Next, the influences on the migration of neural crest cell from the microenvironment of the hindgut through which the neural crest cells migrate were studied. An organ culture system was established to recombine different gut segments together at E11.5 for gut culture in order to trace the migration of neural crest cells from the midgut of the +/+ or Dom/+ embryo to the hindgut of the same or different genotypes. At E11.5, the midgut of both +/+ and Dom/+ embryos had already been fully colonized by neural crest cells, thus an explanted midgut segment (donor midgut) could serve as the source of the neural crest cells, while the caudal half of the hindgut (recipient hindgut) acted as the recipient of the neural crest cells from the donor midgut segment because at this stage, the caudal half of the hindgut was completely devoid of neural crest cells. After three days of culture, when a segment of midgut from the +/+ embryo was used as the donor of migratory vagal neural crest-derived cells and combined with an aneural segment of the hindgut (segment without neural crest-derived cells) from Dom/+ or Dom/Dom embryos, neural crest-derived cells from the midgut segment successfully crossed the combination junction and migrated normally along the hindgut segment to reach its caudal end within a normal developmental time frame. However, the migration of neural crest-derived donor cells from the Dom/+ midgut segment was abnormal in the recipient hindgut with a genotype of +/+, Dom/+ or Dom/Dom as evidenced by the retarded rostrocaudal progression of the vagal neural crest-derived cells and the reduced number of migratory cells in the recipient hindgut segment. These results thus indicate that the migration of the vagal neural crest-derived cells is minimally influenced by the migratory environment of the hindgut of the Dom embryo, and that the neural crest cells themselves may be defective in migration leading to the retarded migration in the hindgut of Dom mouse embryos. / The vagal neural crest cells originating from the region of the neural tube adjacent to somites 1 to 7 migrate along defined pathways to the gastrointestinal tract and then colonize the gut to give rise to the majority of neurons and glia of the enteric nervous system. Mutation of Sox10 in the Dominant megacolon (Dom) mouse, which is an animal model of Hirschsprung's disease, leads to aganglionosis (absence of ganglia) in varying lengths of the hindgut. To investigate the underlying cellular mechanism of aganglionosis, the migration of vagal neural crest cells from the neural tube to the gut (pre-enteric migration) in Dom mouse embryos at E8.5 was firstly traced with extrinsic cell markers, such as wheat germ agglutinin gold conjugates (WGA-Au) or fluorescent dye DiI. After the vagal neural crest cells entered the gut at E9.5, their migration was then followed by the examination of the expression of specific markers for undifferentiated neural crest cells with immunohistochemical staining. It was found that, although vagal neural crest cells in embryos of the three genotypes examined migrated along similar pre-enteric pathways at a similar migratory rate, the numbers of neural crest cells in embryos heterozygous (Dom/+) and homozygous (Dom/Dom) for the Sox10 mutation were significantly reduced when compared with the number of neural crest cells in wild-type (+/+) embryos. After vagal neural crest had entered the gut and from E10.5 onwards, no neural crest-derived cells were found in the gut of Dom/Dom embryos, and the migration of neural crest cells along the Dom/+ gut was significantly retarded from E12.5 onwards as compared with the migration in stage-matched +/+ embryos. / To further trace the cause of defective migration of neural crest cells in the Dom embryo, the proliferation and survival of neural crest cells were investigated with BrdU labeling and TUNEL assay. It was found that, although there was no obvious difference in the proliferating ability of vagal neural crest cells in embryos of all the three Dom genotypes studied during the pre-enteric migration and the migration in the gut, more apoptotic neural crest cells were found along the pre-enteric migratory pathway of Dom/Dom embryos than Dom/+ and +/+ embryos. Therefore, the decreased surviving ability, but possibly not the reduced proliferating ability, of neural crest cells during their pre-enteric migration may be partly responsible for aganglionosis in the hindgut of the Dom mouse. / Wang Liang. / "June 2006." / Adviser: W. Y. Chan. / Source: Dissertation Abstracts International, Volume: 68-03, Section: B, page: 1380. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (p. 287-307). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

