| Description: | When the zygotic genome is first transcribed, a large number of retrotransposons are expressed, including the endogenous retroviruses (ERVs), LINE-1 elements, and the non-autonomous SINE elements. MuERV-L/MERVL retrovirus-like particles are transiently de-repressed and produce 3% of the transcribed mRNAs at the two-cell (2C) stage. Right after the 2C stage, the expression of MERVL-retroelement is silenced. It has been found that this regulated pattern of MERVL expression overlapped with more than one hundred 2C-specific genes that have co-opted regulatory elements from these foreign retroviruses to begin their transcription. |
