Forces in Cellular Growth and Division
von Jörn Hartung
Datum der mündl. Prüfung:2015-12-10
Erschienen:2016-02-05
Betreuer:Prof. Dr. Oskar Hallatschek
Gutachter:Prof. Dr. Stephan Herminghaus
Gutachter:Prof. Dr. Reiner Kree
Gutachter:Prof. Dr. Jörg Enderlein
Gutachter:Prof. Dr. Andreas Janshoff
Gutachter:Prof. Dr. Christoph F. Schmidt
Gutachter:Prof. Dr. Oskar Hallatschek
Dateien
Name:Doktorarbeit_Jörn_Hartung.pdf
Size:66.1Mb
Format:PDF
Zusammenfassung
Englisch
Under confinement cell populations exert growth forces onto their surroundings. Confined cell populations can be found plentiful in nature, e.g. tumors embedded in healthy tissues, microbial populations in stone cavities and in biofilms. Very few microbial studies examine the influence of growth-induced forces due to the common practice to culture cellular populations in free solution and the lack of a well-defined culturing method for confined growth. Here, a microfluidic device is presented that enables one to study Saccharomyces cerevisiae populations (and microbes of similar size) under different growth-induced pressures ranging from 0 to 1 MPa. Our experiments show that the cells behave similarly to driven granular materials encountering narrow orifices. Depending on the geometry of the orifice, used to guide the outflow of cells from the confinement, the strength and durability of cell clots can be controlled in a statistical sense. These cell clots are essential for the increase of growth-induced pressure in the cell populations since they control the degree of confinement the cells experience. Furthermore, the statistics of cell avalanches that occur between breaking and formation of cell clots was studied in detail showing that the survival functions of the cell clot durations follow a power-law decay for large event sizes. Additional experiments showed that the growth rate of a confined cell population decreases exponentially with increasing growth-induced pressure and that this decrease in growth rate is tightly correlated to a delay of cells in the G1 phase of the cell cycle.
Keywords: growth-induced pressure; microfluidics; cell clotting; jamming; Saccharomyces cerevisiae