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BP: Fachverband Biologische Physik

BP 14: Membranes and Vesicles

BP 14.2: Vortrag

Mittwoch, 28. März 2012, 10:00–10:15, H 1028

In vivo high pressure 1H NMR studies on oocytes of Xenopus laevis — •Joerg Koehler, Sebastian Dietz, Werner Kremer, and Hans Robert Kalbitzer — Institute of Biophysics and Physical Biochemistry, University of Regensburg, 93040 Regensburg, Germany

Oocytes of the African Clawed Frog Xenopus laevis are an excellent candidate for in vivo high pressure Nuclear Magnetic Resonance studies. This is due to their relative good resistance against mechanical stress compared to other living cells and on the other hand their quite large cell size.

We studied the oocytes in the pressure range from ambient pressure to 200 MPa by 1H NMR spectroscopy. The strongest signals come from the lipids contained in the oocytes. The signals of the lipids decrease with increasing pressure where the signals assigned to different groups behave differently. Signals due to protons in unsaturated fatty acids show a smaller pressure effect than signal arising from saturated fatty acids. The T2-values measured by a CPMG sequence are only weakly dependent on pressure. The data can be explained by a pressure dependent phase transition in the lipid droplets. The pressure induced effects observed by NMR spectroscopy are completely reversible up to a pressure of 120 MPa, which agrees well with the vitality measurements on pressure treated cells by patch-clamp experiments on the membrane.