A 9.3 kb transposable element of the roo family has been found inserted 3' to 
the Sgs-4 glue protein gene of Drosophila. The X chromosome which carries this 
insert also carries wDZL, a dominant, unstable allele of the white locus caused 
by the insertion of the 13 kb wDZL element. Three deletions isolated from the 
wDZL strain have molecular breakpoints 3' to Sgs-4 that are associated with the 
roo element. Though the deletions eliminate much of the DNA between white and 
Sgs-4, none of the distal breakpoints fall at or near the wDZL element. The 
results suggest that this copia-like element, which is structurally similar to 
an integrated retrovirus, is capable of promoting chromosomal deletions.