1,208 research outputs found
Analysis of Mathieu Equation Stable Solutions in the First Zone of Stability
No full textAbstractThe paper presents the results of a homogeneous Mathieu equation studies. Mathieu equation solutions are oscillations, modulated in amplitude and frequency. In the computational experiments we found dependences of the given oscillations on the ratio of the coefficients. These dependences are shown in graphs that can be used for an approximate estimation of the Mathieu equation solutions without integration
Protocol for analyzing protein-protein interactions by split-luciferase complementation assays in human cell lysates
No full textSummary: Here, we present a lysate-based split-luciferase assay for examining protein-protein interactions (PPIs) in HEK293T cell lysates, exemplified by interactions between subunits of protein phosphatase PP1. We describe steps for storing and re-using lysates, sensor design, assay setup/optimization, and high-throughput screening of compound libraries. We then detail procedures for applying the assay as a research tool to characterize the dynamics of PPIs, which we illustrate with specific examples.For complete details on the use and execution of this protocol, please refer to Claes and Bollen.1 : Publisher’s note: Undertaking any experimental protocol requires adherence to local institutional guidelines for laboratory safety and ethics
Pensar las escalas para pensar las luchas: Autor: Mathieu UHEL
No full textA través de un título sugerente, “pensar las escalas para pensar las luchas”, Mathieu Uhel entreteje la construcción teórico-crítica del concepto escala, generada por la geografía radical anglosajona de finales del siglo XX, con la necesidad/utilidad práctica de la escala para concienciar las luchas sociales. El artículo cumple un doble propósito: por un lado, delinear los elementos de lectura sobre el concepto escala; y, con ello, promover la atención de esta problemática en las luchas contemporáneas. En un primer apartado, Uhel ubica las discusiones académicas en torno a la escala, como herramienta metodológica útil para comprender la complejidad de las sociedades capitalistas; en el segundo apartado, el autor avanza la exposición en torno al contexto de la dimensión escalar del imperialismo capitalista; finalmente, el autor se centra en el rol de la actividad política a escala nacional en la tensa relación entre las imposiciones del capital y la lucha social.Por meio de um título sugestivo, “pensando escalas para pensar lutas”, Mathieu Uhel entrelaça a construção teórico-crítica do conceito de escala, gerado pela geografia radical anglo-saxônica do final do século XX, com a necessidade / utilidade prática escala para aumentar a consciência das lutas sociais. O artigo tem um duplo propósito: por um lado, delinear os elementos de leitura sobre o conceito de escala; e, com isso, promover atenção a esse problema nas lutas contemporâneas. Na primeira seção, Uhel localiza as discussões acadêmicas em torno da escala, como uma ferramenta metodológica útil para compreender a complexidade das sociedades capitalistas; na segunda seção, o autor avança a exposição em torno do contexto da dimensão escalar do imperialismo capitalista; por fim, o autor enfoca o papel da atividade política em escala nacional na tensa relação entre as imposições do capital e a luta social.Mathieu Uhel\u27s suggestive title, “Thinking about scales to think about struggles”, he interweaves the theoretical-critical construction of concept scale, generated by radical Anglo-Saxon geography in the late 20th century, with it´s practical utility to social struggles. The article serves two purposes: on the one hand, Uhel locates academic discussion around scale; and, with this, he promotes attention to this problem in contemporary struggles. In the first section, Uhel locates academic discussions around scale, as a useful methodological tool to understand the complexity of capitalist societies; in the second section, the author advances the argument around the context of the scalar dimension of capitalist imperialism; finally, the author focuses on the role of political activity on a national scale in the tense relationship between the impositions of capital and the social movement
Mathieu Ichou, Les Enfants d’immigrés à l’école
No full textIt is common to hear in the fields of educational and immigration sociology that on average, the children of immigrants do not perform as well in school as children of native-born parents. Mathieu Ichou offers an innovative sociological analysis on a topic that is heavily exploited by political and media discourse, and subject to much scientific controversy. The author takes distance from the homogenized vision of a “second generation” of students who have totally failed academically, and rep..
