The neural crest is a transient population of cells that forms a diverse range of derivatives in vertebrate embryos. Neural crest cells also migrate extensively throughout the embryo. The specification of a number of neural crest derivatives, including pigment cells and neurons and glia of the peripheral nervous system, is dependent on the transcription factor Sox10. In sox10 mutant zebrafish embryos, these neural crest derivatives fail to specify and subsequently the cell differentiation and migration fails leading to apoptosis. Sox10 mutant embryos also display an ear defect although the precise role of Sox10 in the ear is less well defined. Thus Sox10 controls an extensive gene regulatory network that drives the development of an important subset of neural crest derivatives and also functions during ear development. This gene regulatory network is currently poorly defined. The aim of this project was to identify genes that are both direct and indirect targets of Sox10 to further elucidate this gene regulatory network. To achieve this, a microarray approach was adopted. Initially, fluorescence activated cell sorting was employed to enrich for sox10 expressing cells from 24 hours post fertilization sox10:GFP transgenic embryos. The transcriptomes of WT and sox10 mutant cells were compared by microarray analysis to identify differentially regulated genes. A large number of target genes were identified by this method and by an unbiased in situ hybridization screen, 28 genes were validated. Of these, 23 genes were expressed in cells of the neural crest and down-regulated in sox10 mutant embryos. The majority of these genes were expressed in cells of the melanocyte and xanthophore lineages. 5 genes were expressed in the ear (otic vesicle) of which three otic vesicle genes were down-regulated while two otic vesicle genes were up-regulated in sox10 mutant embryos. Unfortunately due to time constraints, a study into the function of one of these target genes could not be completed. The series of validated genes identified during this project has opened new opportunities for research and has identified a number of highly expressed marker genes that will be useful in future studies. In addition, the microarray data presented will be a useful resource to aid the identification of further targets of Sox10.

Adapting the tools of optical microscopy to the large-scale dynamic systems encountered in the development of multicellular organisms provides a path toward understanding the physical processes necessary for complex life to form and function. Obtaining quantitatively meaningful results from such systems has been challenging due to difficulty spanning the spatial and temporal scales representative of the whole, while also observing the many individual members from which complex and collective behavior emerges. A three-dimensional imaging technique known as light sheet fluorescence microscopy provides a number of significant benefits for surmounting these challenges and studying developmental systems. A thin plane of fluorescence excitation light is produced such that it coincides with the focal plane of an imaging system, providing rapid acquisition of optically sectioned images that can be used to construct a three-dimensional rendition of a sample. I discuss the implementation of this technique for use in larva of the model vertebrate Danio rerio (zebrafish). The nature of light sheet imaging makes it especially well suited to the study of large systems while maintaining good spatial resolution and minimizing damage to the specimen from excessive exposure to excitation light. I show the results from a comparative study that demonstrates the ability to image certain developmental processes non-destructively, while in contrast confocal microscopy results in abnormal growth due to phototoxicity. I develop the application of light sheet microscopy to the study of a previously inaccessible system: the bacterial colonization of a host organism. Using the technique, we are able to obtain a survey of the intestinal tract of a larval zebrafish and observe the location of microbes as they grow and establish a stable population in an initially germ free fish. Finally, I describe a new technique to measure the fluid viscosity of this intestinal environment in vivo using magnetically driven particles. By imaging such particles as they are oscillated in a frequency chirped field, it is possible to calculate properties such as the viscosity of the material in which they are embedded. Here I provide the first known measurement of intestinal mucus rheology in vivo. This dissertation includes previously published co-authored material.

