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1.
The relationship between species diversity and ecosystem stability is controversial. Tilman et al. analyse biomass patterns over a decade in a grassland experiment with artificial plant communities, and provide evidence for a positive relationship between the number of plant species and the temporal stability of the ecosystem. Here we use data from a long-term biodiversity experiment with plant communities that were not controlled by weeding in order to show that diverse systems can be both stable and unstable. 相似文献
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Molecular mechanism of anaerobic ammonium oxidation 总被引:7,自引:0,他引:7
Kartal B Maalcke WJ de Almeida NM Cirpus I Gloerich J Geerts W Op den Camp HJ Harhangi HR Janssen-Megens EM Francoijs KJ Stunnenberg HG Keltjens JT Jetten MS Strous M 《Nature》2011,479(7371):127-130
Two distinct microbial processes, denitrification and anaerobic ammonium oxidation (anammox), are responsible for the release of fixed nitrogen as dinitrogen gas (N(2)) to the atmosphere. Denitrification has been studied for over 100 years and its intermediates and enzymes are well known. Even though anammox is a key biogeochemical process of equal importance, its molecular mechanism is unknown, but it was proposed to proceed through hydrazine (N(2)H(4)). Here we show that N(2)H(4) is produced from the anammox substrates ammonium and nitrite and that nitric oxide (NO) is the direct precursor of N(2)H(4). We resolved the genes and proteins central to anammox metabolism and purified the key enzymes that catalyse N(2)H(4) synthesis and its oxidation to N(2). These results present a new biochemical reaction forging an N-N bond and fill a lacuna in our understanding of the biochemical synthesis of the N(2) in the atmosphere. Furthermore, they reinforce the role of nitric oxide in the evolution of the nitrogen cycle. 相似文献
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van Es MA van Vught PW Blauw HM Franke L Saris CG Van den Bosch L de Jong SW de Jong V Baas F van't Slot R Lemmens R Schelhaas HJ Birve A Sleegers K Van Broeckhoven C Schymick JC Traynor BJ Wokke JH Wijmenga C Robberecht W Andersen PM Veldink JH Ophoff RA van den Berg LH 《Nature genetics》2008,40(1):29-31
We identified a SNP in the DPP6 gene that is consistently strongly associated with susceptibility to amyotrophic lateral sclerosis (ALS) in different populations of European ancestry, with an overall P value of 5.04 x 10(-8) in 1,767 cases and 1,916 healthy controls and with an odds ratio of 1.30 (95% confidence interval (CI) of 1.18-1.43). Our finding is the first report of a genome-wide significant association with sporadic ALS and may be a target for future functional studies. 相似文献
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Loss-of-function mutations in LEMD3 result in osteopoikilosis, Buschke-Ollendorff syndrome and melorheostosis 总被引:11,自引:0,他引:11
Hellemans J Preobrazhenska O Willaert A Debeer P Verdonk PC Costa T Janssens K Menten B Van Roy N Vermeulen SJ Savarirayan R Van Hul W Vanhoenacker F Huylebroeck D De Paepe A Naeyaert JM Vandesompele J Speleman F Verschueren K Coucke PJ Mortier GR 《Nature genetics》2004,36(11):1213-1218
Osteopoikilosis, Buschke-Ollendorff syndrome (BOS) and melorheostosis are disorders characterized by increased bone density. The occurrence of one or more of these phenotypes in the same individual or family suggests that these entities might be allelic. We collected data from three families in which affected individuals had osteopoikilosis with or without manifestations of BOS or melorheostosis. A genome-wide linkage analysis in these families, followed by the identification of a microdeletion in an unrelated individual with these diseases, allowed us to map the gene that is mutated in osteopoikilosis. All the affected individuals that we investigated were heterozygous with respect to a loss-of-function mutation in LEMD3 (also called MAN1), which encodes an inner nuclear membrane protein. A somatic mutation in the second allele of LEMD3 could not be identified in fibroblasts from affected skin of an individual with BOS and an individual with melorheostosis. XMAN1, the Xenopus laevis ortholog, antagonizes BMP signaling during embryogenesis. In this study, LEMD3 interacted with BMP and activin-TGFbeta receptor-activated Smads and antagonized both signaling pathways in human cells. 相似文献
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Sucrose, nycodenz, metrizamide and a mixture of equal volumes of sucrose and metrizamide were used as density gradient media for the isolation of retinal rod outer segments. The high osmolarity of sucrose had a strongly negative effect on the nature of the rod outer segments, whereas they were much better preserved using iodinated density gradient media such as nycodenz and metrizamide for their isolation. 相似文献
8.
