From locating a secure home, foraging for food, running away from predators, spatial navigation is an integral part of everyday life. Multiple brain regions work together to form a three-dimensional representation of our environment; specifically, place cells, grid cells, border cells & head direction cells are thought to interact and influence one another to form this cognitive map. Head direction (HD) cells fire as the animal moves through space, according to directional orientation of the animal’s head with respect to the laboratory reference frame, and are therefore considered to represent the directional sense. Interestingly, inactivation of head direction cell-containing brain regions has mixed consequences on spatial behavior. Current methods of identifying HD cells are limited to in vivo electrophysiological recordings in a dry-land environment. We first developed a dry-land version of the MWM in order to carry out behavioral-recording paired studies. Additionally, to learn about HD cells function we quantified expression of neuronal activation marker (c-Fos), and L-amino acid transporter 4 (Lat4) in neurons found within the HD cell dense anterodorsal thalamic nucleus (ADN) in mice after exploratory behavior in an open field, or forward unidirectional movement on a treadmill. We hypothesize that the degree to which ADN neurons are activated during exploratory behavior is influenced by the range of heading directions sampled. Additionally, we hypothesize that c-Fos and Lat4 are colocalized within ADN neurons following varying amounts of head direction exposure. Results indicate that following free locomotion of mice in an open field arena, which permitted access to 360° of heading, a greater number of ADN neurons express c-Fos protein compared to those exposed to a limited range of head directions during locomotion in a treadmill. These findings suggest that the degree of ADN neuronal activation was dependent upon the range of head directions sampled. We observed a high degree of colocalization of c-Fos and Lat4 within ADN suggesting that Lat4 may be a useful tool to manipulate neuronal activity of HD cells. Identifying genetic markers specific to ADN helps provide an essential understanding of the spatial navigation system, and supports development of therapies for cognitive disorders affecting navigation. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2017. / FAU Electronic Theses and Dissertations Collection

Lee, Yuen Shan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (leaves 81-102). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgements --- p.iv / Table of contents --- p.vi / List of Figures --- p.ix / List of Abbreviations --- p.xi / Chapter Chapter 1. --- General introduction --- p.1 / Chapter Chapter 2. --- Literature review / Chapter 2.1 --- History of food allergy research --- p.3 / Chapter 2.2 --- Prevalence of food allergy --- p.4 / Chapter 2.3 --- Clinical symptoms of food allergy --- p.6 / Chapter 2.4 --- Mechanism of food allergy --- p.6 / Chapter 2.4.1 --- Properties of food allergens --- p.7 / Chapter 2.4.2 --- Exposures to food allergens in the gastrointestinal tract --- p.8 / Chapter 2.4.3 --- Oral tolerance and its relationship to food allergy --- p.9 / Chapter 2.4.4 --- Cellular mechanism of food allergy --- p.13 / Chapter 2.5 --- Studies on seafood allergies and allergens --- p.17 / Chapter 2.6 --- Use of animal models in the study of food allergy --- p.22 / Chapter 2.6.1 --- Selection of species and strain for developing animal models --- p.22 / Chapter 2.6.2 --- Parameters of sensitization protocol --- p.25 / Chapter 2.6.3 --- Lessons from animal models --- p.27 / Chapter 2.6.3.1 --- Investigations on pathogenesis of food allergy --- p.27 / Chapter 2.6.3.2 --- Studies on development of therapeutic strategies --- p.28 / Chapter Chapter 3. --- Characterization of hypersensitive responses to recombinant shrimp tropomyosin in mice / Chapter 3.1 --- Introduction --- p.30 / Chapter 3.2 --- Materials and Methods / Chapter 3.2.1 --- Preparation of the recombinant shrimp tropomyosin / Chapter 3.2.1.1 --- Expression of the recombinant shrimp tropomyosin --- p.32 / Chapter 3.2.1.2 --- Extraction and purification of the recombinant protein under native condition --- p.32 / Chapter 3.2.1.3 --- Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) --- p.33 / Chapter 3.2.1.4 --- Quantification of the recombinant protein and detection of level of endotoxin in the protein --- p.34 / Chapter 3.2.2 --- Characterization of hypersensitive responsesin mice / Chapter 3.2.2.1 --- Mice --- p.37 / Chapter 3.2.2.2 --- Sensitization and challenge of mice --- p.37 / Chapter 3.2.2.3 --- Assessment of systemic anaphylaxis responses --- p.38 / Chapter 3.2.2.4 --- Detection of shrimp tropomyosin specific IgE level --- p.39 / Chapter 3.2.2.5 --- Passive cutaneous anaphylaxis (PCA) test --- p.40 / Chapter 3.2.2.6 --- In vitro proliferation assay under stimulation of shrimp tropomyosin --- p.40 / Chapter 3.2.2.7 --- Cytokine profile of splenocytes --- p.42 / Chapter 3.2.2.8 --- Histological examination of small intestine --- p.44 / Chapter 3.2.2.9 --- Statistical analysis --- p.45 / Chapter 3.3 --- Results / Chapter 3.3.1 --- Preparation of the recombinant shrimp tropomyosin --- p.47 / Chapter 3.3.2 --- Induction of systemic anaphylaxis responses after challenge --- p.48 / Chapter 3.3.3 --- Elevated level of shrimp tropomyosin specific IgE --- p.49 / Chapter 3.3.4 --- Passive cutaneous anaphylaxis (PCA) reactions --- p.50 / Chapter 3.3.5 --- Proliferation response of splenocytes under in vitro stimulation --- p.54 / Chapter 3.3.6 --- Cytokine profiles of restimulated splenocytes --- p.58 / Chapter 3.3.7 --- Histology of small intestine --- p.65 / Chapter 3.4 --- Discussion --- p.68 / Chapter Chapter 4. --- General conclusion --- p.78 / References --- p.81

