and gel blot hybridizations were performed as described 5 ecori digests were hybridized with the ds probe radiolabelled 3 4 kb xhoi bamhi subfragment of ac gai t6 has lost u03b4naei sac gus 1 via genetic segregation further experiments showed that the transposed ds interrupts the transcribed region of a gene gai and that the arabidopsis genome contains at least one additional gene sharing significant sequence homology with gai fig2 c a radiolabelled ipcr fragment containing genomic dna adjacent to the 3 u2032 end of the transposed ds in gai t6 was isolated as previously described 24 it was necessary to use considerable caution in the use of this probe since it was potentially contaminated with sequence derived from the t dna 3 u2032 of the ds in a264 which is still present in the gai t6 line however the fact that the probe hybridized with dna from plants lacking any t dna insertion indicated that it was useful for the purposes of cloning the region of genomic dna into which the transposed ds in gai t6 had inserted this probe was shown to hybridize to genomic dna cosmid clones previously identified as being likely to contain gai by map based cloning one of these cosmids was used to identify by hybridization clones from a cdna library made from mrna isolated from aerial plant parts arabidopsis these cdnas were classified according to their hybridization to genomic dna from gai gai and gai t6 some of these clones hybridized weakly.