Talk:Auxotrophy

Wiki Education Foundation-supported course assignment
This article is or was the subject of a Wiki Education Foundation-supported course assignment. Further details are available on the course page. Student editor(s): Akardoust.

Above undated message substituted from Template:Dashboard.wikiedu.org assignment by PrimeBOT (talk) 15:05, 16 January 2022 (UTC)

Ames Test Section
There should be a section added explaining the importance of auxotrophy in the Ames Test. Since the Salmonella are unable to produce their on histidine, i.e. they have an auxotrophic mutation his-, they cannot grow unless they are grown on a medium containing histidine. Chemical compounds, such as cosmetics, preservatives and medications are added to the Salmonella, and they are then attempted to be grown on a medium defficient in his. The amount of colonies that grow are indicative of the mutations that allow them to once again produce histidine. Some colonies will spontaneously mutate due to errors in replication, but the ratio of Salmonella colonies grown on histidine lacking medium that have not been mixed with the compound to those that have been mixed provides a reliable way to measure the mutagenicity of a substance. The auxotrophic mutatants, have transitions, transversion and frameshift mutations that are easly correctable with a simple point mutation to allow for the production of histidine once again. Silver 19:00, 14 February 2007 (UTC)


 * I agree... here is a summary of what I would like to add.


 * AMES TEST (ADD SECTION to page)


 * Ames test is used to determine if a substance caused mutations in DNA.
 * (INSERTING A FIGURE OF HOW IT WORKS (diagram of reversion of control vs mutagen))
 * The Salmonella Mutagenisis test (Ames Test) uses a strain of salmonella that is auxotrophic to histidine to observe how much mutation a substance causes by applying it to the bacteria as it grows on a plate containing histidine then moving the bacteria to a plate without histidine. If the substance does not mutate the genome of the bacteria from auxotrophic to histidine back to phototrophy then the bacteria would not grow on the new plate. So by comparing the ratio of the bacteria on the new plate to the old plate and the same ratio for the control group, it is possible to quantify how mutagenic a substance is, or rather, how much mutation it causes to the DNA.


 * Effect of mutagens on bacteria vs larger organisms
 * It is suggested that if a mutation can arise in bacterial DNA under presence of a mutagen then the same effect would occur for larger organisms causing cancer.
 * Negative Ames Test result suggest that the substance is not a mutagen and would not cause tumor formation in living organisms, however only few of the positive Ames Test resulting chemicals were considered insignificant when tested in larger organisms but the positive Ames Test for bacteria still could not be conclusively linked to expression of cancer in larger organisms. While it can be a possible determinant of tumors for living organisms, humans, animals, and so on, more studies must be completed to come to a the conclusion.

Akardoust (talk) 01:09, 7 November 2017 (UTC)


 * I am thinking of adding some of the above information to the AMES TEST page since it might be excessive for this page. However the AMES TEST sections should be an application section for auxotrophy? I think that would be a good way to present it here. like so ....

The Mutagenicity Test (or Ames Test)
The Salmonella Mutagenisis test (Ames test) uses multiple strains of Salmonella typhimurium that are auxotrophic to histidine to test whether a given chemical can cause mutations by observing its auxotrophy in response to an added chemical compound. The mutation a chemical substance or compound causes is measured by applying it to the bacteria on a plate containing histidine then moving the bacteria to a new plate without sufficient histidine for continual growth. If the substance does not mutate the genome of the bacteria from auxotrophic to histidine back to prototrophic to histidine, then the bacteria would not show growth on the new plate. So by comparing the ratio of the bacteria on the new plate to the old plate and the same ratio for the control group, it is possible to quantify how mutagenic a substance is, or rather, how likely it is to cause mutations in DNA. A chemical is considered positive for Ames test if it causes mutations increasing the observed reversion rate and negative if presents similar to the control group.

I believe if presented well this could be much more useful than just having a smaller AMES TEST page on this page. The two go hand in hand so having easier to understand and summarized explanations of the AMES test here would be a good way to redirect to the more detailed (as it should be) Ames test page.

Akardoust (talk) 23:19, 8 November 2017 (UTC)

Phototrophy
This article contains a circular link to Prototrophy which redirects to auxotroph. This article contains no information on prototrophs other than that they are the opposite of auxotrophs. Recommend Prototrophy added to AFC, link removed, or link changed to red link. Jebus989 (talk) 13:01, 9 January 2009 (UTC)