A family of highly repetitive elements, named LDT1, has been identified in
the gypsy moth, Lymantria dispar. The complete element is 5.4 kb in length
and lacks long-terminal repeats. The element contains two open reading fram
es with a significant amino acid sequence similarity to several non-LTR ret
rotransposons. The first open reading frame contains a region that potentia
lly encodes a polypeptide similar to DNA-binding GAG-like proteins. The sec
ond encodes a polypeptide resembling both endonuclease and reverse transcri
ptase sequences. All members of the LDT1 element family sequenced thus far
have poly-A tails or A-rich tails of 12-18 nucleotides in length, but lack
a poly-A addition signal in the expected location. The amplification of ret
rotransposon insertion junction regions in different gypsy moth individuals
indicates that polymorphisms exist at some of the insertion sites, suggest
ing that this element is or was, until recently, capable of transposition.