9411728 KOCHER Transposons are discrete genetic elements which can move from site to site in the genome. Transposition is a significant source of spontaneous mutation in most, probably all, organisms. It is widely supposed that transposon insertions in coding regions cause loss-of-function (knock-out) mutations. This paradigm is the product of the genetic methods (detection of phenotypic mutants) which have been used to monitor transposon activity. Recent discoveries suggest that many transposons are efficiently spliced from transcribed messages, and so do not induce phenotypic mutations. The proportion of transposon insertion which have no visible phenotypic effect is unknown. Molecular methods will be used to detect transposon insertions based on their DNA structure. A large number of insertions in a target gene will be isolated, and each characterized to determine its phenotype and pattern of splicing. The results will have general implications for understanding the structure of eucaryotic genomes, as well as applied benefits for the use of transposon tools in molecular biology, and the detection and treatment of transposon-induced mutations.
