Development and de novo protein synthetic activity of bovine embryos produced in vitro in different culture systems

In vitro matured (IVM) and fertilized (IVF) putative Day 1 zygotes (Day 0 = IVF) were allocated randomly to culture in formulations based on Synthetic Oviduct Fluid (SOF) medium and identified on the basis of their contrastin g principal supplements, which were 10% v/v steer serum (SS; n = 558) or 4 mg/mL crystalline BSA (SBSA; n = 531) or 3 mg/mL polyvinyl alcohol (SPVA; n = 607) in 9 replicates. SBSA and SPVA also contained 10 mug/mL non-essenti al amino acids, while the former was further supplemented with 20 muL/mL es sential amino acids and the latter with 0.5 mmol/L sodium citrate and 5 ng/ mL epidermal growth factor. Zygotes were cultured in 20 muL drops (4 zygote s per drop) until Day 8 in an atmosphere of 5% CO2, 5% O-2 and 90% N-2 at 3 9 degreesC and droplets were renewed every 48 hours. The incidence of zygot e cleavage was lower (P < 0.05) in SS (mean +/- SEM = 61 +/- 3%) than in SB SA (76 +/- 3%) but not in SPVA (72 +/- 4%) up to Day 3. The SPVA generated a lower yield of blastocysts on Day 7 (12 +/- 2%; P < 0.001) and by Day 8 ( 21 +/- 4%; P < 0.01) than did SS (33 +/- 3%; 40 +/- 3%) and SBSA (30 +/- 3% ; 37 +/- 4%). Cell numbers (n) and diameters (d) of blastocysts on Day 8 we re greater (P < 0.001; Replicates 1 to 5) in embryos from SBSA. (n, 156 +/- 9; d, 203 +/- 4 mum) than in those from SS (n, 81 +/- 4; d, 177 +/- 3 mum) and SPVA (n, 76 +/- 5; d, 167 +/- 3 mum). Embryos produced in SS incorpora ted less H-3-phenylalanine into PCA-precipitable protein (replicates 6 to 9 ; log(10) dpm = 3.03 +/- 0.04) than did embryos cultured in SBSA (3.21 +/- 0.03; P < 0.001) or in SPVA (3.14 +/- 0.03; NS). In conclusion, blastocyst yield was poor in SPVA, but the embryos had metabolic activities similar to those of embryos produced in SBSA. Blastocyst yields from SS were not comp romised but their capacity for de novo protein synthesis was reduced signif icantly. (C) 2001 by Elsevier Science Inc.