Bovine abnormal preimplantation embryos: analysis of segregated cells occurring in the subzonal space and/or blastocoele cavity for their nuclear morphology and persistence of RNA synthesis

Abstract

Bovine embryos in the early blastocyst/blastocyst stage were analysed by [5-3H]uridine labelling followed by electron microscopic autoradiography. In normal control embryos an intact zona pellucida, evenly developed blastomeres and a transparent perivitelline space were seen. In this group, the blastomeres of the trophoblast and embryoblast showed high homogeneous labelling localised in the nucleoplasm and even more intense labelling in the nucleolus. On the contrary, in addition to evident cytoplasmic disintegration, a clearly different labelling pattern and a low labelling intensity were observed in the nuclei of the segregated cells in the subzonal space and in those free in the blastocoele cavity. A typical nuclear morphological feature of these blastomeres was chromatin marginalisation, similar to that observed in embryos treated with actinomycin D for transcription inhibition. It is concluded that the segregated cells are arrested in their further differentiation.

Gene Expression in Mouse Preimplantation Embryos Affected by Apoptotic Inductor Actinomycin D

“…Mouse preimplantation embryonic cells treated with high concentrations of actinomycin D also show massive appearance of cell death with characteristic signs of apoptosis: chromatin marginalization, degeneration of cytoplasm, nuclear fragmentation, specific DNA degradation, phosphatidylserine flip and activation of caspase 3 [2,[13][14][15], which was also documented in the present study. The inhibition of rRNA synthesis after treatment with high concentrations of actinomycin D has also been demonstrated in porcine and bovine blastocysts [15,35].…”

“…It is an antibiotic that is able to bind DNA duplexes and inhibit RNA synthesis. The ability of actinomycin D to induce apoptosis in mouse, bovine, rabbit and Xenopus laevis preimplantation embryos has been demonstrated previously [2,[13][14][15][16]. Furthermore, when compared with TNF-α, actinomycin D shows higher efficiency and a stronger and quicker inducing effect accompanied by low variability in its effectiveness [2].…”

Apoptotic processes and DNA cytosine methylation in mouse embryos arrested at the 2-cell stage

“…The ability of α-amanitin to arrest embryonic development in mouse early embryos (Han et al ., 2005; Zeng & Schultz, 2005) and the ability of both actinomycin D (Pivko et al ., 2002; Ju et al ., 2005; Fabian et al ., 2007a) and TNF-α (Pampfer et al ., 1994; Wuu et al ., 1999) to induce apoptosis in mouse blastocysts have been demonstrated previously.…”

Dose- and time-dependent effects of TNFα and actinomycin D on cell death incidence and embryo growth in mouse blastocysts

“…Experimental treatment of porcine embryos with actinomycin D at low doses evenly caused the selective inhibition of rRNA synthesis. Higher concentrations completely inhibited RNA synthesis in porcine embryos and bovine blastocysts (Tomanek et al ., 1986; Pivko et al ., 2002). A typical nuclear morphology feature of blastomeres in bovine embryos treated with actinomycin D was chromatin marginalization and degeneration of cytoplasm, characteristic signs of apoptosis (Pivko et al ., 2002).…”

“…Higher concentrations completely inhibited RNA synthesis in porcine embryos and bovine blastocysts (Tomanek et al ., 1986; Pivko et al ., 2002). A typical nuclear morphology feature of blastomeres in bovine embryos treated with actinomycin D was chromatin marginalization and degeneration of cytoplasm, characteristic signs of apoptosis (Pivko et al ., 2002). Moreover, actinomycin D injected into the blastocoel of Xenopus laevis embryos extensively reduced the transcription of DNA and higher amounts of injected actinomycin D resulted in embryonic death (van der Velden et al ., 2000).…”