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Golden hamster embryonic genome activation occurs at the two‐cell stage: Correlation with major developmental changes
Author(s) -
Seshagiri Polani B.,
McKenzie Debbie I.,
Bavister Barry D.,
Williamson Judy L.,
Aiken Judd M.
Publication year - 1992
Publication title -
molecular reproduction and development
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.745
H-Index - 105
eISSN - 1098-2795
pISSN - 1040-452X
DOI - 10.1002/mrd.1080320307
Subject(s) - biology , embryo , embryonic stem cell , transcription (linguistics) , embryogenesis , hamster , microbiology and biotechnology , rna , protein biosynthesis , cell , cell division , cleavage (geology) , genetics , gene , paleontology , linguistics , philosophy , fracture (geology)
Abstract The earliest time of onset of embryonic genome activation in golden hamsters was investigated. The inhibition of transcription by α‐amanitin (11 μg/ml) in cultured embryos resulted in a total arrest of development of early 2‐cell embryos (26 hr post‐egg activation); under similar conditions, immediate cleavage divisions of 1‐, late 2‐, 4‐, and 8‐cell embryos were not affected. Electrophoretic analysis of [ 35 S]methionine‐labeled embryonic proteins showed that α‐amanitin treatment apparently inhibited transcription‐dependent protein synthesis in early 2‐cell and, to some extent, in late 2‐cell when compared to 4‐cell embryos. Analysis of total RNA synthesis, using [α 32 P]‐UTP or [ 32 P]‐orthophosphate, showed that there was a high proportion of radioactivity associated with the macromolecular fraction (RNA) at the early and late 2‐cell stages and at the 4‐cell stage compared to that at the 1‐cell stage. These results indicate that the de novo synthesis of RNA, encoded by the embryonic genome, occurs at the 2‐cell stage and that the second and subsequent cleavage divisions of hamster preimplantation embryos are dependent on new transcriptional activity. This initial activity of the embryonic genome in hamsters is coincident with several characteristic features of in vitro development such as a block to development, synthesis of major proteins, change in energy substrate preference, phosphate‐inhibition of development and a requirement for amino acids.