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Allele‐specific detection of nascent transcripts by fluorescence in situ hybridization reveals temporal and culture‐induced changes in Igf2 imprinting during pre‐implantation mouse development
Author(s) -
Ohno Mizuki,
Aoki Nao,
Sasaki Hiroyuki
Publication year - 2001
Publication title -
genes to cells
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.912
H-Index - 115
eISSN - 1365-2443
pISSN - 1356-9597
DOI - 10.1046/j.1365-2443.2001.00417.x
Subject(s) - biology , genomic imprinting , imprinting (psychology) , transcription (linguistics) , embryo , blastocyst , allele , gene , in situ hybridization , genetics , rna , fluorescence in situ hybridization , gene expression , microbiology and biotechnology , embryogenesis , dna methylation , linguistics , philosophy , chromosome
Background Genomic imprinting causes parental‐origin‐specific monoallelic transcription of a subset of mammalian genes in the embryo and adult. There is conflicting evidence, however, for the monoallelic transcription of some imprinted genes, such as Igf2 , in pre‐implantation embryos. Results We have developed an allele‐specific fluorescence in situ hybridization method which involves a pair of oligonucleotide probes designed to detect an intronic polymorphism. The method, called ASO‐RNA‐FISH, enabled us to distinguish allelic nascent Igf2 transcripts in the cell nuclei of early mouse embryos, avoiding signals from the stored oocyte‐specific transcripts. Igf2 transcription was first detectable in two‐cell embryos, and biallelic transcription was predominant up to the morula stage. Then, the maternal allele became silenced during the blastocyst stage. When embryos were cultured in vitro , however, a strong bias to maternal transcription was observed up to the morula stage. Conclusion ASO‐RNA‐FISH revealed that a transition of Igf2 from biallelic to monoallelic transcription occurs in the blastocyst stage. This developmental regulation was modified temporarily by in vitro culture, suggesting a possible link between altered imprinting and abnormalities of the foetuses experienced in vitro culture. ASO‐RNA‐FISH is therefore a powerful technique for the study of allele‐specific gene expression.