cDNA Library Overview and Applications

cDNA libraries are crucial tools in molecular biology research. They provide a stable, manipulable copy of the mRNA content of cells, allowing researchers to investigate gene expression, splice variants, protein interactions and more. Unlike genomic DNA libraries, which include all of the DNA in an organism’s genome (including non-coding regions and introns), cDNA libraries include only those sequences that are transcribed into mRNA and potentially translated into proteins. This makes them particularly useful for studying protein coding genes. Creative Biogene is a biotechnology company which can provide high quality cDNA library construction services for customers worldwide. With years of experience in cDNA library construction, we can provide a series of cDNA library construction services, including standard cDNA library, subtractive cDNA library, normalized cDNA library, full length cDNA library, yeast two-hybrid cDNA library and SSH cDNA library.

Principle of cDNA Library

The mRNA molecules within a cell can serve as templates for the creation of cDNA molecules. These cDNA molecules can then be combined in a single location to form a cDNA library.

Here are some of the key principles behind cDNA libraries:

Represent gene expression: A cDNA library represents the genes that are being actively expressed in a given cell at a particular point in time. Therefore, it is a valuable tool for determining which genes are active within a particular cell.
Reverse transcription: The process of creating cDNA involves a reaction known as reverse transcription. In this reaction, the enzyme reverse transcriptase uses mRNA as a template to synthesize a complementary strand of DNA. This cDNA can then be amplified and cloned into a suitable vector, creating a library of cDNA clones.
Clone selection: By selecting and sequencing specific clones from the cDNA library, researchers can study the sequence and function of individual genes.
Non-coding regions: One advantage of cDNA libraries over genomic DNA libraries is that cDNA libraries do not contain non-coding regions. This is because mRNA, the template for creating cDNA, does not include these non-coding regions. This makes cDNA libraries a more effective tool for gene expression studies.
Tissue-specific: cDNA libraries can be made from a specific tissue or from a particular developmental stage. Using such a library, one can find out which genes are expressed in that tissue or stage of development.
Expression profiling: They can also be used for comparative gene expression studies. By comparing cDNA libraries prepared from different tissues or developmental stages, researchers can determine changes in gene expression patterns.

Fig. 1 An overview of cDNA library preparation and a prototypical two-hybrid approach. (Gillespie, M., 2003)

Advantages of cDNA Library

There are two main benefits to the cDNA library.

In the beginning, it is enhanced by fragments of genes that are being transcribed.
Introns are not the only way to alter the cloned sequences should the objective be to make a eukaryotic protein in bacteria, introns could be a challenge, because the majority of bacteria lack a method to eliminate the introns.

Disadvantages of cDNA Library

A cDNA library is a disadvantage in that it contains only sequences that are found inside mature mRNA.
Introns are not present, nor are other sequences that are altered during transcription. Sequences that aren't transcribed into RNA, like enhancers and promoters are not included in a collection of cDNA.
It is important to note that only certain gene sequences that are expressed inside the organ from which DNA has been isolated make up the cDNA library.
Addition to that, in an cDNA collection, the amount of a particular DNA sequence is determined by the amount of the relevant MRNA within the tissue of interest.
Contrary to this when you look at a genome-wide DNA library, virtually all genes are found at an equal frequency.

Application of cDNA Library

cDNA libraries have become an essential tool for researchers studying functional genomics, developmental biology, and disease pathology. They provide valuable insights into gene function, regulation, and expression.

Gene cloning: cDNA libraries are extensively used in gene cloning, which aids in the production of large quantities of proteins and diagnostic reagents. Once a gene is identified and cloned, it may also be modified for further genetic research.
Gene expression analysis: Since cDNA libraries represent the gene expression profile of a cell at a specific time, they can be used in the analysis of gene expression patterns in different tissues or at different developmental stages. It helps in differentiating expressed genes in normal and pathological conditions.
Comparative genomics: They can be used for comparative genomics among different species. This technique assists in understanding evolutionary development, speciation processes, and function of genes and genomes in different organisms.
Gene therapy: This library can identify functional genes which can be used in gene therapy which is an experimental technique that uses genes to treat or prevent diseases.
Proteomics: It also enables the cloning and expression of proteins for research and therapeutic uses.
Sequencing projects: cDNA libraries often serve as useful resources for large scale sequencing projects.
Target identification: In drug discovery, cDNA libraries help in the process of identifying targets.

References

Gillespie, M. Affordable proteomics: the two-hybrid systems. Curr Opin Mol Ther. 2003, 5(3): 266-270.
Klickstein, L. B. Production of a complete cDNA library. Current Protocols in Molecular Biology. 1989: 5.8. 1-5.8. 8.

* For research use only. Not intended for any clinical use.

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cDNA Library Overview and Applications

Principle of cDNA Library

Advantages of cDNA Library

Disadvantages of cDNA Library

Application of cDNA Library

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