Ames test excision repair system question

In summary: This assumption is important because it helps to identify potential carcinogens and therefore protect public health.In summary, the Ames test is a fast and convenient way to determine if a chemical is mutagenic. It uses auxotrophic bacteria and the depletion of histidine to identify mutagens. The tester strains in the test are mutated to make the cell wall more permeable and the excision repair system less effective, increasing the chances of detecting mutations. This allows the test to distinguish between different types of mutations, such as base substitutions and frameshifts. Additionally, the assumption that the mutagen also acts as a carcinogen is important for identifying potential carcinogens and protecting public health.
  • #1
TytoAlba95
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Hi there.
I have some questions from the Ames test. I am following Wikipedia and a book to understand this concept.
My understanding :
Ames test is a fast and convenient test that uses auxotrophic bacteria (those that cannot grow in histidine lacking medium) to find out if some chemical is mutagenic.
When the bacteria are plated with the mutagen and some his, with the passage of time as his depletes, only prototrophic bacteria survives (those that have undergone reversal mutation due to the mutagen in his gene). This indicated that the agent is mutagenic.

1. 'Also the tester strains carry mutations in the genes responsible for lipopolysaccharide synthesis, making the cell wall of the bacteria more permeable, and the excision repair system to make the test more sensitive.'(from the book)

I don't get this point, ... the excision repair system to make the test more sensitive, at all.
For the first part, I think the mutation is to make the cell more permeable to the mutagen.

2.'Using appropriate strains, compounds causing base substitutions and frameshift mutations can be distinguished' (book)

How's this made possible? Is it through the reversal mechanism only?

3. Also at the beginning of the article in both my references, it has been mentioned that Ames test assumes, that the mutagen also acts as a carcinogen. I couldn't find any application of this assumption in both my references.
 
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  • #2
1.There are mutations in cell wall synthesis system AND in excision repair system to make test more sensitive (Wikipedia). The point is that mutation occurs on one strand only. For mutation to become heritable DNA must be replicated before the mutation is eliminated by reparation system. To increase chances that mutations become heritable excision repair is reduced in test strains.
2.This is explained in Wikipedia article. Some compounds may preferentailly cause certain type of mutation, frameshifts or base substitutuons. Strains with different mutations exist to increase chances to detect a mutagen.
3.It is written (Wikipedia) 'may act as a carcinogen'.
 
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1. What is the Ames test excision repair system?

The Ames test excision repair system is a scientific method used to determine the mutagenicity of a substance. It involves exposing bacteria to the substance and observing if there are any mutations in the DNA of the bacteria.

2. How does the Ames test excision repair system work?

The Ames test excision repair system works by exposing a strain of bacteria that is deficient in DNA repair to a substance. If the substance is mutagenic, it will cause mutations in the bacteria's DNA. The bacteria are then grown on a medium that selects for the mutated cells, making them visible and allowing for quantification of the mutagenicity of the substance.

3. What is the purpose of the Ames test excision repair system?

The purpose of the Ames test excision repair system is to identify potential mutagens in substances. This is important for determining the safety of chemicals and other substances that may come into contact with humans or the environment.

4. What are the limitations of the Ames test excision repair system?

One limitation of the Ames test excision repair system is that it only detects mutagens that cause point mutations in DNA. It may not detect other types of mutations, such as chromosomal mutations. Additionally, the test only uses one strain of bacteria, which may not accurately represent the response of all organisms to a substance.

5. How is the Ames test excision repair system used in scientific research?

The Ames test excision repair system is commonly used in scientific research to evaluate the mutagenicity of various substances. It is also used in the development and testing of new drugs and chemicals to ensure their safety. Additionally, it has been used to identify potential carcinogens and to study the mechanisms of DNA repair.

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