Abstracts - Society for Developmental Biology

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and their target pea3 were down-regulated in pku190 morphants but not fgf10. All these data suggest that pku190 is
important and necessary for the correct timing and spacing of pro-neuromast deposition during lateral line development
and may function through modulating the expression, activation as well as the coordination of Fgf signal and chemokine
receptor Cxcr7b.
Program/Abstract # 374
Pax3 splice form expression and isoform function in the trigeminal placode
Adams, Jason S.; Stark, Michael,Brigham Young, Provo, United States
Pax3 encodes a transcription factor that is necessary for normal ophthalmic trigeminal (opV) placode development and
sensory neuron differentiation. In opV placode cells, Pax3 is expressed from the time of cell specification through ganglion
formation. We show through quantitative RT-PCR that alternative splice forms of Pax3 are present during opV
development. We have named these splice forms, Pax3V1 and Pax3V2, and show that alternative splice forms are
expressed at different transcriptional levels over time. To determine whether the Pax3 isoforms serve functionally distinct
roles during developmental progression of opV sensory neurons, we performed in ovo electroporation of each isoform
prior to significant cell specification. For all isoforms, targeted cells remained in the ectoderm as undifferentiated cells
significantly more than in controls. Misexpression of the Pax3 isoforms also caused a decrease in the number of
differentiated (Islet1+) cells in the opV ganglion. A more careful evaluation of cell count data revealed subtle but
statistically significant differences between the differentiation potential of each isoform. To better understand the roles of
Pax3 isoforms, we repeated the experiments while simultaneously enhancing neurogenesis by blocking Notch signaling
with DAPT. Using this method we clearly observed significantly more differentiation in Pax3V2-targeted cells than in full
length Pax3- or Pax3V1-targeted cells. These results show that the Pax3V2 isoform may contribute to the neuronal
differentiation of opV placodal cells, while full length Pax3 and the isoform Pax3V1 may need to be down-regulated to
allow for neuronal differentiation.
Program/Abstract # 375
Functional characterization of Rdh10 during pancreas development in the mouse
Arregi, Igor; Iliev, Dobromir; Ahmed, Emad; Steinkogler, Karina; Semb, Henrik (Lund University, Lund, Sweden);
Liliana, Minichiello (University of Edinburgh, Edinburgh, United Kingdom); Pera, Edgar (Lund University, Lund,
Sweden)
Maternal vitamin A-derived retinoic acid (RA) is an essential signalling molecule in embryonic development, and
misregulation of this pathway leads to severe malformations. We and others have shown that retinol dehydrogenase-
10(Rdh10) is a key enzyme in RA biosynthesis and is controlled by RA negative feedback regulation in vertebrate embryos
(1-4). Here we present a new conditional knockout model to study Rdh10 function in the mouse. Rdh10 null mutants die
around embryonic day E12.5 and show typical signs of RA deficiency including craniofacial, limb and internal organ
defects. Immunohistochemical analysis shows expression of Rdh10 in the pancreas epithelium. In Rdh10 null mutants the
dorsal pancreas does notform, and the ventral pancreas is reduced in size. Analysis with molecular markers suggests that
the mutant ventral pancreas fails to form a tubular network and exhibits reduced endocrine and exocrine differentiation.
Together, our results reveal novel functions of Rdh10 in pancreas specification, morphogenesis and cell differentiation.
References: 1. Sandell LL, Sanderson BW, Moiseyev G,Johnson T, Mushegian A, Young K, Rey JP, Ma JX, Staehling-
Hampton K, Trainor PA(2007). Genes Dev 21(9):1113-24. 2. Strate I, Min, TH, Iliev D, Pera EM (2009). Development
136, 461-472. 3. Rhinn M, Schuhbaur B, Niederreither K, DolléP. (2011) Proc Natl Acad Sci U S A. 108(40):16687-92.
4. Ashique AM, May SR, Kane MA, Folias AE, Phamluong K, Choe Y, Napoli JL, Peterson AS. (2011) genesis
10.1002/dvg.22002.
Program/Abstract # 376
Apical/basal polarity and differentiation within ESC-derived neural rosettes
Banda, Erin, Wesleyan University, MiddletownUnited States; Germain, Noelle (Middletown, CT, United States); Szmurlo,
Theodore (New Britain, CT, United States); Grabel, Laura (Middletown, CT, United States)
Embryonic stem cell (ESC) in vitro neurogenesis resembles the development of the central nervous system in the early
mammalian embryo. Using a well-defined monolayer protocol that utilizes the BMP-antagonist Noggin, we observe
formation of neural rosettes, in which differentiating neural stem cells (NSCs) are radially arranged around a lumen and
exhibit interkinetic nuclear migration. Additionally, these neural rosettes display a focal localization of the adherens
junction protein N-cadherin at the lumenal surface, as well as localized β1-integrin staining at the periphery, suggesting
formation of an epithelium with apical/basal polarity reminiscent of the embryonic neural tube and developing neocortex.
Notch signaling plays an important role both in the maintenance of this polarized epithelium and in regulating symmetric