Generation of cDNA Libraries for Profiling Gene Expression of Given Tissues or Cells

Complementary DNA (cDNA) library construction is a foundational technique for various organism genome projects and molecular biological approaches. Numerous methods for generating a cDNA library have been applied for different purposes. To profile the gene expression of a given tissue or cells, the researchers often used an oligo-(dT) primed and directional cloned strategy for generating cDNA libraries, and then DNA sequencing to characterize novel genes from those libraries (1 –6 ). The cDNA library derived from the strategy may contain more abundance gene species without significant bias because polymerase chain reaction (PCR) is not usually used for amplifying the double-strain cDNA. However, the strategy needs more sample and abundant message RNA. If there is only a little mRNA, the PCR-based method must been adopted in cDNA library construction. Recently, some researchers utilized cap structure at the 5′ end of eukaryotic mRNA to design novel methods for PCR-based cDNA library construction (7 –11 ). Moreover, the strategy has been applied to identifying gene expression and isolating full-length cDNA (12 –14 ). In our laboratory, the conventional and PCR-based strategies have been utilized for generating some libraries from massive sample (human liver cancer, hypothalamus, pituitary, adrenal gland) and a small amount of RNA (human CD34+ cells), respectively.