Defective Dhyd\gypsy retrotransposons are a major constituent of the lampbrush loop pair Nooses in the short arm of the D.hydei Y chromosome. The loop pair is formed by the male fertility gene Dhyd\noose during the primary spermatocyte stage of spermatogenesis, each loop being a single transcription unit with an estimated length of 260kb. Throughout the loop transcripts Dhyd\gypsy elements are interspersed with blocks of tandemly repetitive Y-specific DNA sequence, Dhyd\ay1.

Dhyd\gypsy elements that are expressed as constituents of the male fertility gene Dhyd\noose in the lampbrush loop pair Nooses have been sequenced. These Dhyd\gypsy elements are all truncated and have lost those sequences that may interfere with the continuity of lampbrush loop transcription, such as the long terminal repeats (LTRs) and the su(Hw) binding sites. In addition, the Dhyd\gypsy elements in the Nooses lampbrush loop pair contain only defective coding regions, which should not allow synthesis of Dhyd\gypsy encoded proteins. These results suggest that any contribution of these Dhyd\gypsy elements to the function of the male fertility gene Dhyd\noose does not depend on a conserved DNA sequence.