Cell and Molecular Imaging Service

Our mission is to provide high-quality electron microscopy images of a large variety of biological samples ranging from macromolecules to tissues. We offer services from conventional and immuno- electron microscopy to electron tomography. We perform sample processing, sectioning and imaging. We are also developing technologies in correlative light/electron microscopy. The service works with IBGC’s teams but it is also open to outside labs.

 


Description

The service is essential for ongoing research projects and makes a significant contribution to understand the organization of living cells and how they function at the molecular level. We have established protocols that maximize the preservation of morphology at the EM level for each of the major model system used in our institute. Routine immuno-localization techniques for antigens such as GFP are also established.

The service is a part of common centers of microscopy network (RCCM). We also provide a CNRS theoretical and practical training covering techniques from sample preparation to data collection of images.

 

Models

We study a large variety of biological samples such as bacteria, yeasts, parasites, human cells, tissues…

eq-imagerie1
Our models

 

Techniques used for ultrastructural and immunogold studies

  • Chemical fixation with aldehydes (glutaraldehyde, paraformaldehyde) and osmium tetroxide

eq-imagerie2
Adherent mammalian cells. Gutaraldehyde/osmium tetroxide fixation. Epon inclusion.

 

 

  • Cryomethods : ultra rapid freezing/cryosubstitution

 

This technique permits to instantly immobilize cellular structures and preserve samples as close to their native state as possible.

eq-imagerie3
Ultra rapid freezing in propane/cryosubstitution and Araldite inclusion of yeast Saccharomyces cerevisiae

The cryomethod techniques also permit the in situ localization of proteins preserving both protein antigenicity and the ultrastructure of the cells.

eq-imagerie4
Examples of protein immunolocalization studies in yeast. Freezing in propane / cryosubstitution.
Left : outer membrane porin of mitochondria localization. Right : presence of mitochondria in the vacuole.

 

  • Thiéry Reaction

The Thiéry reaction permits to visualize polysaccharides by contrasting them but is unable to discriminate between different polysaccharides.

eq-imagerie5
Visualization of polysaccharides in yeast

 

Observation of macromolecules
(negative staining with uranyl acetate 2% in water)

With negative stain, we can observe thin samples (macromolecules) placed on a microscope grid covered with a carbon film.

eq-imagerie6

ATP synthase dimersAmyloid fibersDistorted liposome

 

3D imaging tomography

This technique permits to reconstruct the volume of an object by backprojection from a series of images taken at different angles in conventional electron microscopy.

eq-imagerie7
3D reconstruction of a part of mitochondria

 

Correlative microscopy

Thanks to this technique, the same structure, the same cell or the same event using two different microscopy platforms (fluorescent and electron microscope) can be studied.

eq-imagerie8
Correlative microscopy of mammalian cells

Observations are performed in the electronic imaging service of Bordeaux Imaging Center (BIC) using a Hitachi 7650 transmission electron microscope equipped with a camera SC1000 ORIUS 11Mpx (GATAN).