extrachromosomal arrays in EG6699 for MosSCI

Model Organism: Worms Methods & Reagents
1

Hello,

I am having what appears to be a problem with the EG6699 strain that we obtained from the CGC. This strain was developed by the Jorgensen lab for single-copy insertions via MosSCI.

The strain is: ttTi5605 II; unc-119(ed3) III; oxEx1578. oxEx1578 is: [eft-3p::GFP + Cbr-unc-119]

I understand that they are supposed to lose the extrachromosomal array at certain frequency, producing uncoordinated animals that do not fluoresce, and that these are what you inject. Rescue of the unc phenotype in progeny indicates successful injection.

The problem we are having is that ALL of our animals have Wild-type movement, and all are fluorescent. This appears to be the case at 20C and at 25C. Is it possible that some integration event has occured? Or, is the heritability of the array very high?

If anyone has experience with this strain, or with similar phenomenon, I would like to hear your input.

2

Hi Tangentia,

Our apologies - you are not the only one having the problem. We were made aware that there is a problem with the EG6699 strain by several labs in the last couple of weeks describing the same problem that you have. It is unclear what happened. Either there was a spontaneous integration event of the extra-chromosomal array. Or we submitted the wrong strain.

In any case, I have thawed our frozen stock of EG6699 and that strain segregates Unc-119 animals at a pretty decent frequency. We use a derivative of that strain in the lab frequently and have no trouble with insertions. We’ve sent the strain to the CGC today so it should soon be ready for distribution.

Best
Christian

–
Christian Frøkjær-Jensen
Postdoc Jorgensen lab