【摘 要】
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During mammalian embryonic development,DNA methylation and histone modifications are important in geneexpression regulation and epigenetic reprogramming.In cloned embryos,high levels of DNA methylatio
【机 构】
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The Key Laboratory of Mammalian Reproductive Biology and Biotechnology of the Ministry of Education,
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During mammalian embryonic development,DNA methylation and histone modifications are important in geneexpression regulation and epigenetic reprogramming.In cloned embryos,high levels of DNA methylation andabnormal demethylation were widely observed during the preimplantation period.Little is known about anydifferences in histone modifications between in vitro fertilized (IVF) and cloned embryos during preimplantationdevelopment.In the present study,the distributions and intensity patterns of acetylations in H3 lysine 9,18,and H4lysine 8,5 and tri-methyl-lysine 4,dimethyl-lysine 9 in histone H3 were analysized in cloned and IVF bovinepreimplantation embryos by using indirect immunofluorescence and scanning confocal microscopy.The resultsindicated that the acetylations and methylations of H3K9ac,H3K18ac,H4K5ac,H4K8ac,H3K4me3 and H3K9me2were at high levels in the cloned embryos from the pronuclear to 8-cell stage as compared to IVF embryos atcomparable stages of development.Localization of H4K8ac and H4K5ac in the cloned embryos was abnormal whencompared to the IVF controls.At the blastocyst stage,the distribution and intensity patterns of all of the histonemodifications examined were comparable between cloned and IVF embryos.These results indicated that aberranthistone modifications were observed in cloned embryos prior to donor nuclei genome activation.After zygoticgenome activation,distributions and intensity patterns of histone modifications were comparable in both the clonedand IVF embryos.
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