Het interactoom en de functie van de PP1γ interactor RepoMan bij de vorming van de mitotische spoel
No full textThe role of RepoMan in chromosome-dependent microtubule nucleation
The assembly of a mitotic spindle that makes stable contacts with chromosomes is crucial for accurate cell division. Both the centrosomal and chromosomal pathway of microtubule nucleation contribute to the efficient build-up of the bipolar spindle. The growth of microtubules starts at the γ-tubulin ring complex (γ-TuRC), where γ-tubulin serves as a template for α-/β-tubulin dimers to polymerize. Here, we investigated the role of RepoMan, a chromosome associated protein, in spindle assembly. Using immunofluorescence, we show that a RepoMan knockdown leads to less spread chromosomes in prometaphase. This effect is dependent on the stability of microtubules as shown by nocodazole washout and taxol stabilization assays. This effect is due to the misregulation of the chromosomal pathway of microtubule nucleation since a knockdown of RepoMan leads to a decrease in the size of chromosomal microtubule asters. Using BioID and the newly developed Split-BioID technique, we found that RepoMan interacts with several regulators of spindle stability and α-, β- and γ-tubulin itself. Furthermore, we found that RepoMan co-immunoprecipitates with importin in a RanGTP dependent manner, just like spindle assembly factors such as TPX2, NuSAP1 and Kid. We propose a model where RepoMan regulates the activity or localization of one or more of these newly identified interactors. This can explain RepoMan's stabilizing effect on chromosome-dependent microtubules in prometaphase.status: Publishe
L'impatto dell'attività tintoria sull'ambiente. Firenze alla fine del Medioevo
No full textThe author aims to examine and categorize the range of dyeings materials used in the Florentine wool and silk textile industries in the late Middle Ages, focusing mainly on those produced within the regional space in order to evaluate the impact of the Florentine dyeing activity on the natural environment and the productive landscape of the Tuscan countryside. In particular, the author establishes a line of demarcation between cultivated and uncultivated resources in order to verify which constitutes an indication of the level of industrial development of medieval textile production. This further focuses on how the transition from the exploitation of wild resources to the exploitation of cultivated resources could reflect a greater degree of economic integration between the countryside and the city and contribute to the formation of a regional economic space
De levenscyclus van NPP2, een lysofosfolipase D dat metastase bevordert
No full textNPP2, also known as autotaxin, is a 125-kDa glycoprotein that generates the extracellular signalling molecule lysophosphatidic acid (LPA). The latter can bind five distinct G-protein coupled receptors and activates their downstream pathways, resulting in the stimulation of the proliferation, migration and survival of normal as well as cancer cells. Recently, NPP2 has also been implicated in angiogenesis in both embryonal development and in anstatus: Publishe
Mitotische functie en regeling van het fosfatase stellage-eiwit Repo-Man
No full textReversible protein phosphorylation represents one of the most common posttranslational modifications in eukaryotes. It is tightly controlled inspace and time by protein kinases and protein phosphatases. This also applies to histone H3, one of the most abundant mitotic phosphoproteins. Many protein kinases of histone H3 have already been identified and functionally characterized. In contrast, very little is known on the counteracting phosphatases. Here, we show that PP1 is the major histone H3 phosphatase acting on the mitotically phosphorylated (ph) residues H3T3ph, H3S10ph, H3T11ph, and H3S28ph. In addition, we identify Repo-Man as a histone H3T3ph targeting subunit of PP1 that acts antagonistically to protein kinase Haspin. Consistent with this notion, the Repo-Man/PP1 complex opposes the spreading of H3T3ph to the chromosome arms until metaphase and catalyzes the net dephosphorylation of H3T3ph at the end