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Time-resolved quantifikation of centrosomes by automated image analysis suggests limiting component to set centrosome size in C. elegans embryos [Elektronische Ressource] / eingereicht von Steffen Jaensch

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127 pages
T I M E - R E S O LV E D Q U A N T I F I C AT I O N O F C E N T R O S O M E SB Y A U T O M AT E D I M A G E A N A LY S I SS U G G E S T S L I M I T I N G C O M P O N E N TT O S E T C E N T R O S O M E S I Z E I N C . E L E G A N S E M B RY O SdissertationS T E F F E N J A E N S C HiiT I M E - R E S O LV E D Q U A N T I F I C AT I O N O F C E N T R O S O M E SB Y A U T O M AT E D I M A G E A N A LY S I SS U G G E S T S L I M I T I N G C O M P O N E N TT O S E T C E N T R O S O M E S I Z E I N C . E L E G A N S E M B RY O Sdissertationzur Erlangung des akademischen Grades Doktor rerum naturalium (Dr. rer. nat.)vorgelegt an derTechnischen Universität DresdenFakultät Informatikeingereicht vonDiplom-Informatiker Steffen Jaenschgeboren am 21. Juni 1980 in RüdersdorfGutachter: Prof. Dr. Michael Schroeder (TU Dresden, Fakultät Informatik)Dr. Eugene W. Myers (Janelia Farm Research Campus, USA)Tag der Verteidigung: 02. Dezember 2010Dresden im September 2010Steffen Jaensch: Time-Resolved Quantification of Centrosomes by Automated ImageAnalysis Suggests Limiting Component to Set Centrosome Size in C. Elegans Em-bryos, Dissertation, September 2010To my familyviA B S T R A C TThe centrosome is a dynamic organelle found in all animal cells that serves asa microtubule organizing center during cell division.
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T I M E  R E S O LV E D Q U A N T I F I C AT I O N O F C E N T R O S O M E S B Y A U T O M AT E D I M A G E A N A LY S I S S U G G E S T S L I M I T I N G C O M P O N E N T T O S E T C E N T R O S O M E S I Z E I NE L E G A N SC . E M B R Y O S
dissertation
S T E F F E N J A E N S C H
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T I M E  R E S O LV E D Q U A N T I F I C AT I O N O F C E N T R O S O M E S B Y A U T O M AT E D I M A G E A N A LY S I S S U G G E S T S L I M I T I N G C O M P O N E N T T O S E T C E N T R O S O M E S I Z E I NC . E L E G A N SE M B R Y O S
dissertation
zur Erlangung des akademischen Grades Doktor rerum naturalium (Dr. rer. nat.)
Gutachter:
vorgelegt an der Technischen Universität Dresden Fakultät Informatik
eingereicht von DiplomInformatiker Steffen Jaensch geboren am21. Juni1980in Rüdersdorf
Tag der Verteidigung:
Prof. Dr. Michael Schroeder (TU Dresden, Fakultät Informatik)
Dr. Eugene W. Myers (Janelia Farm Research Campus, USA)
02. Dezember2010
Dresden im September2010
Steffen Jaensch:TimeResolved Quantification of Centrosomes by Automated Image Analysis Suggests Limiting Component to Set Centrosome Size in C. Elegans Em bryos, Dissertation, September2010
To my family
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A B S T R A C T
The centrosome is a dynamic organelle found in all animal cells that serves as a microtubule organizing center during cell division. Most of the centrosome components have been identified by genetic screens over the last decade, but little is known about how these components interact with each other to form a functional centrosome. Towards a better understanding of the molecular organization of the centrosome, we investigated the mechanism that regulates the size of the centrosome in the earlyC. elegansembryo. For this, we monitored fluorescently labeled centrosomes in living embryos and developed a suite of image analysis algorithms to quantify the centro somes in the resulting3D timelapse images. In particular, we developed a novel algorithm involving a twostage linking process for tracking centro somes, which is a multiobject tracking task. This fully automated analysis pipeline enabled us to acquire timeresolved data of centrosome growth in a large number of embryos and could detect subtle phenotypes that were missed by previous assays based on manual image analysis. In a first set of experiments, we quantified centrosome size over develop ment in wildtype embryos and made three essential observations. First, cen trosome volume scales proportionately with cell volume. Second, beginning
at the4cell stage, when cells are small, centrosome size plateaus during the cell cycle. Third, the total centrosome volume the embryo gives rise to in any one cell stage is approximately constant. Based on our observations, we pro pose a ‘limiting component’ model in which centrosome size is limited by the amounts of maternally derived centrosome components.
In a second set of experiments, we tested our hypothesis by varying cell size, centrosome number and microtubulemediated pulling forces. We then manipulated the amounts of several centrosomal proteins and found that the
conserved centriolar and pericentriolar material protein SPD2is one such component that determines centrosome size.
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P U B L I C AT I O N S
Some ideas and figures have appeared previously in the following publication:
S. Jaensch, M. Decker, A. A. Hyman, and E. W. Myers (2010)Automated tracking and analysis of centrosomes in early Caenorhabditis elegans embryos. Bioinformatics 26, i13i20.
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A C K N O W L E D G M E N T S
This thesis describes the research I carried out as a PhD student at the Max Planck Institute of Molecular Cell Biology and Genetics in Dresden, Germany and Janelia Farm Research Campus in Ashburn, Virginia, USA from Septem ber2007to September2010. Many people have contributed in very different
ways to make this period of my life a very exciting, interesting, challenging and pleasant one. I would like to thank...
Professor Dr. Anthony Hyman for giving me the opportunity to do my PhD in his lab and for again and again emphasizing to think in science in terms of
specific questions. With only a single biology class (on neuroscience) during my undergrad, the scientific world of biology was completely new for me; working in your lab gave me great insights and many, many possibilities to explore and learn about this exciting field of research.
Dr. Eugene Myers for hosting me as a visiting student researcher at Janelia Farm and for putting the most abstract ideas into illustrative yet precise words. Gene, thanks for your personal advise and the very active group meeting dis cussions, which both were truly helpful to me. Working and living at the farm was a very special, certainly enjoyable experience, scientifically and personally.
Markus Decker for the close collaboration throughout my entire PhD time. Double the fun, half the frustration and always something to give each other shit about. Markus, I think we made a pretty good team. Thank you for the great time!
My thesis advisory committee members Dr. Pavel Tomancak, Professor Dr. Michael Schroeder and Professor Dr. Frank Juelicher for their constructive comments and guidance through the PhD program.
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