Alzheimer’s disease (AD), one of the major causes of disability and mortality in Western societies, is a progressive age-related neurodegenerative disorder. Increasing evidence suggests the etiology of AD may involve disruptions of zinc (Zn) homeostasis. We hypothesize that disruption of Zn homeostasis leads to alterations of Zn transporter (ZnT) proteins, resulting in increased production of neurotoxic amyloid beta (Aβ) peptide in AD brain. To address this hypothesis we carried out the following studies. 1. We characterized alterations of ZnT-1, ZnT-4 and ZnT-6 in the brain of preclinical AD (PCAD) subjects, who show no overt clinical manifestations of AD but demonstrate significant AD pathology at autopsy. 2. We identified the presence of ZnT-2 in human brain and compared protein levels in the brains of subjects with PCAD, mild cognitive impairment (MCI), early (EAD), and late-stage AD (LAD) to those in age matched normal control (NC) subjects. 3. We examined the relationship between protein levels of ZnT-1, ZnT-2, ZnT-4, ZnT-6 and Aβ produced by H4 human neuroglioma cells (H4-APP) transfected to overexpress amyloid precursor protein (APP), treated with short interfering RNA (siRNA) against each ZnT. Our data show a significant decrease (P < 0.05) of ZnT-1 and a significant increase of ZnT-6 in hippocampus/parahippo-campal gyrus (HPG) of PCAD subjects. In PCAD cerebellum (CER) the data show a significant increase of ZnT-4 and ZnT-6 compared to NC subjects. Levels of ZnT-2 were also significantly decreased in HPG of PCAD subjects compared to NC subjects. In addition, levels of ZnT-2 were significantly (P < 0.05) elevated in SMTG of PCAD and MCI subjects, compared to NC subjects. ZnT-2 was significantly (P < 0.05) elevated in HPG of EAD and LAD, and in SMTG of LAD brains, but was significantly (P < 0.05) decreased in LAD CER compared to NC subjects. siRNA mediated attenuation of each ZnT protein studied (ZnT-2, ZnT-4 and ZnT-6) led to significantly (P < 0.05) decreased production of Aβ compared to controls. Our results suggest alterations in Zn transport may play a role in Aβ processing and contribute to the neuropathology of AD.

The aim of this dissertation was 1) to explore early stage aggregation kinetic behavior of Amyloid-β 1-40 (Aβ1-40) by incorporation of unnatural amino acid pcyanophenylalanine as a site-specific fluorescence reporter, 2) to explore the effect of macromolecules on the aggregation of Aβ1-40. Chapter One provides an introduction of Alzheimer’s disease as an amyloidogenic disease, amyloidogenic peptide and amyloid formation. Details were shown about the research progress of Aβ1-40 aggregation and Aβ1-40’s interaction with polyelectrolytes, and how treatments studies were designed. In Chapter two, using Aβ1-23 as a model molecule, the distinct site-specific dynamics was identified, during amyloid formation, and the structural characteristics of amyloid fibrils were defined by using an unnatural amino acid, p-cyanophenylalanine, as a sensitive fluorescent and Raman probe. The results reveal distinct local environmental changes of specific residues during the aggregation of Aβ1-23. The results also suggest that an edge-to-face aromatic interaction between the F4 and F19 residues from the adjacent in-register β-strands plays a key role in the conformational conversion to form and stabilize β-sheet structure. In Chapter Three, p-cyanophenylalanine was incorporated in the full sequence of Aβ1-40. Site-specific information from p-cyanophenylalanine fluorescence was studied and summarized. In Chapter Four, the inhibiting effect of an anionic polyelectrolyte poly(4- styrenesulfonate) (PSS) on the aggregation of Aβ1-40 peptide was reported. The results demonstrate the strong inhibition potential of PSS on the aggregation of Aβ1-40. Additional studies indicate that the presence of both aliphatic backbone as well as aromatic side chain group in PSS is essential for its inhibition activity. In Chapter Five, it was investigated the effect of two polyelectrolytes, chitosan (CHT) and N-trimethyl chitosan chloride (TMC), on the aggregation of Aβ1-40. Results show that both CHT and TMC exhibit a concentration-dependent decrease of amyloid aggregation suggesting their application as amyloid assembly inhibitors. Their binding mechanism was investigated by computational modeling which shows that Aβ1-40 monomer was primarily stabilized by electrostatic interactions with charged amine and quaternary amines of CHT and TMC respectively. Chapter Six, describes all experimental procedures and instrument setup in detail. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2016. / FAU Electronic Theses and Dissertations Collection

