Abstracts - Society for Developmental Biology

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in zebrafish and Xenopus, but absent in the chicken or mouse. Data from squamate and archosaurian reptiles has markedly
changed our view of the evolution of the segmentation clock inamniotes, pointing to rapid changes in the regulation of
cycling genes relative to other genes in somitogenesis.
Program/Abstract # 16
Genomic control of morphogenesis in ciliated epithelia
Wallingford, John B., University of Texas, Austin, United States
Cilia have emerged recently as essential organelles in developmental, but most studies have focused on solitary, non-motile
primary cilia. By contrast, multi-ciliated cells (MCC), which harbor many dozens of motile cilia play crucial roles in the
development and homeostasis of the airway, brain, and reproductive tracts but remain poorly studied. Here, we will
describe a novel model system for the study of mucociliary epithelia and a battery of approaches that integrate genomics,
bioinformatics, in vivo time-lapse imaging, and experimental embryology to accelerate our understanding of MCCs. In
particular, we will discuss the role of planar cell polarity (PCP) proteins in motile ciliogenesis and the transcriptional
control of cilia structure and function. Finally, MCCs derive from basally-located p63+ progenitor cells, and newly born
MCCs must migrate apically and insert into the epithelium during homeostasis and following injury. We will discuss
genomic and cell biological mechanisms of MCC apical migration and insertion into the epithelium.
Program/Abstract # 17
Zebrafish Placenta-specific 8.1 (Plac8.1) links ubiquitination regulating protein Cops4 to motile cilia
morphogenesis and function
Ma, Haiting, Washington University, St. Louis, United States; Li, Cunxi (Vanderbilt University, Nashville); Sepich, Diane
(Washington U); Coffey, Robert (Vanderbilt U); Solnica-Krezel, Lilianna (Washington U)
Placenta-specific 8 (Plac8) proteins constitute a family of vertebrate-conserved proteins of elusive function. To investigate
the function of Plac8 homologs in vertebrate development, we identified and studied zebrafish Plac8.1, a Plac8
homolog.With an anti-Plac8.1 antibody and immunofluorescence, we found that in multiple tissues. In mesenchymal cells
Plac8.1 was located in cytoplasm and at the cell membrane, while in ciliated epithelia, Plac8.1 was concentrated at the
apical cell membranes where cilia reside. To investigate the function of Plac8.1, we injected into embryos antisense
morpholino oligonucleotides that could efficiently reduce protein levels of Plac8.1 resulting in morphologic features
consistent with cilia defects: a ventrally curved body, left-right asymmetry defects, and kidney cysts. In Plac8.1 deficient
embryos motile cilia numbers in the Kupffer’s Vesicle (KV) and kidney ducts were significantly reduced, and cilia in
kidney ducts were abnormally curled with detached membranes around the ciliary axonemes. Moreover, zebrafish embryos
with deficient Plac8.1 also showed impaired beating of motile cilia in the KV, kidney, and the nasal pit. Finally, to
investigate the molecular mechanism of how Plac8.1 regulates cilia morphogenesis and activity, we found that Plac8.1
bound Cops4, an integral component of the ubiquitination regulating complex COP9 signalosome (CSN). Co-injection of
MOs targeting Plac8.1and Cops4 enhanced defects in cilia morphology and function. Collectively, our results identify
Plac8.1 and Cops4 as new regulators of motile cilia, and suggest that ubiquitination modification might be involved in
motile cilia morphology and function.
Program/Abstract # 18
From neural fate specification to neural plate patterning in Ascidian embryos.
Hudson, Claire, University of Paris, France
One of the defining features of the chordate body plan is the presence of a dorsal hollow central nervous system. We are
studying the formation of this structure using embryos of the ascidian Ciona intestinalis. Ascidians are members of the
urochordates, which forms a sister group to vertebrates. Their larvae exhibit a classical chordate body plan, but develop
with very small cell numbers that adopt stereotypical cleavage patterns. We have been focusing on the formation of the
posterior part of the larval CNS. I will describe the generation of these CNS lineages step-by-step, from the first division
oriented along the animal-vegetal axis that generates the 8-cell stage embryo, to the patterning of the precisely aligned 44
cells of the neural plate. I will describe how at each step, signals of the canonical and non-canonical Wnt pathway, and
ephrin-Eph and FGF/ERK pathways play critical roles in the generation of neural precursors. Subsequently, Nodal,
Delta/Notch and FGF/ERK signals act sequentially on the neural plate such that each neural plate cell receives a different
combination of these three signals and appear to be specified following Cartesian-like grid coordinates. Finally, I will show
evidence that, despite their similarity in structure, the mechanisms governing patterning of the ascidian and vertebrate CNS
appear to be quite distinct.