Entering edit mode
Hi everyone,
I am working with mRNA data from Affy 'drosophila2' arrays and miRNA
data from Affy 'mirna3' arrays. I have identified a list of
differentially expressed mRNAs and miRNAs. I'm having a bit of trouble
with some downstream analyses and I'm hoping someone might be able to
offer some help.
I would like to use my list of differentially expressed miRNAs to
access online databases (e.g. miRBase, microRNA.org
) and extract the names of all the potential target mRNAs. Then I'd
like to use this list of mRNAs to look through my mRNA expression
data. I'm aware of packages like 'RmiR' and 'microRNA' which have
built-in functions for finding miRNA targets, but as far as I can
tell, 'RmiR' uses miRNA databases for humans only and 'microRNA' works
with human and mouse data only. So is there a package I am unaware of
(or another application of 'RmiR'/'microRNA' that I am unaware of) for
looking at drosophila data?
So far I have also considered the 'biomaRt' package to see if the
database query function on there can help me, but I haven't had much
luck. For instance, if I try an example list of miRNAs:
mirna<-c("dme-miR-1002","dme-miR-312","dme-miR-973")
library(biomaRt)
ensembl<-useMart("ensembl",dataset="dmelanogaster_gene_ensembl")
getBM(attributes="mirbase_accession",filters="mirbase_id",values=mirna
,mart=ensembl)
then 'logical(0)' is returned, as if there are no records for those
miRNAs - but by searching the database manually I know the records are
there.
Alternatively I can try:
miRNA <- getBM(c("mirbase_accession","mirbase_id", "ensembl_gene_id",
"start_position", "chromosome_name"), filters = c("with_mirbase"),
values = list(T), mart = ensembl)
which returns a table of various bits of information on miRNAs, but I
cannot adapt this command to just look at my list of miRNAs of
interest (ie. the 'mirna' vector above). I've included the
sessionInfo() output for these at the bottom of the email, but I
suspect my problem is more to do with the fact I'm not going about
this the right way (as opposed to a problem with package versions and
coding etc.). I'm not even sure that using 'biomaRt' will give me the
information I eventually want (the target mRNAs of these miRNAs), I
was just trying it out, to see what it was capable of in terms of
querying these databases. So I apologise for the vagueness. Since I
haven't managed to get very far by myself then it's difficult to be
more specific, but I'd really appreciate it if anyone could offer some
advice, even just to point me in the direction of a useful package
which might have gone unnoticed by me.
Many thanks,
Fiona
Dr Fiona C Ingleby
Postdoctoral Research Fellow
University of Sussex
Email: F.Ingleby@sussex.ac.uk
Website: fionaingleby.weebly.com
> sessionInfo()
R version 2.15.2 (2012-10-26)
Platform: x86_64-apple-darwin9.8.0/x86_64 (64-bit)
locale:
[1] en_GB.UTF-8/en_GB.UTF-8/en_GB.UTF-8/C/en_GB.UTF-8/en_GB.UTF-8
attached base packages:
[1] stats graphics grDevices utils datasets methods base
other attached packages:
[1] biomaRt_2.14.0 affy_1.36.1 Biobase_2.18.0
BiocGenerics_0.4.0
loaded via a namespace (and not attached):
[1] affyio_1.26.0 BiocInstaller_1.8.3 grid_2.15.2
lattice_0.20-14 Matrix_1.0-11 MCMCglmm_2.17
[7] preprocessCore_1.20.0 RCurl_1.95-4.1 tools_2.15.2
XML_3.95-0.2 zlibbioc_1.4.0
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