Expression of PGK-A in the Australian brush-tailed possum, Trichosurus vulpecula (Kerr), consistent with paternal X inactivation.

An extensive survey of erythrocytes of marsupials other than kangaroos for electrophoretic variation if X-linked enzymes revealed two rare PGK-A phenotypes in the phalangerid Trichosurus vupecula and one in Trichosurus caninus. Four putatively heterozygous females expressed only the variant allelic isozyme in some tissues but expressed a trace of the normal isozyme in others. A putatively hemizygous male expressed only the variant isozyme in all tissues. The phenotypic patterns were consistent with those observed in kangaroos known to exhibit partial or complete parternal X inactivation in cells of females. Tow of the T. vulpecula were a mother and her female pouch young, further suggesting that paternal X inactivation occurs in T. vulpecula. This peculiar mechanism of dosage compensation may not be restricted to kangaroos.