Congress Abstracts - Society for Developmental Biology

are currently determining the functional relevance of this Antp interaction in embryonic and adult development in D. melanogaster by
homeotic transformations and in vivo BiFC assays. Taking in account the conservation of the Antp HD and its expose location in helix
II, the functional role of the residues 32 and 36 could be extrapolated to other hox proteins in the functional specificity by proteinprotein
interaction with GTFs in the genetic control of Drosophila melanogaster.
Program/Abstract # 131
Dynamic of p8 and p52 during early embryonic development and spermatogenesis of Drosophila melanogaster
Mandy; Cruz, Grisel; Zurita, Mario (Instituto de Biotecnologia (UNAM), Mexico)
The transcription/DNA-repair factor TFIIH is composed of ten subunits (XPD, XPB, p44, p34, p52, p62, p8, Cdk7, CycH and MAT1)
and is involved in three fundamental processes that are DNA repair, transcription and cell cycle control. It’s known that p8 and p52
proteins physically interact, however, the relevance of this interaction is unknown. In previous studies we have observed that p8 null
organisms are affected in embryonic mitotic divisions and sperm differentiation is arrested at primary spermatocyte stage. Likewise
organisms with hipomorfic p52 present the same spermatogenesis defects. In this work we describe for the first time the in vivo
dynamics of p8 and p52 during the first embryonic mitotic divisions and spermatogenesis of Drosophila melanogaster, by using
transgenic flies expressing p8 and p52 fused to CFP and YFP respectively. In the syncytial blastoderm we observed that both subunits
remain around the chromosomes in the nucleus during prophase, metaphase and anaphase and go to the cytoplasm during telophase
for their subsequent re-joining to the nucleus in the interphase of the next cycle. These observations and the mitotic defects could
suggest a possible role of these proteins in mitosis during embryogenesis. However more studies are necessary to confirm this
hypothesis. Moreover, in testes p8-CFP and YFP-p52 are located at nucleus and nucleolus of primary spermatocytes and seem to colocalize
with bivalent chromosomes during meiosis in these cells. In a p52 mutant background the localization of p8-CFP in testes is
affected and using western blot assays it was observed that levels of others TFIIH components are decreased, not happening the same
in the opposite case. This suggests that p52 and p8 interaction is important to maintain the proper p8 localization and TFIIH stability
in these cells in the fly
Program/Abstract # 132
Paused Pol II Coordinates Tissue Morphogenesis in the Drosophila Embryo
Bothma, Jacques; Lagha, Mounia; Juarez Esposito, Emilia; Ng, Samuel (Univ of California-Berkeley, USA); Stefanik, Laura
(Philadelphia, USA); Tsui, Chiahao (Univ of California-Berkeley, USA); Johnston, Jeffrey; Chen, Kai (Stowers Institute for Medical
Research, USA); Gilmour, David (Philadelphia, USA); Zeitlinger, Julia (Stowers Institute for Medical Research, USA); Levine,
Michael (Univ of California-Berkeley, USA)
Paused RNA Polymerase (Pol II) is a pervasive feature of Drosophila embryos and mammalian stem cells, but its role in development
is uncertain. Here, we demonstrate that there is a spectrum of paused Pol II, which determines the “time to synchrony”--the time
required to achieve coordinate gene expression across the different cells of a tissue. To determine whether synchronous patterns of
gene activation are significant in development, we manipulated the timing of snail expression, which controls the coordinated
invagination of ~1000 mesoderm cells during gastrulation. Replacement of the strongly paused snail promoter with moderately paused
or nonpaused promoters results in stochastic activation of snail expression and the progressive loss of mesoderm invagination.
Computational modeling of the dorsal-ventral patterning network recapitulates these variable and bistable gastrulation profiles, and
emphasizes the importance of timing of gene activation in development. We conclude that paused Pol II and transcriptional synchrony
are essential for coordinating cell behavior during morphogenesis.
Program/Abstract # 133
Cis-acting transcriptional repression establishes a sharp boundary in chordate embryos
Imai, Kaoru; Daido, Yutaka; Kusakabe, Takehiro; Satou, Yutaka (Kyoto, Japan)
The function of Bone morphogenetic protein signaling system in dorso-ventral (DV) patterning of animal embryos is widely
conserved among the Bilateria. In vertebrates, the BMP ligand anti-dorsalizing morphogenetic protein (Admp) is expressed dorsally
and moves to the opposite side to specify the ventral fate. Here we show that Pinhead is an antagonist specific for Admp with an
essential role in establishing the sharp boundary of the ascidian epidermis along the DV-axis. Pinhead and Admp exist in tandem in
the genomes of a wide range of animals. This genomic configuration is important for mutually exclusive expression of these two
functionally opposed genes through cis-acting transcriptional repression. Our data suggest that this dual negative regulatory
mechanism is widely conserved in a wide range of animals.
Program/Abstract # 134
Role of the MADS-box gene AGL19 in the cellular homeostasis of Arabidopsis thaliana root: its cellular and molecular
functions and epigenetic regulation
Hernández Marroquín, Víctor Rogelio; Garay Arroyo, Adriana (Instituto de Ecología, UNAM, Mexico)
MADS-box genes code for transcription factors involved in Arabidopsis thaliana development. Three genes of this family with clear
effects in root development have been characterized in our laboratory – AGL12 (XAL1), AGL14, and AGL17. We also have
preliminary data suggesting that AGL19 is also involved in the proliferation-differentiation equilibrium of the root apical meristem
(RAM). It is well known that AGL19 plays a role during transition to flowering in the shoot apical meristem, that its expression is
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