Molecular Probes and Gene Libraries

Molecular Probes and Gene Libraries - Molecular probes are small DNA or RNA segments that recognize complementary sequences in DNA or RNA molecules and thus allow identification and isolation of these specific DNA sequences from an organism. Antibodies are also occasionally used as probes to recognize specific protein sequences.

Although, initially, these probes were developed and used for genetic engineering research but are now frequently used for a variety of purposes including diagnosis of infectious diseases, identification of food contaminants, variety of microbiological tests, forensic tests (e.g. fingerprinting of murderers or rapists), etc.

Probes can also be used to identify strains of an organism e.g. varieties of a crop species (a plant breeder likes to have a quick test to identify his variety to maintain his patent or breeder's right, so that a competitor may not use it in another name leading to infringement of rights). For basic studies in molecular biology laboratories, the molecular robes are frequently used for identification and isolation of genes or related sequences.

In theory, any nucleic acid (or rarely protein, e.g. antibody) can be used as probe, provided it can be labelled to permit identification and quantitation of the hybrid molecules formed between the probe and the sequence to be identified. In practice; double and single stranded DNAs, mRNA and other RNA's synthesized in vitro are all used as probes.

DNA/RNA probe assays are faster and sensitive, so that many conventional diagnostic tests for viruses and bacteria involving culturing of the organism, are being fast replaced by antibody and DNA probe assays. While culture tests can take days or even months, molecular probe assays can be performed within few hours or minutes.

Therefore, the use of DNA probes has become today's most sophisticated and sensitive technology for a variety of uses involving biological systems both in basic and applied studies including their commercial use.