Publisher Summary This chapter reviews the current state of the knowledge of transcription and translation in Caenorhabditis elegans. Transcription in eukaryotes is accomplished by three RNA polymerases, each transcribing a particular type of RNA; RNA polymerase I transcribes ribosomal RNA, RNA polymerase II transcribes mRNAs and snRNAs, and RNA polymerase III transcribes tRNAs and other low-molecular-weight RNAs. The chapter focuses on RNA polymerase II transcription. The C. elegans gene for the large subunit of RNA polymerase II has been cloned, and has shown to encode a protein that resembles its vertebrate counterparts. For most polymerase II transcribed genes in C. elegans, a sequence fitting the consensus TATA element about 30 bp upstream of the transcriptional start site is found. Recently, a cDNA encoding the TATA box binding protein, or TATA binding protein (TBP) subunit of transcription factor II D (TFIID), has been identified in the nematode. This protein shows extended regions of sequence similarity to vertebrate TBP, binds to a TATA box sequence and can substitute for vertebrate TFIID basal activity in in vitro extracts. These results illustrate a high degree of evolutionary conservation in the basic transcription machinery.

Transcription and translation.

All animal embryos pass through a stage during which developmental control is handed from maternally provided gene products to those synthesized from the zygotic genome. This maternal-to-zygotic transition (MZT) has been extensively studied in model organisms, including echinoderms, nematodes, insects, fish, amphibians and mammals. In all cases, the MZT can be subdivided into two interrelated processes: first, a subset of maternal mRNAs and proteins is eliminated; second, zygotic transcription is initiated. The timing and scale of these two events differ across species, as do the cellular and morphogenetic processes that sculpt their embryos. In this article, we discuss conserved and distinct features within the two component processes of the MZT.

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The maternal-to-zygotic transition: a play in two acts

Genetic control of cell division patterns in the Drosophila embryo

Embryogenesis depends on a highly coordinated cascade of genetically encoded events. In animals, maternal factors contributed by the egg cytoplasm initially control development, whereas the zygotic nuclear genome is quiescent. Subsequently, the genome is activated, embryonic gene products are mobilized, and maternal factors are cleared. This transfer of developmental control is called the maternal-to-zygotic transition (MZT). In this review, we discuss recent advances toward understanding the scope, timing, and mechanisms that underlie zygotic genome activation at the MZT in animals. We describe high-throughput techniques to measure the embryonic transcriptome and explore how regulation of the cell cycle, chromatin, and transcription factors together elicits specific patterns of embryonic gene expression. Finally, we illustrate the interplay between zygotic transcription and maternal clearance and show how these two activities combine to reprogram two terminally differentiated gametes into a totipotent embryo.

Zygotic Genome Activation During the Maternal-to-Zygotic Transition

The three postblastoderm cell cycles of Drosophila embryogenesis are regulated in G2 by string

https://www.cell.com/cell/pdf/0092-8674(86)90771-3.pdf

Caroline P. Kiehle

Papers

Cell cycle control by the nucleo-cytoplasmic ratio in early Drosophila development

Cell proliferation changes during pattern regulation in imaginal leg discs of Drosophila melanogaster.