Li Mei. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (leaves 182-202). / Abstracts in English and Chinese. / Abstract --- p.i / 中文摘要 --- p.iii / Acknowledgements --- p.v / List of Abbreviations --- p.vi / CONTENTS --- p.viii / Chapter Chapter 1 --- General introduction --- p.1 / Chapter 1.1 --- Alkaline phosphatase --- p.1 / Chapter 1.1.1 --- Distribution --- p.1 / Chapter 1.1.2 --- Molecular characteristics of alkaline phosphatase --- p.4 / Chapter 1.1.3 --- Properties of alkaline phosphatase --- p.8 / Chapter 1.1.4 --- Role of alkaline phosphatase --- p.10 / Chapter 1.2 --- Mouse embryonic brain development --- p.18 / Chapter 1.2.1 --- General developing process --- p.18 / Chapter 1.2.2 --- The crainal nerve nuclei in the embryonic mouse brainstem --- p.20 / Chapter 1.2.3 --- The process of neurogenesis in central nerve system --- p.22 / Chapter 1.3 --- Alkaline phosphatase expressed in developing neural tube --- p.26 / Chapter 1.4 --- Summary --- p.30 / Chapter 1.5 --- Objectives of study --- p.31 / Chapter Chapter 2 --- AP expression pattern in embryonic mouse brainstem --- p.33 / Chapter 2.1 --- Introduction --- p.33 / Chapter 2.1.1 --- AP expressed in developing neural tube --- p.33 / Chapter 2.1.2 --- Methods for alkaline phosphatase detection --- p.35 / Chapter 2.2 --- Materials and methods --- p.39 / Chapter 2.2.1 --- Animal and procedure --- p.39 / Chapter 2.2.2 --- Preparation of tissue sections and histochemistry --- p.39 / Chapter 2.2.3 --- Electron microscopy study of AP location --- p.41 / Chapter 2.3 --- Results --- p.42 / Chapter 2.3.1 --- Histochemical demonstration of AP --- p.42 / Chapter 2.3.2 --- Stage-specificity and tissue-specificity of AP activity in the neural tube --- p.43 / Chapter 2.3.3 --- Cytochemical localization of AP activity --- p.46 / Chapter 2.3.4 --- Sencitivity to pH of the histochemical staining for AP --- p.46 / Chapter 2.3.5 --- Inactivation of AP activity --- p.47 / Chapter Chapter 3 --- Quantitative studies of AP activity in embryonic mouse brainstem --- p.48 / Chapter 3.1 --- Introduction --- p.48 / Chapter 3.1.1 --- Basic knowledge about enzyme kinetic study --- p.48 / Chapter 3.1.2 --- Enzyme assay for alkaline phosphatase --- p.50 / Chapter 3.2 --- Materials and methods --- p.52 / Chapter 3.2.1 --- Animals and sample preparation --- p.52 / Chapter 3.2.2 --- Measurement of AP activities --- p.53 / Chapter 3.2.3 --- Data analysis --- p.54 / Chapter 3.3 --- Results --- p.54 / Chapter 3.3.1 --- "Determination of reaction duration, initial velocity and Km of AP activity" --- p.54 / Chapter 3.3.2 --- Comparision of AP activity in the brainstem and cortex and at different stages --- p.55 / Chapter 3.3.3 --- Effects of physical and chemical factors on AP activity --- p.55 / Chapter Chapter 4 --- Electrophoresis study of AP activity --- p.57 / Chapter 4.1 --- Introduction --- p.57 / Chapter 4.2 --- Materials and methods --- p.60 / Chapter 4.2.1 --- AP extraction --- p.60 / Chapter 4.2.2 --- Polyacrylamide gel electrophoresis (PAGE) --- p.61 / Chapter 4.2.3 --- Detection of AP activity --- p.61 / Chapter 4.3 --- Results --- p.62 / Chapter 4.3.1 --- Demonstration of AP activity on the gels --- p.62 / Chapter 4.3.2 --- Comparison of AP from the brain at different stages --- p.62 / Chapter 4.3.3 --- "Comparison of AP in the embryonic brainstem with those in the adult mouse placenta, kidney, liver and intestine" --- p.63 / Chapter 4.3.4 --- Effect of heating and chemical factors on AP activity in the embryonic brainstem --- p.63 / Chapter Chapter 5 --- Study of the cell types expressing AP activity --- p.65 / Chapter 5.1 --- Introduction --- p.65 / Chapter 5.2 --- Materials and methods --- p.67 / Chapter 5.2.1 --- Materials --- p.67 / Chapter 5.2.2 --- Immunostaining of AP in the embryonic brainstem --- p.68 / Chapter 5.2.3 --- Double staining for AP and cells markers --- p.70 / Chapter 5.3 --- Results --- p.70 / Chapter 5.3.1 --- Effectiveness of anti-TNAP antibody on the embryonic mouse brain --- p.70 / Chapter 5.3.2 --- Expression pattern of different neural cell markers at E13.5 --- p.71 / Chapter 5.3.3 --- Co-localization of AP and specific cell markers in E13.5 brain --- p.72 / Chapter Chapter 6 --- Discussion --- p.74 / Chapter 6.1 --- Stage-dependence and tissue-specificity of AP expression in the developing mouse brainstem --- p.75 / Chapter 6.2 --- Possible molecular nature of AP expressed in the developing mouse brainstem --- p.80 / Chapter 6.3 --- The possible cell types that express the enzyme activity --- p.83 / "Figures, Tables, Graphs and Legends" --- p.87 / Appendices --- p.165 / Appendix A: Sources of materials --- p.165 / Appendix B: The process of sample for staining --- p.167 / Appendix C: Protocol of histochemical staining for AP --- p.170 / Appendix D: Protocol of electron microscopy study for AP activity --- p.172 / Appendix E: Protocol of enzyme assay for AP activity --- p.174 / Appendix F: Protocol of immunostaining (ABC method) --- p.175 / Appendix G: Protocol of double staining with fluorescent detection --- p.177 / Appendix H: Protocol of electrophoresis analysis for AP --- p.179 / References --- p.182

