p-element molecular mechanisms

The principle of P-elements in microinjection in Drosophila melanogaster is based on the use of transposons as genetic transformation vectors.

P-elements are transposable DNA sequences naturally present in certain Drosophila populations. They are used to introduce a gene of interest into the insect genome. During microinjection, two types of constructs are injected into early embryos (syncytial stage) :

1. A plasmid containing the gene of interest inserted between the repeat sequences of a P- element deficient (without transposase).

2. A second plasmid encoding the transposase, which recognizes the sequences of the P element and inserts the transgene into the embryo's genome.

The germ cells integrating this transgene will enable transmission to subsequent generations. Adults from these embryos are crossed to identify the transformed individuals, often using a fluorescent or phenotypic marker.

This system is essential in genetics for the study of genes and the engineering of hereditary traits in Drosophila.