I am trying to express my gene of interest using a Tetracycline inducible vector. Although I need my gene of interest of be off and only be turned on for a short period of time when needed, I only have a Tet-off expression vector available to me. So, I need to grow cultures in Tetracycline (or doxycycline)-containing media continously. Now, my questions are: which would you recommend: tetracycline or doxycycline? And how much tetracycline should I use in agar plates or in liquid cultures? What is the half-life of each in the growth media?