Digital Autoradiography

The Department of Criminology

 

Microchannel plate (MCP) detectors have been an integral part of the Space Research Centre's X-Ray and UV Space Instrumentation programme for a number of years. This led to the development of large area, low noise microchannel plates as part of the detector programme for the Chandra X-Ray observatory Mission. The University of Leicester scientists in the project realised that the MCP technology had important implications for biological research. The same imaging detectors for x-rays could be used to image radioisotopes which are used to label drug molecules in medical biological research.

The Trace 90 Autoradiography System From this early pioneering work the bioimaging unit has developed a fully automated digital autoradiography system - Trace 90. It is a fully automated system using a microchannel plate detector, can image all of the more common radiolabels including the difficult to detect isotope 3H (Tritium). Recent work has extended the capability to image high energy gamma emitters such as 99mTc (140kev).

Autoradiography is a well-established technology that is widely used in biological and biochemical research, both in Industrial and Academic establishments. It may be used to visualise the distribution of a radiolabelled chemical in a tissue slice, or to locate radiolabelled chemicals that have been separated from a mixture, by chromatography or electrophoresis, into a one- or two- dimensional matrix. It plays a crucial role in fields ranging from disease diagnosis to drug discovery and toxicology.

A basic enabling technology for proteomics research is 2-D gel electrophoresis, in which the mixture of proteins expressed by a gene is separated into a 2-dimensional matrix of individual “spots” within a gel. Because the spots are invisible to the eye they must be visualised e.g. by autoradiography or one of its variants; each spot is then harvested and analysed, usually by mass spectrometry, to determine the “sequence” of amino acids that make up the primary structure of the protein.

Trace 90 is unique in being able to image problematic radiolabels such as 3H (Tritium) in real time on standard mini 2-D electrophoresis gels (see below). Additionally, the microchannel plate technology from Trace 90 lowers the limits of detection of radiolabelled protein within a gel by as much as an order of magnitude compared with the best current commercial methods and enables the detection of previously non-visualisable proteins. This has the potential to lead to new and safer products for drug development companies.

Comparison of 3H labelled 2-D electrophoresis gels. Left - Control, Right - organophosphate pesticide. Sensitivity much superior to staining

Comparison of 3H labelled 2-D electrophoresis gels

 

2-D electrophoresis is likely to remain the separation technology of choice for the foreseeable future, but it has a major drawback in that the quantities of low-abundance proteins in the gel are beyond the detection limits of currently available visualisation methods, e.g. Silver staining and Coomassie blue. Frequently these low-abundance proteins are slight variants of more common ones and are the agents responsible for, or diagnosis of, disease.

Trace 90 can be used for investigation in a variety of formats including microarrays, microplates and thin tissue slices in addition to the imaging of all common radiolabels. This allows the instrument to be used by different groups of researchers within the same organisation, which can result in a significant cost saving for a laboratory.

 

Bioimaging Unit, 
Space Research Centre, 
Department of Physics,
University of Leicester, University Road, Leicester, LE1 7RH, UK.
Contact: Dr John Lees, +44 (0)116 252 5519, lee@le.ac.uk

Share this page:

Announcements

No current announcements.

Mars Science Laboratory Blog

Find out the latest news about Mars Science Laboratory in Professor John Bridges' Mars Science Laboratory Blog.