Triple transgenic mice generation from different background singles

3 posts / 0 new
Last post
CATFARTS's picture
Triple transgenic mice generation from different background singles

I am wanting to make a triple transgenic animal model where two of the transgenes (tetO-Cre and tissue specific rtTA)  are in FVB/n background and a flox/flox alele is in C57Bl/6.

my initial strategy would be to create Cre/-  flox/flox mice and rtTA/- flox/flox mice and cross those to get Cre/- rtTA/- flox/flox mice for experiments. My concern is that the heterogeneity of background in the triple transgenic mice may scatter the data, requiring very high n for significance, and also that I would have to maintain the single transgenics in their original backgrounds to set up equivalent crosses in future experiments.

We have the FVB/n mice currently and are waiting on transfer of the C57 floxed mouse which will have to be re-derived due to a viral infection. Would it be better for me to start outcrossing the Cre and rtTA lines into C57 background for a few generations to eliminate heterogeneity later? Any suggestions are appreciated.

Evilyn's picture
Catfarts--I just laughed

Catfarts--I just laughed aloud in my quiet office upon reading your username! i<3 it!

Since you are dealing with mice, would you be interested in a new animal colony management software system?  Our mLIMS system is web-based and easy to use:

- Get Started in Just 60 Seconds: No training or manual needed!
- Extensive Data Tracking: Colony information, bar coded cage cards, experiments, measurement data
- Real-Time Information: Instant summaries and reminders
- Teamwork: Collaboration and group-based sharing
- Web-based: No installation and accessible anywhere (cross platform, functional with any browser)
- Maintenance Free: Automatic data backup, data recovery, and continuous improvement
- Cost Effective:  Accounts starting at just $9/mo.

Register for a FREE 30 day trial at

Omai's picture
Hey Catfarts,

Hey Catfarts,

Here is a conversation from an older post on triple knockouts that is fairly detailed.

Background heterogeneity is always a problem in multiple knockout animals. As long as you compare littermate controls, you can usually rule out background genetic noise. Because you will have cre+ and cre-, this comparison is possible. The alternative is 10 generations of backcross to stabilize the line genetically. This is expensive and very time consuming.

Let me know if you need more specific help.