I never injected in a Xenopus embryo, but regarding DNA micro-injection I was able to inject inside the nucleus of a somatic cell. It then takes few hours to get transcribed, spliced and exported into the nucleus to get translated. Having introns on your mRNA will have a faster processing speed. Also it will be more stable.

I injected mostly DNA but the cinetic for mRNA injection should about the same.

I'm attaching some links to paper you might want to read to get a better understanding of the process. I could also point you to people better than me on these techniques.

Good luck,

Eric

http://www.pnas.org/content/105/9/3386.abstract?sid=a973c19b-78b3-4519-928d-3c6e37b9b8d7

http://www.jove.com/video/2387/analysis-mrna-nuclear-export-kinetics-mammalian-cells

hi Gary-

There are a few things to consider.  First, diffusion is pretty rapid, but "uniform translation" is only going to be relative, and would be problematic within the first cell cycle.   Typically, if you inject toward the upper (animal hemisphere) side of the fertilized egg you'll do pretty well.  ( If "uniform translation" is critical you may want to consider stratagies that inject oocytes and mature them- Doug Houston has several methods articles that describes that technique.)  You can track the distribution of your message of interest by co-injecting mRNA that makes a reporter like GFP.  Second, you may wish to consider adding 3' and 5' UTR sequences that enhance translation and stability of the coding region you wish to express.  Commonly added UTRs are from beta-globin.  Finally, you should make sure that your message is capped at the 5'end  and poly-adenylated. These modifications will enhance the translation and stability of the message.  As you probably know, unlike typical somatic cells, the early embryonic cells won't be able to transcribe plasmid until about the 4000 cell stage- so if early translation is what you want- stick to mRNA injection.

Good luck

Dan

hi Gary,

 I injected mRNA at two cell stage several times and often co-injected with GFP RNA, and I must say that according with Eric Folco within few hours it was possible detect GFP in the cell progeny. I normally use just cap and polyA signal in order to guarantee traduction and mRNA stabilization, in this manner I follow GFP positive cells till stage 48-50. I use to inject around 0,5-1ng of RNA into 4-10nl. I hope this will help you.

Thanks all, this is very useful.  I've been thinking about host-oocyte transfer as I'm looking at pretty early targets.  I didn't know about the mRNA UTRs - thanks for that, I'll look into that further.