[Xenopus] J strain update

National Xenopus Resource xenopus at mbl.edu
Tue Jan 3 16:54:38 EST 2017

Dear Xenopus community 
I am writing to follow up on the discussion we had in Crete regarding the NXR and EXRC J strain animals. During the Xenopus conference there was a brief discussion that the J strain animals being sold are not true homozygous J strain animals. We have now sequenced NXR J strain animals and confirmed that they are not homozygous at every chromosome. This was not something we expected when we began breeding these J strain animals and this was beyond our control. 
These J strain frogs have been used successfully for genome editing and RNA-Seq experiments. We have now bred the J strain at the NXR for 5 generations and the animals grow faster now than they did in the past. As many of you are aware they are somewhat smaller than wild type Xenopus laevis but with our successive generations the animals have been growing to larger sizes. So there should not be any fear that these animals cannot be used for such experiments. 
We were recently sent a homozygous J strain mating pair from Japan and obtained our first clutch of embryos 2 weeks ago. These new J strain frogs will be available for purchase in a year. We do not know how well these homozygous J strain will grow, but I will continue to keep you updated. 
However, we still have many of the other J strain available for sale. As mentioned above we have been using these for making mutants and have had little difficulty with CRISPR-Cas or genotyping. So although there are some SNPs we have found them extremely useful for genome editing. 

Should you have any questions do not hesitate to contact me. 


Marko Horb 

If the NXR contributed to your work please cite us in your papers. 

Cite us in the acknowledgements: National Xenopus Resource RRID:SCR_013731 

Cite us in your references: Pearl, E. et al "Development of Xenopus resource centers: the National Xenopus Resource and the European Xenopus Resource Center" Genesis 50, 155-163 

Marko Horb, Ph.D. 
Director, National Xenopus Resource (NXR) 
Marine Biological Laboratory 
7 MBL Street 
Woods Hole, MA 02543 

Email: xenopus at mbl.edu 
Office: 508-289-7627 
Cell: 508-564-3764 


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