Molecular hybridization: what is it?

L’hybridization molecular is a technique making it possible to highlight a nucleic acid sequence within a cell, a tissue or a particular environment, for example to locate a locus on a chromosome. It is based on the principle of complementarity nucleic bases, more particularly between the strands ofDNA or theRNA complementary.

Molecular hybridization method

Hybridization can be carried out in phase liquid (the complementary segments are placed in a solution) or on a support solid (the target complementary sequence being immobilized to facilitate the separation).

The sequence DNA double strand is first denatured, i.e. the strands are separated by the heat or by an alkaline shock. A nucleotide probe, a segment of nucleotides corresponding at least in part to the desired sequence. When the solution is gradually cooled, this probe (which can be DNA or RNA but must be single-stranded) will then pair up with the target strand by forming hydrogen bonds : two links between theadenine (A) and the thymine (T) (or theuracil U) and three between the cytosine (C) and the guanine (G). The part of the unhybridized probe is then removed by washing.

To locate the sequence, use probes labeled with a radioisotope (hot labeling), but there are also cold probes with enzymatic or fluorescent labelling. The probes can be of very variable length, ranging from a few hundred to a few thousand bases.

Applications of molecular hybridization

Hybridization is the basis of many techniques of molecular biology, including amplification and cloning of DNA or the manufacture of DNA chips. These are used to measure gene expression, locate point variations in DNA sequences in the genome or even detect pathogens (by introducing a probe corresponding to part of the genome of the pathogenic organism sought).