Analysis of thymidine kinase gene expression in preimplantation mouse embryos

Kee Lee Dae Kee Lee, Woong Sun, K. Rhee, H. Cho, Choo Lee Chung Choo Lee, K. Kim

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Thymidine kinase (TK) activity was examined during the development of preimplantation mouse embryos. TK activity was increased approximately 20- fold from day 2 embryos (2-cell) to day 5 embryos (late blastocyst). TK activity did not change along with the progression into S-phase of the first and the second cell cycles but increased sharply at S-phase of the third cell cycle. Analysis of TK mRNA with a reverse transcription-polymerase chain reaction (RT-PCR) method showed that the level of TK mRNA was low in ovulated eggs and 1-cell embryos and was hardly detectable in day 2 embryos (2-cell), but sharply increased in day 3 embryos (mixture of 5- to 8-cell and morula). The functional role of 5'-flanking sequence of TK gene was also investigated in preimplantation embryos after microinjection with the DNA construct of 5'- flanking sequence of TK (2.4 kb) linked to bacterial lacZ gene (TK2.5lacZ) into the pronucleus of 1-cell and subsequently by histochemical staining with X-gal. β-Galactosidase activity was first detected in day 3 embryos (8- cell), and 30% of embryos were stained with X-gal in day 4 and day 5 embryos, respectively. These results show that an increase in TK activity occurred after 2-cell stage, and this increase was primarily due to the embryonic activation of TK gene expression. Also, it appears that the 5'-flanking sequence of TK may directly regulate the TK gene expression at the transcriptional level during preimplantation murine development.

Original languageEnglish
Pages (from-to)259-267
Number of pages9
JournalMolecular Reproduction and Development
Issue number3
Publication statusPublished - 1994 Nov 17
Externally publishedYes



  • Cell cycle
  • Embryonic gene expression
  • Preimplantation mouse embryos
  • Thymidine kinase

ASJC Scopus subject areas

  • Genetics
  • Developmental Biology
  • Cell Biology

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