The document discusses the application of radioactive tracers in biology. It provides details on how radioactive tracers work by giving off detectable particles that can be used to create images of organs and structures in the body. The document then discusses specific applications of radioactive tracers in metabolism research, medicine, hydraulic fracturing, and imaging techniques like PET scans. It also discusses how tracers can be used to study isolated organs/tissues, mutant strains of microorganisms, and track biochemical pathways.

1. APPLICATION OF RADIOACTIVE TRACERS TECHNIQUE IN BIOLOGY
SUBMITTED TO:
Dr N. J patel
Associate Professor
Dept. of Biochemistry
B. A. college of Agriculture,
Anand
SUBMITTED BY:
Ganvit Urvashi M.
M sc 1st sem
Genetics and plant breeding
course title: techniques in biochemistry
B. A. college of Agriculture
Anand.

2. RADIOACTIVE TRACERS
• A radioactive tracer, radiotracer, or radioactive label is a chemical compound in
which one or more atoms have been replaced by a radionuclide so by virtue of
its radioactive decay it can be used to explore the mechanism of chemical
reactions by tracing the path that the radioisotope follows from reactants to
products. Radiolabeling or radiotracing is thus the radioactive form of isotopic
labeling. In biological contexts, use of radioisotope tracers are sometimes
called radioisotope feeding experiments.
• Radioisotopes of hydrogen, carbon, phosphorus, sulfur, and iodine have been used
extensively to trace the path of biochemical reactions. A radioactive tracer can also
be used to track the distribution of a substance within a natural system such as
a cell or tissue, or as a flow tracer to track fluid flow. Radioactive tracers are also
used to determine the location of fractures created by hydraulic fracturing in
natural gas production. Radioactive tracers form the basis of a variety of imaging
systems, such as, PET scans, SPECT scans,and technetium scans. Radiocarbon
dating uses the naturally occurring carbon-14 isotope as an isotopic label.

3. HOW DO RADIOACTIVE TRACERS
WORK ?
• Radioactive tracers are used in imaging tests that help find
problems inside the body. These tracers give off particles that can be
detected and turned into a picture to help find problems in organs or
other structures. The tracer is usually given through an intravenous
line placed in a vein.
• But the tracer also may be given by mouth or by inhaling it into the
lungs. The tracer then travels through the body and may collect in a
certain organ or area.
• The types of tests that use radioactive tracers include positron
emission tomography (PET) and nuclear medicine scans to look at
specific organs such as the liver, lungs, kidneys, and gallbladder.

4. WHAT IS THE PRINCIPLE AND
APPLICATION OF TRACERS TECHNIQUE IN
BIOLOGY
• The principle of a tracer study is that it allows the analysis of a
substance and its interactions in the body through the labeling of the
substance with a radionuclide in a manner that does not alter the
substances original properties.

5. APPLICATION
• In metabolism research, tritium and 14C-labeled glucose are commonly used in glucose clamps to
measure rates of glucose uptake, fatty acid synthesis, and other metabolic processes. While
radioactive tracers are sometimes still used in human studies, stable isotope tracers such as 13C are
more commonly used in current human clamp studies. Radioactive tracers are also used to
study lipoprotein metabolism in humans and experimental animals.
• In medicine, tracers are applied in a number of tests, such as 99mTc in autoradiography and nuclear
medicine, including single-photon emission computed tomography (SPECT), positron emission
tomography (PET) and scintigraphy. The urea breath test for helicobacter pylori commonly used a
dose of 14C labeled urea to detect h. pylori infection. If the labeled urea was metabolized by h. pylori
in the stomach, the patient's breath would contain labeled carbon dioxide. In recent years, the use of
substances enriched in the non-radioactive isotope 13C has become the preferred method, avoiding
patient exposure to radioactivity.
• In hydraulic fracturing, radioactive tracer isotopes are injected with hydraulic fracturing fluid to
determine the injection profile and location of created fractures. Tracers with different half-lives are
used for each stage of hydraulic fracturing. In the United States amounts per injection of radionuclide
are listed in the US Nuclear Regulatory Commission (NRC) guidelines. According to the NRC, some
of the most commonly used tracers include antimony-124, bromine-82, iodine-125, iodine-
131, iridium-192, and scandium-46. A 2003 publication by the International Atomic Energy
Agency confirms the frequent use of most of the tracers above, and says that manganese-56, sodium-
24, technetium-99m, silver-110m, argon-41, and xenon-133 are also used extensively because they
are easily identified and measured.

7. • Radiopharmaceuticals
• J.K. Aronson MA, DPhil, MBChB, FRCP, HonFBPhS , HonFFPM ,
in Meyler's Side Effects of Drugs, 2016
• Drugs that interfere with the radiolabeling of blood cells
• There is evidence that some drugs can adversely affect the radiolabeling of
leukocytes. In a survey for the years 1981–97 of instances of unusually low
labeling efficiencies of leukocytes labeled with111In-tropolone and99mTc-
HMPAO, respondents were asked to ascertain which drugs were being taken
on the day of the test. Fifty adverse reports were received during that period.
Many patients were taking drugs that are known to affect leukocyte function,
including azathioprine, cephalosporins, cyclophosphamide, heparin, iron
salts, nifedipine, prednisolone, and sulfasalazine. The author used Bradford–
Hill’s criteria to assess whether the association between two variables was
also one of causation, and thought that there was a high probability that these
drugs had caused the low labeling efficiency.

