title: Increase in DNA fragmentation and apoptosis-related gene expression in frozen-thawed bovine blastocysts.
abstract: Evaluation of apoptosis and expression level of apoptosis-related genes is useful for examining the variation in embryo quality according to environmental change. The objective of this study was to investigate DNA fragmentation and apoptosis-related gene expression patterns in frozen-thawed bovine blastocysts. In vitro produced day 7 blastocysts were frozen by two different vitrification methods (conventional 0.25 ml straw or MVC straw). After thawing, DNA fragmentation of surviving embryos was examined by TUNEL assay, and the expression patterns of their apoptotic genes (survivin, Fas, Hsp 70 and caspase-3) were evaluated using real-time quantitative reverse transcriptase polymerase chain reaction. In vitro survival rates of frozen-thawed embryos were higher following the MVC vitrification method (88.2% re-expanded at 24 h, 77.1% hatching at 48 h) than the conventional (C) vitrification method (77.0% re-expanded at 24 h, 66.7% hatching at 48 h). However, both vitrified methods resulted in a significantly higher apoptotic index (C vitrification method 11.9%, MVC vitrification method 11.0%) than in non-frozen embryos (3.0%). Expression levels of survivin, Fas, caspase-3, and Hsp 70 were also increased in the frozen-thawed embryos compared with non-frozen embryos. These results indicate that the cryopreservation procedure might cause damage that results in an increase in DNA fragmentation and apoptosis-related gene transcription, reducing developmental capacity of frozen-thawed embryos.
authors.affiliation: Maria Infertility Hospital Medical Institute/Maria Biotech, Seoul 130-812, Korea. sppark@mariababy.com
authors.forename: Sae Young
authors.initials: SY
authors.lastname: Park
authors.forename: Eun Young
authors.initials: EY
authors.lastname: Kim
authors.forename: Xiang Shun
authors.initials: XS
authors.lastname: Cui
authors.forename: Jin Cheol
authors.initials: JC
authors.lastname: Tae
authors.forename: Won Don
authors.initials: WD
authors.lastname: Lee
authors.forename: Nam Hyung
authors.initials: NH
authors.lastname: Kim
authors.forename: Se Pill
authors.initials: SP
authors.lastname: Park
authors.forename: Jin Ho
authors.initials: JH
authors.lastname: Lim
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D001755:Blastocyst / Q000378:metabolism* / Q000502:physiology; D002417:Cattle; D002478:Cells, Cultured; D015925:Cryopreservation; D053938:DNA Fragmentation; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*