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How Genes Tell Cellular Construction Crews, ‘Read Me Now!’ (Science Daily)
When egg and sperm combine, the cells of the new embryo multiply so rapidly they largely ignore their DNA, other than to copy it and to read just a few essential genes. The embryonic cells mainly rely on molecular instructions placed in the egg by its mother in the form of RNA.
The cells translate these RNA molecules into proteins that manage almost everything in the first minutes or of the embryo’s life. Then, during the so-called midblastula transition, cells start transcribing massive amounts of their own DNA. How embryonic cells prepare for this moment, and how they flag a small set of genes for transcription before that, holds important information about normal development and disease in animals and in humans.
A new study that sheds light on these questions appears in the Aug. 13 issue of eLife Sciences, authored by researchers at the Stowers Institute for Medical Research. The team, led by Associate Investigator Julia Zeitlinger, Ph.D., shows that in the fruit fly Drosophila melanogaster, genes active in the first two hours of a fertilized egg are read quickly due to special instructions at the beginning of each gene, in a region aptly named the “promoter.”
The dorsal-ventral patterning gene snail (shown in red) is one of the few genes that are active before as well as after the midblastula transition. The segmentation gene paired (shown in green) is turned on during the transition. Cell nuclei are shown in blue. (Credit: Image: Courtesy of Kai Chen)