title: Frequency of sex chromosomal mosaicism in bovine embryos and its effects on sexing using a single blastomere by PCR.
abstract: Assessment of nuclear status is important when a biopsied single blastomere is used for embryo sexing. In this study we investigated the nuclear status of blastomeres derived from 8- to 16-cell stage in vitro fertilised bovine embryos to determine the representativeness of a single blastomere for embryo sexing. In 24 embryos analysed, the agreement in sex determination between a biopsied single blastomere and a matched blastocyst by polymerase chain reaction (PCR) was 83.3%. To clarify the discrepancies, karyotypes of blastomeres in 8- to 16-cell stage bovine embryos were analysed. We applied vinblastine sulfate at various concentrations and for different exposure times for metaphase plate induction in 8- to 16-cell stage bovine embryos. The 1.0 mg/ml vinblastine sulfate treatment for 15 h was selected as the most effective condition for induction of a metaphase plate (> 45%). Among 22 embryos under these conditions, only 8 of 10 that had a normal diploid chromosome complement showed a sex chromosomal composition of XX or XY (36.4%) and 2 diploid embryos showed mosaicism of the opposite sex of XX and XY in blastomeres of the embryo (9.1%). One haploid embryo contained only one X-chromosome (4.5%). Four of another 11 embryos with a mixoploid chromosomal complement contained a haploid blastomere with a wrong sex chromosome (18.2%). In conclusion, assessment of nuclear status of 8- to 16-cell stage bovine embryos revealed that morphologically normal embryos had a considerable proportion of mixoploid blastomeres and sex chromosomal mosaicism; these could be the cause of discrepancies in the sex between biopsied single blastomeres and matched blastocysts by PCR.
authors.affiliation: Institute of Animal Science and Technology, College of Agriculture and Life Sciences, Seoul National University, Suwon, Korea.
authors.forename: Jong Ho
authors.initials: JH
authors.lastname: Lee
authors.forename: Joong Hoon
authors.initials: JH
authors.lastname: Park
authors.forename: Eun Joo
authors.initials: EJ
authors.lastname: Choi
authors.forename: Jong Taek
authors.initials: JT
authors.lastname: Yoon
authors.forename: Chang Sik
authors.initials: CS
authors.lastname: Park
authors.forename: Seong Ho
authors.initials: SH
authors.lastname: Lee
authors.forename: Kyung Soon
authors.initials: KS
authors.lastname: Im
authors.forename: Dong Il
authors.initials: DI
authors.lastname: Jin
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000187:drug effects / Q000502:physiology*; D001757:Blastomeres / Q000187:drug effects / Q000502:physiology*; D002417:Cattle; D004305:Dose-Response Relationship, Drug; D005260:Female; D005307:Fertilization in Vitro; D008297:Male; D008677:Metaphase / Q000187:drug effects; D009030:Mosaicism / Q000235:genetics*; D016133:Polymerase Chain Reaction; D012730:Sex Chromosomes; D012732:Sex Determination Analysis; D014747:Vinblastine / Q000494:pharmacology
chemical_list: D014747:Vinblastine