RNA-Seq uses recently advanced deep-sequencing technology. In standard, a population of RNA (overall or fractionated, including poly(A)+) is converted to a library of cDNA fragments with adaptors attached to one or each ends. each molecule, with or without amplification, is then sequenced in a excessive-throughput manner to acquire short sequences from one stop (single-end sequencing) or each ends (pair-end sequencing).The reads are commonly 30–400 bp, depending on the DNA-sequencing generation used. In precept, any high-throughput sequencing technology25 may be used for RNA-Seq, and the Illumina IG18–21,23,24, carried out Bio systems SOLiD22 and Roche 454 life Science26–28 systems have already been implemented for this cause. The Helicos Biosciences tSMS machine has no longer but been used for posted RNA-Seq research, however is likewise suitable and has the delivered advantage of keeping off amplification of target cDNA. Following sequencing, the ensuing reads are either aligned to a reference genome or reference transcripts, or assembled de novo with out the genomic sequence to supply a genome-scale transcription map that includes each the transcriptional shape and/or stage of expression for each gene.