02073naa a2200241 a 450000100080000000500110000800800410001902400450006010000250010524501190013026000090024952013600025865300210161865300150163970000220165470000150167670000180169170000210170970000170173070000170174770000170176477300500178121185792024-02-06       2019    bl uuuu     u00u1 u    #d7 ahttps://doi.org/10.1530/REP-19-02452DOI1 aCAMARGO, L. S. de A.  aHeat shock during in vitro maturation induces chromatin modifications in the bovine embryo.h[electronic resource]  c2019  aHeat stress compromises bovine oocyte developmental competence but the effects of high temperature during oocyte maturation on embryo chromatin organization is unknown. In this study bovine oocytes were exposed to heat shock (41°C) for 12h during in vitro maturation and then submitted to in vitro fertilization. The heat shock did not affect (P&gt0.05) the cleavage but reduced (P&lt0.01) the blastocyst rate on Day 7 and Day 8. No effect (P&gt0.05) on total cell number was found but the heat shock increased (P&lt0.05) the proportion of apoptotic cells in blastocysts at Day 8. Immunofluorescence analysis of H3K9me3 and HP1 was performed in embryos at 52 h post in vitro fertilization. An accumulation of H3K9me3 in the nuclei of embryos derived from heat-shocked oocytes at 4-cell and 8-cell stages was found. Also, a non-expected higher proportion (P&lt0.05) of 4-cell stage embryos displaying nuclei with increased HP1 fluorescence was observed, suggesting an abnormal chromatin compaction in embryos from heat-shocked oocytes. Embryos at 8-cell stage derived from heat-shocked oocytes displayed lower (P&lt0.05) relative amount of HSP40 transcripts than control ones. In conclusion, heat shock before fertilization has an effect on embryo chromatin, influencing the accumulation of H3K9me3 and HP1 in early embryos as well as further development.  aEmbryo chromatin  aHeat shock1 aAGUIRRE-LAVIN, T.1 aADENOT, P.1 aARAUJO, T. D.1 aMENDES, V. R. A.1 aLOURO, I. D.1 aBEAUJEAN, N.1 aSOUZA, E. D.  tReproductiongv. 158, n. 4, p. 313-322, 2019.