Congress Abstracts - Society for Developmental Biology

Program/Abstract # 250
Embryonic and uterine changes during mouse embryo implantation observed using a clearing technique.
Baiza Gutman, Luis Arturo; Sánchez Santos, Alejandra; Gómez Jiménez, Jaime; Martínez Hernández, María Guadalupe (FES
Iztacala, UNAM, Mexico)
Mouse embryo implantation involves the adhesion of blastocyst to uterine luminal epithelium and the invasion of endometrium by the
trophoblast and includes uterine changes in order to support embryo development. The earliest macroscopic uterine response to
embryo signals is an increased vascular permeability detected after high molecular weight dye injection. Our aim was to analyze
changes during early differentiation of implantation zones by a clearing procedure and its temporal relation with the vascular response
to implantation. Uteri of CD1 mice on 3 to 8 days of gestation where cleared using H 2 O 2 and benzylic alcohol. The vascular response
was detected by extravasation of tripan blue. When we first detected the vascular response on the afternoon of gestation day (GD) 4
(already at 18 h), a morphologically differentiated uterine zone of implantation (IZ) was not clearly defined, furthermore a progressive
growing of antimesometrial endometrium in IZ was observed until the uterine lumen was occluded and the embryo was firmly
adhered in the top of growing endometrium at 17 h on GD 5, these events were followed by the formation of egg cylinder stage
immersed in a mass of decidual tissue (GD 6 to 8). Since early morning on GD 5 a clearly defined IZ and an antimesometrial small
invagination in the center of the zone (implantation chamber) were observed. In conclusion, uterine vascular response to embryo
signals is followed by deep morphological changes in the lumen and wall of uterus associated with the endometrial interaction with
the developing concepti, which can be associated with uterine remodeling and the formation of placenta. Supported by PAPIT,
DGAPA, UNAM, grant IN230611.
Program/Abstract # 251
Directional rearrangement of planar polarised cells underlies the elongation of Drosophila renal tubules.
Saxena, Aditya; Denholm, Barry (University of Cambridge, UK); VijayRaghavan, K (National Centre for Biological Sciences, India);
Skaer, Helen (University of Cambridge, UK)
The Malpighian tubules (MpTs) are single-cell layered epithelial tubes that serve as the principal excretory organs in Drosophila. In a
period lasting only 5 hours during embryonic development, the MpTs undergo a dramatic transformation in shape increasing in length
four-fold whilst the number of cells surrounding the lumen reduces from 8-12 to just 2 cells. This change in tissue architecture occurs
in the absence of cell proliferation or significant changes in cell shape. Using a combination of time-lapse imaging and cell tracking
we find that directional cell intercalation underpins MpT elongation. Employing SLAM protein as a reporter, we show for the first
time that cells in elongating MpTs are planar polarised and that EGF signaling is necessary for the establishment and/or maintenance
of this polarity. Further, live imaging of the actomyosin cytoskeleton reveals that myosin II shows dynamic pulsatile behavior that is
also planar polarised in MpT cells during the process of tissue elongation. We will discuss the molecular and cellular mechanisms by
which EGF signaling regulates planar polarity and we suggest a model in which the direction of cell intercalation is biased by the
generation of asymmetric tensions in tubule cells, resulting from the planar polarised distribution of myosin II.
Program/Abstract # 252
Towards a common model of symmetry breakage: 'early determinants' act in the context of cilia-driven leftward flow
Blum, Martin; Walentek, Peter; Tisler, Matthias (University of Hohenheim, Germany); Danlichik, Michael (Oregon Health & Science
Univ, USA); Schweickert, Axel (University of Hohenheim, Germany)
In fish and mammalian neurula embryos midline epithelia harbor polarized monocilia which rotate in a clockwise manner to produce a
leftward extracellular fluid flow. Flow induces asymmetric gene expression, resulting in asymmetric organ morphogenesis and
placement. In frog, earlier asymmetries were described for serotonin and the ion pump ATP4. The 'ion-flux' model proposed that an
ATP4-generated voltage gradient drives serotonin through gap junctional communication (GJC) to asymmetrically enrich on one side
of the embryo, breaking symmetry upstream of flow. We show that GJC was needed later in development for the transfer of
asymmetric cue(s) from the midline to the lateral plate mesoderm. Serotonin and ATP4 were symmetrically expressed and required for
Wnt-mediated setup of leftward flow. The GRP of ATP4 morphants revealed fewer, shortened and misaligned cilia. ATP4 was
essential for Wnt/ß-catenin regulated Foxj1 induction and Wnt/PCP dependent cilia polarization. Serotonin was involved in the
specification of the superficial mesoderm (SM). The SM represents an epithelium localized above the Spemann organizer, from which
the GRP develops during gastrulation. Importantly, serotonin already accumulates in the epithelial superficial cell layer of the blastula
before SM specification. We hypothesize that other "early" determinants are required for SM specification as well. A model will be
presented which unites opposing hypotheses into a common, evolutionarily conserved mode of symmetry breakage.
Program/Abstract # 253
The Congenital Heart Disease gene, GALNT11, glycosylates Notch to orchestrate cilia type and left-right asymmetry
Yuan, Shiaulou; Boskovski, Marko T. (Yale, USA); Pedersen, Nis Borbye; Goth, Christoffer Knak (University of Copenhagen,
Denmark); Makova, Svetlana (Yale, USA); Clausen, Henrik (University of Copenhagen, Denmark); Brueckner, Martina; Khokha,
Mustafa K. (Yale, USA)
Heterotaxy (Htx) is a disorder of left-right (LR) body patterning, or laterality, that is associated with major congenital heart disease.
The etiology and mechanism underlying most human Htx is poorly understood. In vertebrates, laterality is initiated at the embryonic
left-right organizer (LRO), where motile cilia generate leftward flow that is detected by sensory cilia, which transduce flow into
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