SuperSAGE

Super Sage is a further development of the serial analysis of gene expression ( SAGE ) for qualitative and quantitative analysis of expressed genes.

As with SAGE are from each transcript ( from mRNA was transcribed into cDNA ), enzymatically excised a sequence segment and as a so-called day (English label ) won. Sequenced to as many of these tags and include the different tags, you receive a response to the question of which gene was how frequently read, or how many transcripts which gene present in the sample. Because of new high-throughput sequencing ( Next Generation Sequencing ) puts the tag-based analysis of gene expression, also known as Digital Gene expression profiling (DGE) referred more and more to the fore, since you do not have the limitations of microarrays and it is possible also extremely rare transcripts to quantify exactly.

In Super Sage III restriction enzyme EcoP15I be generated particularly specific tags with the type, which are 26-28 bp in length, in contrast to the previous techniques and Long SAGE Sage with only 14 or 18 bp long tags.

The much longer tags allow a much more precise assignment of tags to the associated transcript and make it possible to detect more transcripts. The accuracy of the tags also allows the Trankripte different organisms to distinguish accurately, so that transcription analyzes of several organisms are possible in the interaction, for example by parasite and host. As in the SAGE protocol called ditags are generated from two tags, which can be amplified by PCR prior to sequencing.

With modern high-throughput sequencing can be sequenced very fast and cheap today millions of these tags so that a very accurate transcription profile is created in which the many rare transcripts such as transcription factors can be accurately detected and counted.

The accuracy of quantification with sufficient amount of sequenced tags exceeds the distance of microarrays. In addition, with super saga new transcripts are identified, and also samples of eukaryotes are examined very closely with as yet unknown, or little known genomes.

The long 26-28 bp tags can be used for further analysis of new transcripts as highly specific primers (eg for RACE) as probes to identify clones in a library, or even for analyzes with higher throughput spotted directly on a microarray and therefore the cost advantage of microarrays can be used.