Study of Sub-cellular Structures upon Low-glucose Starvation in S. Pombe.
Many cells and organisms react to depletion of nutrients with an energy saving program. Here we studied Schizosaccharomyces pombe
; fission yeast) cells and how they respond to nutrient starvation by entering a quiescent state that is characterized by a substantial viscosity increase of the cytoplasm, which we term "cytoplasmic freezing". Recently we found evidence that the transition in viscosity of the cell cytoplasm could be reliably reproduced by starving S. pombe
cells of glucose. Also, there is evidence that septins, a GTP binding protein family, might be involved in generating and maintaining the frozen cytoplasmic state. Here I have confirmed by light microscopy that in the absence of Spn2p the phenomenon of “cytoplasmic freezing” did not happen or occurred much later (Florin, unpublished). Taking advantage of confocal fluorescence microscopy, I have identified the relocation of Spn3p in wild type and Spn2
deleted S. pombe
cells during exponential growth conditions and compared them to the situation upon up to seven days of glucose starvation. In addition using conventional electron microscopy and cryo-electron microscopy, I have imaged for the first time the formation of filamentous septin in starved S. pombe
cells. Similar septin bundles have been reported for different conditions, but not during the kind of starvation conditions reported here (An et al., 2004). I have further confirmed that absence of Spn2
relocates Spn3p upon starvation in S. pombe
by immuno-labeling combined with conventional and cryo-electron microscopy. Also, I have observed by confocal microscopy that neither the deletion of Spn2
nor the "cytoplasmic freezing" state in starved cells affect actin location in S. pombe
. However, actin behaves substantially different before versus after starvation, and during exponential growth its distribution is radically different between wildtype and Spn2
deletion strains. These significant details can help our understanding of the role of septin during glucose starvation in S. pombe
or even in other organisms in the future. Furthermore, by conventional electron microscopy and cryo-electron microscopy I have demonstrated the shape change and fission of mitochondria from elongating tubular structures to separated small ovals upon glucose starvation in S. pombe
. I have also directly observed that during glucose starvation ribosomes tightly assemble at the outer membrane of mitochondria, which is a phenomenon that has not been shown in detail anywhere and its relation to glucose starvation is not well understood. During all the structural studies, I have also tested conditions of a new method that we named cryo-pickling, loosely in association of pickling vegetables etc. to make them tender and/or to preserve them by incubation with a brine solution. Here we tested whether it will be possible to make frozen-hydrated specimens accessible (e.g. vitrified sections) for antibodies…
Advisors/Committee Members: Mark Winey, Andreas Hoenger, Thomas Perkins, Gia Voeltz, Ernst-Ludwig Florin.
to Zotero / EndNote / Reference
APA (6th Edition):
Liu, M. (2015). Study of Sub-cellular Structures upon Low-glucose Starvation in S. Pombe. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/mcdb_gradetds/35
Chicago Manual of Style (16th Edition):
Liu, Minghua. “Study of Sub-cellular Structures upon Low-glucose Starvation in S. Pombe.” 2015. Doctoral Dissertation, University of Colorado. Accessed January 23, 2020.
MLA Handbook (7th Edition):
Liu, Minghua. “Study of Sub-cellular Structures upon Low-glucose Starvation in S. Pombe.” 2015. Web. 23 Jan 2020.
Liu M. Study of Sub-cellular Structures upon Low-glucose Starvation in S. Pombe. [Internet] [Doctoral dissertation]. University of Colorado; 2015. [cited 2020 Jan 23].
Available from: https://scholar.colorado.edu/mcdb_gradetds/35.
Council of Science Editors:
Liu M. Study of Sub-cellular Structures upon Low-glucose Starvation in S. Pombe. [Doctoral Dissertation]. University of Colorado; 2015. Available from: https://scholar.colorado.edu/mcdb_gradetds/35