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Developmental Biology 306 (2007) 355–368 www.elsevier.com/locate/ydbio

Abstracts

Patterning and transcription factors

Program/Abstract # 169 We are exploring the role of basic helix–loop–helix factors The Expression Database (GXD): A resource for in development. Previously, we identified a bHLH factor, developmental biologists Bhlhb4, required for retinal bipolar cell maintenance in the J.H. Finger, T. Hayamizu, I. McCright, C. Smith, J.T. Eppig, mouse. Interestingly, Bhlhb4 belongs to a bHLH subfamily J. Kadin, J. Richardson, M. Ringwald with extremely high percent identity at the bHLH domain, con- The Jackson Laboratory, Bar Harbor, ME, USA served across species lines. There may have also been a gene duplication event leading to the presence of a paralogous gene The Gene Expression Database (GXD) is a large public re- pair in mouse, Bhlhb4 and Bhlhb5. Similar pairs have been source of mouse developmental expression information. Data is detected in other vertebrate and invertebrate species. Due to the obtained from the literature, as well as by direct submission from high level of conservation across species, we are exploring the individual laboratories and large-scale data providers. Various developmental role of Bhlhb4 in diverse species. Thus, we are types of RNA and expression studies are annotated in exploring the expression pattern of Bhlhb4 homologs in S. GXD. A standardized anatomical hierarchy is used to capture purpuratus and Danio rerio. The S. purpuratus sea urchin ge- author's descriptions of expression patterns, and images from nome database Spur_2.1 provided by HGSC at BCM was the publications are included whenever possible. A new feature screened for sequences with a high percent identity with the is up-front access to the images in GXD via your gene-of-in- Bhlhb4 bHLH domain. We identified a sequence of the Bhl- terest. Images are viewed as a series of thumbnails from which hb4 homolog in S. pupuratus, which we have coined spBhlhb4. you can choose to look at any full-size image. All annotated After isolating and subcloning a genomic fragment containing results are then easily accessed from the full-size image page. the coding region of the spBhlhb4 gene, we used it prepare You can search GXD using a variety of parameters that fit your digoxigenin-labeled riboprobes. S. purpuratus embryos (36, 48 requirements. GXD is an integral component of Mouse Genome and 66 h) were then subjected to whole mount in situ hy- Informatics (MGI) (www.informatics.jax.org). Therefore, the bridization using the spBhlhb4 anti-sense riboprobe to detect expression data are combined with the genetic and phenotypic mRNA expression. We found strong and specific hybridization information, linking data from different sources and providing signal in the S. purpuratus archenteron. Currently, we are in the integrated query access to researchers. GXD welcomes direct process of conducting double labeling experiments so as to co- contributions to the database, and accession numbers are pro- localize spBhlhb4 with known developmental markers to vided for inclusion in publications and grants. In addition, GXD confirm the spBhlhb4 expression pattern. provides the literature index, a valuable summary of the deve- lopmental expression data in the scientific literature, and the doi:10.1016/j.ydbio.2007.03.231 Gene Expression Notebook (GEN), a useful tool for a deve- lopmental biologist's laboratory. An Excel-based program, the GEN stores expression data, images and probe information. It Program/Abstract # 171 can also be used to contribute data to GXD. The expression of zic1, zic2, , and zic4 in early chick This work is supported by NICHD grant HD033745. embryos Ariel McMahon, Kristin Junette, Christa Merzdorf doi:10.1016/j.ydbio.2007.03.230 Department of Cell Biology and Neuroscience, Montana State University, Bozeman, MT, USA Program/Abstract # 170 Zic family transcription factors play multiple roles in early Exploring the expression pattern of basic helix–loop–helix, neural development. zic are highly conserved, particularly Bhlhb4 in their zinc finger domains and in the regions immediately Nam X. Nguyen 1, Takae Kiyama 2, Debra E. Bramblett 3 surrounding the zinc fingers. The chick genome suggests that the 1 Biology, University of St. Thomas, Houston, TX 77006, USA zic4 and zic1 genes are adjacent and transcribed in opposite 2 Biochem and Mol. Biol., M. D. Anderson Cancer Center directions, as in other vertebrates. The zic2 and zic3 genes are on Houston, TX 77030, USA separate and we have not yet found evidence of a

