High pressure freezing

Now that biology has truly entered the post genomics era, there is an ever-increasing demand for both structural and spatial information on the myriad of proteins encoded by the genomes being sequenced.Technological developments in light microscopy such as confocal and two photon microscopy, combined with developments in immunolabelling and fluorescent protein technology, have revolutionised the study of cell structure. However, all these techniques are limited in resolution and for fine detail at the sub-cellular level, electron microscopy (EM) is still essential.

Faithful preservation of cell structure is imperative if electron microscope images are to be correctly interpreted, and the use of ultra-rapid freezing techniques prior to any chemical fixation is the ideal procedure for preparing tissue for electron microscopy. A recent BBSRC grant awarded to Chris Hawes in the School of Life Sciences at Oxford Brookes University has funded the purchase of a BAL-TEC HPM 010 High Pressure Freezer, one of only four such machines in the UK. This machine permits the cryo-preservation of relatively large samples of biological material by subjecting specimens to 2100 bar during the freezing procedure, thus preventing the nucleation of ice crystals and specimen damage. A postdoctoral research assistant Dr Eric Hummell, an expert in plant electron microscopy, has been employed to help run the facility alongside Barry Martin, the Cell Biology Laboratory Manager at Oxford Brookes University who has many years of experience in cryo-microscopy techniques.

The High Pressure Freezing Facility at Oxford Brookes University, combined with freeze-substitution processing is available to BBSRC grantholders wishing to prepare specimens for structural and immunocytochemical studies.

 Dr Ulla Neumann and Barry Martin with the BAL-TEC HPM010 high pressure freeezing apparatus

Plant Golgi stacks in a tobacco root cap cell that was high pressure frozen