Questions about oligos file

Hi,

I´m not sure I quite understand how the oligos file should look like. I searched through the forum, but didn´t find what I was looking for.
So, I have both forward and reverse barcoded primers- cca 90 forward and 4 reverse and 2 linkers.

Do I somehow have to specify the combinations of barcodes and primers, or is it just enough to list them?

Can I trim both primers simultaneously or do I have to do forward first and then reverse?

Does it matter if I don´t know which was the forward sequencing primer, e.g. can I just name “forward” the actual forward primer (27f in this case)?

Is it necessary to specify linker sequences?

Thank you very much in advance for answering my questions.

I’d encourage you to download the Schloss SOP dataset and look at how that oligos file is set up and use it as a model. Then be sure you look at:

http://www.mothur.org/wiki/Trim.flows
http://www.mothur.org/wiki/Trim.seqs

Once you do this, feel free to post your oligos file and we can help you more from there…
Pat

THanks Pat for your quick answer, I actually read those before posting (sometimes I don´t express myself precise enough, sorry), and I also realized I could simply add linkers to the primer sequence in the meantime, which I also did (though i still don´t know if that is necessary; does bc have to “sit” directly on the primer?), but the part of it I don´t get is how to handle reverse primers and barcodes (reverse has bc 2,3,5,6 )? Run it twice, once for fw and once for rw (with silencing unnecessary parts)? Apart from linkers, my questions stay basically the same…

This is how my oligo for forward primer looks like:

forward TCAGAGTTTGATCCTGGCTCAG
#reverse CATGCTGCCTCCCGTAGGAGT

barcode ACGAGTGCGT MID.01
barcode ACGCTCGACA MID.02
barcode AGACGCACTC MID.03
barcode AGCACTGTAG MID.04
barcode ATCAGACACG MID.05
barcode ATATCGCGAG MID.06
barcode CGTGTCTCTA MID.07
barcode CTCGCGTGTC MID.08
barcode TCTCTATGCG MID.10
barcode TGATACGTCT MID.11
barcode CATAGTAGTG MID.12
etc.

Would for reverse look something like this?

#forward TCAGAGTTTGATCCTGGCTCAG
reverse CATGCTGCCTCCCGTAGGAGT

#barcode ACGAGTGCGT MID.01
barcode ACGCTCGACA MID.02
barcode AGACGCACTC MID.03
#barcode AGCACTGTAG MID.04
barcode ATCAGACACG MID.05
barcode ATATCGCGAG MID.06
#barcode CGTGTCTCTA MID.07
#barcode CTCGCGTGTC MID.08
etc.

Does it make any sense? Should/could they be combined?
I´d appreciate if you could try to explain that part to me. Thanks a lot.
A.

Your strategy looks right. One small but important thing for processing the reverse sequences would be to relabel the reverse primer as forward and the forward as the reverse. It’s probably easiest to add the linkers/spacers to the primer sequences.

Hope this helps,
Pat

Thanks a lot for the answer.
Just to be sure I got it right: I should reverse the sequences and relabel the primers?
It´s my first 454 dataset and I don´t want to make some cardinal mistake in the first step already :).

When you run the second oligos set you want to do flip=T. Also, for future reference, you generally only want to sequence in one direction :0