Abstract not available

Includes bibliographical references (leaves 142-168) Aim was the purification and identification of the early primitive ectoderm-like (EPL) cell induction signals within the medium conditioned by the human hepatocellular carcinoma cell line HepG2 and the localisation of the signals that induce EPL cell and primitive ectoderm formation.

Congenital heart disease (CHD) is the major cause of death in the first year of life, the estimated incidence being 0.5-5% of live births; therefore it is important to understand the genetic causes underlying the complex process of heart formation to help prophylaxis, diagnosis and treatment of affected patients. CHD is the commonest phenotype associated with left-right (LR) disorders. LR asymmetry is determined during embryonic development. The three major body axes ? antero-posterior, dorso-ventral and left-right ? are patterned at gastrulation. LR asymmetry is established shortly after the two other major axes are patterned. The process of LR determination can be sub-divided into four integrated steps: 1. breaking of molecular symmetry in the gastrulation organizer; 2. transfer or relay of this asymmetric information to the lateral plate mesoderm (LPM), from which most internal organs will be formed; 3. reinforcement and propagation of asymmetric cues throughout the LPM and 4. conversion of asymmetric molecular information into proper organ morphogenesis. The goal of this work is to investigate mechanisms involved at two specific points in the laterality pathway: the initial generation/maintenance of asymmetric gene expression in the LPM and the morphogenetic translation of these early events into correct heart formation in the mouse. My emphasis has been on the characterization of laterality targeted cells via careful analysis of Pitx2c expression using a Pitx2c-lacZ reporter transgene, the role of BMP signalling, via Smad1, in generation/maintenance of early asymmetric signalling in the LPM, and the later involvement of both Smad1 and Pitx2 in cardiac morphogenesis through analyses of knockout mice.

Schizophrenia is a devastating psychiatric disorder that affects approximately 1% of the population. The main treatments for schizophrenia are antipsychotic drugs that target dopamine receptors, yet the underlying biological mechanisms through which they alleviate the symptoms of schizophrenia remain ill defined. In this study, we used microarray analysis to profile the expression changes of thousands of genes simultaneously, following antipsychotic drug treatment of mice. Mice were treated chronically (28 days), or for a novel intermediate time-point (7 days), with one of three antipsychotic drugs: clozapine, haloperidol or olanzapine. The use of three drugs enabled us to discern antipsychotic-specific effects co-regulated by multiple drugs, rather than the side effects of individual compounds. Transcript profiling and validation by quantitative PCR of whole brain tissue revealed antipsychotic drug regulation of genes in diverse biological pathways, including: dopamine metabolism, neuropeptide and second-messenger signalling, neurogenesis, synaptic plasticity, cell adhesion, myelination, and voltage-gated ion channels. The regulation of voltage-gated channels by antipsychotic drugs has been suggested previously by electrophysiological studies, although thorough analysis has not been undertaken in vivo. Therefore, the second aim of this study was to characterise the regional mRNA and protein expression of two genes altered by multiple APDs, the voltage-gated potassium channel ??-subunit (Kcna1) and voltage-gated potassium channel interacting protein (Kchip3). Regional characterisation and expression analyses were carried out by immunohistochemistry, in situ hybridisation, and Western blot analysis of mouse brain regions of interest to schizophrenia and its treatment. Following 7-day haloperidol treatment we observed up-regulation of Kcna1 in the striatum and dentate gyrus, with increased protein in the striatum, hippocampus and midbrain; and down-regulation of Kchip3 in the striatum, with decreased protein in the cortex, hippocampus and midbrain. These studies implicate voltage-gated potassium channels in the antipsychotic drug regulation of midbrain dopaminergic neuronal activity, adult neurogenesis and/or striatothalamic GABAergic neuronal inhibition. These findings indicate that regulation of potassium channels may underlie some of the mechanisms of action of antipsychotic drugs, and that voltage-gated ion channels may provide alternative drug targets for the treatment of schizophrenia.

