title: Bicoid gradient formation and function in the Drosophila pre-syncytial blastoderm.
abstract: Bicoid (Bcd) protein distributes in a concentration gradient that organizes the anterior/posterior axis of the Drosophila embryo. It has been understood that bcd RNA is sequestered at the anterior pole during oogenesis, is not translated until fertilization, and produces a protein gradient that functions in the syncytial blastoderm after 9-10 nuclear divisions. However, technical issues limited the sensitivity of analysis of pre-syncytial blastoderm embryos and precluded studies of oocytes after stage 13. We developed methods to analyze stage 14 oocytes and pre-syncytial blastoderm embryos, and found that stage 14 oocytes make Bcd protein, that bcd RNA and Bcd protein distribute in matching concentration gradients in the interior of nuclear cycle 2-6 embryos, and that Bcd regulation of target gene expression is apparent at nuclear cycle 7, two cycles prior to syncytial blastoderm. We discuss the implications for the generation and function of the Bcd gradient.
authors.affiliation: Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States.
authors.forename: Zehra
authors.initials: Z
authors.lastname: Ali-Murthy
authors.affiliation: Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States.
authors.forename: Thomas B
authors.identifier: http://orcid.org/0000-0002-6879-7066
authors.initials: TB
authors.lastname: Kornberg
mesh_terms: D000818:Animals; D001756:Blastoderm / Q000737:chemistry* / Q000502:physiology*; D004330:Drosophila / Q000196:embryology*; D029721:Drosophila Proteins; D005786:Gene Expression Regulation; D018398:Homeodomain Proteins / Q000032:analysis* / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis; D015534:Trans-Activators / Q000032:analysis* / Q000378:metabolism*
chemical_list: D029721:Drosophila Proteins; D018398:Homeodomain Proteins; D012333:RNA, Messenger; D015534:Trans-Activators; C056478:bcd protein, Drosophila
keywords: <i>d. melanogaster</i>; bicoid; developmental biology; drosophila; embryo; krüppel; oocyte; stem cells