title: Restricted development of mouse triploid fetuses with disorganized expression of imprinted genes.
abstract: Eukaryotic species commonly contain a diploid complement of chromosomes. The diploid state appears to be advantageous for mammals because it enables sexual reproduction and facilitates genetic recombination. Nonetheless, the effects of DNA ploidy on mammalian ontogeny have yet to be understood. The present study shows phenotypic features and expression patterns of imprinted genes in tripronucleate diandric and digynic triploid (DAT and DGT) mouse fetuses on embryonic day 10.5 (E10.5). Measurement of crown-rump length revealed that the length of DGT fetuses (1.87 ± 0.13 mm; mean ± standard error of the mean) was much smaller than that of diploid fetuses (4.81 ± 0.05 mm). However, no significant difference was observed in the crown-rump length between diploid and DAT fetuses (3.86 ± 0.43 mm). In DGT fetuses, the expression level of paternally expressed genes, Igf2, Dlk1, Ndn, and Peg3, remained significantly reduced and that of maternally expressed genes, Igf2r and Grb10, increased. Additionally, in DAT fetuses, the Igf2 mRNA expression level was approximately twice that in diploid fetuses, as expected. These results provide the first demonstration that imprinted genes in mouse triploid fetuses show distinctive expression patterns independent of the number of parental-origin haploid sets. These data suggest that both DNA ploidy and asymmetrical functions of parental genomes separately influence mammalian ontogeny.
authors.affiliation: Laboratory of Animal Breeding and Reproduction,Graduate School of Agriculture,Hokkaido University,Sapporo 060-8589,Japan.
authors.forename: Wataru
authors.initials: W
authors.lastname: Yamazaki
authors.affiliation: Laboratory of Animal Breeding and Reproduction,Graduate School of Agriculture,Hokkaido University,Sapporo 060-8589,Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Takahashi
authors.affiliation: Laboratory of Animal Breeding and Reproduction,Graduate School of Agriculture,Hokkaido University,Sapporo 060-8589,Japan.
authors.forename: Manabu
authors.initials: M
authors.lastname: Kawahara
mesh_terms: D000818:Animals; D004624:Embryo Transfer; D047108:Embryonic Development / Q000235:genetics; D005260:Female; D005307:Fertilization in Vitro; D005333:Fetus / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental; D018392:Genomic Imprinting; D008297:Male; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D010312:Parthenogenesis; D057885:Triploidy
keywords: Fetal growth; Gene expression; Genomic imprinting; Triploid