{"id":2958,"date":"2026-08-22T21:01:07","date_gmt":"2026-08-22T20:01:07","guid":{"rendered":"https:\/\/seamlessbio.de\/?page_id=2958"},"modified":"2026-08-23T00:43:30","modified_gmt":"2026-08-22T23:43:30","slug":"what-is-tet-free-fbs","status":"publish","type":"page","link":"https:\/\/seamlessbio.de\/de\/what-is-tet-free-fbs\/","title":{"rendered":"What is Tet-Free FBS?"},"content":{"rendered":"
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Quick Definition<\/p>\n

What is Tet-Free FBS?:<\/strong> Tet-Free FBS (tetracycline-free FBS) is fetal bovine serum confirmed to contain no detectable tetracycline or doxycycline. It is required for inducible gene expression systems (Tet-On, Tet-Off, TRE-based systems) where trace tetracyclines in standard FBS cause constitutive or leaky transgene expression independent of the inducer.<\/p>\n<\/div>\n

Why standard FBS interferes with Tet systems<\/h2>\n

Tetracyclines in standard FBS originate from cattle feed additives and veterinary antibiotics. Trace amounts (1\u2013100 ng\/mL) remain after processing. In a Tet-On system where doxycycline at 10\u20131,000 ng\/mL drives transgene expression, even 10 ng\/mL background from FBS creates partial activation \u2014 making the uninduced control unreliable with high background\/induction ratio.<\/p>\n

Diagnosing Tet system leakiness from FBS<\/h2>\n

If your Tet-On cell line shows expression in the uninduced state, test by replacing your current FBS with Tet-Free FBS. If background expression drops, FBS tetracycline contamination was the cause \u2014 one of the most common findings in inducible expression system troubleshooting.<\/p>\n

Key Facts<\/h2>\n