Autoradiography

Technique in Biology

1. AUTORADIOGRAPHY
•SYED SHOAIB QASIM
•M.sc,B.Ed,KSET
•Guest Faculty Govt Science College
Bangalore(Dept of Zoology)

2. WHAT WE WILL STUDY ?
Definition
Principle
Methodology
Types
Factors affecting autoradiography

3. Definition:
It is a bioanalytical technique used to visualize the distribution of
radioactive labelled substance with radioisotope in a biological sample.
•Ex :If we want to study about DNA or DNA sequencing we will isolated
the DNA and radiolabel that DNA by using suitable radioactive
isotopes.(
35
S,
3
H,
14
C,
32
P )
•By using this we can understand the localization of cell, tissue's
biomolecule’s in the body of an organisms.
•It is a very sensitive method and widely used in biological experiments
•It is also used for quantitative analysis and carried out by densitometric
analysis.

4. Note: (What is densitometer?)
Adensitometeris a device that measures the degree of darkness (the optical density)
of a photographic or semitransparent material or of a reflecting surface.
Thedensitometeris basically a light source aimed at a photoelectric cell.

5. PRINCIPEL
oRadioisotope will emit the radiation and emitted radiation will ionize the photographic emulsion or film
and ultimately
dark spots will occur.
oPhotographic emulsion or film is combination of AgX(silver halid) with gelatine.
oAgX Ag X Ag(atom)
radiation
oThe radiation emitted are ß-radiations sometimes even γ-radiations are also used so these radiations will
ionize the
ophotographic emulsion. (AgXGelatine)
oThe dark black spot which is observed is because of reduction of AgXinto Ag(atom) and the thickness of
this emulsion
is 5-50 μm.

6. DIFFERENCE BETWEEN AUTORADIOGRAPHY &
NORMAL PHOTOGRAPHIC PLATE
•Autoradiography
Quantity of AgXis higher than
that of gelatine.
•Photographic plate
Quantity of AgXis lower and that
of gelatine will be higher.

7. METHODOLOGY OF AUTORADIOGRAPHY
I.Take tissue or cell of living entity in a slide (sample) (fig I)
II.Put the slide into the emulsion containing alkyl halidand gelatine
(fig II)
III.Put the sample in dark room and keep it for a specified time ,
Then the radioisotope will
emit the radiation and Ag will show dark spots. (fig III & IV)
IV. Wash the emulsion and observe under electron microscope or
densitometer. (fig V)

8. TYPES

9. FACTORSAFFECTINGAUTORADIOGRAPHY
I.Energy of radiation : ß-radiations(
35
S,
3
H,
14
C,
32
P )
commonly used.
II.Distance and thickness of sample :-should be less
III.Grain size and amount of AgX:-smaller grain size
IV.Thickness of emulsion :-should be less.
V.Exposure time :-should be optimum.

10. For queries
Contact :953545810
Email: [email protected]
https://www.linkedin.com/in
/syed-shoaib-qasim-
524b5b64/
Stay Home Stay Safe
Prepared during Covid19