Hi Kyle, good to hear from you, We assembled C0080 (araC) with I13504 (RBS . GFP . terminators), with I13504's backbone pSB1A2. The ligated plasmid was transformed into top10 e.coli. We do most of our work in top10 and don't normally see anything like the fluorescence we saw, including in cells with either of C0080 or I13504. The promoter appeared to be strong, in that GFP was visible and bright in cells without needing UV light to visualize it. (Of course, pSB1A2 is a high copy number plasmid and that would magnify the promoter's effect.) Unfortunately, the lab doesn't have the equipment for quantifying fluorescence (yet! it's in next year's budget). I did verify the construct by PCR for length, to make sure we had what we thought we had. The lengths for C0080, I13504 and C0080.I13504 all checked out, so we're pretty sure source parts are ok and the digestion + ligation worked. I can send along the primers we use if you like. As for the presence of araE in our strain, I can't say. Our project originally called for including promoter R0080, which is activated by araC instead of repressed by it as I0500 is. R0080 is also activated by arabinose, but we weren't planning on using that (and never looked up all the details relevant to arabinose). Since then, the plan has changed, and it looks unlikely that we'll be using araC or promoters sensitive to it at all. The plan at the time called for araC and GFP under control of the same promoter, and I came up with an easy fix, switch GFP and araC around in the construct. Even if araC acts as a promoter, it would be directly adjacent to a terminator, and hopefully whatever junk product results from transcription there wouldn't be troublesome. It's not a very nice solution, and not usable in every situation, but anyways. Why might there be a promoter in araC? It might be a mutation, or it might be present in araC naturally and not have been an issue for anyone until now. I'm not completely up on my literature for pBad and araC, so I don't know how likely that scenario is though. I never did contact the person who submitted the part. In retrospect, that's a good idea, I'll see if I can track down an email address. I hope I've been of some help! Patrick On 8/9/07, Schutter, Kyle wrote: Hey Patrick, I am a member of the Brown iGEM team and I noticed that you commented on araC gene with some experience you had.  While I couldnt figure out how you were using araC, it seems that you have already been testing it.  (In the registry you say that you put it in front of RBS>GFP>term.)  We were planning on using araC but as you say, it seems to have a constitutive promoter embedded in the code somewhere.  I was wondering if had talked to whoever added the gene to the library as to why there might be this promoter in the gene, (It should be directly from E coli) or whether the observed flourescence was due to the bacteria strain you are using or some other factor.  If you could send me the info on the construct you used to test this (ie, in plasmid x, in HB101 cells, measured gfp with a flourimeter, etc)  that would be sweet and we could help to figure out what is wrong with this part so that it might be useful in the future.  Also I assume you are using the pBAD/araC BBa_I0500 promoter as well.  What has your experience with that been?  It seems to me that the size of the promoter is due to it also containing an araC gene.  Does this mean that araC is always expressed?  Also, dont you need araE inorder to transport arabinose into the cell?  if so where is the araE gene? I hope your summer has been going well for you and I wish you the best of luck.  Hopefully we can help you figure out what is up with the mystifying araC. peaceout, kyleschutter