title: Genomic imprinting of XX spermatogonia and XX oocytes recovered from XX<-->XY chimeric testes.
abstract: We produced XX<-->XY chimeras by using embryos whose X chromosomes were tagged with EGFP (X*), making the fluorescent green female (XX*) germ cells easily distinguishable from their nonfluorescent male (XY) counterparts. Taking advantage of tagging with EGFP, the XX* "prospermatogonia" were isolated from the testes, and the status of their genomic imprinting was examined. It was shown that these XX cells underwent a paternal imprinting, despite their chromosomal constitution. As previously indicated in sex-reversal XXsxr testes, we also found a few green XX* germ cells developed as "eggs" within the seminiferous tubules of XX*<-->XY chimeric testes. These cells were indistinguishable from XX* prospermatogonia at birth but resumed oogenesis in a testicular environment. The biological nature of the "testicular eggs" was examined by recovering the eggs from chimeric testes. The testicular eggs not only formed an egg-specific structure, the zona pellucida, but also were able to fuse with sperm. The collected testicular eggs were indicated to undergo maternal imprinting, despite the testicular environment. The genomic imprinting did not always follow the environmental conditions of where the germ cells resided; rather, it was defined by the sex that was chosen by the germ cells at early embryonic stage.
authors.affiliation: Genome Information Research Center and Graduate School of Pharmaceutical Sciences, Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: Ayako
authors.initials: A
authors.lastname: Isotani
authors.forename: Tomoko
authors.initials: T
authors.lastname: Nakanishi
authors.forename: Shin
authors.initials: S
authors.lastname: Kobayashi
authors.forename: Jiyoung
authors.initials: J
authors.lastname: Lee
authors.forename: Shinichiro
authors.initials: S
authors.lastname: Chuma
authors.forename: Norio
authors.initials: N
authors.lastname: Nakatsuji
authors.forename: Fumitoshi
authors.initials: F
authors.lastname: Ishino
authors.forename: Masaru
authors.initials: M
authors.lastname: Okabe
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000235:genetics / Q000502:physiology; D002678:Chimera / Q000235:genetics*; D005260:Female; D018392:Genomic Imprinting; D008297:Male; D051379:Mice; D009865:Oocytes / Q000502:physiology*; D019849:Sex Determination Processes; D013093:Spermatogonia / Q000166:cytology / Q000502:physiology*; D013737:Testis / Q000502:physiology*; D014960:X Chromosome / Q000502:physiology; D014998:Y Chromosome / Q000502:physiology
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