Sulfo-SMCC Prevents Annealing of Taxol-Stabilized Microtubules In Vitro

Microtubule structure and functions have been widely studied in vitro and in cells. Research has shown that cysteines on tubulin play a crucial role in the polymerization of microtubules. Here, we show that blocking sulfhydryl groups of cysteines in taxol-stabilized polymerized microtubules with a commonly used chemical crosslinker prevents temporal end-to-end annealing of microtubules in vitro. This can dramatically affect the length distribution of the microtubules. The crosslinker sulfosuccinimidyl 4-(N-maleimidomethyl)cyclohexane-1-carboxylate, sulfo-SMCC, consists of a maleimide and an N-hydroxysuccinimide ester group to bind to sulfhydryl groups and primary amines, respectively. Interestingly, addition of a maleimide dye alone does not show the same interference with annealing in stabilized microtubules. This study shows that the sulfhydryl groups of cysteines of tubulin that are vital for the polymerization are also important for the subsequent annealing of microtubules.Comment: 3 figure

Konfirmatorische Analyse der Struktur und Konstrukte

Das Lehrevaluationsinstrument PraQ mit Ratingskalen zur Selbst- und Fremdeinschätzung von Aspekten der Praktikumsqualität liefert in einem theoretischen und kompetenzorientierten Rahmen Maße für die Qualität von Praktika. Zielgruppe sind alle naturwissenschaftlichen Anfängerpraktika bis zum vierten Fachsemester an Hochschulen, zunächst begrenzt auf den deutschsprachigen Raum. Das 3L-Modell der Praktikumsqualität definiert hierbei den relevanten Lernzuwachs, die Lehrkompetenz der Betreuenden und die Qualität der Lernumgebung von Praktika. Die Testevaluationsstudie umfasst Studien zur inhaltlichen Adäquatheit der Konstrukte und Items, strukturelle Untersuchungen der Zuordnung von Items und der Konstrukttrennbarkeit, externale Vergleiche mit etablierten Messinstrumenten sowie Multiperspektivitätsanalysen. Gemäß Expert*innenurteilen darf der PraQ inhaltlich als Messinstrument aller relevanten Aspekte der Praktikumsqualität verstanden werden. Strukturell zeigen sich in explorativer und konfirmatorischer Faktorenanalyse gut den Items zuzuordnende, reliable Faktoren, die eine getrennte Interpretation der Einzelkonstrukte zulassen. Vergleiche mit Alternativmodellen zeigen die sehr gute Passung des Grundmodells zu den erhobenen Daten. Dies bedeutet, dass Praktikumsleitende bei der Interpretation ihrer Evaluationsergebnisse die Konstrukte getrennt interpretieren dürfen und so gesicherter mögliche Interventionen im Praktikum an eben jenen Konstrukten ansetzen. Bezogen auf die fachdidaktische Forschung lässt sich schlussfolgern, dass die PraQ-Skalen inhaltlich umfassend und strukturell adäquat ihre betreffenden Konstrukte messen, was sie bereits als Messinstrument auch für andere Kontexte, in denen die enthaltenen Konstrukte Relevanz besitzen, nutzbar macht

The Filament Sensor for Near Real-Time Detection of Cytoskeletal Fiber Structures

A reliable extraction of filament data from microscopic images is of high interest in the analysis of acto-myosin structures as early morphological markers in mechanically guided differentiation of human mesenchymal stem cells and the understanding of the underlying fiber arrangement processes. In this paper, we propose the filament sensor (FS), a fast and robust processing sequence which detects and records location, orientation, length and width for each single filament of an image, and thus allows for the above described analysis. The extraction of these features has previously not been possible with existing methods. We evaluate the performance of the proposed FS in terms of accuracy and speed in comparison to three existing methods with respect to their limited output. Further, we provide a benchmark dataset of real cell images along with filaments manually marked by a human expert as well as simulated benchmark images. The FS clearly outperforms existing methods in terms of computational runtime and filament extraction accuracy. The implementation of the FS and the benchmark database are available as open source.Comment: 32 pages, 21 figure

