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Electron Microscopy

The facility is currently equipped with two aging transmission electron microscopes: a Jeol 1200EX, from 1985, and a Philips CM10, from 1990. These two machines are to be replaced this year with a new Jeol JEM-1400 machine. This 120kV machine will be fitted with a high-contrast pole-piece for analysis of biological samples and supplied with a bottom mounted Gatan Orius CCD camera (4008 x 2672 pixels). The addition of a CCD camera, which can operate at real-time viewing speeds, as well as a plate film camera will allow rapid and cheap image acquisition. Further, the fitting of this digital camera will allow automation of many procedures that are now carried out manually (focusing, stigmation, alignment, exposure setting) and will also allow auto-montaging.

Image of the Electron Microscopy Facility

The facility has recently acquired a Leica EM AFS2/FSP automatic freeze substitution device. This machine is capable of freeze substitution and progressive lowering of temperature techniques as well as allowing low temperature embedding and polymerisation of resins. Previously at SCRI, embedding and polymerisation have been done at high temperature, so acquisition of this machine will allow adoption of techniques that better preserve immunogenicity of samples for immunogold labelling studies. High pressure freezing (HPF) followed by freeze substitution is considered the optimum method for sample preservation. SCRI does not have its own HPF device, but can access the Leica EM-PACT of Dundee University’s Centre for High Resolution Imaging and Processing in Cell and Molecular Biology (CHIPs).

This year the EM facility has disposed of its somewhat archaic, twenty seven year old Jeol T200 scanning electron microscope. However, SEM studies can still be performed through access to a field emission scanning electron microscope (FE-SEM) and environmental scanning electron microscope (ESEM) housed within the CHIPs facility.

In the past the work of the electron microscopy unit was primarily focused on the analysis of plant viruses and their interactions with host plants. Although the unit still carries out work on plant viruses, it now has a broader remit to provide electron microscope support to projects across the institute. Examples of some recent work are given below.