Regulation of blastocyst stage gene expression and outgrowth interferon tau activity of somatic cell clone aggregates

Area of Science:

• * Reproductive biology
• * Developmental biology
• * Genetics

Background:

• * Mammalian somatic cell cloning exhibits inefficiencies linked to abnormal gene expression due to reprogramming errors.
• * In mice, aggregating four-cell stage clones improves gene expression and development.
• * The impact of clone aggregation at later developmental stages on bovine embryos remains unclear.

Purpose of the Study:

• * To investigate if aggregating bovine clones at the blastocyst stage influences gene expression.
• * To assess the effect of clone aggregation on trophectoderm function as a marker of developmental potential.

Main Methods:

• * Profiling gene expression (Oct4, Dnmt1, Dnmt3, Glut1, Glut3, PolyA) in single and aggregated bovine cloned embryos at the blastocyst stage using real-time RT-PCR.
• * Comparing gene expression patterns to in vitro fertilization (IVF) embryos.
• * Analyzing interferon tau bioactivity in blastocyst outgrowths to evaluate trophectoderm function.

Main Results:

• * Individual bovine clones showed more frequent significant deviations in gene expression compared to IVF embryos.
• * Aggregation reduced these deviations for Oct4, Dnmt1, Dnmt3, and PolyA, but not Glut1 or Glut3.
• * Both single clones and aggregates exhibited reduced in vitro extraembryonic potential compared to IVF embryos, with no benefit from aggregation.

Conclusions:

• * Aggregating bovine clones at the blastocyst stage alters preimplantation gene expression patterns.
• * Clone aggregation does not rescue impaired trophectoderm function in vitro.
• * Later stage aggregation may partially correct gene expression but does not fully restore developmental potential in bovine clones.