Expression of XIST was analysed in chorion, allantois, liver, lung, and brain. This revealed
biallelic expression from all tissues examined except chorion samples which showed preferential
paternal expression. Bisulphite sequencing of an exon 1 CpG island from liver samples indicated
methylation of the maternal copy only. Comparative sequence analysis suggests that the CpG-rich Xist
minimal promoter and the Tsix promoter CpG island (associated with imprinted mouse Xist/Tsix
transcripts) are not conserved in cattle (Dindot SV et al 2004).
Exclusive expression of MAOA from the maternal allele indicated preferential inactivation of the
paternal X chromosome in bovine placentae (Xue F et al, 2002).