Molecular biology question

[Mo-tongji]

A farming couple in Nothern Michigan consult their physician about severe skin rashes and ulcers noted over the past year. They also have lost many cattle over the past year, and claim that their cattle feed changed in consistency and smell about 1 year ago. Chemical analysis of the feed shows high concentrations of Polychlorinated Biphenyls, a fertilizer related to known carcinogens. The physician sends the chemical to a laboratory for carcinogen testing, which is performed initially and rapidly by

A. Inoculation of the chemical into nude mice
B. Incubation of mutant bacteria with the chemical to measure the rate of reverse mutations
C. Incubation with stimulated white blood cells to measure the impact on DNA replication
D. Computer modeling based on the structures of related carcinogens
E. Incubation with Mammilian cell structures to measure the rates of malignant transformation.

[Mo-tongji]

The answer is B. Ames Test, a test for identifying potential carcinogens by studying the frequency with which they cause histidine-producing genetic mutants in bacterial colonies of the genus Salmonella (S. typhimurium) initially lacking the ability to synthesize histidine. Toxic chemicals that are carcinogens ( mutagens ) are placed in the of the plate and result in reversing the original mutations, so that histidine is synthesized and the mutated revertants multiply in histidine-free media. Preliminary incubation with liver homogenates may precede the bacterial assay, since many carcinogens are converted to active forms by metabolism in the liver. All carcinogens in humans also cause mutagenesis in the Ames Test.

[DNA 105]

Thanks for the share. I had somewhere read the name of the test but not how exactly it works. Where did you get this if may I know?

[Mo-tongji]

Originally Posted by DNA 105

Thanks for the share. I had somewhere read the name of the test but not how exactly it works. Where did you get this if may I know?

It was from a bunch of printed questions I was using after each chapter. It really fascinated me, that's why I shared it. The questions were given to me by a friend.