of mitosis. During (pro)metaphase PP1/Repo-Man is prevented fromcausing a net dephosphorylation of centromeric H3T3ph. This can be explained by the Aurora B-mediated phosphorylation of Repo-Man at Ser893 (S893), which prevents its association with histones. We also identified PP2A as a mitotic interactor of Repo-Man that dephosphorylates S893 and thereby promotes the targeting of Repo-Man to chromosomes and the dephosphorylation of H3T3ph by PP1. Thus, Repo-Man-associated PP1 and PP2A collaborate to oppose the chromosomal targeting of Aurora B. We propose that the reciprocal feedback regulation of Haspin and Repo-Man by Aurora B generates a robust bistable response that culminates in the centromeric targeting of the CPC during prometaphase.status: Publishe
Regeling van het fosfatase stellage-eiwit RepoMan tijdens de celcyclus
No full textProtein kinases and phosphatases are antagonistically acting enzymes that cooperate to control the speed, amplitude and specificity of phosphorylation signals in numerous cellular processes, including mitosis. Early mitotic events are characterized by bulk phosphorylation of specific proteins by kinases such as CDK1/Cyclin B and Aurora B. The mitotic exit depends on protein phosphatases, mainly PP1 and PP2A, which remove phosphate groups from mitotic phosphoproteins and re-establish the interphase state. We are interested in the antagonistically acting enzymes Aurora B and PP1:RepoMan. During prometaphase, PP1-RepoMan dephosphorylates Histone 3 at Threonine 3 along the chromosome arms to promote the centromeric enrichment of Aurora B. This is dynamically opposed by CDK1-mediated phosphorylation of the PP1-binding domain of RepoMan and by Aurora B itself, which inhibits RepoMan binding to histones. The reciprocal regulation between RepoMan and Aurora B results in the enrichment of Aurora B at the centromeres, where the kinase is maximally active and prevents erroneous kinetochore-microtubules attachments. During anaphase, Aurora B localizes to the spindle midzone and PP1-RepoMan is massively recruited to the chromosomes, where it catalyzes the bulk dephosphorylation of mitotic-exit substrates. Aurora-B overexpression in cancer is often associated with chromosome mis-segregation. The main molecular pathways that regulate Aurora-B abundance in cells are well understood. Moreover, small molecule inhibitors of Aurora B are being used in clinical trials to treat cancer patients. RepoMan is also frequently overexpressed in human cancers. However, it is not known if RepoMan and Aurora B are co-overexpressed and, importantly, which mechanisms control RepoMan levels in tumor cells. By using publicly available datasets, we found that RepoMan and Aurora-B co-overexpression correlated with tumor aggressiveness in some types of tumors. Then, by using biochemical approaches we showed that RepoMan levels oscillate similarly to Aurora B, increasing in G2/M phase and declining at the mitotic exit and in interphase. Interestingly, both RepoMan and Aurora B mRNA levels are controlled by the transcription factor FOXM1 and their protein downregulation is mainly controlled by ubiquitin-mediated proteasomal degradation. During mitotic exit and early G1, RepoMan and Aurora B are both targeted by the ubiquitin ligase APC/C-CDH1, while during G1/S phase their levels are kept low by E3 complex SCF-FBXW7. The existence of a cell-cycle co-regulation of RepoMan:Aurora B pair indicate that cells should benefit from having balanced levels of the two enzymes. Mathematical modeling revealed that co-oscillations in RepoMan:Aurora B level generate a dynamic bistable system that is more robust to stochastic changes. A theoretical model also predicted that cells with high RepoMan concentration are more vulnerable to treatment with Aurora-B inhibitors, which was validated experimentally. We speculate that tumor cells use multiple ways to keep the balance between RepoMan and Aurora B in order to proliferate with mild/advantageous levels of aneuploidy. Disturbing this balance, chemically or genetically, might be a novel and more specific therapeutic approach for the treatment of cancer patients.status: Publishe
- …
