Protein synthesis and phosphorylation by elongating 13-15-day-old cattle blastocysts.
Most early embryonic loss in cattle occurs during the period of blastocyst formation and elongation. In this study de novo protein synthesis and phosphorylation by 13-15-day-old cattle blastocysts was determined. Blastocysts were classified by dimension into spherical, ovoid and elongated stages and cultured under oil for 4 h in drops of KSOM medium containing either 35S-methionine or 32P-orthophosphate. Protein content increased with shape from spherical to ovoid to elongated. There were differences (P<0.05) within and among days in the percentage of radiolabel incorporated. Incorporation of 35S-methionine increased with embryo protein content. However, incorporation of 35S-methionine into TCA-insoluble material, expressed per microg of protein, decreased with shape (P<0.001) with more than a 10-fold difference between spherical and elongated 13-day-old blastocysts. Incorporation of 32P-orthophosphate also tended to decrease with shape, with a 3-fold difference between spherical and elongated Day 13 blastocysts. It was concluded that, from Day 13, protein synthesis and phosphorylation, when expressed per unit of protein, decreased from a much higher level, which in the present study was around the time the blastocysts began to elongate.
Morris
D G
DG
Animal Reproduction Department, Teagasc, Agriculture and Food Development Authority, Athenry, Co. Galway, Ireland. dmorris@athenry.teagasc.ie
Diskin
M G
MG
Sreenan
J M
JM
D000818:Animals; D001755:Blastocyst / Q000378:metabolism*; D002417:Cattle / Q000196:embryology*; D046508:Culture Techniques; D005260:Female; D005865:Gestational Age; D008715:Methionine / Q000378:metabolism; D010710:Phosphates / Q000378:metabolism; D010761:Phosphorus Radioisotopes; D010766:Phosphorylation; D011247:Pregnancy; D014176:Protein Biosynthesis; D013462:Sulfur Radioisotopes
D010710:Phosphates; D010761:Phosphorus Radioisotopes; D013462:Sulfur Radioisotopes; D008715:Methionine