Effect of different sequential and two-step culture systems on the development, quality, and RNA expression profile of bovine blastocysts produced in vitro.

摘要

In the present study, we examined the effect of two-step and sequential culture systems on the development, quality, and gene expression profile of bovine embryos generated by in vitro fertilization. Presumptive zygotes were randomly allocated to four culture treatments: (1) KSOM[THIN SPACE]+[THIN SPACE]0.4% BSA for 3 days, and then KSOM[THIN SPACE]+[THIN SPACE]5% FBS to day 7 (K-K/FBS); (2) KSOM[THIN SPACE]+[THIN SPACE]0.1% BSA for 3 days, and then SOF[THIN SPACE]+[THIN SPACE]5% FBS to day 7 (K-S/FBS); (3) KSOM[THIN SPACE]+[THIN SPACE]0.1% BSA for 3 days, and then SOF[THIN SPACE]+[THIN SPACE]0.8% BSA to day 7 (K-S/BSA); and (4) KSOM[THIN SPACE]+[THIN SPACE]0.4% BSA for 3 days, and then KSOM[THIN SPACE]+[THIN SPACE]0.8% BSA to day 7 (K-K/BSA). Culture medium had no effect on cleavage rate. However, a significant difference (P[THIN SPACE]<[THIN SPACE]0.01) was observed with the two-step culture systems, yielding higher rate of blastocysts (37 and 32% for K-K/FBS and K-K/BSA, respectively) compared to sequential culture systems (26 and 28% for K-S/FBS and K-S/BSA, respectively). Embryos cultured in sequential K-S/FBS developed slowly, had a lower hatching rate, fewer cells, and a higher apoptosis rate compared to other treatments. Gene expression analysis showed alterations of DNMT1, OCT-4, and SOD2 in embryos cultured in sequential K-S/FBS and SOD1 in embryos cultured in two-step K-K/BSA. In conclusion, in vitro culture systems may have an impact not just in the developmental potential and quality of the generated embryos but also in the gene expression profile, which suggests that changes in the culture medium composition can modulate global gene expression. Copyright Copyright 2011 Wiley-Liss, Inc.