Figure 1.

Sex chromosome complements of the mice with MSYq deficiencies and relevant control mice. (a) XY^RIII control, illustrating the previously documented male specific gene content of the mouse Y chromosome. The short arm (shown expanded) carries seven single copy genes, one duplicated gene (Zfy), and multiple copies of Rbmy. MSYq carries multiple copies of the Ssty gene family. (b) XY^Tdym1 control. This male has a normal Y gene complement except that a 11 kb deletion has removed the testis determinant Sry; the Sry deletion is complemented by an Sry transgene located on an autosome. (c) The variant Y^RIIIqdel has a deletion removing about two-thirds of MSYq. (d) The variant Y^Tdym1qdel has a large deletion removing about nine-tenths of MSYq, together with the small 11 kb deletion removing Sry (complemented by an Sry transgene). (e) XSxr^aY* ^X mice are male because of the presence of the Y^RIII short arm derived, sex reversal factor Sxr^a attached distal to the X pseudo-autosomal region (PAR). Sxr^a comprises most of the Y short arm except for a substantial reduction in copies of Rbmy. The Y* ^X chromosome is in effect an X chromosome with a deletion from just proximal to Amel (close to the X PAR boundary) to within the DXHXF34 sequence cluster adjacent to the X centromere. It provides a second PAR, which is essential in order to avoid meiotic arrest. CEN, centromere; kb, kilobase; TEL, telomere.