The absence of a Ca2+ signal during mouse egg activation can affect parthenogenetic preimplantation development, gene expression patterns, and blastocyst quality

N. T. Rogers, G. Halet, Y. Piao, J. Carroll, M. S.H. Ko, K. Swann

Research output: Contribution to journalArticle

49 Citations (Scopus)

Abstract

A series of Ca2+ oscillations during mammalian fertilization is necessary and sufficient to stimulate meiotic resumption and pronuclear formation. It is not known how effectively development continues in the absence of the initial Ca2+ signal. We have triggered parthenogenetic egg activation with cycloheximide that causes no Ca2+ increase, with ethanol that causes a single large Ca2+ increase, or with Sr2+ that causes Ca2+ oscillations. Eggs were co-treated with cytochalasin D to make them diploid and they formed pronuclei and two-cell embryos at high rates with each activation treatment. However, far fewer of the embryos that were activated by cycloheximide reached the blastocyst stage compared to those activated by Sr2+ or ethanol. Any cycloheximide-activated embryos that reached the blastocyst stage had a smaller inner cell mass number and a greater rate of apoptosis than Sr2+ -activated embryos. The poor development of cycloheximide-activated embryos was due to the lack of Ca2+ increase because they developed to blastocyst stages at high rates when co-treated with Sr2+ or ethanol. Embryos activated by either Sr2+ or cycloheximide showed similar signs of initial embryonic genome activation (EGA) when measured using a reporter gene. However, microarray analysis of gene expression at the eight-cell stage showed that activation by Sr2+ leads to a distinct pattern of gene expression from that seen with embryos activated by cycloheximide. These data suggest that activation of mouse eggs in the absence of a Ca2+ signal does not affect initial parthenogenetic events, but can influence later gene expression and development.

Original languageEnglish
Pages (from-to)45-57
Number of pages13
JournalReproduction
Volume132
Issue number1
DOIs
Publication statusPublished - 2006 Jul

ASJC Scopus subject areas

  • Reproductive Medicine
  • Embryology
  • Endocrinology
  • Obstetrics and Gynaecology
  • Cell Biology

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