title: In vitro manipulation of mammalian preimplantation embryos can alter transcript abundance of histone variants and associated factors.
abstract: Manipulation of mammalian embryos and gametes in vitro reduces viability. Specific causes for these reductions are still largely undetermined. Accumulating evidence suggests that survival rates and developmental competency may be reduced following disruptions in the epigenetic regulation of gene expression. Chromatin-based epigenetics can regulate the transcriptome through the establishment of different transcriptionally permissive and repressive chromatin environments. Recently, support has been gathering for the hypothesis that the in vitro embryo displays reduced viability due to abnormal remodelling of the paternal chromatin, which is hypothesized to result in global transcriptional repression. In this study, we have used quantitative real-time PCR to document the effect of in vitro culture on the transcription of genes that code for proteins that are directly involved in the establishment of chromatin environments. We compare in vitro embryos to embryos generated through parthenogenetic activation to determine how the absence of paternal chromatin remodeling affects transcriptional activity. Through these studies, we show that the expression of many genes encoding for histone proteins and other modifiers involved in chromatin-based epigenetic regulation are perturbed by in vitro culture. In addition, we show that the expression of many candidate genes was reduced in in vitro embryos but not in parthenogenetic embryos. These results support the hypothesis that events linked to remodeling of paternal chromatin may influence transcriptional activity in the in vitro embryo and that chromatin-based reprogramming events in developing embryos are dynamically responsive to prevailing conditions.
authors.affiliation: CSIRO Food Futures National Research Flagship, Australia. g.kafer@uq.edu.au
authors.forename: Georgia R
authors.initials: GR
authors.lastname: Kafer
authors.forename: Peter L
authors.initials: PL
authors.lastname: Kaye
authors.forename: Marie
authors.initials: M
authors.lastname: Pantaleon
authors.forename: Ralf J
authors.initials: RJ
authors.lastname: Moser
authors.forename: Sigrid A
authors.initials: SA
authors.lastname: Lehnert
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000378:metabolism*; D002843:Chromatin / Q000378:metabolism*; D042002:Chromatin Assembly and Disassembly; D044127:Epigenesis, Genetic; D005260:Female; D018507:Gene Expression Regulation, Developmental; D006657:Histones / Q000096:biosynthesis*; D008297:Male; D051379:Mice; D014158:Transcription, Genetic
chemical_list: D002843:Chromatin; D006657:Histones