Presenter: Miranda Grounds
References: Alberts, p174-176, 730.
Rogers A (1979) Techniques of autoradiography. 3rd Edition. Elsevier, North Holland pp429.
Radiography is the visualisation of the pattern of distribution of radiation. In general, the radiation consists of X-rays, gamma (g ) or beta (b ) rays, and the recording medium is a photographic film. For classical X-rays, the specimen to be examined is placed between the source of radiation and the film, and the absorption and scattering of radiation by the specimen produces its image on the film. In contrast, in autoradiography the specimen itself is the source of the radiation, which originates from radioactive material incorporated into it. The recording medium which makes visible the resultant image is usually, though not always, photographic emulsion.
History
The first autoradiography was obtained accidently around 1867 when a blackening was produced on emulsions of silver chloride and iodide by uranium salts. Such studies and the work of the Curies in 1898 demonstrated autoradiography before, and contributed directly to, the discovery of radioactivity. The development of autoradiography as a biological technique really started to happen after World war II with the development of photographic emulsions and then stripping film (see Rogers, 1979) made of silver halide. Radioactivity is now no longer the property of a few rare elements of minor biological interest (such as radium, thorium or uranium) as now any biological compound can be labelled with radioactive isotopes opening up many possibilities in the study of living systems.
Radioisotopes,
The mass of the atomic nuclei can vary slightly (=isotopes) for a particular element although the number of electrons remains constant and all the isotopes have the same chemical properties. The nuclei of radioactive isotopes are unstable and they disintegrate to produce new atoms and, at the same time, give off radiations such as
References: Rogers A (1979) Techniques of autoradiography. 3rd Edition. Elsevier, North Holland pp429. Wash in double distilled water Use Ilford Hypan Rapid Fixer (leaflet T1812)