Hi,

Yes, if your old file is in gff format, the new file is also in gff format.

Note that the liftOver program usage statement says:

>    -gff  File is in gff/gtf format.  Note that the gff lines are converted
>          separately.  It would be good to have a separate check after this
>          that the lines that make up a gene model still make a plausible gene
>          after liftOver

This means that each part of a gene in gff format will be run through 
liftOver separately.  The potential problem is that different parts of 
the same gene may be lifted to totally different locations in the new 
assembly.  If you are okay with that caveat, then gff format is okay for 
you.

If you would rather ensure that an entire gene is lifted as a unit, you 
need to convert it to a different format, such as genePred or BED.  See 
descriptions of various file formats here:
http://genome.ucsc.edu/FAQ/FAQformat.html

The warning message you saw gives one way to convert your gff file into 
a genePred file:

> WARNING: -gff is not recommended.
> Use 'ldHgGene -out=<file.gp>' and then 'liftOver -genePred <file.gp>'

It is referring the command-line utility available in the source tree 
(http://hgdownload.cse.ucsc.edu/downloads.html#source_downloads) called 
ldHgGene.  The utility will convert your gff file to a genePred file.

Alternatively, if you don't have the source tree already, an easier way 
to convert the file would be to upload it as a custom track, here:
http://genome.ucsc.edu/cgi-bin/hgCustom

Then go to the Table Browser (http://genome.ucsc.edu/cgi-bin/hgTables), 
select the custom track you just made, choose "region: genome" and 
"output format: BED".  Enter a filename in the "output file" field to 
download the file to your computer.

If you use the genePred or BED version of your file, you will not get 
the warning about gff files.

--
Brooke Rhead
UCSC Genome Bioinformatics Group



On 03/12/11 00:34, [email protected] wrote:
> Hi,
>    As oldfile is gff file
>    I used liftOver as below
>    "./liftOver alltrans.gff -gff mm5ToMm8.over.chain newfile.bed unmapped"
>    but the proagramm gave some warning of "gff"
>    How do I next?
>    Is gff format file ok?
>    According to the userguid, gff is ok
> 
>    Another question, I want to know, if my oldfile is gff, is new file gff, 
> too?
> 
> 
> 
> _______________________________________________
> Genome maillist  -  [email protected]
> https://lists.soe.ucsc.edu/mailman/listinfo/genome
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