Position effect variegation
The position-effect variegation (PEV) is a phenomenon in genetics .
discovery
Hermann Muller , Nobel Prize Winner for Medicine 1946, described in 1930 the model organism Drosophila melanogaster a “variegated” (means something like “multicolored” or “colored”) chromosomes - mutation phenotype after X-ray irradiation .
This phenomenon has been referred to as position effect variegation in the following. It opened up experimental access to the isolation and molecular analysis of genes that control heterochromatic chromatin states and gene silencing . In PEV, after relocation to a new gene locus in the vicinity of constitutive heterochromatin , euchromatic gene regions are variably heterochromatized, i.e. variably shut down. The classic example is the Drosophila w [m4] (called white-mottled-4) mutant. In this mutation, an inversion of the X chromosome brings the white gene close to pericentric heterochromatin. Normally the white gene is expressed in every cell of the Drosophila eye, which leads to a red eye phenotype . In the Drosophila with the w [m4] mutation, the eye color is a red and white mosaic, thus “multicolored”, “colorful” or variegated in English . The white gene, which is responsible for the eye color in Drosophila , is heterochromatized in some of the cells .
See also
Individual evidence
- ^ HJ Muller: Types of visible variations induced by X-rays in Drosophila. In: J. Genet. 22/1930, pp. 299-335.
literature
- R. Festenstein et al: Locus control region function and heterochromatin-induced position effect variegation. In: Science 271/1996, pp. 1123-5.