Mutations of the gene encoding the inositol polyphosphate 5-phosphatase OCRL1 are responsible for causing two disorders in humans: Lowe syndrome and type 2 Dent's disease (Dent-2). Lowe syndrome (oculocerebrorenal syndrome of Lowe) is an X-linked genetic disorder that causes multisystem defects affecting predominantly the eyes, brain and kidneys. Dent-2 disease is very similar to Lowe syndrome, but it affects primarily the kidneys with little or no symptoms in the brain and eyes. The enzymatic activity, structure and binding partners of the OCRL1 protein have been described and progress on the cellular functions of OCRL1 has been made. However the studies to date have not provided the necessary insight to explain the tissue-specific defects observed in Lowe syndrome and Dent-2 patients. In order to investigate the role of OCRL1 and the consequences of its deficiency in a physiological context an animal model is required. We have chosen the zebrafish for this study due to its suitability for investigating vertebrate early development and the abundance of research techniques available for this model organism. We have studied the expression of OCRL1 in zebrafish and its role in the early embryonic development. We have also investigated its role in the endocytic function of the zebrafish larval pronephric kidney. Finally we have investigated its role in ciliogenesis and function of pronephric cilia. Our studies show that OCRL1 depletion does not cause gross developmental defects, nor affects the development of pronephros, but impairs their endocytic activity. We have also shown, that efficient pronephric uptake requires OCRL1 interactions with clathrin, Rab GTPase family proteins, APPL1 and IPIP27A/B. Our studies link the reduced uptake with lowered levels of megalin receptor, which is responsible for the bulk of protein reabsorption in the kidney. Together our results strongly suggest that defects in this process are responsible for low molecular weight proteinuria present in Lowe syndrome and Dent-2 patients and zebrafish is a suitable model to study the renal aspect of these diseases.

Kwok Hin-Fai. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (leaves 84-100). / Abstracts in English and Chinese. / Abstract (in English) --- p.i / Abstract (in Chinese) --- p.iv / Acknowledgement --- p.vi / Table of contents --- p.vii / List of figures --- p.xi / List of tables --- p.xiv / Symbols and abbreviations --- p.xv / List of fish names mentioned in the thesis --- p.xviii / Chapter Chapter 1 --- General Introduction / Chapter 1.1 --- Gonadotropins / Chapter 1.1.1 --- Structure --- p.1 / Chapter 1.1.2 --- Function --- p.4 / Chapter 1.2 --- Gonadotropin receptor / Chapter 1.2.1 --- Structure --- p.5 / Chapter 1.2.2 --- Expression --- p.7 / Chapter 1.2.3 --- Signaling / Chapter 1.2.3.1 --- cAMP-mediated pathway --- p.7 / Chapter 1.2.3.2 --- Phospholipase C-mediated pathway --- p.9 / Chapter 1.2.4 --- Regulation of expression --- p.12 / Chapter 1.2.5 --- Desensitization of receptors / Chapter 1.2.5.1 --- Uncoupling --- p.13 / Chapter 1.2.5.2 --- Internalization --- p.13 / Chapter 1.3 --- Structure of ovarian follicles --- p.14 / Chapter 1.4 --- The project objectives and long-term significance --- p.16 / Chapter Chapter 2 --- Cloning and Characterization of Zebrafish Follicle-stimulating Hormone (FSH) and Luteinizing Hormone (LH) Receptors ´ؤ Evidence for Distinct Functions of FSH and LH in Follicle Development / Chapter 2.1 --- Introduction --- p.19 / Chapter 2.2 --- Materials and Methods / Chapter 2.2.1 --- Animals and chemicals --- p.22 / Chapter 2.2.2 --- Isolation of total RNA --- p.22 / Chapter 2.2.3 --- Cloning of zebrafish FSHR (zfFSHR) and LHR (zfLHR) cDNA fragments from the zebrafish ovary --- p.23 / Chapter 2.2.4 --- Rapid amplification of 5´ةcDNA ends (5'-RACE) and full-length cDNA --- p.24 / Chapter 2.2.5 --- Isolation of ovarian follicles --- p.25 / Chapter 2.2.6 --- Sampling of the ovaries from sexually immature zebrafish --- p.25 / Chapter 2.2.7 --- Reverse transcription-polymerase chain reaction (RT-PCR) --- p.25 / Chapter 2.2.8 --- Construction of expression plasmids --- p.26 / Chapter 2.2.9 --- Transient transfection and reporter gene assay --- p.27 / Chapter 2.2.10 --- Establishment and characterization of stable zfFSHR or zfLHR-expressing cell lines --- p.28 / Chapter 2.3 --- Results / Chapter 2.3.1 --- Cloning of FSHR and LHR cDNA from the zebrafish ovary --- p.29 / Chapter 2.3.2 --- Functional characterization of zfFSHR and zfLHR --- p.30 / Chapter 2.3.3 --- Expression of zfFSHR and zfLHR during sexual maturation --- p.31 / Chapter 2.3.4 --- Stage-dependent expression of zfFSHR and zfLHR in the ovarian follicles --- p.32 / Chapter 2.4 --- Discussion --- p.33 / Chapter Chapter 3 --- Down-regulation of FSHR and LHR Expression in the Zebrafish Follicle Ceils by Gonadotropin (hCG) and Its Sigaling Mechanism / Chapter 3.1 --- Introduction --- p.51 / Chapter 3.2 --- Materials and Methods / Chapter 3.2.1 --- Animals --- p.54 / Chapter 3.2.2 --- Chemicals and hormones --- p.54 / Chapter 3.2.3 --- Primary follicle cell culture --- p.55 / Chapter 3.2.4 --- Total RNA isolation --- p.55 / Chapter 3.2.5 --- "Validation of semi-quantitative RT-PCR assays for FSHR, LHR and GAPDH" --- p.56 / Chapter 3.2.6 --- Data analysis --- p.57 / Chapter 3.3 --- Results / Chapter 3.3.1 --- Validation of semi-quantitative RT-PCR assays --- p.57 / Chapter 3.3.2 --- Gonadotropin regulation of FSHR and LHR expression in cultured zebrafish ovarian follicle cells --- p.58 / Chapter 3.3.3 --- Effect of db-cAMP and forskolin on FSHR and LHR expression --- p.59 / Chapter 3.3.4 --- Effects of H89 on hCG-induced suppression of FSHR and LHR expression --- p.60 / Chapter 3.4 --- Discussion --- p.60 / Chapter Chapter 4 --- General Discussion --- p.75 / Chapter 4.1 --- Cloning of zebrafish FSHR and LHR cDNAs and demonstration of receptor specificity --- p.77 / Chapter 4.2 --- Evidence for the differential expression of FSHR and LHR in the zebrafish ovarian and follicle development --- p.78 / Chapter 4.3 --- Down-regulation of FSHR and LHR expression in the zebrafish follicle cells by gonadotropin (hCG) --- p.79 / Chapter 4.4 --- Future research direction --- p.80 / References --- p.84

So Wai-Kin. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (leaves 100-127). / Abstracts in English and Chinese. / Acknowledgement --- p.I / Abstract (in English) --- p.II / Abstract (in Chinese) --- p.IV / Table of contents --- p.VI / List of Figures --- p.X / Symbols and Abbreviations --- p.XII / List of fish names mentioned in the thesis --- p.XIV / Chapter Chapter 1 --- General Introduction / Chapter 1.1 --- Pituitary --- p.1 / Chapter 1.2 --- Gonadotropins --- p.1 / Chapter 1.2.1 --- Structure --- p.2 / Chapter 1.2.2 --- Signaling --- p.3 / Chapter 1.2.3 --- Expression --- p.5 / Chapter 1.2.4 --- Functions --- p.7 / Chapter 1.2.4.1 --- Gonadotropin actions on gametogenesis --- p.7 / Chapter 1.2.4.2 --- Gonadotropin actions on steroidogenesis --- p.8 / Chapter 1.2.5 --- Regulation --- p.9 / Chapter 1.2.5.1 --- Neuroendocrine control --- p.10 / Chapter 1.2.5.1.1 --- Gonadotropin-releasing hormone (GnRH) --- p.10 / Chapter 1.2.5.1.2 --- Dopamine (DA) --- p.12 / Chapter 1.2.5.2 --- Gonadal steroid feedback --- p.12 / Chapter 1.2.5.2.1 --- Positive feedback --- p.13 / Chapter 1.2.5.2.2 --- Negative feedback --- p.14 / Chapter 1.2.5.3 --- Paracrine regulators within pituitary --- p.15 / Chapter 1.3 --- Objectives of the present study --- p.16 / Chapter Chapter 2 --- "Molecular Cloning and Functional Characterization of Zebrafish FSHβ, LHβ and GTHα subunits" / Chapter 2.1 --- Introduction --- p.19 / Chapter 2.2 --- Materials and methods --- p.21 / Chapter 2.2.1 --- Chemicals --- p.21 / Chapter 2.2.2 --- Animals --- p.21 / Chapter 2.2.3 --- Genomic DNA isolation --- p.22 / Chapter 2.2.4 --- Total RNA isolation --- p.22 / Chapter 2.2.5 --- Cloning of zebrafish FSHp，LHβ and GTHa fragments --- p.23 / Chapter 2.2.5.1 --- LHβ and GTHα --- p.23 / Chapter 2.2.5.2 --- FSHβ --- p.23 / Chapter 2.2.6 --- "5'- and 3'-RACE of zebrafish FSHp, LHβ and GTHα subunits" --- p.24 / Chapter 2.2.7 --- Construction of expression constructs --- p.25 / Chapter 2.2.8 --- Cell culture and transfection of Flp-In´ёØ CHO cell --- p.26 / Chapter 2.2.9 --- Recombinant production of zebrafish FSH and LH --- p.27 / Chapter 2.2.10 --- Reverse transcription-polymerase chain reaction (RT-PCR) analysis --- p.27 / Chapter 2.2.11 --- Northern blot hybridization --- p.28 / Chapter 2.2.12 --- SEAP reporter gene assay --- p.28 / Chapter 2.2.13 --- Data analysis --- p.29 / Chapter 2.3 --- Results --- p.30 / Chapter 2.3.1 --- "Cloning of zebrafish FSHβ, LHβ and GTHα subunits" --- p.30 / Chapter 2.3.2 --- "Expression of zebrafish FSHp, LHβ and GTHα in the zebrafish pituitary" --- p.31 / Chapter 2.3.3 --- Recombinant production of zebrafish FSH and LH --- p.32 / Chapter 2.3.4 --- Functional analysis of zebrafish FSH and LH --- p.33 / Chapter 2.4 --- Discussion --- p.34 / Chapter Chapter 3 --- "Spatial Expression Patterns of Zebrafish FSHβ, LHβ and GTHα Subunits in the Pituitary and Their Temporal Expression Profiles during Sexual Maturation and Ovulatory Cycle" / Chapter 3.1 --- Introduction --- p.58 / Chapter 3.2 --- Materials and methods --- p.61 / Chapter 3.2.1 --- Chemicals --- p.61 / Chapter 3.2.2. --- Animals --- p.62 / Chapter 3.2.3 --- Total RNA isolation from zebrafish pituitaries and reverse transcription --- p.62 / Chapter 3.2.4 --- Validation of RT-PCR on single pituitary --- p.63 / Chapter 3.2.5 --- Real-time PCR --- p.64 / Chapter 3.2.6 --- Tissue preparation for in situ hybridization --- p.64 / Chapter 3.2.7 --- In situ hybridization --- p.65 / Chapter 3.2.8 --- Data analysis --- p.66 / Chapter 3.3 --- Results --- p.66 / Chapter 3.3.1 --- "PCR amplification of FSHβ, LHβ and GTHα and GAPDH in single zebrafish pituitary" --- p.67 / Chapter 3.3.2 --- "Establishement of real-time RT-PCR for zebrafish FSHβ, LHβ and GTHa and GAPDH" --- p.67 / Chapter 3.3.3 --- "Temporal expression profiles of zebrafish FSHβ, LHβ and GTHα subunits during sexual maturation" --- p.67 / Chapter 3.3.4 --- "Temporal expression profiles of zebrafish FSHp, LHβ and GTHα subunits during ovulatory cycle" --- p.68 / Chapter 3.3.5 --- "In situ hybridization of zebrafish FSHβ, LHβ and GTHα" --- p.69 / Chapter 3.4 --- Discussion --- p.70 / Chapter Chapter 4 --- General Discussion / Chapter 4.1 --- Cloning of zebrafish gonadotropin subunit cDNAs --- p.91 / Chapter 4.2 --- Bioactivity and receptor specificity of recombinant zebrafish FSH and LH --- p.91 / Chapter 4.3 --- Expression of gonadotropin subunits during zebrafish sexual maturation and ovulatory cycle --- p.92 / Chapter 4.4 --- "Localization of FSHβ, LHβ and GTHα subunits in zebrafish pituitary" --- p.93 / Chapter 4.5 --- Contributions of the present study --- p.94 / Chapter 4.6 --- Future prospects --- p.95 / References --- p.100

The prevalence of stress and anxiety disorders in modern society is increasing, but the development of new treatments decreasing due to high research costs and low success rates in clinical trials. The latest type of compounds introduced to treat anxiety and depression was the specific serotonin reuptake inhibitors (SSRI), which was introduced in 1987. Since then, no new class of compounds have been introduced, suggesting that the need to find alternative targets in treating mental disorders is needed. In this thesis I have used the zebrafish as a model organism to study the modulation of behaviours through intracellular signalling pathways, known to be involved in learning, memory and anxiety. First, using the pro-convulsant compound, pentylenetetrazole (PTZ), an automated tracking system was established to quantify and analyse swimming behaviour in larvae zebrafish. Pentylenetetrazole induces seizures in zebrafish at high concentrations, however this thesis identifies that the combination of a