MUTATION

To see the mutations, a team of biophysicists built 1000 microscopic channels into a computer like chip and placed a single bacterial cell at the closed end of each the channel, along with plenty of nutrients to survive. The bacteria carried a modified DNA repair protein that caused any mutations to glow yellow. Then, for 8 hours up to 3 days, the researchers took a picture every few minutes as new bacterial cells were formed, pushed down the channel, and then swept away by fluid flowing across the ends of these channels. Automated image processing let them count the number of mutations and assess how well the cells were doing. Dead cells signaled a deadly mutation; slower growing cells signaled a detrimental change.

In a new study, biophysicists have documented individual mutations as they happen in bacterial cells.

According to its developers, the technique can be applied to assess mutation dynamics in other types of cells, even human cancer cells. The researchers eventually hope to be able to monitor mutation rates real time in entire organisms, such as zebra fish, to see whether different tissues have different mutation rates.








Here, a protocol is presented to perform a fluctuation assay and estimate microbial mutation rate using phenotypic markers.

This protocol will enable researchers to assay mutations in diverse microbes and environments, determining how genotype and ecological context affect spontaneous mutation rates.












Mutations are changes in the DNA. A single mutation can have a large effect, but in many cases, evolutionary change is based on the accumulation of many mutations.

Gene flow is any movement of genes from one population to another and is an important source of genetic variation.

1 of 3: individual mutations as they happen in bacteria

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2 of 3: Measuring Microbial Mutation Rates with the Fluctuation Assay

3 of 3: MUTATION AS A SOURCE OF VARIATION

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