101 |
Investigation of the cardiovascular effects of apelinHamilton-Smith, Katherine Mary January 2011 (has links)
Apelin was discovered in 1998 as the endogenous peptide ligand of the orphan APJ receptor. The apelin system is well conserved across vertebrate species and is reported to have cardiovascular effects including positive inotropy, vasodilation, vasoconstriction and cardioprotection during ischaemia. Recent studies in human healthy volunteers and in chronic heart failure patients have highlighted the apelin system as a potential target for drug development. However, the cellular and molecular pathways through which apelin acts remain poorly understood. This study aimed to confirm the inotropic and vasoactive actions of apelin and to further examine the proposed cardioprotective effects of apelin under ischaemic and hypoxic conditions. Cardioprotection is defined as a mechanism, for example induced by a drug, which reduces injury in response to ischaemia or hypoxia. In vivo in the anaesthetised rat, apelin was administered as a bolus dose via the cannulated jugular vein and mean arterial pressure was measured by cannulation of the carotid artery. Pyr-apelin-13 had no effect on heart rate or mean arterial pressure. Apelin-13 decreased mean arterial pressure by approximately 20 mmHg, although the effect was highly variable among animals. Apelin-16 consistently lowered heart rate, but had no effect on mean arterial pressure. In rat isolated mesenteric arteries, studied using wire myography, apelin-13 and apelin-36 had no vasodilator or vasoconstrictor effect. In rat isolated right ventricular papillary muscles and right atrial strips, no change in tension, time to peak or time to relax was observed in response to pyr-apelin-13 despite responding to standard pharmacological stimuli such as noradrenaline and increased calcium concentrations in the bathing medium. In isolated, perfused rat heart (Langendorff), infusion of apelin-16 for 15 minutes did not alter developed pressure, rate of rise or rate of fall detected by an intraventricular balloon positioned in the left ventricle throughout the infusion. As the isolated perfused hearts did not demonstrate an inotropic effect in response to apelin, no cardioprotective studies were carried out in this model. Cardioprotective studies of apelin were performed in zebrafish embryos 3 – 5 days post fertilisation (dpf). I developed a hypoxia-recovery model in which we could test the effect of pharmacological agents, including apelin, on the hypoxia-recovery response. In zebrafish embryos 3 dpf, 2h hypoxia (1% oxygen) reduced heart rate and wall motion amplitude (to approximately 90% of control) and contraction velocity and relaxation velocity (to approximately 80% of control). All parameters recovered during a subsequent 2h in normoxia. Incubation in pyr-apelin-13 for 1h prior to and throughout hypoxia did not affect the depression in heart rate observed on exposure to hypoxia. However, apelin incubation resulted in an improvement in wall motion amplitude and relaxation velocity and a significant improvement in contraction velocity after hypoxia and throughout recovery. Pyr-apelin-13 had no inotropic or chronotropic effect on baseline heart function in embryos 3 dpf or in isolated hearts from embryos. However, apelin knockdown using a morpholino targeting the exon 2/intron 2 boundary of apelin pre-mRNA resulted in a high mortality rate and a severe total body and cardiovascular phenotype, suggesting that endogenous apelin is crucial during development in zebrafish embryos. In order to test pharmacological agents more efficiently, I developed a semi-quantitative scoring method to screen a larger number of embryos in a reduced time period. Heart rate and circulation was defined as normal, reduced or absent after 2h and 4h in hypoxia and during recovery in normoxia. The abundance of apelin and HIF-1α mRNA was measured using quantitative RT-PCR. In zebrafish 5 dpf, a marked decrease in apelin mRNA expression was observed after 4h, but not 2h, hypoxia and this was not accompanied by a change in HIF-1α mRNA expression. In zebrafish 5 dpf, exogenous pyr-apelin-13 did not affect the proportion of embryos with normal heart rate and circulation at any timepoint in this model. However, desferrioxamine (iron chelator) and α-ketoglutarate (metabolite involved in aerobic respiration) significantly increased the proportion of embryos with normal heart rate and circulation during the recovery phase. In summary, apelin-13 and apelin-16 were effective in lowering mean arterial pressure and heart rate, respectively, in the anaesthetised rat. However, apelin-13 did not vasodilate or vasoconstrict rat isolated mesenteric arteries. There was no effect of apelin on contractility parameters in rat isolated papillary muscles or in the isolated, perfused rat heart which made it difficult to pursue a cardioprotective effect in this model. In zebrafish, endogenous apelin appeared to be crucial in the development of the embryo, while exogenous apelin had no inotropic effect on cardiac function. In hypoxia-recovery, we demonstrate a cardioprotective effect of apelin in zebrafish 3 dpf, but not zebrafish 5 dpf.
