DNA Libraries

DNA libraries have been invaluable tools for molecular biology research. They have facilitated the study of the genes and genomes of complex organisms by providing a method of producing large amounts of easily manipulated DNA for the investigation of any region of interest from the cloned DNA representative of the entire genome. A DNA library is a collection of DNA clones constructed in vitro by inserting the fragments of source DNA into a cloning vehicle or vector, which contains all elements required for the delivery of the foreign DNA fragments and stable propagation as a plasmid, a bacteriophage or an artificial chromosome in the host cells. Depending on their DNA source, DNA libraries can be categorized as cDNA libraries, genomic DNA libraries, and oligo libraries. The genomic DNA libraries could further be classified into plasmid, phage, cosmid, P1, BAC, PAC, BIBAC, PBC, and YAC libraries, according to the cloning vectors used. Genomic DNA libraries could be constructed with insert sizes from several up to a million base pairs (bp), depending on research purposes and cloning technologies. Many strategies and techniques have been developed and used for construction of DNA libraries from plants, animals, insects and microbes. DNA libraries are essential resources and tools for all research areas of molecular cell biology and molecular medicine, from gene discovery, cloning, and characterization to gene therapy.