r/labrats • u/AutoModerator • 27d ago

open discussion Monthly Rant Thread: December, 2024 edition

Welcome to our revamped month long vent thread! Feel free to post your fails or other quirks related to lab work here!

Vent and troubleshoot on our discord! https://discord.gg/385mCqr

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u/CDK5 Lab Manager - Brown 2d ago

Recently purchased this Cre mouse from Jax.

Jackson states the strain is hemizygous for the transgene on the X-chromosome.

I bred three litters with the Cre mouse, and PCR genotyping shows all twenty-one pups express Cre.

Am I missing something? If it's hemizygous shouldn't only 50% of pups express Cre?

Or did we hit the lottery?: The odds of all pups getting the transgene is 1 in 2,097,152.

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u/OrganizationActive63 1d ago

Assuming you have CMV Cre. If so, your males are hemizygous but their females are homozygous. So if you got females, 100% of offspring will be positive

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u/CDK5 Lab Manager - Brown 1d ago

Assuming you have CMV Cre

That is what be bought: three females with CMW Cre on one of the X chromosomes.

If so, your males are hemizygous but their females are homozygous

We are still talking about the F0's right?

If so: Jax claims the females are hemi.

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u/OrganizationActive63 1d ago

Females can't be hemi - hemi means X/0. Females are homozygous or heterozygous. When I bought them, they maintained a homozygous colony with homozygous females and hemizygous males. Otherwise, 1/2 the males produced would be WT and not worth their time.

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u/OrganizationActive63 1d ago

From the JAX website - "When maintaining a live colony, these mice are bred as homozygotes. "