Degradation of maternal cdc25c during the maternal to zygotic transition is dependent upon embryonic transcription.
To gain a better understanding of the molecular differences that may contribute to cleavage arrest and the poorer development associated with laboratory produced embryos, a series of experiments were conducted to quantitate the message levels of the cell cycle controller cdc25c, over the maternal to zygotic transition (MZT) in 4-cell in vivo- and in vitro-derived porcine embryos. The experiments were designed to measure both maternal and embryonic derived cdc25c transcripts by quantitative reverse transcription-competitive polymerase chain reaction (RT-cPCR), determine the point of the transition to zygotic genome activation, and study the interaction between initial embryonic transcription and maternal cdc25c degradation. Analysis of in vivo- and in vitro-derived embryos revealed no difference in cdc25c message level for any of the times P4CC (P > 0.05). Comparison of control embryos from 5- to 33-hr P4CC revealed a reduction in transcript quantities in the 10-hr P4CC group that was maintained at later time points (P < 0.05). Embryos cultured in the RNA polymerase inhibitor, alpha-amanitin, from cleavage to 5-, 10-, 18-, 25-, or 33-hr P4CC displayed no difference in cdc25c levels when compared to controls at similar time points (P > 0.05). However, if embryos were first exposed to alpha-amanitin after 18-hr P4CC with this treatment continuing to 33 hr, the levels of cdc25c transcript were reduced (P < 0.04) when compared to those embryos that were first exposed to the inhibitor at either 5- or 10-hr P4CC. This finding and the comparison of these same embryos to the 0-33-hr alpha-amanitin and control groups allowed us to conclude that cdc25c transcription began between 10- and 18-hr P4CC, with the degradation of maternal cdc25c message dependent on transcriptional initiation.
Anderson
J E
JE
Department of Animal Science, University of Missouri, Columbia, Missouri 65211, USA.
Matteri
R L
RL
Abeydeera
L R
LR
Day
B N
BN
Prather
R S
RS
D000546:Amanitins / Q000494:pharmacology; D000818:Animals; D018797:Cell Cycle Proteins / Q000378:metabolism*; D004622:Embryo, Mammalian / Q000187:drug effects / Q000502:physiology*; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D016133:Polymerase Chain Reaction; D012313:RNA / Q000235:genetics / Q000378:metabolism; D012016:Reference Values; D013552:Swine; D014158:Transcription, Genetic; D015053:Zygote / Q000502:physiology*; D020687:cdc25 Phosphatases / Q000378:metabolism*
D000546:Amanitins; D018797:Cell Cycle Proteins; D019384:Nucleic Acid Synthesis Inhibitors; D012313:RNA; D020687:cdc25 Phosphatases