Dnmt1 and Dnmt3 of the winter skate (leucoraja ocellata)

Abstract

Chromatin management throughout vertebrate development is a stringently controlled and dynamic process. One event involved in that process is the covalent modification of cytosine nucleotides by the addition of a methyl group to the fifth carbon atom of the pyrimidine ring. Enzymes involved in establishing and maintaining DNA methylation patterns (DNA-methyltransferases: Dnmts) have been isolated and characterized in the teleost and mammalian lineages. There are structural similarities between enzymes as well as basic developmental expression patterns but there are fundamental differences in gene number and function in the context of two very different reproductive strategies. Subclass Elasmobranchii displays a wide variety of reproductive strategies and studying genome management in this subclass could provide great insight into the key differences and similarities in DNA methylation observed in the tetrapod and teleost models. I have isolated and characterized the first full length cDNAs of the maintenance and de novo methyltransferases ( Dnmt1 andDnmt3 respectively) from the Winter Skate (Leucoraja ocellata ), a member of subclass Elasmobranchii. Evidence is presented for multiple Dnmt3 splice variants as well as at least two Dnmt3 retrotransposed pseudogenes. Preliminary experiments indicate that the early developmental methylation dynamics observed in both mammals and teleosts may also be present in L. ocellata.