the precursor of miRbase are reformatted as fasta file starting from those produced by http://miRExpress.mbc.nctu.edu.tw
U are changed in T and > is added in front to the mir name and a return is substittuted to tab

U T
actual release miRbase 17
^p ^p>
^t ^p

in the case of mmu
mmT
mmu
actual release mir17

#perl script to trim ends is derived by
#http://centre.bioinformatics.zj.cn/mirtools/adaptortrim.php
#perl Adapter_trim1.pl -i hsa_miRNA_w3linkermod.fastq -o prova.txt -f 2 -q 1