"Alzheimer’s disease (AD) is a neurodegenerative disorder that currently affects an estimated 4.2 million to 5.8 million Americans. Although the cause of AD is not fully known, the current working model proposes that amyloid precursor protein (APP) is unnaturally cleaved by beta and gamma secretases to form the highly neurotoxic peptide beta-amyloid (Aâ) which engages cell surface receptors to cause cell death through a series of events involving oxidative stress and apoptosis. An in vitro model for AD uses cultured human SHSY-5Y (commonly abbreviated SHSY) neuroblastoma cells treated with Yankner peptide, an 11 amino acid peptide representing Aâ residues 25-35 that strongly binds receptor. Treatment of SHSY cells with 20 µM Yankner peptide strongly induces cellular apoptosis. Synthetic peptide human ependymin-1 (hEPN-1) is a derivative of a naturally occurring protein within the human brain, previously shown by our laboratory to upregulate antioxidative enzymes in SHSY cells, and AP-1 transcription factor associated with long-term memory formation. Since hEPN-1 has anti-oxidative potential as a therapeutic, we hypothesized that hEPN-1 can reverse the neurotoxic effects of Yankner peptide treatment of cultured human SHSY neuronal cells. Microtiter dishes were plated with SHSY cells under control conditions (no Yankner peptide), in the presence of 20 µM Yankner peptide, or in the presence of Yankner peptide plus various concentrations of hEPN-1 therapeutic, then cultured for 3 days to 80% confluency. Unattached dying cells were gently washed away, then the residual cells were monitored by measuring cell number, cell viability (Trypan blue exclusion), LDH activity per mg protein (an indirect measure of cell viability), and nuclear blebbing (a measure of apoptosis). Statistical significance was determined using a One Way ANOVA under the LSD stringency, using SPSS. In three independent trials, average cell numbers per microtiter well decreased 44.7% (from 3.11 x 105 to 1.72 x 105) in the presence of 20 µM Yankner peptide (p < 0.05 compared to control), were 2.73 x 105 when 75 µM hEPN-1 was added simultaneously with Yankner (p < 0.05 compared to Yankner), and were 2.96 x 105 when 75 µM hEPN-1 was added 24 hrs post-Yankner (p < 0.05 relative to Yankner alone). The control mean was not statistically distinguishable from either of the hEPN-1-treated samples (p = 0.220 and p = 0.671, respectively). With respect to the trypan blue data, in three independent trials, the mean percent viable cells (excluding trypan blue) decreased 41.0% (from 68.7% to 40.5%) in the presence of 20 µM Yankner peptide (p < 0.001 relative to control), was 60.7% when 75 µM hEPN-1 was added simultaneously with Yankner (p < 0.001 relative to Yankner alone), and was 61.4% when 75 µM hEPN-1 was added 24 hrs post-Yankner (p < 0.001 relative to Yankner alone). The control mean was not statistically distinguishable from either of the hEPN-1-treated samples (p = 0.013 and 0.03, respectively). In the LDH activity experiments, in four independent trials, the average LDH OD decreased 80.8% (from 0.47 to 0.09) in the presence of 20 µM Yankner peptide (p < 0.001 relative to control), was 0.47 when 75 µM hEPN-1 was added simultaneously with Yankner (p < 0.001 relative to Yankner alone), and was 0.48 when 75 µM hEPN-1 was added 24 hrs post-Yankner (p < 0.001 relative to Yankner alone). The control mean was not statistically distinguishable from either of the hEPN-1-treated samples (p = 0.174 and 0.479, respectively). Although previous reports in the literature indicated LDH expression is constitutive in SHSY cells (thus its activity is an indirect measure of cell numbers or viability), it was possible the hEPN-1 treatments upregulated LDH activity. So to ensure our observed changes in LDH activity levels did not represent changes per unit protein, the LDH activity values were divided by the mg of protein present in the