Lam Shi Ying Joyce. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 107-114). / Abstract in English and Chinese. / Chapter CHAPTER 1 --- GENERAL INTRODUCTION --- p.1-19 / Chapter CHAPTER 2 --- EXPRESSION OF PROTEIN KINASE C (PKC) ISOFORMS IN THE VENTRAL TEMPORAL (VT) AND DORSAL NASAL (DN) RETINAL GROWTH CONES OF MOUSE EMBRYOS / INTRODUCTION --- p.20-22 / MATERIALS AND METHODS --- p.22-24 / RESULTS --- p.24-31 / DISCUSSION --- p.31-37 / FIGURES --- p.38-46 / Chapter CHAPTER 3 --- EFFECTS ON MOUSE NASAL AND TEMPORAL RETINAL NEURITES TO CHONDROITIN SULPHATES (CS) AFTER ALTERATION OF PKC ACTIVITY / INTRODUCTION --- p.47-48 / MATERIALS AND METHODS --- p.49-51 / RESULTS --- p.51-59 / DISCUSSION --- p.60-67 / FIGURES --- p.68-74 / Chapter CHAPTER 4 --- EFFECTS ON AXON ROUTING AFTER ALTERATION OF PKC ACTIVITY ON GUIDANCE OF RETINAL GANGLION CELL AXONS AT THE OPTIC CHIASM OF MOUSE EMBRYOS / INTRODUCTION --- p.75-76 / MATERIALS AND METHODS --- p.77-80 / RESULTS --- p.80-89 / DISCUSSION --- p.89-95 / FIGURES --- p.96-103 / Chapter CHAPTER 5 --- GENERAL CONCLUSION --- p.104-106 / REFERENCES --- p.107-114

Chiasm cells, which include glia and neurons, are generated early before any retinal axon arrives at the midline of the mouse ventral diencephalon. These cells have been shown to affect retinal axon growth and patterning in the optic chiasm. In this study, we used EdU (5-ethyny1-2'-deoxyuridine) for birthdating these chiasm cells, aiming to find out when these cells are generated; then we tried to trace their fates at later stages of development. EdU injection at embryonic day (E) 9.5 to El 1 labeled a number of chiasmatic neurons and radial glial cells at E13, which were immunoreactive for SSEA-1 and RC2, respectively. After colocalization studies, we found that most of these neurons were born as early as E9.5, while a large number of radial glial cells were born as from El 1. Both E9.5-born chiasmatic neurons and Ell-born radial glia decreased by E14-E16; the radial glia even disappeared finally from the midline. Furthermore, we found that some chiasmatic neurons underwent apoptotic cell death as from El 4, and that the radial glia likely differentiated into other cell types after finishing their retinal axon guidance mission at the midline. So it is reasonable that some of the earliest born chiasm cells disappear during development. / During development, retinal ganglion cell axons grow from the eye to the ventral diencephalon, where axons from the two eyes converge and segregate into crossed and uncrossed projections, forming the optic chiasm. This pattern is critical for binocular vision. Although significant progress has been obtained over the past decades, how retinal axon growth and guidance are regulated at the chiasm is largely unknown. Our research will focus on those problems. / In the last part of this thesis, we investigated the retinal axon pathway in the ventral diencephalon of the Sox10Dom mutant embryos and gamma-crystallin mutant embryos. Our findings indicate that Sox10 may not contribute to axon guidance in the developing optic pathway whereas gammaA-crystallin may only play a role in the later uncrossed axons. / N-methyl-D-aspartate (NMDA) receptor is one of the ionotropic glutamate receptors, which are important in synaptic plasticity, apart from implications in dendritic spine remodeling, neurite outgrowth, elongation and branching and glutamate neurotoxicity. There are several subtypes of NMDA receptor channel subunits, NR1, NR2A-D, NR3A&B. The functional diversity of NMDA receptor resides in the different assembly of subunits. In this study, we used RT-PCR to analyze the mRNA expression of all the NMDA receptor subunits in mouse embryos. After that we chose the NR1, NR2B and NR3A antibodies to investigate NMDA receptor subunit expression in the optic pathway during mouse optic pathway development. Using immunohistochemistry, we found that NR1, NR2B and NR3A were expressed in the mouse retina and optic pathway as from E13 when the optic chiasm is forming. Expression of the NMDA receptor subunits were found in the inner cell layers and along retinal axons. Colocalization studies showed that NR1, NR2B and NR3A were localized on the ganglion cells and their axons. In the ventral diencephalon, these subunits were expressed extensively, but NR1 and NR3A were particularly strong along the optic nerve and optic tract. Furthermore, to identify the function of NMDA receptor during optic chiasm development, we cultured E14 retinal explants on laminin and poly-D-ornithine in the presence of the NMDA receptor antagonists MK-801 or Dextrorphan-D-tartrate. These two antagonists can significantly inhibit the retinal axon outgrowth, suggesting that the NMDA receptor promotes retinal axon outgrowth in the retinofugal pathway during optic chiasm development. / Li, Jia. / Adviser: Chan Sun On. / Source: Dissertation Abstracts International, Volume: 73-02, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 145-158). / 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.

