Contains a third copy of the 2.9kb fragment that is duplicated in wc. Two copies of the 2.9kb fragment are present on the 3' side of the FB element (relative to the direction of transcription of the w gene), and there is one copy on the 5' side of the FB element. In addition 1kb DNA has been deleted from the FB element, with most or all of the deletion occurring within the left inverted repeat.
FB elements
Eye colour: white.
Collins, Rubin.
Stable allele.