Congress Abstracts - Society for Developmental Biology

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chimaeras. The cytokine LIF, necessary for ESC self-renewal, supported the expansion of this population, but did not directly support Nanog positive epiblast-like ESCs. Thus 2i and LIF support a totipotent state comparable to early embryonic cells that coexpress embryonic and extraembryonic determinants. Program/Abstract # 534 Cell fate decisions regulating stem cell origins during preimplantation mouse development Ralston, Amy (UC-Santa Cruz, USA) Using the mouse embryo, we aim to understand the origins and regulation of stem cells during development. Our approach is to examine the roles of stem cell factors in cell fate decisions in the mouse early embryo. Oct4 and Sox2 are essential regulators of pluripotency in embryonic stem cells, where they regulate each other’s expression. However, we show that in the mouse blastocyst, neither zygotic nor maternal Oct4 is required for expression of Sox2, nor is maternal/zygotic Sox2 required for Oct4. Rather, Oct4 and Sox2 both regulate formation of the primitive endoderm, an extraembryonic tissue. Primitive endoderm cell fate is known to depend on FGF signals from the epiblast, suggesting that the requirement for Oct4 and Sox2 in primitive endoderm development could be non cell-autonomous. We show that while Sox2 regulates primitive endoderm development non cell-autonomously upstream of FGF signaling, Oct4 regulates primitive endoderm cell-autonomously downstream of FGF signaling. Finally, we examine stem cell factors thought to be required for trophectoderm, another extraembryonic lineage of the blastocyst. Maternal Cdx2 and Sox2 are each thought to be required for trophectoderm development. However, deletion of Cdx2 in the female germline does not disrupt trophectoderm cell fate nor mouse development. We also show that maternal Sox2 is not required for trophectoderm development. Rather, we show that the trophectoderm-specifying pathway upstream of Cdx2 also regulates expression of Sox2. Ultimately, our data support regulative, rather than deterministic, models of early mammalian development. Program/Abstract # 535 Cell competition in the mammalian epiblast selects cells with higher Myc levels Clavería, Cristina; Giovinazzo, Giovanna; Sierra, Rocío; Torres, Miguel (Spanish National Centre for Cardiovascular Research (CNIC), Spain) The epiblast is the mammalian embryonic tissue that contains the pluripotent stem cells that generate the whole embryo. We have established a method for inducing functional genetic mosaics in the mouse. Using this system we found that induction of a mosaic imbalance in c-Myc expression provokes the expansion of cells with higher c-Myc levels through the apoptotic elimination of cells with lower levels, without disrupting development. In contrast, a homogeneous shift in c-Myc levels did not affect epiblast cell viability, indicating that the observed competition results from comparison of relative c-Myc levels between epiblast cells. During normal development we found that c-Myc levels are intrinsically heterogeneous among epiblast cells, and that endogenous cell competition refines the epiblast cell population through the elimination of cells with low relative c- Myc levels. These results show that natural cell competition in the early mammalian embryo contributes to the selection of the epiblast stem-cell pool. Program/Abstract # 536 The study of the first heart field cardiac progenitor cells via ES cell derivation Kokkinopoulos, Ioannis; Saba, Rie; Ishida, Hidekazu (Queen Mary Univ of London, UK); Hamada, Hiroshi (Osaka Univ, Japan); Suzuki, Ken; Yashiro, Kenta (Queen Mary Univ of London, UK) The heart is the first visible organ during vertebrate embryogenesis. It originates from the most anterior part of lateral plate mesoderm. Cardiac progenitor cells (CPCs) are divided into two major populations, occupying the first and second heart fields during development. First heart field CPCs are labelled with Nkx2-5 and/or Tbx5 and are mainly destined to from the left ventricle and atria of the heart, while the second heart field CPCs, labelled with Isl1, will give rise to the right ventricle and the outflow tract. To date, it has been shown that Nkx2-5 + CPCs are able to give rise to smooth muscle cells and cardiomyocytes, while Isl1 + CPCs are multipotent able to differentiate to cardiomyocytes, smooth muscle and endothelial cells. There has been no report examining the potential of Tbx5 + cells as CPCs, to date. To better understand CPCs onset, we have performed single cell cDNA analysis on cells from the early allantoic bud (EB) stage to early headfold (EHF) stage on embryonic day (E) 7.5. This study showed that Tbx5 + , Nkx2.5 + and Tbx5 + /Nkx2.5 + cells are the three major CPC subpopulations. As heart development proceeds, the Tbx5 + cell population begins to diminish, with the Tbx5 + /Nkx2.5 + to steadily increase while approaching the late allantoic bud (LB) stage. By the early somite stage, no Tbx5 + cells are present. To test the hypothesis of whether Tbx5 + /Nkx2.5 + CPCs descend from Tbx5 + CPCs, we generated a tamoxifen-inducible BAC Tbx5 (CreERT2/+) ;Rosa26R YFP/- transgenic mouse. With this system, we are able to trace Tbx5 + CPCs in vivo as well as deriving ES cell lines from these transgenic mice Tbx5 + CPCs for tracing analysis in vitro. We will present our findings with this newly established experimental system. Program/Abstract # 537 Single-Cell cDNA Analyses of embryonic cardiac progenitor cells Yashiro, Kenta; Kokkinopoulos, Ioannis; Saba, Rie; Ishida, Hidekazu (Queen Mary University of London, UK); Saga, Yumiko (Natl Inst of Genetics, Japan); Azuma-Kanai, Masami (Tokyo Med and Dental Univ, Japan); Kitajima, Keiko; Meno, Chikara (Kyushu Univ, Japan); Kanai, Yoshiakira (The Univof Tokyo, Japan); Koopman, Peter (The Univ of Queensland, Australia); Hamada, Hiroshi (Osaka Univ, Japan); Suzuki, Ken (Queen Mary Univ of London, UK) 154