Yra žinoma, jog nervinės ląstelės gali regeneruoti savo aksonus po periferinės, o tam tikrais atvejais ir po centrinės nervų sistemos pažeidimų. Tačiau aksonų augimas yra sudėtingas, o jo reguliacija turi kritinę įtaką tiek neuronų vystymęsi, tiek regeneracijoje. Vekiami aplinkinių ląstelių, išskiriamų pritraukiančiųjų ir atstumiančiųjų molekulių, aksonai augdami nuolat keičia augimo kryptis iki kol pasiekia galutinius taikinius. Dorsalinių ragų ganglijų (DRG) aksonų augimas priklauso nuo semaforinų klasės molekulių. Sekretuojantys, ar su membrana surišti semaforinai dalyvauja įvairiuose biologiniuose procesuose, tokiuose, kaip centrinės ir periferinės nervų sistemos (CNS ir PNS) vystymęsi ir regeneracijoje, širdies ir kraujagyslių vystymęsi ir imuninės sistemos funkcijose. DRG aksonų vystymasis ir išlikimas smarkiai priklauso nuo nervų augimo faktoriaus (NGF). Darbo tikslas buvo įvertinti NGF koncentracijos įtaką DRG aksonų augimo atsakams į semaforiną 3A. 15 parų pelių embrionų DRG buvo preparuojami iš C57/Bl linijos pelių embrionų. DRG neuronų auginimui naudoti sterilūs dengiamieji stikleliai buvo padengiami poli-L-lizino 0,01 mg/ml ir laminino 0,01 mg/ml tirpalu, pagamintu GBSS terpėje. Aksonų augimo kūgelių vertinimas buvo atliekamas praėjus 60 minučių, o aksonų ilgio vertinimas - praėjus 16 valandų po DRG pasodinimo. Tam, kad nustayti DRG apoptozės lygį, DRG neuronuose priklausomai nuo NGF koncentracijos buvo įvertinta Bcl-2, Bax, c-jun genų raiška, naudojant RT - PGR... [toliau žr. visą tekstą] / It is known that nerve cells can regenerate their axons after damage to peripheral and in some cases central nervous system (PNS and CNS). However, axon growth over longer distances, especially in central nervous system, is complicated. Regulation of axon growth is a critical event both in neuronal development and regeneration. To reach their proper targets, axons rely upon the actions of attractive and repulsive guidance molecules. It is known that growth of dorsal root ganglion (DRG) axons depend on guidance molecules of semaphorin class. Secreted and membrane bound semaphorins participate in diverse biological processes, including development and regeneration of central and peripheral nervous system, cardiovascular development, and immune system functioning. In addition to regulation of DRG axon growth by semaphorin class molecules, DRG axon growth and survival is strongly dependent on nerve growth factor (NGF). The aim of this study was to evaluate responses of DRG axons to semaphorin 3A in dependence of NGF concentration. DRG were dissected from C57/Bl mice E15 embryos in dissection HBSS/glucose medium. DRG were plated on cover slips coated with laminin and poly-L-lysine and grown in Neurobasal medium supplemented with 2% of B27 supplement. To evaluate collapse rate the morphology of axons growth cones were evaluated after 60 minutes and axons length were evaluated 16 hours after DRG plating. To evaluate DRG survival and level of apoptosis in dependence of NGF... [to full text]

