Tuesday, May 29, 2012

BREAKTHROUGH DISCOVERY: Tet-assisted bisulfite sequencing (TAB-Seq), a new method for mapping methylation to single base resolution of entire genome


BREAKTHROUGH DISCOVERY


Tet-assisted bisulfite sequencing (TAB-Seq), a new method for mapping methylation to single base resolution of entire genome

DNA methylation regulating gene expression is a known fact but study of this 5-hydroxylmethylcytosines (5hmC) has been hampered by the lack of a method to map it at single-base resolution on a genome-wide scale. Affinity purification-based methods (which are used currently) cannot precisely locate 5hmC nor accurately determine its relative abundance at each modified site.  For the first time a revolutionary  genome-wide approach  named “ Tet-assisted bisulfite sequencing (TAB-Seq)” has been devised by Scientists from University of Chicago, Ludwig Institute for Cancer Research, University of California, San Diego and Emory University.  This method,  when combined with traditional bisulfite sequencing can be used for
 mapping 5hmC at base resolution and quantifying the relative abundance of 5hmC as well as 5mC. They applied this method to embryonic stem cells and confirmed  widespread distribution of 5hmC in the mammalian genome and found  sequence bias and strand asymmetry at 5hmC sites. High levels of 5hmC and reciprocally low levels of 5mC near but not on transcription factor-binding sites were observed. The relative abundance of 5hmC varied significantly among distinct functional sequence elements, suggesting different mechanisms for 5hmC deposition and maintenance. This method is expected to transform the epigenetic studies totally.
                                                         (Picture Courtesy: Cell)


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