Better understanding of the underlying mechanism of differentiation of cardiac progenitor cells (CPCs) is vital for the production of the cells from pluripotent stem cells or from directly reprogrammed somatic cells to use in regeneration therapy to treat the heart failure patients as well as congenital heart diseases. However, our knowledge is still insufficient for generating a sufficient amount of pure, high quality cardiomyocytes or other cell types of the heart for the clinical arena. Therefore further study is required. Currently, CPCs are classified into two major groups, the first heart field cells and the second heart field cells. The first heart field cells are destined mainly to the atria and the left ventricle, represented by T-box transcription factor Tbx5 as well as homeodomain transcription factor Nkx2-5 expression. The second subgroup is destined to the right ventricle and the outflow tract, represented by LIM-homeodomain transcription factor Isl1 expression. Thus far, Nkx2-5-expressing CPCs and Isl1-expressing CPCs have been shown to be multipotent to differentiate into cardiomyocytes, smooth muscle cells and endothelium/endocardium. On the other hand, Tbx5-expressing CPCs have not been elucidated in detail. To understand embryonic CPCs in detail, we have performed single cell cDNA analyses of mouse embryonic CPCs. Whole mount in situ hybridization revealed that both of Nkx2-5 and Tbx5 expression begins from the early allantoic bud stage to early head fold stage. We have constructed single cell cDNAs from this initial stage of embryonic CPCs in mouse embryos. We will discuss the issues which this study has raised; (1) Detailed information of subpopulations of the initial CPCs and (2) a novel hypothethical model of a lineage tree of CPCs’ progenies. Program/Abstract # 538 A novel somatic role of Piwi in the central nervous system of the ascidian Ciona intestinalis Shimai, Kotaro (Konan U, Japan); Horie, Takeo (Univ of Tsukuba, Japan); Nishitsuji, Koki (Okayama Univ, Japan); Shirae- Kurabayashi, Maki; Nakamura, Akira (RIKEN CDB, Japan); Kusakabe, Rie (Kobe Univ, Japan); Nakai, Kenta (The Univ of Tokyo, Japan); Inoue, Kunio (Kobe Univ, Japan); Kusakabe, Takehiro G. (Konan Univ, Japan) Piwi proteins and the small non-cording RNA, called Piwi-interacting RNAs (piRNAs) are required for the maintenance and formation of germline cells, the repression of transposable elements, and the epigenetic gene expression control. Recent reports showed that the Piwi/piRNA pathway also has roles in cell differentiation. For example, the Piwi expression is detected in the somatic or multipotent stem cells in sponges, ctenophores, planarians, and colonial ascidians. Several cancer cell lines have the elevated Piwi expression. Moreover, the epigenetic control by Piwi is involved in the synaptic plasticity of Aplysia sensory neurons. In this study, we explored a somatic role of Piwi in chordates by looking at a piwi orthologue of the ascidian Ciona intestinalis. The Ciona genome contains three piwi/argonaute family genes, Ci-piwi-like1, Ci-piwi-like2, and Ci-Argonaute. Maternal Ci-piwi-like1 proteins are localized during early embryogenesis, and later they are co-localized with the vasa-homolog, CiVH in a few cells in the endodermal strand of the larva. Interestingly, Ci-piwi-like1 transcripts are also expressed conspicuously in the larval brain, including some differentiated sensory organs and a part of ependymal cells. Brain ependymal cells in the Ciona larva are known to be stem-cell-like cells for the adult nervous system. Using a photo-convertible fluorescent protein Kaede, we examined developmental fate of the larval cells expressing Ci-piwi-like1 during metamorphosis, and found that some of these cells were kept and exhibited a neuron-like feature in the central nervous system of juveniles. Our results suggest that cells expressing Piwi contribute to the formation of the adult nervous system. Program/Abstract # 539 Investigating the Role of SOX9 in Human Neural Stem Cells Hui, Man Ning; Wu, Ming Hoi; Chan, Ken Kwok-Keung; Cheung, Martin (The Univ of Hong Kong, China) Neural stem cells (NSCs) exist in both embryonic and adult nervous tissues and are characterized by their self-renewal capacity and multipotency that contribute to the formation of three major cell types in the central nervous system (CNS): neurons, oligodendrocytes and astrocytes. The tremendous therapeutic potential of NSCs to treat the neurodegenerative diseases and repair brain injuries has provoked intensive study in the molecular regulation of their induction, maintenance and differentiation. Previous study reported that Sox9, a member of SoxE transcription factors family, plays important roles in directing the formation and the maintenance of NSCs in both mouse and chick CNS [1], as well as the cell fate switch between neural and glial [2]. Whether it plays similar roles in human NSCs (hNSCs) is still unknown. Our RT-qPCR analysis showed that SOX9 is expressed at a basal level in human embryonic stem cells (hESCs) and upregulated upon commitment into neural lineage and maintained at a high level in hESCs-derived hNSCs. We therefore hypothesized that SOX9 might also involve in the induction, maintenance and differentiation of hNSCs. To test this, we have generated a hESC line (HES2) stably expressing short hairpin RNA (shRNA) against SOX9 . Upon neural induction, commitment of SOX9-knockdown hESCs to neural fate still occurs suggesting that SOX9 is not required for the neural induction. Characterization of the impact of SOX9 knockdown on self-renewal capacity and differentiation of hESCs-derived NSCs are ongoing. References: 1. Scott, C.E., et al., Nature neuroscience, 2010, 13(10): p. 1181-9. 