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Article
Onset of transcription in bovine oocytes and preimplantation embryos
Molecular Reproduction and Development
  • Erdogan Memili, University of Wisconsin-Madison
  • Tanja Dominko, University of Wisconsin-Madison
  • Neal L. First, University of Wisconsin-Madison
Document Type
Article
Abstract

The transition from the maternal to embryonic control of early embryonic development (MET) in mammals is not fully understood. The objective of this study was to determine the amount of transcriptional activity in immature oocytes containing germinal vesicle (GV), mature metaphase II arrested oocytes (MII), 2-, 4- and 8-cell bovine embryos by labeling with 35S-UTP followed by isolation of total RNA and autoradiography. Expression of counts per minute (CPM) per cell showed that incorporation of 35S-UTP in GV oocytes was significantly higher than the background (P < 0.01) and decreased sharply by the time the oocytes reached MII arrest. Incorporation significantly increased during the 2-cell stage and remained at the same level during the 4- and 8-cell stages. Uptake remained constant throughout different development stages (P > 0.05) with the highest variability observed during the 2-cell stage. When CPM were expressed per oocyte or embryo incorporation remained high at the GV stage, decreased to the background levels at the time of MII and increased again at the 2-cell stage. It remained at the same level during the 4-cell stage but increased significantly for the second time during the 8-cell stage. Uptake remained at the same level until the 8-cell stage when a significant increase was observed. The negative controls showed a significantly lower amount of incorporation compared to the positive control (P < 0.05). Similar results were observed by autoradiography. Our observations suggest that MET starts as early as the 2-cell stage in bovine embryos.

DOI
10.1002/(SICI)1098-2795(199809)51:1<36::AID-MRD4>3.0.CO;2-X
Publication Date
9-1-1998
Citation Information
Erdogan Memili, Tanja Dominko and Neal L. First. "Onset of transcription in bovine oocytes and preimplantation embryos" Molecular Reproduction and Development Vol. 51 Iss. 1 (1998) p. 36 - 41 ISSN: 1040452X
Available at: http://works.bepress.com/erdogan-memili/53/