1. ##从rfam下载所有的序列##
wget ftp://ftp.ebi.ac.uk/pub/databases/Rfam/12.0/fasta_files/*
cat RF*.gz>Rfam.all.fa.gz
##Convert a multi-line FASTA file to a single-line FASTA file:
zcat Rfam.all.fa.gz | fasta_formatter -w 0 | gzip >Rfam.nowrap.fa.gz
##Remove empty lines, replace spaces with underscores, and keep just "ribosomal" sequences:
zcat Rfam.all.nowrap.fa.gz | sed'/^$/d' | sed's/\s/_/g' | awk'BEGIN {RS=">"; ORS="";} tolower($1) ~ /ribosomal_rna/ {print ">"$0}' | gzip >Rfam.rRNA.nowrap.fa.gz
####Set a variable for species of interest. For example:
species="homo_sapiens"
species="mus_musculus"
species="drosophila_melanogaster"
species="mycobacterium"
species="mycobacterium_tuberculosis"
####Extract species-specific ribosomal sequences:
zcat Rfam.rRNA.nowrap.fa.gz | grep -A 1 -i"${species}" | grep -v'^--$' | fasta_formatter -w 80 > rRNA.${species}.fa
###建立索引##
samtools faidx rRNA.${species}.fa
bowtie2-build rRNA.${species}.fa rRNA.${species}
2. 从ensemble下载ncRNA.fa
##Convert a multi-line FASTA file to a single-line FASTA file:
zcat Homo_sapiens.GRCh38.ncrna.fa.gz | fasta_formatter -w 0 | gzip > Rfam.nowrap.fa.gz
##提取rRNA
grep -A 1 "rRNA" Rfam.nowrap.fa > hg19.rRNA.fa
##将两个数据库得到的fa合并在一起
cat hg19.rRNA.fa rRNA.${species}.fa > all.human.rRNA.fa
问题:这样建的库仍然不是完整的rRNA databse,目前还没有找到一个完整的rRNA数据库。。
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