title: Ooplast-mediated developmental rescue of bovine oocytes exposed to ethidium bromide.
abstract: Ooplasm transfer has been used successfully to treat infertility in women with ooplasmic insufficiency and has culminated in the birth of healthy babies. To investigate whether mitochondrial dysfunction is a factor in ooplasmic insufficiency, bovine oocytes were exposed to ethidium bromide, an inhibitor of mitochondrial DNA replication and transcription, during in-vitro maturation (IVM). Exposure of immature oocytes to ethidium bromide for 24h during IVM hampered meiotic resumption and the migration of cortical granules. However, a briefer treatment with ethidium bromide during the last 4h of IVM led to partial arrest of preimplantation development without affecting oocyte maturation. Ooplasm transfer was then performed to rescue the oocytes with impaired development. In spite of this developmental hindrance, transfer of normal ooplasm into ethidium bromide-treated oocytes resulted in a complete rescue of embryonic development and the birth of heteroplasmic calves. Although this study unable to determine whether developmental rescue occurred exclusively through introduction of unaffected mitochondria into ethidium bromide-damaged oocytes, e.g. ethidium bromide may also affect other ooplasm components, these results clearly demonstrate that ooplasm transfer can completely rescue developmentally compromised oocytes, supporting the potential use of ooplasm transfer in therapeutic applications.
authors.affiliation: Departamento de Ciências Básicas, Faculdade de Zootecnia e Engenharia de Alimentos, Universidade de São Paulo, Pirassununga, São Paulo, Brazil. chiarattimr@gmail.com
authors.forename: Marcos Roberto
authors.initials: MR
authors.lastname: Chiaratti
authors.forename: Christina Ramires
authors.initials: CR
authors.lastname: Ferreira
authors.forename: Felipe
authors.initials: F
authors.lastname: Perecin
authors.forename: Simone Cristina
authors.initials: SC
authors.lastname: Méo
authors.forename: Juliano Rodrigues
authors.initials: JR
authors.lastname: Sangalli
authors.forename: Lígia Garcia
authors.initials: LG
authors.lastname: Mesquita
authors.forename: Júlio César
authors.initials: JC
authors.lastname: de Carvalho Balieiro
authors.forename: Lawrence Charles
authors.initials: LC
authors.lastname: Smith
authors.forename: Joaquim Mansano
authors.initials: JM
authors.lastname: Garcia
authors.forename: Flávio Vieira
authors.initials: FV
authors.lastname: Meirelles
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002417:Cattle; D003593:Cytoplasm / Q000378:metabolism / Q000637:transplantation*; D047108:Embryonic Development / Q000187:drug effects; D004996:Ethidium / Q000494:pharmacology*; D005260:Female; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects / Q000502:physiology; D009865:Oocytes / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism
chemical_list: D000255:Adenosine Triphosphate; D004996:Ethidium