low level of PTZ and subjecting the fish to alternating cycles of light and dark induced a reversed response to light and dark. A group of compounds with known anti-seizure effects were subsequently screened, which found that a combinational treatment with diazepam and two types of neurosteroids reversed the PTZ-induced light dark response. Secondly, using the same automated analysis setup, the effect of cAMP modulators was studied on behaviour in zebrafish larvae. Our lab has previously established that Rolipram, a PDE4 inhibitor, causes anxiety thigmotaxis in zebrafish larvae. In this thesis we treated zebrafish larvae with Rolipram and other compounds modulating cAMP, which greatly increased the swimming activity, which was reversed by subsequently treating with PD0325901. To test if the pharmacological modulation of cAMP-levels through the inhibition of other PDEs would lead to increased locomotor activity, a small library of PDE inhibitors was screened, and 4 compounds were identified that caused an increase in locomotion – three of these compounds were PDE4-inhibitors. Finally, by using two behavioural assays, I found that in adult fish Rolipram cause anxiety-like phenotypes, which is also reversible by MAPK-inhibition.

Neutrophils are an important cell in host defence and migrate rapidly to sites of inflammation when the host is compromised (e.g., in infection or wounding). There, they produce and/or release inflammatory mediators (e.g., LTB4, TNF, IL-8) and ingest and degrade pathogens (e.g., by release of granule proteins and reactive oxygen species). Neutrophils then undergo apoptosis and are cleared by phagocytes such as macrophages, to allow efficient resolution of inflammation. Inducing neutrophil apoptosis by pharmacological means could be a therapeutic strategy to dampen inflammation in diseases where neutrophils are prevalent, e.g., acute respiratory distress syndrome (ARDS) and rheumatoid arthritis (RA). Inhibition of cyclin-dependent kinases (CDKs) using CDK inhibitor (CDKi) compounds induces mammalian neutrophil apoptosis in vitro, and can drive resolution of inflammation in vivo in mouse models. Evidence indicated that this is due to inhibition of CDK9 and CDK7-mediated transcription of the anti-apoptotic protein Mcl-1. The hypothesis of this project was that CDK9, CDK7 and Mcl-1 are pivotal regulators of resolution of inflammation in vivo. The model selected to test this hypothesis was tailfin injury of embryonic zebrafish (Danio rerio). Zebrafish are optically transparent and reporter transgenic lines with neutrophils labelled by enhanced GFP (EGFP - Tg[mpx:EGFP]i114) and macrophages (Tg[MPEG1:mCherry]) have been created, permitting the imaging of the behaviour of these cells in vivo. The model of tailfin transection was chosen to cause an inflammatory response in these animals, with neutrophil and macrophage recruitment to the tailfin. This response was manipulated using CDKi compounds and specific gene knockdowns (using morpholino and CRISPR/cas9 technologies). It was shown that CDKi compounds could reduce neutrophil numbers at 24 h post-injury at the transected tailfin, but did not affect macrophage numbers. The CDKi AT7519 increased neutrophil apoptosis at 12 h post-injury. Specific CDK9 knockdown using morpholinos or CRISPR/cas9 also reduced neutrophilic inflammation at the tailfin 24 h after transection, accompanied by increased apoptosis levels at 8 h in the morpholino-treated group. Inhibition of an endogenous CDK9 inhibitor, LaRP7, had the opposite effect and increased neutrophil numbers; and could oppose the neutrophil- reducing effect of AT7519 and CDK9 morpholino knockdown. Preliminary genetic knockdown studies into the roles of CDK7 and Mcl-1 have been carried out. Taken together, the results demonstrate CDK9 is important in the resolution of neutrophilic inflammation, indicating that manipulation of CDK9 activity could be a good target for therapeutic intervention in inflammatory disease.

