| dc.contributor.advisor | Jakobs, Stefan Prof. Dr. | |
| dc.contributor.author | Lange, Felix | |
| dc.date.accessioned | 2021-11-22T16:10:30Z | |
| dc.date.available | 2021-11-29T00:50:04Z | |
| dc.date.issued | 2021-11-22 | |
| dc.identifier.uri | http://hdl.handle.net/21.11130/00-1735-0000-0008-599A-7 | |
| dc.identifier.uri | http://dx.doi.org/10.53846/goediss-8959 | |
| dc.identifier.uri | http://dx.doi.org/10.53846/goediss-8959 | |
| dc.language.iso | eng | de |
| dc.rights.uri | http://creativecommons.org/licenses/by-nc-nd/4.0/ | |
| dc.subject.ddc | 570 | de |
| dc.title | Mitochondrial adaptation at the neuronal presynapse | de |
| dc.type | doctoralThesis | de |
| dc.contributor.referee | Rehling, Peter Prof. Dr. | |
| dc.date.examination | 2021-02-25 | |
| dc.description.abstracteng | Synaptic transmission poses a major energy consuming process in the brain, but how neurons
maintain a constant energy supply during extended synaptic activity and how presynaptic
mitochondria contribute to the energy supply remains elusive. The mitochondria are key
organelles to account for the majority of ATP newly synthesised in neuronal cells. Hence, the
present study aimed at unravelling the structural adaptation of mitochondria to an increase in
presynaptic energy demand. To this end, I first characterized the mitochondrial membrane
architecture and how it changes in response to different energy sources using transmission
electron microscopy. As a model system, several cancer cell lines were used in addition to
primary hippocampal neuronal cultures isolated from rat brain. In all tested cancer cell lines, a
long-term metabolic switch to ketosis induced significant changes in the mitochondrial
structure reflected by an increase of the mitochondrial diameter as well as a significant
increase in the abundance of crista membranes. In contrast, a metabolic switch to glycolysis
resulted in a decrease of the mitochondrial diameter and a reorientation of the crista
membranes in parallel to the mitochondrial outer membrane in these cells. Likewise, in
cultivated hippocampal neurons, the metabolic switch to ketosis induced a 20 % increase of
crista membranes. Interestingly, only about 35 % of the neuronal presynapses showed a
mitochondrial occupation which was not influenced by chemical depolarization with high
concentrations of potassium chloride (KCl), suggesting that induced presynaptic activity does
not affect the travelling of axonal mitochondria to the presynapses of hippocampal neurons.
Furthermore, I used the cochlear nucleus of mice before and after the onset of hearing as a
model system for presynaptic states of low and high-energy demand. Here, the synaptic
morphology together with the presynaptic mitochondrial structure using Focused Ion Beam
Scanning Electron Microscopy (FIB-SEM) was assessed. The volume of the synaptic boutons,
the synaptic vesicle pool as well as the post-synaptic density were increased in synapses after
the onset of hearing. Beyond that, the mitochondrial volume in these presynapses increased
significantly. This suggests that synapses and mitochondria undergo major structural changes
to serve the higher energy demands after the onset of hearing. Intriguingly, synapses
containing mitochondria displayed an overall larger volume, synaptic vesicle pool and
postsynaptic density when compared to synapses lacking mitochondria in mice before and
after the onset of hearing. In conclusion, mitochondria play a key role in shaping presynaptic
structure and are thus pivotal for synaptic transmission.
In order to gain functional insights into the role of mitochondria in synaptic transmission in
addition to the structural information obtained by TEM, I developed novel correlative imaging
V
tools. These tools include live cell 3D correlative light and electron microscopy (3D CLEM),
which allows to monitor relevant mitochondrial targets by fluorescent labelling and
subsequently correlate the functional information with structural aspects, and high-accuracy
CLEM allowing for high spatial resolution of the detected features in both, light and electron
microscopy.
These protocols built the foundation for an extended correlative approach. There, I combined
high-accuracy CLEM with nanoscale secondary ion mass spectrometry (NanoSIMS). This, for
the first time, allowed extracting the functional and structural information together with the
chemical composition of subcellular areas of the same resin-embedded specimen. These tools
could now be applied to study individual players in mitochondrial function by simultaneously
getting information of their impact on synaptic structure and chemical composition. | de |
| dc.contributor.coReferee | Jahn, Reinhard Prof. Dr. | |
| dc.contributor.thirdReferee | Rizzoli, Silvio O. Prof. Dr. | |
| dc.contributor.thirdReferee | Wichmann, Carolin Prof. Dr. | |
| dc.contributor.thirdReferee | Outeiro, Tiago Fleming Prof. Dr. | |
| dc.subject.eng | Mitochondria | de |
| dc.subject.eng | Presynapse | de |
| dc.subject.eng | Structure | de |
| dc.subject.eng | Neuronal Cells | de |
| dc.subject.eng | Microscopy | de |
| dc.identifier.urn | urn:nbn:de:gbv:7-21.11130/00-1735-0000-0008-599A-7-9 | |
| dc.affiliation.institute | Göttinger Graduiertenschule für Neurowissenschaften, Biophysik und molekulare Biowissenschaften (GGNB) | de |
| dc.subject.gokfull | Biologie (PPN619462639) | de |
| dc.description.embargoed | 2021-11-29 | |
| dc.identifier.ppn | 1778294189 | |