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991.
992.
Marilena Ciciarello Emanuele Roscioli Barbara Di Fiore Laura Di Francesco Fabrizia Sobrero Delphine Bernard Rosamaria Mangiacasale Amnon Harel Maria Eugenia Schininà Patrizia Lavia 《Chromosoma》2010,119(6):651-668
The GTPase Ran regulates nucleocytoplasmic transport in interphase and spindle organisation in mitosis via effectors of the
importin beta superfamily. Ran-binding protein 1 (RanBP1) regulates guanine nucleotide turnover on Ran, as well as its interactions
with effectors. Unlike other Ran network members that are steadily expressed, RanBP1 abundance is modulated during the mammalian
cell cycle, peaking in mitosis and declining at mitotic exit. Here, we show that RanBP1 downregulation takes place in mid
to late telophase, concomitant with the reformation of nuclei. Mild RanBP1 overexpression in murine cells causes RanBP1 to
persist in late mitosis and hinders a set of events underlying the telophase to interphase transition, including chromatin
decondensation, nuclear expansion and nuclear lamina reorganisation. Moreover, the reorganisation of nuclear pores fails associated
with defective nuclear relocalisation of NLS cargoes. Co-expression of importin beta, together with RanBP1, however mitigates
these defects. Thus, RanBP1 downregulation is required for nuclear reorganisation pathways operated by importin beta after
mitosis. 相似文献
993.
994.
Plant and soil carbon accumulation following fire in Mediterranean woodlands in Spain 总被引:1,自引:0,他引:1
We measured plant and soil carbon (C) storage following canopy-replacing wildfires in woodlands of northeastern Spain that
include an understory of shrubs dominated by Quercus coccifera and an overstory of Pinus halepensis trees. Established plant succession models predict rapid shrub recovery in these ecosystems, and we build on this model by
contrasting shrub succession with long-term C storage in soils, trees, and the whole ecosystem. We used chronosequence and
repeated sampling approaches to detect change over time. Aboveground plant C increased from <100 to ~3,000 g C m−2 over 30 years following fire, which is substantially less than the 5,942 ± 487 g C m−2 (mean ±1 standard error) in unburned sites. As expected, shrubs accumulated C rapidly, but the capacity for C storage in
shrubs was <600 g C m−2. Pines were the largest plant C pool in sites >20 years post fire, and accounted for all of the difference in plant C between
older burned sites and unburned sites. In contrast, soil C was initially higher in burned sites (~4,500 g C m−2) than in unburned sites (3,264 ± 261 g C m−2) but burned site C declined to unburned levels within 10 years after fire. Combining these results with prior research suggests
two states for C storage. When pine regeneration is successful, ~9,200 g C m−2 accumulate in woodlands but when tree regeneration fails (due to microclimatic stress or short fire return intervals), ecosystem
C storage of ~4,000 g C m−2 will occur in the resulting shrublands. 相似文献
995.
Amina Rhouati Georges Istamboulie Montserrat Cortina-Puig Jean-Louis Marty Thierry Noguer 《Enzyme and microbial technology》2010,46(3-4):212-216
Enzyme spectrophotometric assays based on acetylcholinesterase (AChE) inhibition were used in combination with Artificial Neural Network (ANN) chemometric analysis for the resolution of pesticides mixtures of chlorpyriphos, dichlorvos and carbofuran. Electric eel (EE) AChE and the recombinant B394-AChE from Drosophila melanogaster were selected due to their different sensitivities to insecticides. These enzymes were used in association with phosphotriesterase (PTE), an enzyme allowing to discriminate between organophosphate and carbamate insecticides. The combined response of three enzymes systems composed of EE-AChE, EE-AChE + PTE, and B394-AChE + PTE was modelled by means of ANN. Specifically, an ANN was constructed where the structure providing the best modelling was a single hidden layer containing four neurons. To prove the concept, a study to resolve pesticide mixtures was done with spectrophotometric measurements. Finally the developed system was successfully applied to the determination of carbofuran, CPO and dichlorvos pesticides in real water samples. 相似文献
996.
Agostino Sorgonà Giovanni Cacco Lugi Di Dio Wolfgang Schmidt Paula Jay Perry Maria Rosa Abenavoli 《Acta Physiologiae Plantarum》2010,32(4):683-693
Spatial–temporal variation of the regulation and the kinetics of net nitrate (NO3
−) uptake rate (NNUR) along the tap root of Citrus aurantium L. were analysed. Suberin incrustation in the peripheral cell layers and plasma membrane (PM) H+-ATPase localisation, anatomical and physiological factors involved in NO3
− uptake were also investigated. The results clearly indicated a spatially uniform distribution of the regulation process,
accompanied by a temporal heterogeneous pattern of the kinetics of NO3
− uptake along citrus tap root. In particular, kinetic analysis had a biphasic pattern, saturating (high affinity transport
system) and linear (low affinity transport system), in response to increasing external NO3
− concentrations in each root region, where 200 μM NO3
− represented the threshold separating these two systems. Kinetic parameters, K
m and V
max, clearly indicated that apical segments reached the maximum value of induction before basal segments. Hence, the apical root
zones, early exhibiting the maximum of potential capacity to absorb the NO3
−, could be considered more efficient than basal root segments for acquiring NO3
− from external solution. Suberin incrustations in the hypodermal cell layer, characterised by uniform fluorescence intensity
among the root segments, could be responsible for the unchanged NNUR, while the PM H+-ATPase could explain the temporal pattern of NNUR. 相似文献
997.
