FUNCTIONAL IDENTIFICATION OF THE SEGREGATION DISTORTER LOCUS OF DROSOPHILA-MELANOGASTER BY GERMLINE TRANSFORMATION

Segregation Distorter (SD) is a meiotic drive system in D. melanogaste r that results in the failure of SD/SD+ males to transmit SD+ homologs owing to the induced dysfunction of spermatids carrying the normal ch romosome. Segregation distorter (Sd), the gene primarily responsible f or this distorted transmission, is associated with a novel 12-kb restr iction fragment containing a tandem duplication of a 5-kb wild-type se gment of genomic DNA. When introduced into appropriate genetic backgro unds by germline transformation, this 12-kb fragment causes full level s of distortion and directs the expression of an Sd-specific 4-kb tran script. Transformants that have lost part of this segment are unable t o cause distortion and do not express the 4-kb transcript. These resul ts identify the tandem duplication as Sd.