Instruct-ERIC France 1 has an open call for a PhD position.
Characterization of nanometric probes for cryo electron tomography.
Important biological properties such as membrane-less compartmentalization, phase separation, condensate formation, weak or transient interaction are only occurring in the crowded environment of the intact cell. A current challenge is to identify key functional sites for transcription within the cell nucleus, and to determine their structure and molecular environment.
Cryo-Electron Microscopy approaches have been developed to visualize molecular assemblies in their cellular environment1. Three-dimensional (3-D) reconstruction of the cell is performed by cryo-Electron Tomography (cryo-ET) of thin cellular slices which are produced by cryo-sectioning the samples2 or by using a focused ion beam (FIB) to mill thin lamellae3. Cryo-ET reconstructions have revealed large molecular assemblies, such as mitochondria, ribosomes, nuclear pore complexes or cytoskeleton in molecular details1.
Molecular complexes with low cell abundance or too small to be recognized by their shape must be identified using a dense electron probe detectable by electron microscopy. We have synthesized gold-based probes that can be delivered into living cells. These gold nanoparticles are coupled with antibody derivatives to selectively label target proteins.
The objective of the thesis is to reveal gold particles in cell sections and tomograms to detect rare protein complexes such as RNA polymerase II molecules, to determine their spatial distribution and to identify their cellular interaction partners.
A graduate student with a background in physics or cell biology would benefit from interdisciplinary training in biological sample preparation, FIB/SEM imaging and data interpretation. The first part of the thesis will be devoted to study the state of the art of in situ labelling approaches, and to get familiar with the instruments. A second part of the thesis will be devoted to the characterization of newly synthesized electron dense markers and their behaviour in a cellular environment. In a third part, the student will use electron-dense nanoparticles conjugated with probes recognizing RNA polymerase II. He/she will experiment data collection on a Titan cryo-electron microscope in both standard imaging mode and cryo-electron tomography mode.
More information and how to apply can be obtaine via this link