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Frequency of sex chromosomal mosaicism in bovine embryos and its effects on sexing using a single blastomere by PCR

Published online by Cambridge University Press:  14 February 2003

Jong Ho Lee
Affiliation:
Institute of Animal Science and Technology, College of Agriculture and Life Sciences, Seoul National University, Suwon 441-744, Korea
Joong Hoon Park
Affiliation:
Institute of Animal Science and Technology, College of Agriculture and Life Sciences, Seoul National University, Suwon 441-744, Korea
Eun Joo Choi
Affiliation:
Institute of Genetic Engineering, College of Agriculture, Hankyong National University, Ansung, Korea
Jong Taek Yoon
Affiliation:
Institute of Genetic Engineering, College of Agriculture, Hankyong National University, Ansung, Korea
Chang Sik Park
Affiliation:
Division of Animal Science and Resources, Chungnam National University, Daejeon, Korea
Seong Ho Lee
Affiliation:
College of Visual Image & Health, Kongju National University, Kongju City, Korea
Kyung Soon Im
Affiliation:
Institute of Animal Science and Technology, College of Agriculture and Life Sciences, Seoul National University, Suwon 441-744, Korea
Dong Il Jin
Affiliation:
Department of Applied Biological Science, Sunmoon University, Asan City, 338-840, Korea

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.

Type
Research Article
Copyright
2003 Cambridge University Press

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