Includes bibliographical references (leaves 142-168) / x, 168 leaves : ill. (chiefly col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Aim was the purification and identification of the early primitive ectoderm-like (EPL) cell induction signals within the medium conditioned by the human hepatocellular carcinoma cell line HepG2 and the localisation of the signals that induce EPL cell and primitive ectoderm formation. / Thesis (Ph.D.)--University of Adelaide, Dept. of Molecular Biosciences (Biochemistry), 2001

published_or_final_version / Medical Sciences / Master / Master of Medical Sciences

published_or_final_version / Anatomy / Master / Master of Philosophy

Congenital cataract is a leading cause of visual disability among children worldwide. It has a heterogeneous genetic basis; the cellular and molecular mechanisms for cataractogenesis remain elusive. A spontaneously occurred autosomal dominant mouse mutant named Secc, which displays small eye, cataract and closed eyelid, has been obtained in our laboratory. By gene mapping and DNA sequencing, we identified a single nucleotide deletion at position 273 of the Cryga gene, leading to a frame-shift from the 3rd Greek Key motif of the A-crystallin (Cryga). The aim of this study is to investigate the pathogenic mechanisms underlying the development of cataract in the Secc mutant, as a disease model for understanding human congenital cataract. Initial phenotype analysis showed that cataract was initiated in E14.5 CrygaSecc mutant embryos, the nuclei of the primary lens fibres were scattered and failed to align in the equatorial region. By E16.5, the secondary lens fibre cells were abnormally arranged with poor lens suture formation. Apoptotic cells were found in the centre of the lens as shown by TUNEL assay, cytoskeleton and cell adhesion in the lens centre were disturbed as shown in immunohistochemistry analysis. Previously by western blotting it was found that mutant -crystallins were enriched in the insoluble fraction. I hypothesized that mutant A-crystallins might be misfolded and protein aggregates were then formed. In this study, aggregation was observed in semi-thin sections stained with toluidine blue. By co-staining using custom-made anti-Secc antibody, CrygaSecc protein was found to be ubiquitinated and was wrapped around by vimentin. Clearly, in the Secc mutant lens, aggresomes were formed for the disposal of the misfolded proteins and to maintain cell survival. However, ultimately cell death would occur in the mutant lens and contributed to cataract formation. It is known that misfolded proteins would trigger unfolded protein response (UPR) and heat shock protein (HSP) responses to facilitate folding and to prevent misfolded proteins from intoxicating the cell. In order to determine which stress response pathway was triggered, gene expression analysis by qRT-PCR was performed. The expression of genes involved in the UPR pathways including BiP, CHOP and spliced variant of XBP-1 were all up-regulated significantly in E14.5 and 16.5 mutant lenses. In addition, among different ER stress related genes, cytosolic chaperones and autophagy related genes, Hsp70 and BiP were upregulated, while Hsp40 and Hsp90aa were downregulated in the homozygotes. The results suggested that both UPR and HSP response pathways were triggered during cataractogenesis in the Secc mutant. In conclusion, mutant A-crystallin appeared to trigger UPR, HSPs and cell death in the fibre cells, while autophagy was not triggered. In the lens fibre cells, the ubiquitin-proteasomal pathway was utilized for the removal of misfolded CrygaSecc proteins. However, the stress perpetuated as the lens grew and produced more mutant proteins. The mutant cells lost their normal cell adhesion, failed to maintain the proper lens architecture, leading to cataract formation. Similar cellular mechanisms could be implicated in human congenital cataract or age-related cataract development. / published_or_final_version / Biochemistry / Doctoral / Doctor of Philosophy