Robust control mechanisms ensure faithful inheritance of an intact genome through the processes of mitosis and cytokinesis. Different populations of the cytoplasmic dynein motor defined by specific dynein adaptor complexes are required for the formation of a stable bipolar mitotic spindle. This study analysed how different dynein subcomplexes contribute to spindle formation and orientation. Various dynein subpopulations were identified by mass spectrometry. I have shown that the dynein light chain 1 (DYNLL1) directly interacts with the kinetochore localised Astrin-Kinastrin complex as well as the spindle microtubule associated complex formed by CHICA and HMMR. I have characterised both complexes and identified unique functions in chromosome alignment and mitotic spindle orientation, respectively. I have found that Kinastrin (C15orf23) is the major Astrin-interacting protein in mitotic cells and is required for Astrin targeting to microtubule plus ends proximal to the plus tip tracking protein EB1. Fixed cell microscopy revealed that cells over-expressing or depleted of Kinastrin mislocalise Astrin. Additionally, depletion of the Astrin-Kinastrin complex delays chromosome alignment and causes the loss of normal spindle architecture and sister chromatid cohesion before anaphase onset (Dunsch et al., 2011). Using immunoprecipitation and microtubule binding assays, I have shown that CHICA and HMMR interact with one another, and target to the spindle by a microtubule-binding site in the amino-terminal region of HMMR. CHICA interacts with DYNLL1 by a series of conserved TQT motifs in the carboxy-terminal region. Depletion of DYNLL1, CHICA or HMMR causes a slight increase in mitotic index but has little effect on spindle formation or checkpoint function. Fixed and live cell microscopy reveal, however, that the asymmetric distribution of cor tical dynein is lost and the spindle in these cells fails to orient correctly in relation to the culture surface (Dunsch et al., 2012). These findings presented here suggest that the Astrin-Kinastrin complex is required for normal spindle architecture and chromosome alignment, and that per turbations of this pathway result in delayed mitosis and non-physiological separase activation, whereas HMMR and CHICA act as par t of a dynein-DYNLL1 complex with a specific function defining or controlling spindle orientation.

This master's thesis deals with the problems of tool changing of vertical turning lathe. Specifically about modular system of spindle locking in a ram. The master's thesis is shows types of structural design, choosing the best design with supporting technical - economics evaluation. After this is realized series of calculation controls. These define dimensions of the mechanical parts.

No description available.

Chromosome alignment and orientation within the spindle in mitosis and meiosis are determined by chromosome-microtubule interaction. Evidence suggests that within the acentrosomal spindle the mechanism of chromosome positioning is different from in mitotic spindle but its molecular bases are not well understood. I investigated how chromosome-microtubule interactions position the chromosomes within the spindle using Drosophila oocytes. I addressed the role and molecular mechanisms of kinetochore and chromosome interaction with microtubules in this process. I developed new live imaging reagents to observe dynamic chromosome-microtubule interaction. Live imaging combined with inactivation of kinetochores in oocytes revealed that kinetochore-microtubule attachment is required for three-step chromosome positioning in Drosophila oocytes: de-congression, change of orientation and re-congression. Augmin, a γ-tubulin recruiting complex, has been previously shown to be important for chromosome congression specifically in oocytes. Live imaging further showed that Augmin facilitates chromosome congression particularly in early stages of spindle assembly. Study of Augmin dynamics revealed that Augmin stably associates with spindle polar regions, specifically in oocytes. This meiotic regulation of Augmin function may contribute to generation of force pushing chromosomes toward spindle equator. Sentin protein has been shown to be important for microtubule plus end dynamics in mitosis. In meiosis, sentin mutant results in reduced distance between centromeres of homologous chromosomes. However, its meiotic role is unknown. Live imaging of the sentin mutant showed that in oocytes Sentin is required for preventing premature stabilization of kinetochore-microtubule attachments. As conclusion, I have used live imaging to reveal molecular basis of the interaction between chromosomes and microtubules particularly important for oocytes.

No description available.

Düsseldorf, Univ., Diss., 2003. / Computerdatei im Fernzugriff.

Düsseldorf, Univ., Diss., 2003. / Computerdatei im Fernzugriff.

Düsseldorf, Universiẗat, Diss., 2003.

Düsseldorf, Universiẗat, Diss., 2001.

The spindle checkpoint ensures proper chromosome segregation by monitoring kinetochore-microtubule interactions: unattached kinetochores recruit checkpoint proteins that combine to form a diffusible inhibitor which delays anaphase, thus buying cells time to fix attachment errors. Although the major checkpoint proteins were identified some 25 years ago, we have only just begun to understand how they assemble at unattached kinetochores to generate the crucial checkpoint signal. Much of this can be attributed to the difficulty associated with studying these proteins at the kinetochores, which are highly complex and thus often make clean dissection of function impossible. To circumvent this problem, a synthetic version of the spindle checkpoint was engineered on an ectopic location on a chromosome arm away from kinetochores in S. pombe. This work describes how the co-targeting of only two checkpoint components, the outer kinetochore protein Spc7 and the checkpoint kinase Mph1, was found to be sufficient to successfully generate a checkpoint-dependent metaphase arrest and how this paves the way for a clearer, more joined-up understanding of how the checkpoint works.