Vonk WI de Bie P Wichers CG van den Berghe PV van der Plaats R Berger R Wijmenga C Klomp LW van de Sluis B 《Cellular and molecular life sciences : CMLS》2012,69(1):149-163
Menkes disease (MD) is an X-linked recessive disorder characterized by copper deficiency resulting in a diminished function
of copper-dependent enzymes. Most MD patients die in early childhood, although mild forms of MD have also been described.
A diversity of mutations in the gene encoding of the Golgi-resident copper-transporting P1B-type ATPase ATP7A underlies MD. To elucidate the molecular consequences of the ATP7A mutations, various mutations in ATP7A associated with distinct phenotypes of MD (L873R, C1000R, N1304S, and A1362D) were analyzed in detail. All mutants studied
displayed changes in protein expression and intracellular localization parallel to a dramatic decline in their copper-transporting
capacity compared to ATP7A the wild-type. We restored these observed defects in ATP7A mutant proteins by culturing the cells
at 30°C, which improves the quality of protein folding, similar to that which as has recently has been demonstrated for misfolded
ATP7B, a copper transporter homologous to ATP7A. Further, the effect of the canine copper toxicosis protein COMMD1 on ATP7A
function was examined as COMMD1 has been shown to regulate the proteolysis of ATP7B proteins. Interestingly, in addition to
adjusted growth temperature, binding of COMMD1 partially restored the expression, subcellular localization, and copper-exporting
activities of the ATP7A mutants. However, no effect of pharmacological chaperones was observed. Together, the presented data
might provide a new direction for developing therapies to improve the residual exporting activity of unstable ATP7A mutant
proteins, and suggests a potential role for COMMD1 in this process. 相似文献
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A new, tenth subunit of TFIIH is responsible for the DNA repair syndrome trichothiodystrophy group A 总被引:21,自引:0,他引:21
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Giel Tanghe Corinne Urwyler-Rösselet Philippe De Groote Emmanuel Dejardin Pieter-Jan De Bock Kris Gevaert Peter Vandenabeele Wim Declercq 《Cellular and molecular life sciences : CMLS》2018,75(15):2827-2841
RIPK4 is a key player in epidermal differentiation and barrier formation. RIPK4 signaling pathways controlling keratinocyte proliferation and differentiation depend on its kinase activity leading to Dvl2, Pkp1 and IRF6 phosphorylation and NF-κB activation. However, the mechanism regulating RIPK4 activity levels remains elusive. We show that cultured keratinocytes display constitutive active phosphorylated RIPK4 while PKC signaling can trigger RIPK4 activation in various non-keratinocyte cell lines, in which RIPK4 is present in a non-phosphorylated state. Interestingly, we identified the SCFβ-TrCP ubiquitin E3 ligase complex responsible for regulating the active RIPK4 protein level. The SCFβ-TrCP complex binds to a conserved phosphodegron motif in the intermediate domain of RIPK4, subsequently leading to K48-linked ubiquitinylation and degradation. The recruitment of β-TrCP is dependent on RIPK4 activation and trans-autophosphorylation. β-TrCP knock-down resulted in RIPK4-dependent formation of actin stress fibers, cell scattering and increased cell motility, suggesting that tight control of RIPK4 activity levels is crucial to maintain cell shape and behavior in keratinocytes. 相似文献