sample, and all four experimental samples were statistically indistinguishable (p values = 0.184, 0.995, 0.872, respectively, relative to control). In the nuclear blebbing experiments, in five independent trials, the mean percent blebbed nuclei (a measure of apoptosis) doubled from 7.5% to 16.0% in the presence of 20 µM Yankner peptide (p < 0.001 relative to control), was 6.7% when 75 µM hEPN-1 was added simultaneously with Yankner (p < 0.001 relative to Yankner alone), and was 6.5% when 75 µM hEPN-1 was added 24 hrs post-Yankner (p < 0.001 relative to Yankner alone). The decreased apoptosis observed in the hEPN-1-treated samples was however, not statistically significant (p = 0.381 and 0.279, respectively). Overall, the data suggest that hEPN-1 can protect human neuronal cells from Yankner-induced cell death, whether added simultaneous to the insult, or 24 hrs post. Because the therapeutic can act 24 hrs post-insult, it may interfere with a late-stage apoptotic event. As there is currently no known drug that blocks Yankner-induced toxicity, the hEPN-1 therapeutic shows potential in combating the underlying apoptosis of Alzheimer’s disease."

Alzheimer's disease (AD) is the commonest neurodegenerative disorder that has become increasingly prevalent in most countries. The chronic progressive deteriorating course is characterized by great variations in individual pathways of decline. This abstract summarizes the findings of a prospective study to examine the factors that affect clinical decline in a group of Chinese subjects with Alzheimer's disease (AD). / At the follow up, 19 (18.3%) subjects had died. 74 (71.2%) subjects were alive and were reassessed. Of the subjects reassessed, 49 (66.2%) remained stable at the same CDR, and 25 subjects (33.8%) had deteriorated to a more advanced stage of dementia. A significant deterioration in global cognitive scores (MMSE and DRS) was found (paired t-tests, p&lt;.001). The estimated annual deterioration in MMSE and DRS scores was 1.34 and 4.93. There was a non-significant trend for overall reduction of NP symptoms at the follow up, but a sizable proportion of subjects still exhibited a variety of NP symptoms. / Development of research plan and study objectives is discussed in the third chapter. Due to escalating problem of care for dementia sufferers, a prospective study to examine the clinical factors that affect decline in Chinese elderly people with AD is needed. Four main research objectives are developed. The first objective is to examine the clinical profiles of Chinese subjects with AD. The second objective is to evaluate the relationships between different clinical dimensions of the dementia syndrome. Thirdly, the differences in clinical characteristics between mild and moderate AD would be examined. Finally, significant factors that affect the rate of clinical decline would be determined. / The baseline global cognitive performances were similar among different outcome groups. The 'deteriorated' group had a higher educational level (One way ANOVA, F=4.85, p=.01, Bonferroni comparisons). There was an excess of number of cerebrovascular risk factors (CVRF) in subjects who had deteriorated (Kruskal Wallis test, z=6.6, p=.04). For subjects with CDR 1 at baseline, a significant excess of Apo E4 allele was found in those who had deteriorated at follow up (Pearson chi square 5.72, p=.017; OR = 6.3, CI 1.3 to 30.53). The difference in Apo E4 allele frequency was not significant in subjects with CDR 2 at the baseline. The 'Deceased' group had more advanced age, lower scores in the recognition tests of the Hong Kong List Learning Test (HKLLT) (Kruskal Wallis test, z=8.06, p=.008) and significantly higher scores of 'Parkinsonian signs' (Mann-Whitney U, z=2.99, p=.003). Concerning baseline NP syndromes, 70% of subjects in the 'Affective' groups remained stable at follow up; 31.8% of subjects in the 'Disturbing' groups died, another 31.8% deteriorated at follow up. Logistic regression analysis revealed that a lower score of recognition test of HKLLT, a higher score of 'Parkinsonian signs' and old age were significant predictors for mortality at the 22-month follow up. No significant predictor, apart from a higher premorbid educational level, for the deterioration to a more advanced level of dementia could be