Topology counts: force distributions in circular spring networks

Filamentous polymer networks govern the mechanical properties of many biological materials. Force distributions within these networks are typically highly inhomogeneous and, although the importance of force distributions for structural properties is well recognized, they are far from being understood quantitatively. Using a combination of probabilistic and graph-theoretical techniques we derive force distributions in a model system consisting of ensembles of random linear spring networks on a circle. We show that characteristic quantities, such as mean and variance of the force supported by individual springs, can be derived explicitly in terms of only two parameters: (i) average connectivity and (ii) number of nodes. Our analysis shows that a classical mean-field approach fails to capture these characteristic quantities correctly. In contrast, we demonstrate that network topology is a crucial determinant of force distributions in an elastic spring network.Comment: 5 pages, 4 figures. Missing labels in Fig. 4 added. Reference fixe

Note on Comparability of MicroCog Test Forms

This study investigated the differences between the Standard and Short forms of MicroCog by comparing Domain scores for a clinical sample of 351 substance abusers which gave a significant difference between scores on the Spatial Processing Domain. Implications for research and clinical use are discussed

MODELAGEM DE UM SOFTWARE PARA SUBSIDIAR A ORGANIZAÇÃO DE EVENTOS: O CASO DA UNIVATES

Com o crescimento das instituições de ensino superior aumenta também a necessidade de disciplinar os processos. A Tecnologia da Informação (TI) assume papel fundamental neste contexto, oferecendo as ferramentas de suporte à automação das rotinas organizacionais. Um dos processos que se torna cada vez mais importante nas IES é a organização de atividades de extensão. Assim como o ensino e a pesquisa, a extensão faz parte da essência e finalidade das instituições de ensino superior (IES), sobretudo das comunitárias (ICES). Este trabalho apresenta os requisitos para subsidiar o desenvolvimento de uma solução computacional (software), visando a simplificar, automatizar e acompanhar a organização de eventos (palestras, congressos, encontros, reuniões, recepções, entrega de preamiações, simpósios, semanas acadêmicas e outros) realizados no Centro Universitário UNIVATES por meio de sua Assessoria de Eventos, setor ligado a Pró-Reitoria de Pesquisa, Extensão e Pós-Graduação (PROPEX). O levantamento de requisitos foi realizado por meio de entrevistas e análise documental

The Transnational Firm Collective Bargaining in Europe: Historical Dynamics, Ways and Challenges

La directiva sobre los comités de empresas europeos (CEE) de 1994, reclamada insistentemente por las organizaciones sindicales, fue un factor determinante para el posterior desarrollo de la negociación colectiva de empresa transnacional, pero fue también una fuente de dificultades para dichas organizaciones, ya que establecía, a nivel europeo, un nuevo canal de representación que se les escapaba en parte. Ante la ausencia de un marco jurídico para la negociación colectiva de empresa transnacional, las federaciones sindicales europeas (FSE) establecieron sus propias reglas internas para retomar el control de esta dinámica y afirmar un derecho exclusivo de negociación y de firma de acuerdos transnacionales. Sin embargo, dicha dinámica se enfrenta a la persistencia de otras prácticas de negociación, entre otras las de los CEE de empresas transnacionales (ETN) alemanas, pero también de otros países, que desean seguir con el control de dichas negociaciones.The directive on European works councils of 1994, insistently demanded by trade unions, has been a decisive factor for the subsequent development of the transnational firm collective bargaining. But it has also been a source of problems for these organizations, as long as it established a new European channel of representation that was in part out of their control. Considering the lack of a regulatory framework for the collective bargaining in the transnational firms, the European trade union federations established their own internal rules in order to get the control back and support an exclusive right of bargaining and signing transnational agreements. Nevertheless, this dynamic faces the persistence of other bargaining practices. Among others, those developed by German and some other countries transnational firms that want to keep the control of their own bargaining practices