Hi Julie, Its a tricky one. Keeping the G1 peak in the same place makes sense if you are either overlaying or using consistent markers (although the latter would be obviated by using an 'automated' program). But the purist would argue that you should keep the machine voltage the same for all samples. One thing to bear in mind is the experiment itself. Which type of cells the researcher is using, what they have done to them etc. I often see the peak shift a little after treatment which can be due to the treatment itself. If there is a clear single G1 peak and not a biphasic one then its unlikely that the entire population has suddenly become aneuploid. There will be differences that may be observed due to wildly differing cell concentrations and cycling state. Its always best to keep cell and dye concentration the same in all tubes if you can and allow sufficient time for the staining to equilibrate before running them. As Yoav said in his response there are some things you can do to convince the users that its legit to move the peak slightly. Mixing a small aliquot of the samples is probably the most convincing. Spiking the sample is another way but I would do this as early in the processing as possible. Derek On 12/12/06 3:38 pm, "Julie Bertout" <julie.bertout@ibl.fr> wrote: > Hello, > I have a question about cell cycle analysis using IP : > a researcher is interested in studying the effect of drugs on cell cycle. > He is doing IP staining on cells after different treatments. > I adjusted the peak 2n at 200 with the control cells but with some > conditions the peak 2n shifts a little bit (higher or lower depending on > the condition) so my question is : > do I have to adjust the peak at 200 for each conditions (so we can do an > overlay after) or keep the same cyto settings and adjust the marker? > > Thank you for your answers > > Julie Bertout > cytometry lab > Institut Pasteur de Lille > 1 rue du professeur Calmette > 59800 Lille > France -- *************************************************************** Derek Davies Voice: (44) 020 7269 3394 FACS Laboratory, FAX: (44) 020 7269 3479 London Research Institute, e_mail: derek.davies@cancer.org.uk Cancer Research UK mobile: 07790 604112 44 Lincolns Inn Fields, London, UK. Web Page: http://science.cancerresearchuk.org/sci/facs/ In tenebris lux ***************************************************************Received on Thu Dec 14 13:18:00 2006
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