of pathological alterations in synaptic function. This article reviews recent progress on the study of the molecular heterogeneity, localization, function, structure, regulation and pharmacology of the glycine transporter 相似文献
69.
Marco Graziano Raul Benito Josep V. Planas Arjan P. Palstra 《BMC developmental biology》2018,18(1):10
Background
Male European seabass, already predominant (~?70%) in cultured stocks, show a high incidence (20–30%) of precocious sexual maturation under current aquaculture practices, leading to important economic losses for the industry. In view of the known modulation of reproductive development by swimming exercise in other teleost species, we aimed at investigating the effects of sustained swimming on reproductive development in seabass males during the first year of life in order to determine if swimming could potentially reduce precocious sexual maturation.Methods
Pre-pubertal seabass (3.91?±?0.22 g of body weight (BW)) were subjected to a 10 week swimming regime at their optimal swimming speed (Uopt) in an oval-shaped Brett-type flume or kept at rest during this period. Using Blazka-type swim tunnels, Uopt was determined three times during the course of the experiment: 0.66 m s??1 at 19?±?1 g BW, 10.2?±?0.2 cm of standard length (SL) (week 1); 0.69 m s??1 at 38?±?3 g BW, 12.7?±?0.3 cm SL (week 5), and also 0.69 m s??1 at 77?±?7 g BW, 15.7?±?0.5 cm SL (week 9). Every 2 weeks, size and gonadal weight were monitored in the exercised (N?=?15) and non-exercised fish (N?=?15). After 10 weeks, exercised and non-exercised males were sampled to determine plasma 11-ketotestosterone levels, testicular mRNA expression levels of genes involved in steroidogenesis and gametogenesis by qPCR, as well as the relative abundance of germ cells representing the different spermatogenic stages by histological examination.Results
Our results indicate that sustained swimming exercise at Uopt delays testicular development in male European seabass as evidenced by decreased gonado-somatic index, slower progression of testicular development and by reduced mRNA expression levels of follicle stimulating hormone receptor (fshR), 3-beta-hydroxysteroid dehydrogenase (3βhsd), 11-beta hydroxysteroid dehydrogenase (11βhsd), estrogen receptor-beta (erβ2), anti-mullerian hormone (amh), structural maintenance of chromosomes protein 1B (smc1β), inhibin beta A (inhba) and gonado-somal derived factor 1 (gsdf1) in exercised males as compared with the non-exercised males.Conclusions
Swimming exercise may represent a natural and non-invasive tool to reduce the incidence of sexually precocious males in seabass aquaculture.70.
Johannes W. S. A. Osterloh Arjan C. Videler Gina M. P. Rossi Sebastiaan P. J. van Alphen 《Tijdschrift voor gerontologie en geriatrie》2018,49(5):210-212
Behavioural counselling by nurses can enhance quality of life in elderly with a personality disorder. Although nurses have a crucial role in day-to-day treatment, there is a lack of evidence-based approaches. Based on the cognitive therapy, the treatment protocol Cognitive Model for Behavioural Interventions (CoMBI) provides an alternative nursing approach for personality disorders. 相似文献