MEST (mesoderm specific transcript) is reported to be imprinted in pig placentas at 75 and 90 days
of gestation as well as in 75
day fetal heart, muscle, kidney, lung and liver (Xu
C et al, 2007). However, the paper only describes monoallelic expression, without parental
origin, in an unspecified number of animals (at least 5). Of concern, all animals apparently
expressed the 156 bp A allele.
Paternal expression was supported by low expression in parthenogenetic embryos (Bischoff
SR et al, 2009).
Tissue-specific imprinting of MEST has been reported. MEST was paternally expressed in skeletal
muscle, fat, pituitary, heart, kidney, lung, stomach, and uterus, whereas it was reported to be
preferentially maternally expressed in spleen and liver (Zhang FW et al, 2012).