The document summarizes the Ames test, which is used to determine if a chemical is mutagenic or carcinogenic. It works by mixing bacteria that require histidine to grow with the test chemical and rat liver enzymes. If the chemical causes a reverse mutation allowing bacteria to grow without histidine, it is considered mutagenic. The test is important for screening chemicals, pharmaceuticals, cosmetics and other substances before human use due to its low cost and ability to identify many carcinogens. However, it also has limitations as some carcinogens may not be detected.

1. Prepared By : Lalit G. Borse
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DEPARTMENT OF PHARMACOLOGY
SNJB’s SHRIMAN SURESHDADA JAIN COLLEGE OF PHARMACY,
NEMINAGAR,CHANDWAD.

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CONTENTS
• Introduction
• Mutation
• Principle
• Method
• Limitations
• Importance of test
• Some products with possible mutagens
• References

3. Ames test was brought by Bruce N. Ames in 1970.
Because the assay doesn’t use a live model, it is
inexpensive easy and fast.
Animal test for all compound is inexpensive and
time expensive thus Ames test is used.
The Ames test is a bacterial short-term test to
determine whether a chemical is mutagenic or not.
And one of the most important part about this test
is that involves mixing of the test compound with
rat liver enzyme.
INTRODUCTION
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4. MUTATION
• In most easy language any change in the sequence of DNA is called as Mutation.
• These DNA sequence are like guidelines to cell.
• Any change in the DNA sequence cause messing up of instructions.
• And blocks the normal functioning of the cell.
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Fig 1. Gene mutation

5. This test is based on the principle of reverse mutation or back mutation. so the test
is also known as bacterial reverse mutation assay.
Test organism: Ames test uses several strains of bacteria (salmonella ,E. Coli ) that
carry mutation.
It carries a mutation in a gene that contains histidine. It is an auxotrophic mutant
(nutritional – requirement mutant).
It loses its ability to mix histidine , a particular type of amino acid, by using the
ingredients of the culture media. They are his strain and they need histidine in
growth media.
PRINCIPLE
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Once we put His- salmonella in a medium that has certain chemicals, it will react
with the medium there by causing histidine encoding gene mutation.

6. Hence, it regains the ability to blend histidine causing reverse mutation.
Reverse mutation is made possible because of the chemical mutagen.
Hence, it is safe to say that the Ames test determines the mutagenic property of a
variety of chemicals.
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Fig 2. Salmonella typhimurium

7. METHOD
• Isolate an auxotrophic strain of salmonella Typhimurium for histidine. (i.e.His-
ve)
• Prepare a test suspension of his – ve Salmonella Typhimurium in a plain buffer
with test chemical .
• Also prepare a control suspension of His-ve Salmonella Typhimurium but
without test chemicals.
• Incubate the suspensions at 37°C for 20 minutes.Lalit Borse 7

8. 5. Prepare the two agar plate and spread the suspension on agar plate.
6. Incubate the plates at 37⁰C for 48 hours.
7. After 48 hours count the number of colonies in each plate.
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fig 4. Negative Ames Test Fig 5. Positive Ames Test

10. IMPORTANCE
• Ames test is important nowadays because the amount of chemical product used
today can be carcinogenic.
• Ames test are usually applied in the pharmaceutical industry prior to using them in
animal and human , if the sample fails in Ames test its production is stopped.
• Many cosmetics are now first tested in Ames test before their commercial
production.
• It is test for mutagenicity not carcinogenicity . However , most of the mutagens
(more than 90% ) detected by Ames test are responsible for cancer.
• It is used to detect the defective gene of bacteria can be mutated into functional
gene.
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USES
While Ames test is used to identify the revert mutations which are present in
strains, it can also be used to detect the mutagenicity of environmental samples
such as drugs, dyes, reagents, cosmetics, waste water, pesticides and other
substances which are easily solubilized in a liquid suspension.
MERITS
 Simple, rapid and robust bacterial assay.
 Ease and low cost of the test make it invaluable for screening substances in
our environment for possible carcinogenicity.
 Ames test can detects suitable mutants in large population of bacteria with
high sensitivity.

12. LIMITATIONS
• There are some chemicals that are non mutagenic , but they become mutagenic
when they come in contact in body metabolism.
• So to see that rat liver extract is mixed with the nutrient media.
• And then bacterial sample is inoculated.
• But from the idea negative test will not show any growth, but the growth can
occur due to spontaneous mutation.
• Some substances that cause cancer in laboratory animals ( e.g. Dioxin) do not
give a positive Ames test.
• Ames assay consists of Salmonella typhimurium strains and so it is not a perfect
model for human.
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13. Some products with possible mutagens
1. Birth control pills:
• Many components in birth control pills are carcinogenic.
• It can cause breast cancer, cervix and ovary cancer.
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14. 2. Nail polish:
• Nail polish contain many products one of the is Dibutyl phthalate .
• When they arte used in access they can cause basal cell carcinoma,
malignant carcinoma and dermal cancers .
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15. 3.Lead :
•Recent ban on Maggie is due to the amount of lead found in it .
•Lead damages almost inside out body .
•The most bizarre consequence is adenocarcinoma ( stomach cancer )
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REFERENCES
• Charnley G (2002). “Ames Test”. Encyclopedia of Public Health. eNotes.com.
• Ames BN (May 1979). “Identifying environmental chemicals causing mutations
and cancer”. Science. 204(4393):587-93.
• Hayatsu, Hiroka (1991), Mutagens in Food: Detection and Prevention, CRC
Press,pp. 286 pages.
• Hakura A, Suzuki S, Satoh T (January 1999). “Advantage of the use of human
liver S9 in the Ames test”. Mutation Research. 438(1) : 29-36.
• Mortelmans K, Zeiger E (November 2000). “The Ames Salmonella/microsome
mutagenicity assay”. Mutation Research.455 (1-2) : 29-60.
• https://en.m.Wikipedia.org/wiki/Ames_test

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