Mutagenesis is the generation of mutants resulting of the exposure of organisms to radiations, chemicals or viruses. Mutants are individuals whose RNA or DNA has been affected, mutated, in a way that changes one or several of the organism characteristics. It then becomes different from the wild type and is therefore called a mutant.
Mutations are errors in the copying of the genetic material (the DNA or RNA). Genes are made up of introns and exons, exons are the part that code for proteins. A mutation is a change of one of the bases (A, C, G or T, see genetics) or more into other ones or a suppression of these bases. If the mutation affects one exon or more and if the error is not corrected by the cell, affected genes won’t be able to code for their proteins or will code for ones that are a little different.
However, it is important to point out that mutations appear naturally almost at each reproduction cycle. In fact, the genetic material is copied each time a cell divides. In humans, there are about 1 million cell divisions per day during which about 50 000 errors in the copying of the genetic material happen. Mutations can occur deliberately under cellular control during specific processes.
It is interesting to point out that genetic mutation is a fundamental mechanism at the base of evolution and adaptation to changes. In fact, mutations can provoke the apparition of proteins which can help the organisms to be more adapted to their environment.
But, when the mutation is not controlled or too important, it can cause severe damages like the knock-out of certain genes that are indispensable to the well-being of the organism. Cystic fibrosis, for example, is a dreadful hereditary disease of the exocrine glands and it is provoked by the mutation of only one base of a specific gene.
By looking into the genome of the organism, scientists are able to tell which gene has been mutated provoking the loss of which specific function.
Provoking the knock-out of certain functions randomly experimentally through mutagenesis allows scientists to see which genes are indispensable for which precise characteristic of the organism.
Mutagenesis is one of the tools which are, at the moment, helping the scientists to better understand what the function of genes in an organism is.
On Ectocarpus siliculosus, for instance, mutagenesis provoked by the exposition of the algae to U.V light is helping researchers to understand how the alternation between the gametophyte and the sporophyte is controlled genetically.
Interesting web site in French: http://www.nature.ca/genome/03/c/10/03c_14_f.cfm
Contributed by Stephanie Ries
