The Nooses lampbrush 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.

Y chromosome lampbrush loop gene. Male fertility gene.

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.

The male fertility gene Dhyd\noose forms the lampbrush loop pair Nooses. Two thirds of the loop consists of the Y-specific Dhyd\ay1 family of repetitive repeats, one half of the remaining third is represented by defective retrotransposons of the Dhyd\gypsy family. Using Dhyd\ay1 and Dhyd\gypsy sequences as probes for transcript in situ hybridisation demonstrates that transcription of neither sequence is defective in the loops formed by a male sterile allele of Dhyd\noose. Therefore transcription of Dhyd\ay1 and Dhyd\gypsy is required, but not sufficient for the function of Dhyd\noose.

Male fertility gene.

The chromosomal position of the lampbrush loop pair Nooses, and of Dhyd\noose is defined by the Dhyd\ay1 repeats that are interspersed by co-transcribed Y-associated sequences.