Webtag
Webtag is an on-line bioinformatics tool providing oligonucleotide sequences (usually called tags or anchors) that are absent from a specified genome. These tags can be appended to gene specific primers for reverse transcriptase polymerase chain reaction (RT-PCR) experiments, circumventing genomic DNA contamination. Background RT-PCR is a technique used for the detection of even very low copy mRNA transcripts. The sensitivity of the technique also makes it susceptible to DNA contamination. Since PCR is unable to distinguish between cDNA targets and genomic DNA contamination, false positives and/or erroneous quantitative results are possible. In order to overcome genomic DNA contamination in transcriptional studies, reverse template-specific polymerase chain reaction, a modification of RT-PCR is used. The possibility of using tags whose sequences are not found in the genome further improves reverse specific polymerase chain reaction experiments. The use of anchors, or tags, in the 5' region of a gene specific primer or poly-T tail allows for RNA-specific amplification, and constitutes a viable strategy. Techniques such as RS-PCR and (EXACT) RT-PCR are based on the integration of such tags (unique sequences not present in genomic DNA) in the 5' end of the first strand cDNA, permitting RNA-specific amplification without loss of sensitivity. Webtag This