8. MEDICINE TRACERS
•
Radioactive isotopes and radioactively labelled molecules are used as tracers to
identify abnormal bodily processes. This is possible because some elements tend
to concentrate (in compound form) in certain parts of the body – iodine in the
thyroid, phosphorus in the bones and potassium in the muscles. When a patient is
injected with a compound doped with a radioactive element, a special camera can
take pictures of the internal workings of the organ. Analysis of these pictures by a
specialist doctor allows a diagnosis to be made.
• The thyroid gland, situated in the neck, produces a hormone called thyroxine,
which regulates the rate of oxygen use by cells and the generation of body heat.
Within each molecule of thyroxine, there are 4 iodine atoms. If a patient is made
to drink a solution of sodium iodide that has been doped with radioactive iodine-
131, most of it will end up in the thyroid gland. A special camera can capture
the radiation emitted by the iodine-131, and an image of the gland can be
constructed. An assessment can then be made about the shape, size and
functioning of the gland

9. POSITRON EMISSION TOMOGRAPHY
(PET)
• Positron emission tomography (PET)
• A positron emission tomography (PET) scan measures important body
functions, such as blood flow, oxygen use and glucose use. The information
gathered helps doctors find out how well organs and tissues are functioning.
• Radionuclides used in PET scanning are isotopes with short half–lives, such
as carbon-11 (~20 min), nitrogen-13 (~10 min), oxygen-15 (~2 min) and
fluorine-18 (~110 min). These radionuclides are added into compounds
normally used by the body such as glucose (or variations of glucose), water
or ammonia. Such labelled compounds are known as radiotracers. In some
situations, the patient is required to breath oxygen gas labelled with oxygen-
15.

10. • The radionuclides used in PET decay by a process called positron
emission. A positron is the antimatter version of the electron. When a
positron meets an electron, an annihilation event occurs, resulting in the
production of two gamma rays. The two emitted gamma rays travel in
opposite directions.
• The scanning instrument picks up the location of these gamma rays and,
with the aid of a powerful computer, generates a map of where these
events are occurring. By combining the PET scan with a CT scan, a
more complete picture of how well an organ is functioning can be made.
• Due to the short half-lives of most radioisotopes, the radiotracers must
be produced using a cyclotron (a type of particle accelerator) and
radiochemistry laboratory that are close to the PET imaging facility.
The half-life of fluorine-18 is long enough such that fluorine-18 labelled
radiotracers can be manufactured commercially at an off-site location.

12. • Isolated organs, tissues and cells:
• Cultures of the organs, tissues and cells growing under controlled aseptic
conditions can be used for feeding experiments. The radioactive tracers
can be introduced by this process to the parenchymatous tissue of shoots,
leaves, roots or other plant structures and the further analysis of such
plant material can provide important information’s about the
incorporation of the labeled compounds for the determination of the sites
of synthesis of particular compounds. Isolated roots are also extensively
used for the circulation of biogenetic pathways for tropane alkaloids in
the roots of the solanaceous plants. The studies on the petal discs have
been used for the elucidation of pathways for essential oil components
such as rose oil. Isolated shoots, and leaves can be maintained in a
suitable sterile medium for the studies on Nicotiana and Datura spp. In
such types of studies on rooted leaves to get large organization of roots
facilitates the study of the tobacco alkaloid, for their biogenetic sites
which is generally considered to be root

13. • Mutant strains:
• Mutant strains of lower plants like fungi and microorganisms are
produced in nature which lacks one or other enzyme because of which
the normal metabolic pathways are gently affected.
• In such mutant strains metabolites are found at the intermediate stage
and needs artificial supply of another intermediate. Such mutant strains
can be used in the biosynthetic studies of the natural products. The
biogenetic pathways of the gibberellins are mostly similar in both higher
plants and Gibberellafugikuroi.
• The mutant strainsGibberellacan be used to obtain variety of novel
C20isoprenoid compounds which are produced at level of geranyl
pyrophosphate in mevalonic acid pathway. Very interesting results have
been obtained by the studies on the ultraviolet induced strains of
Clavicepspurpures.

14. • These mutant strains can produce amino acids of diverse nature. When
the rye plant is introduced with the spore culture of these mutant
strains.
• The sclerocia produced demonstrate the blockages of biogenetic
pathway of certain intermediates and there by the accumulation of
specific alkaloids (ergot alkaloid) is blocked.
• The blockage occurs after the formation of ChanoclavineI in mutant
strains to such strains if agroclavine and other intermediates had been
supplied artificially it indicated the reinstallation of normal pathway to
produce final or specific alkaloid compounds completely