identified. / The fifth chapter reports the main research findings. The mean (SD) age at the baseline assessment was 78.18 (5.97) years. The mean (SD) of the Chinese version of the Mini-Mental State Examination (MMSE) and Mattis Dementia Rating Scale (DRS) scores were 16.21(3.69) and 94.88(13.17) respectively. Subjects with moderate AD (Clinical Dementia Rating, CDR=2), compared to subjects with mild AD (CDR=1), performed worse across all cognitive tests. NP symptoms, as evaluated by the Chinese version of the Neuropsychiatric Inventory (NPI), were prevalent and could be classified into 3 subgroups using Latent Class Analysis (LCA): the 'non-disturbing', 'affective' and 'disturbing' groups. The severity of soft neurological signs (SNS) and NP symptoms was more prominent as dementia became more severe. Strong associations between 'Motor coordination' and Sensory integration' signs with cognitive functions were found. The association between NP syndromes and cognitive functions were not as significant. / The following chapter describes the methodology. A group of 104 Chinese subjects with NINCDS-ADRDA criteria for AD were assessed twice in a naturalistic observational study with an average duration of 22 months. Comprehensive evaluation of cognitive, neuropsychiatric (NP), neurological characteristics, cerebrovascular risk and Apolipoprotein E gene polymorphism status was performed at the baseline. The progression of cognitive and clinical decline was compared at the follow up assessment. Baseline and follow up characteristics of cognitive, neuropsychiatric (NP) symptoms and soft neurological signs (SNS) were compared with a group of normal control (NC-FU, CDR=0) and questionable dementia (QD-FU, CDR=0.5). Significant factors influencing progression to a more advanced dementia and mortality were determined. / The introductory chapter outlines the major findings of recent studies on the clinical aspects of AD. Clinical AD is found in 3.6 % of Hong Kong Chinese elders over 70 years old. Literature review suggested that it is a genetically predisposed complex disorder with disease manifestations strongly modulated by health and lifestyle factors. / The last chapter lays out the conclusions of this study. Careful characterization of clinical profile should be emphasized in the management of elderly suffering from AD. This information will be useful for the assessment of prognosis and the formulation of care plan for AD sufferers. / The second chapter focuses on review of recent literature concerning factors that affect cognitive deterioration and clinical decline in AD. The potential determinants of disease progression included genetic predispositions, cognitive and neuropsychiatric profiles, neurological deficits and medical comorbidity. / The sixth Chapter comprises the discussion. The findings of this study provided information about the rate of cognitive and clinical decline in Chinese subjects with AD. The performance characteristics in cognitive tests, inter-subject variations, prevalence of Apo E4 allele and NP symptoms are potential factors that would influence the assessment of cognitive function with time. The universal occurrence of NP symptoms in AD supported a biological explanation for this clinical dimension. The findings also support the notion that cognitive and NP symptoms are relatively independent dimensions of the clinical dementia syndrome. The association between SNS and severity of cognitive impairment suggests that bedside neurological assessment is a feasible way to detect subtle neurological deficits in subjects with very early AD. The presence of 'Parkinsonian signs' predicted mortality, which indicated that the presence of co-morbid subcortical pathology play a significant role in determining the overall outcome. It appeared that trait factors such as the presence of the Apo E4 allele, a higher educational level and pre-existing cerebrovascular diseases, are associated with a faster rate of disease progression, although individual factors may operate differently at different phase of illness. / Lam Chiu Wa. / Source: Dissertation Abstracts International, Volume: 67-11, Section: B, page: 6299. / Thesis (M.D.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (p. 150-185). / 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.

