MEIOTIC DRIVE ON ABERRANT CHROMOSOME-1 IN THE MOUSE IS DETERMINED BY A LINKED DISTORTER

An aberrant chromosome 1 carrying an inverted fragment with two amplif ied DNA regions was isolated from wild populations of Mus musculus. Me iotic drive favouring the aberrant chromosome was demonstrated for het erozygous females. Its cause was preferential passage of aberrant chro mosome 1 to the oocyte. Genetic analysis allowed us to identify a two- component system conditioning deviation from equal segregation of the homologues. The system consists of a postulated distorter and responde r. The distorter is located on chromosome 1 distally to the responder, between the ln and Pep-3 genes, and it acts on the responder when in trans position. Polymorphism of the distorters was manifested as varia tion in their effect on meiotic drive level in the laboratory strain a nd mice from wild populations.