Genetic Transformation

Genetic transformation is a process that involves the introduction and expression of foreign genes in a host organism. This expression can result from the extrachromosomal, or episomal, presence of genes in nuclei that may persist if the introduced DNA has a mechanism for replication. Extrachromosomal expression, however, is most often transient as the DNA becomes diluted with cell division. Expression also can result from the integration of foreign DNA into somatic chromosomes that can persist through the lifetime of the organism, but not be inherited. Alternatively, foreign genes may be stably inherited if incorporated into the genome of the germ-line, known as germ-line transformation. This is the most common type of genetic transformation in insects.

Transient or somatic transformation can be achieved in several ways, and most often is used for testing promoter regulatory sequences. Most simply, DNA, usually in the form of circular plasmid molecules, is introduced into tissue by...