Whaat are ests? and what are its applications

Priya sarda

Expressed sequence tags (ESTs) are relatively short DNA sequences (usually 200–300 nucleotides) generally generated from the 3′ ends of cDNA clones from which PCR primers can be derived and used to detect the presence of the specific coding sequence in genomic DNA. Expressed Sequence Tags (ESTs) are short, usually unedited sequences obtained by single-pass sequencing of cDNA clones from any cDNA library. Analyzing and comparing ESTs can provide information on gene expression, function and evolution. Large-scale EST sequencing has become an attractive alternative to plant genome sequencing.  Advantages  #They have proved to be a valuable tool for gene discovery and plant metabolism analysis.  #Several plant-specific EST databases have been created which provide access to sequence data and bioinformatics-based tools for data mining.  #Searching EST collections allows pre-selection of genes for preparing cDNA arrays, targeted to bring maximum information on specialized processes, like stress response, symbiotic nitrogen fixation etc.  #ESt-based molecular markers such as SNP, SSR, and are fast developing tools for breeders and researchers. Application of EST #Identify unknown genes and to map their position with a genome.  #ESTs provide researchers with a quick and inexpensive route for discovering new genes.  #For obtaining data on gene expression and regulations.  #Constructing genome maps #Economical approach  identify and characterize expressed genes.  #EST represent a snapshot of genes expressed in a given tissue and at a given developmental stage.