Alzheimer’s disease is the most common form of dementia among older adults, and directly contributes to the third leading cause of death in the United States. Although amyloid plaques and tau-loaded neurofibrillary tangles have been identified as the main pathological features of Alzheimer’s disease for more than one hundred years, the molecular mechanism is still poorly understood and treatments are limited to palliative care. Oligomeric Amyloid beta plays a crucial synaptotoxic role in Alzheimer’s disease, and hyperphosphorylated tau facilitates Amyloid beta toxicity, but the link between the two remains controversial. Since tau is a microtubule associated protein and microtubules are critical for neuronal functions, regulation of dynamic microtubules may serve as the link between Amyloid beta and tau. Here I propose a model in which Amyloid beta can induce changes in MT dynamics in dendrites and axons that are primary to tau hyperphosphorylation, while these MT changes are sufficient to cause tau hyperphosphorylation and necessary for Amyloid beta synaptotoxicity through tau. My thesis work further characterizes mammalian excitatory presynaptic boutons as hotspots for activity-dependent dynamic microtubule nucleation that is required for synaptic transmission during neuronal activation or Amyloid beta-induced neuronal injury through tau.

Alzheimer’s disease (AD) is the most commonly diagnosed form of dementia in the aged, and is characterised by a progressive decline in memory, language and other cognitive functions, together with deterioration in behavioural, emotional and social skills. The earliest clinical symptoms include episodic memory loss and dysnomia. This is followed by other signs of cortical impairment including apraxia, agnosia, and visuospatial impairment. In advanced stages, victims become mute, cannot walk and are incontinent; they therefore become totally dependent on carers. AD is the third leading cause of death in the aging population after heart disease and cancer. The incidence of AD doubles every 5 years in subjects between the ages of 65 and 85 years, affecting one in three by the age of 80. AD is characterised by the existence of intracellular and extracellular amyloid deposits in the brain. Extracellular amyloid deposits consist of plaques, whereas the deposits within and around blood vessels are referred to as cerebral amyloid angiopathy (CAA). Neurofibrillary tangles (NFT) are characteristically found in AD; however, they are also found in some other neurodegenerative disorders such as tuberose sclerosis, amyotrophic lateral sclerosis, parkinson-dementia complex and dementia pugilistica.

Alzheimer’s disease (AD) progressively impairs cognitive and functional abilities. Research on pharmacological treatment of AD is shifting to earlier forms of the disease, including preclinical stages. However, assessment methods traditionally used in clinical research may be inappropriate for these populations. The Alzheimer Disease Assessment Scale-cognitive (ADAS-cog), a commonly used cognitive battery in AD research, is most sensitive in the moderate range of cognitive impairment. It focuses on immediate recall and recognition aspects of memory rather than retention and delayed recall. As clinical trials for dementia continue to focus on prodromal stages of AD, instruments need to be retooled to focus on cognitive abilities more prone to change in the earliest stages of the disease. One such domain is delayed recall, which is differentially sensitive to decline in the earliest stages of AD. A supplemental delayed recall subtest for the ADAS-cog is commonly implemented, but we do not know precisely where along the spectrum of cognitive dysfunction this subtest yields incremental information beyond what is gained from the standard ADAS-cog. An item response theory (IRT) approach can analyze this in a psychometrically rigorous way. This study’s aims are twofold: (1) to examine where along the AD spectrum the delayed recall subtest yields optimal information about cognitive dysfunction, and (2) to determine if adding delayed recall to the ADAS-cog can improve prediction of functional outcomes, specifically patients’ ability to complete basic and instrumental activities of daily living. Results revealed differential functioning of ADAS-cog subtests across the dimension of cognitive impairment. The delayed recall subtest provided optimal information and increased the ADAS-cog’s measurement precision in the relatively mild range of cognitive dysfunction. Moreover, the addition of delayed recall to the ADAS- cog, consistent with my hypothesis, increased covariation with instrumental but not basic activities of daily living. These findings provide evidence that the delayed recall subtest slightly improves the ADAS-cog’s ability to capture information about cognitive impairment in the mild range of severity and thereby improves prediction of instrumental functional deficits.