|
102 |
The bone morphogenetic protein (BMP) system in zebrafish ovary. / CUHK electronic theses & dissertations collectionJanuary 2011 (has links)
Li, Cheuk Wun. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 121-135). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.
|
103 |
Expression and regulation of gonadotropins (fshb, lhb) and growth hormone (gh) during ovarian differentiation and pubertal onset of female zebrafish. / CUHK electronic theses & dissertations collectionJanuary 2012 (has links)
雙酚-A(bisphenol-A, BPA)廣泛地應用於人類的日常生活中,它是具有雌激素活性的化學物質。近年來,它對人類健康的影響引起了廣泛的關注。研究表明,胎儿期或嬰儿期暴露於BPA中會造成女性卵巢發育紊亂、青春期提前和性早熟。除青鱂、花溪鱂、大菱鮃、金魚、鯉、褐鱒魚和斑馬魚外,BPA對其它硬骨魚生殖功能的影響鮮見報導。而BPA對硬骨魚生殖軸的影響方面更是知之甚少。此外,在斑馬魚中,生殖發育的主要事件,包括性腺分化和青春期開始時間,以及青春期腦垂體激素如GTHs(FSH和LH)的時空表達模式仍然是一個未知數。因此,弄清這些問題不僅有助於理解GTHs在早期性發育中的作用,也有利於研究BPA對斑馬魚生殖軸的影響。 / 利用組織學分析方法、雙色熒光原位雜交(FISH)技術、實時定量PCR技術、蛋白質組分析和在體(活體)試驗,本文研究了斑馬魚性別分化和青春期開始的時間、腦垂體激素FSH(fshb)和LH(lhb)亞基在個體發育過程中特別是性別分化和青春期開始階段的表達模式;同時探討了在青春期之前BPA對斑馬魚生殖軸的影響。從早期的發育階段至性成熟的各個時間點分別收集樣本,用以建立斑馬魚性別分化和青春期開始的時間表及GTHs在其個體發育過程中的表達譜。利用組織學方法檢測性腺發育階段。斑馬魚的頭部(含整個腦和腦垂體)則用於FISH分析以了解其GTHs的表達譜。為分析BPA對斑馬魚生殖功能的影響,將受精後20天的幼魚暴露於濃度為10 μM的BPA中,同時以17β-雌二醇(E2, 10 nM)和睾酮(T, 10 nM) 作為陽性對照。處理20天后分別取其腦、腦垂體、肝臟和卵巢進行組織學、原位雜交、基因表達分析和蛋白質組學分析。 / 雌性斑馬魚青春期的第一個形態學標誌是從初級生長(PG)卵泡第一次轉變為/過渡到卵黃發生階段(PV);我們的結果表明此過程大約發生在受精後第45天。同時,青春期的啟動似乎高度依賴於身體的生長。另外,原位雜交結果顯示,fshb基因的表達遠早於lhb基因, 在受精後4天就能檢測到fshb的mRNA信號(~2-3細胞/腦垂體);而lhb的表達則在性別分化時約受精後25天才可檢測到。有趣的是, 表達lhb的細胞數量在青春期前非常少(~5-6 細胞/腦垂體),而青春期期間及之後則大幅增加。相反,在青春期之前,大量細胞表達fshb;青春期期間,表達fshb的細胞數量僅略有增加。因此,我們的結果顯示LH在雌性斑馬魚青春期啟動中具有重要的作用。另一方面,雖然BPA和E2可促進斑馬魚卵巢的分化,但它們亦能顯著抑制卵巢的生長發育。同時,BPA和E2都能明顯抑制垂體fshb的表達,這與其對卵巢大小的抑製作用似乎有密切的相關性。T對垂體fshb的表達無明顯的影響。進一步的結果顯示,BPA和E2不會影響GTHs上游調節基因(包括kiss1, kiss2, gnrh2 和gnrh3)的表達。在肝臟中,BPA和E2顯示出不同的效應。E2能誘導斑馬魚肝增生而導致其腹部水腫;而BPA暴露處理則無此效應。這些結果表明BPA具有雌激素的作用,可影響雌性斑馬魚的生殖功能,但從本研究所使用的劑量效應來看,它卻並不完全具有E2的全部效應。 / Being an estrogenic chemical and its ubiquitous presence in our daily lives, the effects of bisphenal A (BPA) on human health have received tremendous attention in recent years. Studies on the effects of BPA on female reproductive system have shown that early exposure to BPA during the prenatal or postnatal period impairs reproductive functions, including disruption of ovarian development, advanced pubertal onset, and the induction of an early, and persistent estrus. In teleost fish, few studies have been reported on the effects of BPA on reproductive function, except in medaka, Kryptolebias marmoratus, turbot, goldfish, common carp, brown trout and zebrafish. Despite these studies, the effects of BPA on reproductive axis remain largely unknown in teleost fish. On the other hand, in the zebrafish model, the major developmental events of reproduction, including the timing of puberty onset, the spatiotemporal expression patterns of key pituitary hormones such as GTHs (FSH and LH) during gonadal differentiation and puberty development remain largely unknown. Therefore, the information on these issues in zebrafish not only is valuable for understanding the roles of GTHs in early sexual development; also facilitate our study on the effects of BPA on the reproductive axis in the zebrafish. / Using histology analysis, double-colored fluorescent in situ hybridization (FISH), real-time qPCR, proteomic analysis and in vivo treatment, this study was undertaken to explore the timing of sex differentiation and puberty onset, the ontogenic expression patterns of FSH (fshb) and LH (lhb) subunits in the zebrafish pituitary with particular emphasis on the stage of sexual differentiation and puberty onset, and the effects of BPA on the reproductive axis in zebrafish during prepubertal period. To define the timeline of sex differentiation and puberty onset, and the ontogenic expression profiles of GTHs, the zebrafish were collected at different time points from