Papers Published
Abstract:
Imprinted gene identification in animals has been limited to eutherian mammals, suggesting a significant role for intrauterine fetal development in the evolution of imprinting. We report herein that M6P/IGF2R is not imprinted in monotremes and does not encode for a receptor that binds IGF2. In contrast, M6P/IGF2R is imprinted in a didelphid marsupial, the opossum, but it strikingly lacks the differentially methylated CpG island in intron 2 postulated to be involved in imprint control. Thus, invasive placentation and gestational fetal growth are not required for imprinted genes to evolve. Unless there was convergent evolution of M6P/ IGF2R imprinting and receptor IGF2 binding in marsupials and eutherians, our results also demonstrate that these two functions evolved in a mammalian clade exclusive of monotremes.
Keywords:
Amino Acid Sequence • Animals • Carrier Proteins • DNA, Complementary • Echidna • Evolution* • Genomic Imprinting* • Insulin-Like Growth Factor II • Introns • Male • Mammals • Molecular Sequence Data • Opossums • Platypus • Receptor, IGF Type 2 • Sequence Alignment • Sequence Analysis, DNA • Sequence Homology, Amino Acid • genetics • genetics* • metabolism*