published_or_final_version / Anatomy / Doctoral / Doctor of Philosophy

published_or_final_version / Anatomy / Doctoral / Doctor of Philosophy

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

Neuronal migration is an essential aspect of nervous system development; improper or incomplete neuronal migration can lead to debilitating disorders. The model organism Caenorhabditis elegans has 302 neurons and is ideal for studying nervous system development. The cytoplasmic adaptor protein, MIG-10, is necessary for the long range anteroposterior migration during embryogenesis of the neurons CAN, ALM, and HSN. Mutations in the mig-10 gene result in incomplete migrations of all three neurons. MIG-10 is a homologue of the vertebrate proteins lamellipodin and RIAM-1, which are involved in directing actin polymerization during axon outgrowth and guidance. RIAM-1 is known to interact with proteins from the Ras GTPase family. The MIG-10 protein has a pleckstrin homology (PH) domain, a Ras-associating (RA) domain, and a proline-rich region. We used a yeast two-hybrid system to investigate which Ras family proteins MIG-10 interacts with. Three isoforms of MIG-10, MIG-10A, MIG-10B, and MIG-10C, as well as the RAPH domain alone, were used as baits. No evidence of interaction was observed for any of the baits used. These results do not reject our hypothesis as the constitutively active Ras clones may need to be used or there may not be a direct interaction between MIG-10 and the Ras family members. We are currently screening a C. elegans cDNA library for interactions with all three isoforms of MIG-10. In the future we plan to investigate how MIG-10 may be involved in the WAVE/SCAR actin nucleation pathway.

Hao Yanli. / "July 2004." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (p. 113-134). / 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.

Myelination of axons in the central and peripheral nervous system (CNS and PNS) is required for saltatory propagation of nerve impulses. Myelinated axons are organized in functionally distinct membrane domains and the correct formation and maintenance of these domains is fundamental for the correct propagation of the electrical impulse; however, the underlying mechanisms by which these domains are specified are just starting to be unravelled. The paranodal junctions (PNJs) have been shown to contribute to node formation in the CNS and to domain maintenance both in the CNS and PNS. In this thesis I have studied the function of the linkage of the PNJs to the axonal cytoskeleton in regulating these processes by using a combination of knock out and transgenic rescue strategies. Further, I have initiated studies on the live imaging of node assembly. I have shown that the link between the PNJ and the axonal cytoskeleton is required for both the correct timing of oligodendrocyte process migration and for clustering nodal proteins at heminodes, before nodes of Ranvier are formed. Failure to correctly regulate these events during development results in shorter internodes in adults. Further, I have shown the importance of the axonal paranodal cytoskeleton in the maintenance of the node of Ranvier, both in CNS and PNS. In the absence of a link between the PNJ and the axonal cytoskeleton, paranodes disassemble, which causes disruption of both nodal and juxtaparanodal domains. Electron microscopy shows that, despite paranodal disruption, transverse bands are preserved when the anchorage of the PNJ to the axonal cytoskeleton is removed. Surprisingly, the preservation of these structures is associated with the amelioration of the neurological defects seen in mice lacking PNJs. In order to study nodal assembly, I have initiated studies on the transport of the nodal proteins Neurofascin186 and β1Nav tagged with fluorescent tags in transgenic mice, in order to analyse axonal transport during development. I have exploited the triangularis muscle explant preparation and have analysed transport of nodal proteins in young and adult mice. I have shown that transport speeds decrease with age and that the two proteins are transported at different speeds in young animals, but these differences do not persist in adults. This suggests that during myelination these proteins are transported in different vesicles and that this may change during development.