From the beginning: the basal transcription machinery and onset of transcription in the early animal embryo.

Transcription onset in the early animal embryo is a fundamental process required for proper embryonic development. Depending on the species, transcription onset occurs at what specifically appears to be different developmental stages. However, studies in early embryos from different animal models have shown that components of the basal transcription machinery play fundamental and highly regulated roles at the onset of transcription. The state of the basal transcription machinery in the embryo seems to be equivalent in different organisms at transcription onset. The dynamic balance between putative activators and repressors as well as the chromatin/cytoplasmic ratio seem to be coordinated with basal transcription factors in order to activate zygotic transcription. Here we discuss and compare the regulation of the basal transcription machineries and their activation in early embryos of different model organisms. [ABSTRACT FROM AUTHOR]