Chung Kit Ying. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references (leaves 90-104). / Abstracts in English and Chinese. / Chapter Chapter 1 --- General Introduction --- p.1-22 / Chapter Chapter 2 --- Expression of Chondroitin Sulfate Proteoglycans (CSPGs) in the Chiasm of Mouse Embryos / Introduction --- p.23-24 / Materials and Methods --- p.25 -27 / Results --- p.28-33 / Discussion --- p.34-40 / Figures --- p.41-45 / Chapter Chapter 3 --- Effects on Axon Routing after Removal of Chondroitin Sulfate Proteoglycans by Enzymatic Digestion / Introduction --- p.46 -47 / Materials and Methods --- p.48 -50 / Results --- p.57 / Discussion --- p.57-61 / Figures --- p.62-66 / Chapter Chapter 4 --- Immediate Effects of Prenatal Monocular Enucleation on the Cellular and Molecular Environment in the Development of Retinofugal Pathway / Introduction --- p.67-69 / Materials and Methods --- p.70-72 / Results --- p.73.77 / Discussion --- p.78-82 / Figures --- p.83-86 / Chapter Chapter 5 --- General Conclusion --- p.87-89 / References --- p.90 -104

Leung Kin Mei. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (leaves 106-125). / Abstracts in English and Chinese. / Chapter CHAPTER 1 --- GENERAL INTRODUCTION --- p.1-11 / Chapter CHAPTER 2 --- ENZYMATIC REMOVAL OF CHONDROITIN SULFATES ABOLISHES THE AGE-RELATED ORDER IN THE OPTIC TRACT OF MOUSE EMBRYOS / INTRODUCTION --- p.12-13 / MATERIALS AND METHODS --- p.13-18 / RESULTS --- p.18-24 / DISCUSSION --- p.24-29 / FIGURES --- p.30-39 / Chapter CHAPTER 3 --- EXPRESSION OF PHOSPHACAN AND NEUROCAN IN THE DEVELOPING MOUSE RETINOFUGAL PATHWAY / INTRODUCTION --- p.40-42 / MATERIALS AND METHODS --- p.42-43 / RESULTS --- p.44-49 / DISCUSSION --- p.49-55 / FIGURES --- p.56-61 / Chapter CHAPTER 4 --- HEPARAN SULFATE PROTEOGLYCAN EXPRESSION IN THE OPTIC CHIASM OF MOUSE EMBRYOS / INTRODUCTION --- p.62-63 / MATERIALS AND METHODS --- p.63-65 / RESULTS --- p.66-70 / DISCUSSION --- p.70-76 / FIGURES --- p.77-82 / Chapter CHAPTER 5 --- EXPRESSION OF NEURAL CELL ADHESION MOLECULES IN THE CHIASM OF MOUSE EMBRYOS / INTRODUCTION --- p.83-85 / MATERIALS AND METHODS --- p.85-88 / RESULTS --- p.88-92 / DISCUSSION --- p.92.95 / FIGURES --- p.96-102 / Chapter CHAPTER 6 --- GERNEAL CONCLUSION --- p.103-105 / REFERENCES --- p.106-125

Shan Sze Wan. / "July 2004." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (p. 125-139) / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

