Methylation of specific CG residues in the mammalian genome results in 
tissue-specific patterns of gene expression, which are critical for cell 
differentiation. Embryos that fail to establish and maintain proper DNA 
methylation patterns show severe developmental abnormalities as is the case of 
DNA methyltransferase 1 (Dnmt1) -deficient embryos. Dnmt1 is the main 
maintenance methyltransferase in the mouse and its expression is regulated by a 
splicing mechanism that dictates the expression of stage-specific isoforms. 
Little is known about Dnmt1 expression in the cow and isoforms of Dnmt1 are yet 
unknown in this species. Here we demonstrate that the previously described 
bovine Dnmt1 transcript is ubiquitously expressed in embryos and fetal tissue. 
In addition, we report the identification of a splice variant of the bovine 
Dnmt1, which shows a ubiquitous expression pattern. This new transcript was 
detected using 5'RACE and genomic mapping and its expression pattern was shown 
to be consistent with a tissue-specific mode of regulation. Furthermore, our 
analysis shows that the expression of an oocyte-specific isoform of Dnmt1 is 
unlikely to occur in cattle. The newly reported isoform of Dnmt1 was 
demonstrated to be, similarly to Dnmt1a, polyadenylated and if translated 
possess the functional domains necessary for maintenance and de novo 
methyltransferase activity.