Thymidine block and PI staining Frederic.Grosjean at
Wed Jun 30 08:49:13 EST 2004

Dear Flowers,

Someone in our facility is synchronizing cells using double thymidine block (BJAB and
HeLa cells), but while performing cell cycle analysis post synchronization release a
clear shift towards lower PI fluorescence intensity is visible compared to
non-synchronized control. According to that same person, the cells were all stained at
the same time with equivalent cell concentration exposed to similar PI quantity (for 15
minutes at 37C). Cells were fixed with 70% EtOH. Could it be that thymidine treatment
affect stainability ?  Could PI react with thymidine alone and thus lower the amount that
will stain DNA ?

Any help is welcome.

Best regards,


Dr Frederic Grosjean
Ludwig Institute for Cancer Research
Lausanne Branch
Chemin des Boveresses 155
1066 Epalinges
Tel. +41-21-692 58 66
Fax. +41-21-653 44 74

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