Effects of Glucose Availability on Mitochondrial Dynamics

Sammanfattning

Mitochondria are dynamic organelles which play a central role in the cellularenergy metabolism and intracellular signaling. Changes in mitochondrialmovement and organisation have been linked to metabolic states, cellularstress and disease development. The purpose of this thesis was to investigatehow different glucose concentrations affect mitochondrial movement in livingMDCK II cells, as well as to evaluate the use of automated analysis methodsfor quantification of mitochondrial dynamics.Living MDCK II cells expressing mitochondria-targeted GFP were imagedwith fluorescence microscopy under three different glucose conditions:high glucose, low glucose and a physiological baseline. Mitochondrialtrajectories were extracted and analysed using the Python-based frameworkNellie together with a custom Python analysis pipeline. The mitochondrialmovement patterns were characterised by calculating the mean squareddisplacement (MSD), anomalous diffusion exponent (alpha), velocity, stepdisplacement and confinement ratio. The results were compared with anindependent AI-based pipeline, generated with the large language modelClaude.The results showed that mitochondrial motion was predominantly confinedin all glucose concentrations, with alpha-values below 1 for the large majorityof trajectories. High glucose concentration showed somewhat elevated valuesfor MSD, velocity and step displacement when compared with values forlow and baseline concentrations of glucose, but the statistical differenceswere generally small. The comparison between the Nellie-based pipeline andthe AI-based pipeline revealed similar overarching trends between glucoseconditions, although there were differences in absolute values.The thesis showed that automated motion analysis can be used to quantifymitochondrial motion in living cells, while changes in glucose concentrationproduced only moderate effects on mitochondrial movement under theexperimental conditions used in this project.