Victoria Lumbreras Belmiro Vilela Sami Irar Montserrat Solé Montserrat Capellades Marc Valls Maria Coca Montserrat Pagès 《The Plant journal : for cell and molecular biology》2010,63(6):1017-1030
Mitogen‐activated protein kinase (MAPK) cascades have important functions in plant stress responses and development and are key players in reactive oxygen species (ROS) signalling and in innate immunity. In Arabidopsis, the transmission of ROS and pathogen signalling by MAPKs involves the coordinated activation of MPK6 and MPK3; however, the specificity of their negative regulation by phosphatases is not fully known. Here, we present genetic analyses showing that MAPK phosphatase 2 (MKP2) regulates oxidative stress and pathogen defence responses and functionally interacts with MPK3 and MPK6. We show that plants lacking a functional MKP2 gene exhibit delayed wilting symptoms in response to Ralstonia solanacearum and, by contrast, acceleration of disease progression during Botrytis cinerea infection, suggesting that this phosphatase plays differential functions in biotrophic versus necrotrophic pathogen‐induced responses. MKP2 function appears to be linked to MPK3 and MPK6 regulation, as indicated by BiFC experiments showing that MKP2 associates with MPK3 and MPK6 in vivo and that in response to fungal elicitors MKP2 exerts differential affinity versus both kinases. We also found that MKP2 interacts with MPK6 in HR‐like responses triggered by fungal elicitors, suggesting that MPK3 and MPK6 are subject to differential regulation by MKP2 in this process. We propose that MKP2 is a key regulator of MPK3 and MPK6 networks controlling both abiotic and specific pathogen responses in plants. 相似文献
998.
Alma Dal Pozzo Ming-Hong Ni Emiliano Esposito Sabrina Dallavalle Loana Musso Alberto Bargiotti Claudio Pisano Loredana Vesci Federica Bucci Massimo Castorina Rosanna Foderà Giuseppe Giannini Concetta Aulicino Sergio Penco 《Bioorganic & medicinal chemistry》2010,18(1):64-72
Five RGD peptide–camptothecin (CPT) conjugates were designed and synthesized with the purpose to improve the therapeutic index of this antitumoral drug family. New RGD cyclopeptides were selected on the basis of their high affinity to αv integrin receptors overexpressed by tumor cells and their metabolic stability. The conjugates can be divided in two groups: in the first the peptide was attached to the drug through an amide bond, in the second through a hydrazone bond. The main difference between the two spacers lies in their acid stability. Affinity to the receptors was maintained for all conjugates and their internalization into tumor cells was demonstrated. The first group conjugates showed lower in vitro and in vivo activity than the parent drug, probably due to the excessive stability of the amide bond, even inside the tumor cells. Conversely, the hydrazone conjugates exhibited in vitro tumor cell inhibition similar to the parent drug, indicating high conversion in the culture medium and/or inside the cells, but their poor solubility hampered in vivo experiments. On the basis of these results, information was acquired for additional development of derivatives with different linkers and better solubility for in vivo evaluation. 相似文献
999.
Gaëlle Cane Amandine Ginouvès Sandrine Marchetti Roser Buscà Jacques Pouysségur Edurne Berra Paul Hofman Valérie Vouret‐Craviari 《Cellular microbiology》2010,12(5):640-653
Microbes regulate a large panel of intracellular signalling events that can promote inflammation and/or enhance tumour progression. Indeed, it has been shown that infection of human intestinal cells with the Afa/Dr diffusely adhering E. coli C1845 strain induces expression of pro‐angiogenic and pro‐inflammatory genes. Here, we demonstrate that exposure of cryptic‐like intestinal epithelial cells to C1845 bacteria induces HIF‐1α protein levels. This effect depends on the binding of F1845 adhesin to the membrane‐associated DAF receptor that initiates signalling cascades promoting translational mechanisms. Indeed, inhibition of MAPK and PI‐3K decreases HIF‐1α protein levels and blocks C1845‐induced phosphorylation of the ribosomal S6 protein. Using RNA interference we show that bacteria‐induced HIF‐1α regulates the expression of IL‐8, VEGF and Twist1, thereby pointing to a role for HIF‐1 in angiogenesis and inflammation. In addition, infection correlates with a loss of E‐cadherin and cytokeratin 18 and a rise in fibronectin, suggesting that bacteria may induce an epithelial to mesenchymal transition‐like phenotype. Since HIF‐1α silencing results in reversion of bacteria‐induced EMT markers, we speculate that HIF‐1α plays a key role linking bacterial infection to angiogenesis, inflammation and some aspects of cancer initiation. 相似文献
1000.
Isaac Almendros Josep M Montserrat Marta Torres Constancio González Daniel Navajas Ramon Farré 《Respiratory research》2010,11(1):1-6