Congress Abstracts - Society for Developmental Biology

covering the surface by connections formed through protein interactions. At certain confocal sections of EB, instead of a round
boundary, a polygonal boundary was observed even though the EB appeared round under conventional microscope. In these polygonal
boundaries, β-catenin positive guarding epithelial cells were positioned on every corner of the polygon. In the inner portion of the EB,
undifferentiated β-catenin positive cells express β-catenin in the nucleus. As the initially simple shape of EB becomes more and more
intricate during development, we revealed that more β-catenin positive cells were also observed in this complex structure. Based on
these results, we predicted β-catenin to play different roles while guarding epithelial cells or undifferentiated stem cells in the inner
portion of EB in in vitro culture system. In this early differentiation process, phosphorylation of β-catenin may be a critical factor for
fate determination of the human stem cell.
Program/Abstract # 410
Organ-specific regulation of steroidogenesis by Hoxb9
Gardiner, Jennifer (Institute of Cancer Research, UK)
The gonads and adrenal cortex are derived from the same cell population, known as the adreno-gonadal primordium (AGP). The organ
primordia separate from one another at around E11 in the mouse, and the testis and adrenal gland produce different steroidogenic
enzymes from E13.5. Steroidogenesis is controlled by a master regulator transcription factor, steroidogenic factor 1 (Sf1). However,
the genetic cues directing differential steroid production are currently poorly understood. Hox genes are well-documented regulators
of embryonic patterning. Differential Hox gene expression was observed in the developing steroidogenic organs; Hoxb9 is expressed
in the adrenal gland, Hoxd9 in the testis. In order to investigate the role of Hox genes in regulation of steroidogenesis, we have
generated a transgenic mouse, named Sf1:Hoxb9, in which Hoxb9 is misexpressed under the control of Sf1. Sf1:Hoxb9 mice exhibit an
increase in the number of ‘adrenal-like’ cells – those producing enzymes involved in adrenal steroidogenesis - in the developing testis
from E13.5. We have investigated the cause of this phenotype, and further analysed the requirement for Hoxb9 in adrenal
steroidogenesis in vitro.
Program/Abstract # 411
Cell fate mapping and specification of the coelomic lining epithelium in the avian embryo
Arraf, Alaa; Yelin, Ronit; Schultheiss, Thomas M. (Technion-Israel Institute of Technology, Israel)
Background: The coelomic lining epithelium of the embryo is composed of a single cell layer that invests the external surface of the
viscera and the inner surface of the body wall. Studies indicate that the coelomic lining epithelium is an active tissue which
participates in organogenesis of different significant organs including heart epicardium, liver, lung and gonads, but the full extent of
the developmental potential of the coelomic lining is not known. Specification of the precise differential anatomical site in the anterioposterior
axis, and the temporal sequence of the emergence of the lining cells are crucial for understanding of the molecular and
cellular regulators that determines the coelomic lining cells` fate. Methods: We are using a cell tracking technique in which
microinjection of the fluorescent vital DiI into the coelomic cavity of stage 12 avian embryo is analyzed after different time points of
incubation. In addition we use histological methods, including in situ hybridization and immunohistochemistry to detect coexpression
of DiI with specific markers of the candidate`s coelomic lining derived cells. Plastic sections of different stages embryos
are used to study exact morphological development in the coelomic cavity region. Results: We have validated that coelomic injection
of DiI at different stages, labels only the coelomic lining and not any of the underlying mesenchymal cells. We will present initial
results regarding the cell fates of coelomic lining epithelium -derived cells and the timing of their departure from the coelomic lining.
Program/Abstract # 412
Scarb2a is essential for Notochord Development in Zebrafish
Díaz Téllez, Abigail; Carrillo Rosas S.; Ramos Balderas J.; Zampedri C.; Maldonado E. (Universidad Nacional Autonoma de
México, Mexico Distrito Federal, Mexico)
Scarb2 is a membrane glycoprotein, whit two tran-membrane sites, 11 sites for N-glycosylation and a C-terminal di-leucine motif.
Mutations in Scarb2 were described as a causing of Action Myclonus Renal Failure Syndrome (AMRF), which is characterized by
progressive myoclonus epilepsy. Zebrafish has three copies of scarb2 (scarb2a, scarb2b and scab2c). Scarb2a insertional-mutant was
obtained in a large-scale forward genetic screening. This mutant is characterized by the presence of vesicular bodies in the brain at 1
dpf and hypopigmentation at 2 dpf both phenotypes are restored at 3 dpf. However, since 1 dpf scarb2a mutant shows defects in the
notochord formation. Therefore, we are using this mutant as model to gain better understanding in how Scarb2 works during
notochord formation. Through electronic microscopy, we have observed that vacuole notochord cells of scarb2a mutant are smalles.
In situ hybridization revealed that scarb2a is expressed in the brain and in the notochord at early stages, also in the Scarb2a mutants
there is a disordes in collagen II expression. Actually, experiments are ongoing to decipher if the defect in the notochord of scar2a
Zebrafish mutant are cell autonomous or non-autonomous.
Program/Abstract # 413
Developmental hierarchy, cell fate regulation and carcinogenesis: a view from the Drosophila model
Sinha, Pradip (Indian Institute of Technology Kanpur, India)
Not all cells in a lineage hierarchy transform neoplastically when oncogenically targeted. Developmental disposition of a target cell,
therefore, is a critical cancer determinant. A growing body of literature now shows that a majority of cancer cells of origin display
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