title: Disparate consequences of heat stress exposure during meiotic maturation: embryo development after chemical activation vs fertilization of bovine oocytes.
abstract: Consequences of heat stress exposure during the first 12 h of meiotic maturation differed depending on how and when bovine oocytes were activated. If heat-stressed oocytes underwent IVF at ~24 h, blastocyst development was less than for respective controls and similar to that obtained for nonheat-stressed oocytes undergoing IVF at 30 h (i.e. slightly aged). In contrast, if heat-stressed oocytes underwent chemical activation with ionomycin/6-dimethylaminopurine at 24 h, blastocyst development was not only higher than respective controls, but also equivalent to development obtained after activation of nonheat-stressed oocytes at 30 h. Developmental differences in chemically activated vs IVF-derived embryos were not related to fertilization failure or gross alterations in cytoskeletal components. Rather, ionomycin-induced calcium release and MAP kinase activity were less in heat-stressed oocytes. While underlying mechanisms are multifactorial, ability to obtain equivalent or higher development after parthenogenetic activation demonstrates that oocytes experiencing heat stress during the first 12 h of meiotic maturation have the necessary components to develop to the blastocyst stage, but fail to do so after fertilization.
authors: Department of Animal Science, Institute of Agriculture, UT AgResearch, The University of Tennessee, Knoxville, Tennessee 37996-4574, USA.
authors: L A
authors: LA
authors: Rispoli
authors: J L
authors: JL
authors: Lawrence
authors: R R
authors: RR
authors: Payton
authors: A M
authors: AM
authors: Saxton
authors: G E
authors: GE
authors: Schrock
authors: F N
authors: FN
authors: Schrick
authors: B W
authors: BW
authors: Middlebrooks
authors: J R
authors: JR
authors: Dunlap
authors: J J
authors: JJ
authors: Parrish
authors: J L
authors: JL
authors: Edwards
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism; D000225:Adenine / Q000031:analogs & derivatives / Q000494:pharmacology; D000375:Aging / Q000502:physiology; D000818:Animals; D002118:Calcium / Q000378:metabolism; D061207:Calcium Ionophores / Q000494:pharmacology; D002417:Cattle; D047108:Embryonic Development / Q000187:drug effects; D005260:Female; D005306:Fertilization; D005307:Fertilization in Vitro; D006358:Hot Temperature; D015759:Ionomycin / Q000494:pharmacology; D016200:Maturation-Promoting Factor / Q000378:metabolism; D008540:Meiosis; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D009865:Oocytes / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism
chemical_list: D061207:Calcium Ionophores; D015759:Ionomycin; C001020:N(6),N(6)-dimethyladenine; D016200:Maturation-Promoting Factor; D020928:Mitogen-Activated Protein Kinases; D000225:Adenine; D002118:Calcium