In the present study using zebrafish as the model organism, we have investigated the function of UII/UII-receptor (UIIR) signaling pathway during early embryogenesis. Herein we presented five lines of evidence supporting the hypothesis that UII/ UIIR signaling pathway is required for normal determination of asymmetric axis during early embryogenesis. First, function-loss of UII results in a concordant randomization of viscus asymmetries in embryos, including abnormalities in cardiac looping and positioning of visceral organs. Second, knockdown of UII randomizes the left-sided expression of asymmetrical genes including lefty2, spaw and pitx2c in the lateral plate mesoderm (LPM) and bmp4 in the developing heart domain and the LPM. Third, reduced UII levels interfere with the normal organogenesis of Kupffer's vesicle (KV), an organ implicated in the early steps of left-right (L-R) patterning of embryos. Fourth, repression of UII function perturbs the asymmetrical distribution of free Ca2+ (intracellular Ca2+) at the region surrounding embryo KV during early somitogenesis, which is one of the signaling mechanisms that propagandize and amplify the early clue of left-right (L-R) asymmetry. Fifth, depressing UII levels alters the normal pattern of Bmp and Nodal signaling, which modulate the establishment of L-R axis of developmental embryo. Collectively, these observations support a model in which UII/UIIR signal system takes part in the early molecular events of L-R asymmetry patterning of embryo by modulating Bmp and Nodal signaling, regulating KV normal morphogenesis, so then, maintaining the asymmetrical distribution of free intracellular Ca2+ at the peripheral region surrounding embryo KV. This study documents a role of UII/UIIR signaling pathway in the establishment of L-R axis of embryos which promises to reveal the molecular mechanisms responsible for human congenital diseases with heterotaxy. / Urotensin II (UII) is the most potent vasoconstrictor identified so far. This cyclic peptide stimulates its G protein-coupled receptor (GPR) to modulate cardiovascular system function in humans and in other animal species. / Li, Jun. / Advisers: Christopher HK Cheng; Mingliang He. / Source: Dissertation Abstracts International, Volume: 73-02, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 143-168). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Thesis (Ph.D.)--Memorial University of Newfoundland, 2002. / Includes bibliographical references.

Thesis (M.S.)--University of Michigan, 1994. / Includes bibliographical references.

Thesis (M.Sc.)--Memorial University of Newfoundland, Faculty of Medicine, 1999. / Typescript. Bibliography: p. 115-134.

O ácido retinóico (AR) é essencial para a embriogênese. A principal enzima sintetizadora de AR durante o desenvolvimento é a ALDH1A2 (RALDH2), uma retinaldeído desidrogenase que converte retinaldeído a AR. Para entendermos como o gene da aldh1a2 é regulado identificamos regiões evolutivamente conservadas (ECRs) em vertebrados e testamos seu potencial regulatório. Identificamos uma ECR localizada no intron1 da aldh1a2, conservada em anfíbios, aves e mamíferos que atua como um enhancer em estruturas derivadas de ectoderme, endoderme e mesoderme. Animais transgênicos transientes e permanentes mostram a ativação desse enhancer na região da placa do teto do tubo neural e epicárdio, local onde esse enhancer é ativado em células derivadas do órgão pro-epicárdico após o contato e/ou proximidade com células do miocárdio. A identificação de um enhancer conservado no gene da aldh1a2 suporta a idéia de que esse gene possui uma regulação modular e mostra que a abordagem evolutiva é uma eficiente ferramenta para a identificação de mecanismos de controle desse gene. / Retinoic acid (RA) is essential for embryogenesis. The key RA synthetic enzyme during early development is ALDH1A2 (RALDH2), a retinaldehyde dehydrogenase that converts retinaldehyde into RA. To understand how aldh1a2 is regulated we screened the gene for evolutionary conserved regions (ECRs) among vertebrates and assayed their regulatory potential. We describe an aldh1a2 intron 1 ECR (identified as RALDH2.2) that is conserved in amphibians, avians and humans and acts as an enhancer in derivatives of ectoderm, endoderm and mesoderm. Transient and stable transgenesis in mice reveal strong activity of the raldh2 intron 1 enhancer at the roof plate of the neural tube and at the growing epicardium. Transgenic mice indicate that the enhancer is activated in proepicardium-derived cells by contact and/or close proximity to the myocardium. The identification of an aldh1a2 conserved enhancer supports the idea of a modular regulation and shows that the evolutionary approach is an efficient tool to identify control mechanisms of the aldh1a2 gene.