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Modification of actions of heat shock on development and apoptosis of cultured preimplantation bovine embryos by oxygen concentration and dithiothreitol
Author(s) -
de Castro e Paula L.A.,
Hansen P.J.
Publication year - 2008
Publication title -
molecular reproduction and development
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.745
H-Index - 105
eISSN - 1098-2795
pISSN - 1040-452X
DOI - 10.1002/mrd.20866
Subject(s) - biology , embryo , blastocyst , dithiothreitol , andrology , embryogenesis , reactive oxygen species , oxygen , apoptosis , shock (circulatory) , heat shock protein , microbiology and biotechnology , biochemistry , chemistry , medicine , organic chemistry , gene , enzyme
Preimplantation embryos exposed to elevated temperatures have reduced developmental competence. The involvement of reactive oxygen species in these effects has been controversial. Here we tested hypotheses that (1) heat shock effects on development and apoptosis would be greater when embryos were cultured in a high oxygen environment (air; oxygen concentration = ∼20.95%, v/v) than in a low oxygen environment (5% oxygen) and (2) that these effects would be reversed by addition of the antioxidant dithiothreitol (DTT). Heat shock of 41°C for 9 hr reduced development of two‐cell embryos and Day 5 embryos to the blastocyst stage embryos when in high oxygen. There was no effect of heat shock on development when embryos were in low oxygen. Furthermore, induction of TUNEL‐positive cells in Day 5 embryos by heat shock only occurred when embryos were in high oxygen. Addition of DTT to two‐cell embryos either did not reduce effects of a heat shock of 41°C for 15 hr on development or caused slight protection only. In contrast, treatment of Day 5 embryos with DTT reduced effects of heat shock on development and apoptosis. In summary, oxygen tension was shown to be a major determinant of the effects of heat shock on development and apoptosis in preimplantation bovine embryos. Protective effects of the antioxidant DTT were stage specific and more pronounced at later stages of development. Mol. Reprod. Dev. 75: 1338–1350, 2008. © 2008 Wiley‐Liss, Inc.