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Effect of heat stress during in vitro maturation on developmental competence of vitrified bovine oocytes
Author(s) -
VendrellFlotats M,
Arcarons N,
Barau E,
LópezBéjar M,
Mogas T
Publication year - 2017
Publication title -
reproduction in domestic animals
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.546
H-Index - 66
eISSN - 1439-0531
pISSN - 0936-6768
DOI - 10.1111/rda.13055
Subject(s) - in vitro maturation , vitrification , blastocyst , andrology , oocyte , hsp70 , cryopreservation , chemistry , embryo , embryogenesis , heat shock protein , biology , microbiology and biotechnology , biochemistry , medicine , gene
Contents Heat‐shock protein 70 ( HSP 70) plays a crucial role as intracellular cytoprotectant and molecular chaperone. A phenomenon of heat stress ( HS ) leads to production of these proteins that could be beneficial to cells during cryopreservation, which is also a stressful process for the cell. This study aimed to evaluate the protective effect of exposure of bovine oocytes to moderate HS during in vitro maturation ( IVM ) prior vitrification. First, oocytes were subjected to HS (41.5°C for 1 hr) at 0, 4, 8, 12 or 16 of IVM . Oocytes in vitro matured for 20 hr served as control group. Presence of HSP 70 was detected at 20 hr by immunofluorescence. HSP 70 expression was significantly higher when oocytes were subjected to HS at 8 hr of IVM . Next, oocytes were distributed into four groups: Control: IVM oocytes; VIT : oocytes vitrified/warmed at 20 hr of IVM ; HS : oocytes subjected to HS at 8 hr of IVM ; HS ‐ VIT : oocytes subjected to HS at 8 hr of IVM and vitrified/warmed at 20 hr of IVM . Oocytes were fertilized at 24 hr of IVM , and cleavage and blastocyst yield were assessed. No significant differences were observed among treatments when cleavage rate was evaluated. However, fresh control and HS oocytes resulted in a significantly higher ( p < .05) blastocyst rate when compared to VIT and HS ‐ VIT groups, although no significant differences within fresh or vitrified groups were observed. In conclusion, HS did not have a negative impact on the oocyte competence but HS applied before vitrification, offered no benefits for embryo development.