Hi,

Scientists use cre-lox to do a conditional (sometimes inducible by applying Tamoxifen) change in the genome. Usually it is either knock-out or an overexpression of a certain gene. You can simply do genotyping with specific primers to altered/non altered sequence. To test if it worked on expression level, you can simply do RT-qPCR to evaluate the abundance of transcripts of interest. So to say, if it is a KO, you should not have the mRNA from the altered gene, if it is OE - you should have much more mRNA.

You can use practical cre-inducible fluorescent tags, introduced into Rosa26 locus, for example. Then all the cells, where Cre was expressed, would be fluorescent. People use that to pinpoint cells, where the recombination was successful. Keep in mind that there are various different Cre's available for different cell types, where Cre is expressed constantly or it is inducible by Tamoxifen. Cre-lox system is a perfect tool for genetic discovery.

You can also have a look at tetO-(r)tTA system, which is also widely used.

Good luck,

Michail

https://www.jax.org/news-and-insights/jax-blog/2011/september/cre-lox-breeding-for-dummies

https://www.jax.org/news-and-insights/2015/april/introduction-to-tet-expression-systems

https://en.wikipedia.org/wiki/Tetracycline-controlled_transcriptional_activation

https://en.wikipedia.org/wiki/Cre-Lox_recombination

Thank you very much Michail Yekelchyk