Dear Jeremy,

Thank you for your advice!

However when I tried this out I got some more questions.

I am dealing with a bacterium which has about 4000 genes. When I tried Cuffmerge to merge everything with reference annotation, I got a merged file of only 50 lines. If I left out the reference annotation file, Cuffmerge returned me a merged file of 4000 lines (which is more reasonable).

However this difference didn't happen if I use Cuffcompare to merge all the files. With or Without reference annotation, the merged file are both of 4000 lines. If I continue to Cuffdiff with this Cuffcompare file, I got over 1000 significantly changed genes.

Could you give me some suggestion on this? Should I just trust the Cuffcompare file?

Is it possible that there might be some problem with my reference annotation file?

Thank you very much,

Qian



On Sun, Mar 3, 2013 at 9:59 AM, Jeremy Goecks <jeremy.goecks@emory.edu> wrote:
> My question is, if I need to compare between 5 time points, should I do comparison pairwise?

No, do them all at once with Cuffdiff:

(a) set 'Perform Replicate Analysis' to 'Yes';
(b) create 5 replicate conditions, one for each time point;
(c) add your replicates for each time point.

There's a Cuffdiff flag to do time series analysis, but it isn't implemented yet in Galaxy, so you'll get pairwise comparisons for all conditions. You can use the filtering tool to reduce Cuffdiff outputs to only the timepoint comparisons.


> I will use cuffmerge to merge 0hour-1, 0hour-2, 0hour-3, 1hour-1,1hour-2.1hour-3 to generate one cuffmerge file.

Correct.

> Then I will run cuffdiff using the merged file, include two groups, group 1 is 0 hour (add 0hour 1-3 in group 1) and group 2 is 1hour (add 1hour1-3 in group 2).

Use the process I described above to do all pairwise comparisons in one run.

Good luck,
J.





--
Qian Dong
Bauer Lab, MCBD
Simon Hall: 313-317
212 S. Hawthorne Dr.
Bloomington, IN 47405
Email:dong3@indiana.edu
Lab Phone:812-855-8443