The general purpose of this study was to investigate the relationship between neuropsychological tests scores and perfusion deficits, based upon measures of regional cerebral blood flow (rCBF) taken from the single photon emission computed tomography (SPECT) scans of patients suffering from dementia of the Alzheimer type (DAT). The study was designed to determine if DAT patients categorized as having left hemisphere, right hemisphere, diffuse, or an absence of perfusion deficits, as measured by SPECT, would be accurately grouped into their respective categories, and if they would exhibit the corresponding neuropsychological deficiencies usually associated with lateral hemispheric asymmetries.Selected subjects were 80 right handed, DAT patients from the North Broward Medical Center - Memory Disorder Center, in Pompono Beach, Florida, who had been administered a neuropsychological test battery, and a SPECT scan.Through several ANOVA's that were calculated for each of the neuropsychological variables, it was concluded that DAT patients who suffered from perfusion deficits exhibited significantly lower levels of neuropsychological functioning than DAT patients without perfusion deficits.These analyses revealed significantly lower levels of neuropsychological performance in the perfusion deficit group on the combination of left hemisphere WAIS-R subtests (Information, Similarities & Vocabulary), WMS - Logical Story (p < .01), WRAT-R Reading, WRAT-R Mathematics, WMS Paired Associates, and the Rey Complex Figure (p < .05).A separate step-wise discriminant function analysis indicated that a combination of the neuropsychological variables could not accurately classify the DAT patients into their respective right hemisphere, left hemisphere, diffuse, or absence of perfusion deficit groups. The discriminant function classified only 32.5% of the grouped cases accurately. Of the original thirteen neuropsychological variables, only Paired Associates immediate recall of the WMS entered the discriminant analysis equation. This accounted for only 23% of the total variability that could be explained by differences between the perfusion deficit groups. In several post hoc ANOVA's using the Bonferroni method of multiple comparisons, it was revealed that the absence of perfusion deficit group scored significantly higher than the other groups on the majority of the left hemisphere neuropsychological measures. However, none of the right hemisphere neuropsychological measures attained significance. / Department of Educational Psychology

Alzheimer’s disease (AD) is the most prevalent form of dementia. There is considerable evidence that AD is caused by accumulating amyloid beta peptides in the brain, as a result of amyloid precursor protein (APP) cleavage by secretase enzymes. The presenilin proteins are central to the gamma-secretase cleavage of the intramembrane domain of APP. Aberrant splicing and point mutations in the human presenilin genes, PSEN1 and PSEN2, have been linked to familial forms of AD, through aberrant APP cleavage resulting in irregular amyloid beta formation. Paper 1 gives a review of the literature on AD research and how animal models are used to elucidate mechanisms of AD pathogenesis. The zebrafish model is used in this thesis to investigate genes with potential relevance to AD initiation and pathogenesis. Paper 2 demonstrates that lowlevel aberrant splicing of exon 8 in psen1 transcripts in zebrafish embryos produces potent dominant negative effects that increased psen1 transcription, cause a dramatic hydrocephalus phenotype, decreased pigmentation and other developmental defects. Similar effects are also observed after low-level interference with splicing of exon 8 in psen2 transcripts. In paper 3, a microarray analysis was performed to analyse global gene expression changes to illuminate the molecular aetiology of the phenotypic effects described in paper 2. Of the 100 genes that showed greatest dysregulation after psen1 or psen2 manipulation, 12 genes were common to both treatments. Five of these have known function and showed increased expression. Cyclin G1 (ccng1) was of