Black dots contaminant in stable cell lines - antibiotics - (Jun/28/2016 )

Hello!

I'm facing the "black dot contamination" problem in my stable cell line. The problem is that I cannot throw this culture away so I started to use the antibiotics (Cipro/Piper/Tazo, 10 ug/ml each + Pen/Strep) described in this paper http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2849847/.

(*stable cell lines were made by transfection of a sleeping beauty transposon vector (pSBTet-BP) inducible by doxycycline with a Blue Protein for visualizing Puromycin positive clones).

Strangely, after 1-3 days of treatment, most of the blue fluorescence of my positive stable cell line pool started to disappear!

Do guys know if Ciprofloxacin and/Piperacillinlin and/or Tazobactam can interfere in gene expression or it just decreasing cell fluorescence for no reason?

Thank you in advance!

Have you been culturing the cells with dox while doing the other treatments? If not, you might be losing the signal by methylation of the inserted gene.