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Surface scattering: On the interfacial effect of Ca++-ions at mitochondria model membranes

Vejleder: Beate Klösgen

Deltagerantal: 1 studerende

Projektbeskrivelse

Apoptosis is a process best described as “programmed cell death”. Once initiated, it is a way of no return. Functionally, it is biology’s routine method for recycling old cells, to be replaced by well-working new ones. Ca++-ions are presumed to play a key role in the early steps of the apoptotic process, but the details of their impact at the membrane interface of mitochondria membranes is not yet fully understood. The combination of high-resolution experiments like surface scattering by X-rays and neutrons was therefore chosen to contribute solid data to the conjectures.

The accumulation of Ca++-ions into model membranes of varying charge and packing density was studied by Langmuir compression of model monolayers combined with surface scattering experiments with both X-rays and neutrons. The use of neutrons provides the option of contrast variation by H/D-variants of the lipids in the membrane, hence enhancing the visibility of the ions.  Data were taken by neutron reflectometry, GIXD (grazing incidence X-ray diffraction),  GIXOS (grazing incidence X-ray off-specular scattering) and XRF (X-ray fluorescence). The results report on the insertion and accumulation affinity of the Ca++-ions into the interface, on their localization in the monolayer,  electron density distribution at the interface, and on the change of in-plane crystallographic order upon the interaction.

The bachelor (or master) project shall focus on the analysis of existing recent data, collected in scattering experiments at beamlines SURF (neutron; ISIS, Oxford) and P08 (X-ray; PetraIII, Hamburg). The data involve the change of phase state during Langmuir compression, and the related structural impacts. The students will not conduct actual experiments for their project at the beamlines, but be invited as a hands-on student to upcoming new experiments. During their mostly computer-based project work, the students will analyse selected examples from the data sets. The will learn basics about scattering theory, as is reflectometry, x-ray fluorescence, and crystallography in 2D. They will be trained how to use professional software for the data processing, from data reduction to detailed analysis and data interpretation. The results shall be assembled and compared to older results and actual literature. The findings shall be compiled and discussed, to be filed into a thesis text.

Institut for Fysik, Kemi og Farmaci Syddansk Universitet

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Sidst opdateret: 23.08.2021