Imprinting of Nesp55 gene in cattle.

Studies in mouse and human have established that the exon encoding the neuroendocrine secretory protein Nesp55 is transcribed exclusively from the maternal allele. To study the imprinting status of Nesp55 in cattle, we examined transcripts of this exon in a wide range of tissues from four fetuses and the dam of one of the fetuses (not all tissues were examined in all subjects). A polymorphic site was used to determine transcript status as monoallelic or biallelic. The expression analysis was by direct sequencing of RT-PCR products amplified from the tissues. Nesp55 transcripts were detected in many tissues, in contrast to previous studies in which Nesp55 was detected by immunoassays in endocrine and nervous tissues only. In all five individuals, Nesp55 showed monoallelic expression. In one of the fetuses, parental origin of the expressed allele could not be determined; in the others monoallelic expression was clearly maternal. Thus, bovine Nesp55 is maternally expressed like its counterparts in mouse and human.