doi:10.1016/j.ydbio.2007.03.229 356 ABSTRACTS / Developmental Biology 306 (2007) 355–368 zic5 gene. We have generated in situ probes that are specific for Goosecoid (Gsc), a homeobox gene, was the first gene found the zic1, zic2, zic3, and zic4 genes in chick. While there is to be specifically expressed in Spemann's organizer. In the considerable overlap in the expression patterns of these genes, present study, we show that knock-down of Gsc in Xenopus by there are also distinct differences. zic2 and zic3 are strongly Morpholino oligomers (MO) leads to loss of head structures and expressed in the entire dorsal neural tube, including the brain, expansion of ventral tissues. Unlike in the mouse, our results trunk, and tail tip. zic1 expression is strong in the dorsal brain, demonstrate a requirement of Gsc for head formation and axis but weaker in the dorsal neural tube of the trunk. zic4 appears to patterning in early Xenopus development. In search of down- be expressed exclusively in the head region. During somite stream mediator genes, we found that the effects of Gsc development, zic1 is expressed dorsomedially in epithelial completely depend on the BMP antagonist Chordin. Ectopic somites, while zic2 expression begins well after somites have expression of mouse Gsc mRNA lead to induction of a secon- given rise to distinct dermomyotome and sclerotome regions. dary axis. Co-injection of Chordin MO prevented this inductive zic1–3 are expressed strongly in the dorsomedial parts of more capability of Gsc mRNA in 97% of the embryos. Evidence for mature somites, particularly in the posterior portions. zic2 is the regulation of Chordin by Gsc is further provided by quantitative only family member expressed in the periotic mesoderm in the PCR and in situ hybridization, showing that Gsc MO decreases hindbrain. zic2–4 are expressed in the developing eye and all zic Chordin expression in gastrulating embryos. Moreover, loss-of- genes are expressed in the optic stalk. Among the zic genes, only function experiments in animal cap explants revealed mutual zic2 is expressed in the limb buds. We are currently analyzing repression of Gsc and the ventral homeobox transcription zic3 and zic4 expression in more detail. factors Vent1 and Vent2. MO-mediated knock-down of Vent1/2 caused strong dorsalization of the embryos, which could be doi:10.1016/j.ydbio.2007.03.232 suppressed by Gsc MO. Our results suggest that Gsc and Vent1/ 2 have opposing activities during gastrulation and act as regu- lators of each other in mesoderm patterning. Program/Abstract # 172 A microarray screen for direct targets of the Zic1 doi:10.1016/j.ydbio.2007.03.234 transcription factor Sabah M. Hassan, Shuzhao Li, Christa Merzdorf Department of Cell Biology and Neuroscience, Montana State Program/Abstract # 174 University, Bozeman, MT, USA TFIIH trafficking and its nuclear assembly during early Drosophila embryo development The transcription factor zic1 plays important roles in a variety Javier Aguilar-Fuentes, Viviana Valadez-Graham, of developmental processes. In vertebrates, these include patter- Enrique Reynaud, Mario Zurita ning the early neural plate, development of the neural crest, Department of Developmental Genetics and Molecular somite development, and formation of the cerebellum. In Physiology, Institute of Biotechnology, UNAM, Cuernavaca, addition, zic1 promotes cell proliferation. To increase our under- Morelos, Mexico standing of the molecular mechanisms that underlie these pro- cesses, we have conducted a DNA microarray screen with We present the analysis of the dynamic of the transcription Affymetrix gene chips to identify downstream target genes of factor IIH (TFIIH) during early Drosophila embryo develop- zic1. The screen was performed using Xenopus ectodermal ex- ment. TFIIH consists of ten sub-units: cyclin-dependent kinase plants. By using an inducible zic1 construct (zic1GR) and the 7 (Cdk7), cyclin H and MAT1 (CAK), two helicases Xpb/Hay protein synthesis inhibitor cycloheximide, the screen was de- and Xpd, and p34, p44, p52, p42, p62 and p8 (core). We found signed to discover direct targets of the Zic1 transcription factor. that the TFIIH core is initially located in the cytoplasm of One new gene that was identified in this screen is the putative syncytial blastoderm embryos, after the mitotic division 10 and protease Xfeb that contributes to hindbrain patterning. We give a until the cellular blastoderm the core moves from the cytoplasm general overview of the genes identified in this screen and will to the nucleus. The CAK complex has a different behaviour in discuss our findings from the screen with respect to genes in- early embryonic stages. The CAK is mostly cytoplasmic during volved in neural crest development and in anterior–posterior cellularization and even during gastrulation. However, both patterning. components are positioned at promoters of genes that are activated at the onset of transcription. Later in development, the doi:10.1016/j.ydbio.2007.03.233 CAK complex becomes mostly nuclear and co-localizes in most chromosomal regions with the TFIIH core, but not in all sites, suggesting that the CAK complex could have a role in Program/Abstract # 173 transcription of some loci without interaction with the TFIIH Requirement of Goosecoid in early Xenopus development: core. We also demonstrate that the CAK and the core coexist in A loss-of-function study the early embryo cytoplasm, however they do not interact until Veronika Sander, Bruno Reversade, E.M. De Robertis they are in the nucleus. Our data suggests that the complete Howard Hughes Medical Institute, University of California, assemble of the ten sub-units TFIIH occurs during the activation Los Angeles, CA, USA of zygotic transcription. In addition, we demonstrate that the