particular interest as the human CCNG1 protein shows increased immunoreactivity in the cytoplasm of neurons in human AD brains. Phylogenetic and conserved synteny analysis confirmed the orthology of zebrafish ccng1 with human CCNG1. Expression of zebrafish ccng1 in developing embryos at 24 hours post fertilization (hpf) was observed in the eye, tectum and somites. Decreased Ccng1 expression does not lead to any developmental defects and also cannot rescue the hydrocephalus or pigmentation phenotypes of embryos with aberrant splicing of psen1 exon 8. An analysis of zebrafish ccng1 function in paper 4 (thesis chapter in the form of a manuscript) indicates that truncation of Ccng1 appears to cause developmental defects in the brain, notochord and somites, however, it does not decrease the level of normal ccng1 transcript. The CCNG1 paralogue, Cyclin G2, (CCNG2), is also expressed in zebrafiish (ccng2). Decreasing the expression of Ccng2 results in similar effects on embryo development as truncating Ccng1. Therefore, the truncated forms of Ccng1 potentially interfere with Ccng2 function in a dominant negative manner. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1342482 / Thesis (Ph.D.) -- University of Adelaide, School of Molecular and Biomedical Science, 2008

Alzheimer’s disease (AD) is the most prevalent form of dementia. There is considerable evidence that AD is caused by accumulating amyloid beta peptides in the brain, as a result of amyloid precursor protein (APP) cleavage by secretase enzymes. The presenilin proteins are central to the gamma-secretase cleavage of the intramembrane domain of APP. Aberrant splicing and point mutations in the human presenilin genes, PSEN1 and PSEN2, have been linked to familial forms of AD, through aberrant APP cleavage resulting in irregular amyloid beta formation. Paper 1 gives a review of the literature on AD research and how animal models are used to elucidate mechanisms of AD pathogenesis. The zebrafish model is used in this thesis to investigate genes with potential relevance to AD initiation and pathogenesis. Paper 2 demonstrates that lowlevel aberrant splicing of exon 8 in psen1 transcripts in zebrafish embryos produces potent dominant negative effects that increased psen1 transcription, cause a dramatic hydrocephalus phenotype, decreased pigmentation and other developmental defects. Similar effects are also observed after low-level interference with splicing of exon 8 in psen2 transcripts. In paper 3, a microarray analysis was performed to analyse global gene expression changes to illuminate the molecular aetiology of the phenotypic effects described in paper 2. Of the 100 genes that showed greatest dysregulation after psen1 or psen2 manipulation, 12 genes were common to both treatments. Five of these have known function and showed increased expression. Cyclin G1 (ccng1) was of particular interest as the human CCNG1 protein shows increased immunoreactivity in the cytoplasm of neurons in human AD brains. Phylogenetic and conserved synteny analysis confirmed the orthology of zebrafish ccng1 with human CCNG1. Expression of zebrafish ccng1 in developing embryos at 24 hours post fertilization (hpf) was observed in the eye, tectum and somites. Decreased Ccng1 expression does not lead to any developmental defects and also cannot rescue the hydrocephalus or pigmentation phenotypes of embryos with aberrant splicing of psen1 exon 8. An analysis of zebrafish ccng1 function in paper 4 (thesis chapter in the form of a manuscript) indicates that truncation of Ccng1 appears to cause developmental defects in the brain, notochord and somites, however, it does not decrease the level of normal ccng1 transcript. The CCNG1 paralogue, Cyclin G2, (CCNG2), is also expressed in zebrafiish (ccng2). Decreasing the expression of Ccng2 results in similar effects on embryo development as truncating Ccng1. Therefore, the truncated forms of Ccng1 potentially interfere with Ccng2 function in a dominant negative manner. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1342482 / Thesis (Ph.D.) -- University of Adelaide, School of Molecular and Biomedical Science, 2008