2. Stolt, C.C., et al., Genes & development, 2003, 17(13): p. 1677-89. Program/Abstract # 540 Gene expression and functional analysis indicate that taurine affects the proliferation and survival pathways of neural precursor cells Ramos-Mandujano, Gerardo; Hernández-Benítez, Reyna; López-Guzmán, Karla; Pasantes, Herminia (UNAM, Mexico) We recently reported a positive influence of taurine on growth and neuronal formation increasing markedly the number of neural precursor cells (NPCs) as well as the number of neurons formed upon differentiation. This was found in NPCs cells from mice adult 155
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International Society of Developmen
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neural crest cells (hNCC)) human em
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activity may determine the orientat
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Developmental cell signaling pathwa
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opposed roles during early gastrula
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functions by the recruitment of add
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function validated with explant stu
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Program/Abstract # 48 Modeling regu
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surface of the embryo. In zebrafish
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morphologies. Our analyses not only
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junctional proteins (RPE patterning
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Program/Abstract # 78 In vivo recep
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Program/Abstract # 85 Guts and gast
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Program/Abstract # 92 The C. elegan
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Program/Abstract # 98 A gradient of
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Program/Abstract # 106 Developing a
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NSCs, but not in neurons, bind not
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abnormalities in the development of
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Tbx4 and contributes to Tbx4 repres
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downregulated by polycomb-group pro
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Zac1 expression in the developing c
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understanding the mechanisms that u
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Program/Abstract # 156 Systematic I
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Program/Abstract # 163 Size regulat
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TACC3 was localized around the DNA
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Penaeid shrimp represent an importa
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tubule. Using live imaging of cultu
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show that cell polarity is disrupte
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process. However, a clear mechanist
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Zhang, Haoran; Wong, Elaine Yee-man
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condition. Kanyon embryos have a mi
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Program/Abstract # 218 Lfng regulat
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works in concert with basal cues fr
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medaka genome. These miRs are encod
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facilitan cambio en patrón morfoge
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coordinately regulate the expressio
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downstream asymmetric signals. The
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viability and morphology of over 20
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owser. The genomic differences obse
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evolutionary analysis to study the
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teleostei. Our data evidenced that
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ontogeny. The typical condition for
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examples whose Shh expression requi
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insights into the ancestral role of
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Program/Abstract # 308 Mechanistic
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Patients with Joubert Syndrome and
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Program/Abstract # 323 Drosophila g
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signalling during gut and enteric n
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normally form, hence producing prox
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survival in Shh mutant embryos foll
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conserved in amniotes other than ch
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Page 133 and 134: Program/Abstract # 462 Retinaldehyd
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Congress Abstracts - Society for Developmental Biology

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