Dyslexia is a neurodevelopmental disorder that affects between 5% and 12% of school-aged children. Individuals with dyslexia have difficulties in learning to read despite normal IQ levels and adequate socio-economical and educational opportunities. Dyslexia has a strong genetic component, but only a few candidate genes have been characterized to date. The KIAA0319 gene is a strong dyslexia candidate found to be associated with dyslexia in independent studies. The KIAA0319 genetic variants associated with dyslexia reside in a regulatory region. Studies in rat suggested that this gene is required for neuronal migration during early cortex formation. The KIAA0319-like (KIAA0319L) is a KIAA0319 homolog in structure and has recently been shown to play a role in dyslexia. I used zebrafish as a model organism both to study the effects of non-coding variants and to characterise kiaa0319 gene function. I used Gateway Tol2 technology to study the role of regulatory sequences. While these experiments led to inconclusive results, they highlighted some of the challenges but also the feasibility of using zebrafish as model organism to study genetic associations. In parallel, I studied the kiaa0319 function with knockout and knockdown experiments. Additionally, I conducted a detailed gene expression analysis with different in situ hybridisation protocols showing kiaa0319 ubiquitous expression in the whole embryo before 12 hours post fertilisation, with later specification to the eyes, brain, otic vesicle and notochord. Additionally, I have tested for the expression of kiaa0319l and showed similar expression pattern to the kiaa0319, but with significantly lower expression of kiaa0319l in zebrafish notochord. My data show, for the first time, that kiaa0319 has stage-specific expression in the brain and notochord during zebrafish early development, suggesting kiaa0319 specific role in the development of these structures. These results are in line with recent mouse studies. With this project I support the idea of kiaa0319 role being extended beyond the brain function and propose a role for kiaa03019 in the visual system and in the notochord.

Yu, Man Ying Susana. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (leaves 103-117). / Abstracts in English and Chinese. / Abstract (in English) --- p.i / Abstract (in Chinese) --- p.iv / Acknowledgement --- p.vi / Table of contents --- p.viii / Symbols and abbreviations --- p.xii / Scientific names --- p.xiv / List of figures --- p.xv / Chapter Chapter 1 --- General Introduction --- p.1 / Chapter 1.1 --- Structure of ovarian follicles --- p.1 / Chapter 1.2 --- Regulation of ovarian follicle development --- p.3 / Chapter 1.2.1 --- Endocrine regulation --- p.3 / Chapter 1.2.1.1 --- Gonadotropins- FSH and LH --- p.3 / Chapter 1.2.1.2 --- Co-gonadotropin- growth hormone --- p.5 / Chapter 1.2.2. --- Paracrine regulation --- p.6 / Chapter 1.2.2.1 --- Activin --- p.6 / Chapter 1.2.2.2 --- Insulin-like growth factor I (IGF-I) --- p.7 / Chapter 1.3 --- The GH-IGF-I axis --- p.7 / Chapter 1.3.1 --- The somatomedin hypothesis --- p.8 / Chapter 1.3.2 --- "Structure and signaling of GH, GHR" --- p.8 / Chapter 1.3.3 --- Structure and signaling of IGF system --- p.9 / Chapter 1.3.4 --- Role of GH-IGF system in reproduction --- p.11 / Chapter 1.3.5 --- GH action in ovarian functions --- p.12 / Chapter 1.3.6 --- IGF-I action in ovarian functions --- p.13 / Chapter 1.3.7 --- The mini GH-IGF axis within the ovary --- p.14 / Chapter 1.4 --- Objectives of present study --- p.14 / Chapter Chapter 2 --- "Expression Profiles of the GH-IGF System in the Ovary of Zebrafish, Danio rerio" --- p.19 / Chapter 2.1 --- Introduction --- p.19 / Chapter 2.2 --- Material and Methods --- p.21 / Chapter 2.2.1 --- Animals --- p.21 / Chapter 2.2.2 --- Isolation of tissues and different stages of follicles from the zebrafish --- p.22 / Chapter 2.2.3 --- Separation of somatic follicle layers and oocytes --- p.22 / Chapter 2.2.4 --- Primary follicle cell culture --- p.22 / Chapter 2.2.5 --- Total RNA extraction --- p.23 / Chapter 2.2.6 --- Reverse transcription --- p.23 / Chapter 2.2.7 --- "Validation of semi-quantitative RT-PCR assays for GH (gh), GHR (ghr), IGF-I (igf1), IGF-II (igf2), and IGF-I receptor (igf1r)" --- p.24 / Chapter 2.2.8 --- Data analysis --- p.25 / Chapter 2.3 --- Results --- p.25 / Chapter 2.3.1 --- Validation of semi-quantitative RT-PCR assays --- p.25 / Chapter 2.3.2 --- Spatial expression of GH-IGF in different tissues of zebrafish --- p.26 / Chapter 2.3.3 --- "Localization of gh, ghr, igf1, igf2 and igf1r within the zebrafish follicle" --- p.26 / Chapter 2.3.4 --- Temporal expression profiles of GH-IGF system during folliculogenesis --- p.28 / Chapter 2.4 --- Discussion --- p.28 / Chapter Chapter 3 --- Regulation of the GH-IGF-I System and Its Cross-talk with the Activin System in the Zebrafish Ovary --- p.43 / Chapter 3.1 --- Introduction --- p.43 / Chapter 3.2 --- Material and methods --- p.45 / Chapter 3.2.1 --- Animals --- p.45 / Chapter 3.2.2 --- Chemicals and hormones --- p.45 / Chapter 3.2.3 --- Primary follicle cell culture --- p.45 / Chapter 3.2.4 --- Preparation of ovarian fragments --- p.45 / Chapter 3.2.5 --- Total RNA extraction --- p.45 / Chapter 3.2.6 --- RT-PCR --- p.47 / Chapter 3.2.7 --- Construction of real-time PCR standards --- p.47 / Chapter 3.2.8 --- Real-time PCR and semi-quantitative RT-PCR --- p.48 / Chapter 3.2.9 --- Data analysis --- p.49 / Chapter 3.3 --- Results --- p.49 / Chapter 3.3.1 --- "Expression of growth hormone (gh), growth hormone receptors (ghr1 and ghr2\ IGF-I (igf1), IGF-II (igf2), IGF-I receptor (igf1ra and igf1rb), activin subunits (inhba and inhbb) and follistatin (fst) in cultured zebrafish ovarian fragments" --- p.49 / Chapter 3.3.2 --- "Establishment of real-time RT-PCR for zebrafish inhba, inhbb and bactin" --- p.50 / Chapter 3.3.3 --- GH regulation of activin expression in cultured zebrafish follicle cells --- p.50 / Chapter 3.3.4 --- GH regulation of IGF-I in cultured zebrafish follicle cells --- p.51 / Chapter 3.3.5 --- IGF-I regulation of activin expression in cultured zebrafish follicle cells --- p.51 / Chapter 3.3.6 --- Activin regulation of IGF system --- p.52 / Chapter 3.4 --- Discussion --- p.52 / Chapter Chapter 4 --- Production of recombinant zebrafish growth hormone --- p.69 / Chapter 4.1 --- Introduction --- p.69 / Chapter 4.2 --- Material and Methods --- p.71 / Chapter 4.2.1 --- Animals --- p.71 / Chapter 4.2.2 --- Construction of expression plasmids pPIC9K/zfGH --- p.71 / Chapter 4.2.3 --- Production of recombinant zebrafish GH using Pichia pastoris --- p.73 / Chapter 4.2.4 --- SDS-PAGE and silver staining --- p.74 / Chapter 4.2.5 --- Purification --- p.74 / Chapter 4.2.6 --- Primary follicle cell culture --- p.75 / Chapter 4.2.7 --- Zebrafish hepatic cell culture --- p.76 / Chapter 4.2.8 --- RNA extraction and RT-PCR --- p.76 / Chapter 4.2.9 --- Real-time PCR --- p.77 / Chapter 4.2.10 --- Cell culture and transient transfection --- p.78 / Chapter 4.2.11 --- Luciferase reporter gene assay --- p.78 / Chapter 4.2.12 --- Data analysis --- p.79 / Chapter 4.3 --- Results --- p.79 / Chapter 4.3.1 --- Production of recombinant zebrafish GH --- p.79 / Chapter 4.3.2 --- Effect of recombiant zfGH on the expression of activin β Aand βB in cultured zebrafish follicle cells --- p.80 / Chapter 4.3.3 --- Effect of zfGH on the expression of igf1 in cultured zebrafish hepatic cells --- p.80 / Chapter 4.3.4 --- Luciferase reporter gene assay --- p.81 / Chapter 4.4 --- Discussion --- p.81 / Chapter Chapter 5 --- General Discussion --- p.94 / Chapter 5.1 --- Overview --- p.94 / Chapter 5.2 --- Major achievements of the present study --- p.95 / Chapter 5.2.1 --- Demonstration of a local mini-GH-IGF-I axis within the zebrafish ovary --- p.96 / Chapter 5.2.2 --- Differential expression profiles of the GH-IGF system during folliculogenesis --- p.96 / Chapter 5.2.3 --- The inter-relationship of GH-IGF and activin-follistatin systems --- p.96 / Chapter 5.2.4 --- Production of recombinant zebrafish GH --- p.97 / Chapter 5.3 --- Future prospects --- p.97 / References --- p.102 / Symbols and Abbreviations / Symbols / α Alpha / β Beta / Abbreviations / 20β-HSD 20β-hydroxysteroid dehydrogenase / bp Base pair / cAMP Cyclic adenosine monophosphate / cDNA Complementary cDNA / CHO Chinese hamster ovary / "DHP 17α, 20β-dihydroxy-4-prenane-3 -one" / DNA Deoxyribonucleic acid / EGF Epidermal growth factor

GWAS (Genome wide association studies) have aided in the discovery of various novel variants associated with diabetes. However, a detailed study is required to uncover the role of these genes and to determine how their dysfunction affects pathophysiology. Previous work in the lab has been successful in establishing zebrafish as an efficient model to characterise the effects of these candidate genes. Consequently, efforts have been also made to establish zebrafish as an efficient model system for drug screening as well. The current POP (Proof of principle) study aims to find whether treatment with tolbutamide drug in zebrafish carrying MODY (Maturity onset diabetes of the young) mutations has the similar effects in humans. The study employed zebrafish carrying five (gck, hnf1a, hnf1ba, hnf1bb, pdx1) CRISPR induced MODY orthologues. The zebrafish larvae were supplemented with tolbutamide drug from 5dpf till 10dpf (day post fertilisation). At 10dpf, larvae were screened for various glycaemic traits, whole body glucose and lipids as well body size. CRISPR-CAS9- induced mutations were quantified using paired end sequencing. The results showed that treatment with tolbutamide had a significant effect on the hyperglycaemic outcome induced by hnf1bb, hnf1a, and pdx1 mutations which was in line with the known effects of the drug in humans. In conclusion, the POP study proved to be successful in leveraging zebrafish as an efficient model system for, in vivo characterisation of drugs and can likely help to identify novel targets for therapeutic interventions.