Need some worm help

Hi everyone,

I’ve got a couple of quick questions. I am currently in a lab based on C. elegans and we are taking a test tomorrow on RNAi. I’m new to all of this, so please forgive my ignorance. What I would like to know has to do with the RNAi feeding libraries. Specifically, when creating the library, what does the tetracycline select for, and what does ampicillin select for? I’ve looked all over the web, but I’m not finding anything on the why/how, only that they are present, which I already know. Any help is appreciated. Thanks!

timmons and fire 2001