Hi is there any package to extract three types of intergenic regions (i.e. Tendem, convergent,divergent ) in granges object from genomic and GFF file.
Hi is there any package to extract three types of intergenic regions (i.e. Tendem, convergent,divergent ) in granges object from genomic and GFF file.
The genFeatures()
function in systemPipeR
allows you to compute intergenic regions. The vignette for the Ribo-Seq workflow of systemPipeR
package gives some examples (and/or consult ?genFeatures
). The sub-classification of the intergenic regions you mention could be obtained downstream by using the plus/minus strand orientation of the genes defining the intergenic regions. The naming scheme of the intergenics by their neighboring genes (e.g. geneID1__geneID2) could help here but this would require some additional coding for you. If this is a common used case then I am happy to add this functionality to the to-do list for next update. Alternatively, one could discuss whether the utility to extract intergenic regions from TxDbs could become part of the GenomicFeatures
package. In the past there were some discussions about this I believe.
Thomas
makeTxDbFromGFF()
from GenomicFeatures
fails to produce a TxDb
. Something in your GFF is not meeting the expected format. This is usually fixable by debugging the GFF. However, would you mind using Biomart as source of your annotations (GFF) instead? If this is fine then please try the following which works just fine:
> library(GenomicFeatures); library("biomaRt"); library(systemPipeR)
> txdb <- makeTxDbFromBiomart(biomart = "ensembl", dataset = "scerevisiae_gene_ensembl")
> myfeatures <- c("tx_type", "promoter", "intron", "exon", "cds", "intergenic")
> feat <- genFeatures(txdb, featuretype=myfeatures, reduce_ranges=FALSE, upstream=1000, downstream=0)
Created feature ranges: protein_coding, ncRNA, tRNA, snoRNA, pseudogene, snRNA, rRNA
Created feature ranges: promoter
Created feature ranges: intron
Created feature ranges: exon
Created feature ranges: cds
Created feature ranges: intergenic
Now the intergenic ranges can be extracted with feat$intergenic
. Note: using feature="all"
will give you an error for fiveUTR/threeUTR
since those return empty objects. I will change this to a warning in the next update of systemPipeR.
Thomas
Hi,
If your intergenic regions are annotated in your GFF file, then just import the file with the import()
function from the rtracklayer package. This will return you a GRanges object with various metadata columns. One of them will be named type
and it will tell you the type of feature for each range in the GRanges object. Your 3 types of intergenic regions should show up there.
H.
If you used http://downloads.yeastgenome.org/curation/chromosomal_feature/saccharomyces_cerevisiae.gff
it doesn't seem to contain information about the intergenic regions, unfortunately. That's why the GRanges object you got with rtracklayer::import()
doesn't contain these regions either. The next thing to try is what Thomas suggested. I assume it worked for you because you accepted his answer. If you're still struggling with this, you would need to provide some details about what you've done so far and what problems you ran into.
Cheers,
H.
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Hi Thomas, Thanks for your suggestion. when i tried to install above metioned package it is giving following warning and library is not loaded.
> source("http://bioconductor.org/biocLite.R") # Sources the biocLite.R installation script
biocLite("systemPipeR") # Installs systemPipeR from Bioconductor
*** installing help indices ** building package indices ** testing if installed package can be loaded * DONE (spatial) The downloaded source packages are in ‘/tmp/RtmpcmPuuP/downloaded_packages’Warning messages:
HI Thomas somehow i installed package ‘systemPipeR’ but genFeatures() is not available. I am also sending you session info
Hi Thomas, As per your advice i successfully installed the 'systemPipeR'. I am triying to find intergenic regions from .gff file from this. link http://downloads.yeastgenome.org/curation/chromosomal_feature/saccharomyces_cerevisiae.gff
When i tried to get make txdb databse from gff file , txdb is not created . Commands and sessoninfo are given below
Can u suggest me the process to get intergenic regions of Saccharomyces cerevisiae
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