Studies on Metatherian Sex Chromosomes V. Activity of the Paternally Derived Allele at the X-linked Pgk-A Locus in Some Tissues of the Kangaroos Macropus giganteus and M. parryi

In pretty-face wallabies (M. parryi) all adult males express either the N or the VP allozyme of the X-linked enzyme phosphoglycerate kinase, PGK-A, in all their tissues examined. Some females do likewise, but others express both. ·In about half of these latter females N is much stronger than VP and in the other half VP predominates. The more strongly expressed form is presumed to be of maternal origin although no pedigree data are available. This hypothesis is supported by data from a related species, the eastern grey kangaroo (M. giganteus). The tissues of four females of this species which were known to be heterozygous for the N and VB allozymes have been typed for their PGK-A phenotypes. Some tissues express only the maternally derived allozyme, i.e. they manifest complete inactivation of the paternally derived allele at this locus. The paternally contributed allozyme was detectable in other tissues, but it was usually much less pronounced than the maternal one. In no instance· was the paternal allozyme more pronounced than the maternal one. Heterozygotes produced from reciprocal crosses were accordingly phenotypically different.