Frequency of sex chromosomal mosaicism in bovine embryos and its effects on sexing using a single blastomere by PCR.
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.
Lee
Jong Ho
JH
Institute of Animal Science and Technology, College of Agriculture and Life Sciences, Seoul National University, Suwon, Korea.
Park
Joong Hoon
JH
Choi
Eun Joo
EJ
Yoon
Jong Taek
JT
Park
Chang Sik
CS
Lee
Seong Ho
SH
Im
Kyung Soon
KS
Jin
Dong Il
DI
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
D014747:Vinblastine