# Phenotype of GCaMP6 (Ai148/Ai162) + Cre mouse lines **URL:** \ **Category:** Science\ **Tags:** experiment-design, celltype\ **Created:** [January 6, 2025, 5:10pm UTC](https://community.brain-map.org/t/phenotype-of-gcamp6-ai148-ai162-cre-mouse-lines/4045 "2025-01-06T17:10:36Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![mthunemann](https://yyz1.discourse-cdn.com/flex027/user_avatar/community.brain-map.org/mthunemann/32/2107_2.png) [@mthunemann](https://community.brain-map.org/u/mthunemann)\ **Post date:** [January 6, 2025, 5:10pm UTC](https://community.brain-map.org/t/phenotype-of-gcamp6-ai148-ai162-cre-mouse-lines/4045/1 "2025-01-06T17:10:37Z")
Dear Community, we want to express GCaMP6s or 6f in Layer 5 pyramidal neurons. We use the Rbp4-Cre\_KL100 line and see delayed growth (postnatally) in Ai148 x Cre mice, but Ai162 x Cre mice seem to be fine. Mice have about 50% size and body weight compared to Bl6 animals at the time of weaning and gain very slowly thereafter. I was wondering if that has been observed in your hands (at the Allen Institute) or somewhere else? Thanks a lot! ---
**Author:** ![ray.sanchez](https://yyz1.discourse-cdn.com/flex027/user_avatar/community.brain-map.org/ray.sanchez/32/679_2.png) [@ray.sanchez](https://community.brain-map.org/u/ray.sanchez)\ **Post date:** [January 10, 2025, 5:48pm UTC](https://community.brain-map.org/t/phenotype-of-gcamp6-ai148-ai162-cre-mouse-lines/4045/2 "2025-01-10T17:48:03Z")
Thank you for your question! I’ve relayed this question to some of our in-house experts on these mouse lines and will follow up soon with more information about expected phenotype. ---
**Author:** ![ray.sanchez](https://yyz1.discourse-cdn.com/flex027/user_avatar/community.brain-map.org/ray.sanchez/32/679_2.png) [@ray.sanchez](https://community.brain-map.org/u/ray.sanchez)\ **Post date:** [January 13, 2025, 10:13pm UTC](https://community.brain-map.org/t/phenotype-of-gcamp6-ai148-ai162-cre-mouse-lines/4045/3 "2025-01-13T22:13:44Z")
Hello, I’ve included some additional info on our experience with these mouse lines from one of our experts on this topic below. If you could provide us with more information on how many crosses you’ve done with these lines, it sounds like that might be useful to know. Thank you! > Ai148 and Ai162 are identical except for the GCaMP (one is GCaMP6f and the other is GCaMP6s) so there really shouldn’t be any difference between the two. That said though, both lines have a tTA-WPRE which we now know (with experience) can be toxic depending on the cell type its being expressed in. This doesnt explain the phenotype being described though. How many crosses have they done? ---
**Author:** ![mthunemann](https://yyz1.discourse-cdn.com/flex027/user_avatar/community.brain-map.org/mthunemann/32/2107_2.png) [@mthunemann](https://community.brain-map.org/u/mthunemann)\ **Post date:** [January 13, 2025, 10:35pm UTC](https://community.brain-map.org/t/phenotype-of-gcamp6-ai148-ai162-cre-mouse-lines/4045/4 "2025-01-13T22:35:49Z")
Hi, thanks for the reply! We have repeatedly (currently 3 breeding) with smaller weanlings of Rbp4-Cre/Ai148 (mother: Rbp4-Cre / father: Ai148). We did Rbp4-Cre / Ai162 (father: Ai162 / mother: Rbp4-Cre) a while ago without any obvious issues. We will try those again and will also check if it matters if the respective transgenes come from mother and father. I will post that here…