Ames test
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This document discusses the Ames test, which is used to determine if chemicals are mutagenic and potentially carcinogenic. It describes how the Ames test works using a histidine-requiring strain of salmonella bacteria that is exposed to test chemicals - if mutations occur that allow bacterial growth, the chemical is considered mutagenic. The document provides background on Bruce Ames who developed the test, and explains the process and applications of the Ames test in determining cancer risk from chemicals, and its use in biotechnology and industry.
Ames test
- 1. Made by: Manoah Prakash Ram SoS In Biotechnology Pt.Ravishankar Shukla University Raipur(C.G)
- 2. CONTENTS Introduction. About Mutation. Chemicals Mutagens. Some products with chemical mutagens. About Ames test History and Basic Idea Process of Ames test Importance and Application of Ames test in Biotechnology. References
- 3. Introduction • Bacteria are often known as harmful organism. •But originally they are research guinea pigs. •This is due to their availability, fast reproduction and metabolic activity.
- 4. Bacteria can prevent cancer Bacteria have many application in the field of science. One of them is they can prevent cancer from happening. this is possible by Ames test. But first we should know how cancer are caused. Any mutation that alters the normal functioning and division of cell is termed as cancer. And these mutation may be caused internally or by Carcinogens. This must be kept in mind that all the cancers are made by mutations but all the mutations are not cancers. Before moving further we should know what is mutation.
- 5. 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 cells
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- 7. Causes of mutation By radiation The source can be of Many types: By sun By Uranium By Microwaves X-rays Etc.
- 8. Chemicals Mutagens Some mutation can also be caused by the components they are called as mutagens. These mutagens can be chemical or biological. But in these topic we are going to discuss about the chemical mutagens. These chemical mutagens migrate inside the cell and mutate the host DNA.
- 9. Some Products with possible mutagens •Air fresheners •Air freshener contains many chemicals like: •Acetaldehyde •1-4,dichlorobenzene •Methylpyrrolidone •1-3 dichloro-2 propanol •These chemicals can cause mutation in bronchiolar cells of lungs
- 10. Some Products with possible mutagens •Birth control pills •Many components in birth control pills are carcinogenic. •It can cause breast cancer, cervix and ovary cancer.
- 11. Some Products with possible mutagens •Nail polish •Nail polish contain many products one of them is Dibutyl phthalate •When they are used in access they can cause basal cell carcinoma, malignant carcinoma and dermal cancers
- 12. Some Products with possible mutagens •Lead •Recent ban on maggie is due to the amount of lead found in it. •Lead damages almost everything inside out body. •The most bizarre consequence is adenocarcinoma (stomach cancer)
- 13. Ethylene bromide which is used to set leaded gasoline to vaporize them and send them to engine and exhaust. Ziram used to prevent fungus disease in plant is also carcinogenic. Some medical drugs like isoniazide which show mutagenic properties in biological system. AF-2 once used in Japanese food product is carcinogenic in nature. Saccharine used in sugar-free can be carcinogenic but they do not give positive Ames test. Safrole used as flavoring in beer is also mutagenic in nature. And many more
- 14. How to tell that product is carcinogenic or not? That is why the Ames test came into existence. In Ames test a special strain of salmonella typhimurium is used which is histidine lacking. These histidine lacking bacterial strain cannot grow on its own. The chemical mutagen is then added to the nutrition media. this mutagen revert back the action of histidine producing gene and they start their normal functioning. If the bacterial sample show growth in the media plate having chemical mutagen this show the test is positive ,if growth is not obtained then test is negative.
- 15. History of Ames test •Ames test was brought forward by Bruce Ames in 1970. •He is professor in university of california,berkely. •In department of biochemistry. •He developed this method because previous methods were expensive and time consuming.
- 16. Ames test procedure in this test the salmonella typhimurium strain is used which is mutant. The mutation is the histidine synthesis' gene so the bacteria is called as (his-) histidine minus strain. This strain of bacteria cannot grow without histidine amino acid. When the bacteria is inoculated in the media plate without histidine amino acid in them they are unable to grow even if they are placed in suitable environment for prescribed time.
- 17. But here the case is for chemical mutagens. As we are using his- strain of bacteria. this bacteria cannot grow on normal media plate. But if the chemical is mutagen is added in the media plate this chemical mutagen will turn the his- gene to his+ gene. due to the activity of mutagenic chemical compound. Now due to the mutation this bacterial strain will produce their own histidine and can grow on plate. This type of mutation is called as back mutation.
- 18. Pictogram of Ames test
- 19. But it is not that simple. 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 the bacterial sample is inoculated. But from the idea the negative test will not show any growth, but the growth can occur due to spontaneous mutation. And this is the only limitation of this test.
- 21. Spontaneous mutation can give us false positive result. So to understand the difference between spontaneous mutation and mutagenicity. If the bacterial colony are obtained scattered they show that bacteria is there because of spontaneous mutation. And if the colony are aggregated they show that the mutagenicity is brought forward by the chemical mutagens. But if you get scattered colony you should cross check your experiment. But if the media plate is blank this is the confirmation that the chemical is non mutagenic.
- 22. Negative Ames test Positive Ames test
- 23. 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 organic product which are thought to be safe for the human use are termed carcinogenic in Ames test Many cosmetics are now first tested in Ames test before their commerial production.
- 24. Application in Biotechnology Smoker urine test for mutagenicity is possible by the use of Ames test. Primary DNA damage test can be done through Ames test This test is highly sensible for testing the mutagenicity of water and solid soil sample from the nuclear war zone. by Muta-chromoplate kit. Type analysis of soil and petroleum product for mutagenicity.
- 25. References Prescott’s Microbiology (Textbook by Christopher J. Woolverton, Joanne M. Willey, and Linda Sherwood. Bruce N. Ames; William E. Durston; Edith Yamasaki Frank D. Lee (1973).Review paper. Wikipedia On Ames test. NCBI on applications. Study.com for lectures and pictures Kimbley’s biology paper US