early development stage to sexual maturation. The gonadal developmental stage was analyzed by histological examination. For the expression profiles of GTHs, the head of each fish including the brain and pituitary was sampled for FISH analysis. To investigate the influence of BPA on the reproductive function, Juvenile zebrafish of 20 day post-fertilization (dpf) were exposed to BPA (10 μM) for 20 days followed by sampling the brain, pituitary, liver and ovary for histological, in situ hybridization, expression analyses and proteomic analyses at 40 dpf. 17β-estradiol (E2, 10 nM) and testosterone (T, 10 nM) were also used as a positive control. / In female zebrafish, the first morphological sign for puberty is the first wave of follicle transition from the primary growth (PG) to previtellogenic stage (PV), our results showed that it occurs around 45 day post fertilization (dpf). Meanwhile, the puberty onset was highly depending on the somatic growth. The expression of fshb was much earlier than that of lhb with its mRNA signal detectable (2-3 cells/pituitary) shortly after hatching (4 dpf). In contrast, lhb expression became detectable at the time of sex differentiation (~25 dpf). Interestingly, the number of lhb-expressing cells was very low (~5-6 cells/pituitary) before puberty but increased dramatically during and after puberty onset. In contrast, the expression of fshb was abundant before puberty with only a slight increase in cell number during puberty onset. Our result strongly suggests an important role for LH at the puberty onset of female zebrafish. On the other hand, although BPA and E2 both promoted ovarian differentiation, they significantly suppressed the ovarian growth afterwards in the zebrafish. Meanwhile, both BPA and E2, but not T, dramatically decreased the expression of fshb in the pituitary, which was well correlated with the suppression of ovarian size. However, the expression of the upstream regulators of GTHs, including kiss1, kiss2, gnrh2 and gnrh3, was not affected by BPA and E2. Interestingly, at the liver level, BPA and E2 displayed different effects. E2 induced abdominal swelling due to a significant hepatic hyperplasia. However, BPA exposure had no such effect on the liver. These results indicate that BPA has estrogenic effects on female reproduction, but it does not mimic E2 in all aspects, at least for the dose tested in the present study. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Chen, Weiting. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 93-120). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese. / Abstract in English --- p.I / Abstract in Chinese --- p.III / Acknowledgement --- p.V / Table of contents --- p.VI / List of figures and tables --- p.IX / Symbols and abbreviation --- p.XI / Chapter Chapter 1 --- General Introduction / Chapter 1.1 --- Pituitary --- p.1 / Chapter 1.1.1 --- Structure --- p.1 / Chapter 1.1.2 --- Functions in reproduction --- p.2 / Chapter 1.2 --- Gonadotropins --- p.2 / Chapter 1.2.1 --- Structure --- p.2 / Chapter 1.2.2 --- Expression profile --- p.2 / Chapter 1.2.3 --- Regulation --- p.4 / Chapter 1.3 --- Gonadal development --- p.8 / Chapter 1.3.1 --- Sex differentiation --- p.8 / Chapter 1.3.2 --- Puberty initiation --- p.10 / Chapter 1.4 --- Objectives of the present study --- p.12 / Chapter Chapter 2 --- Puberty Initiation is Dependent on the Body Growth but not Age in Female Zebrafish / Chapter 2.1 --- Introduction --- p.15 / Chapter 2.2 --- Materials and methods --- p.16 / Chapter 2.2.1 --- Animals --- p.16 / Chapter 2.2.2 --- Sampling and measurement of body weight and body length --- p.16 / Chapter 2.2.3 --- Paraffin section and H & E staining --- p.17 / Chapter 2.2.4 --- Statistical analysis --- p.17 / Chapter 2.3 --- Results --- p.17 / Chapter 2.3.1 --- Growth curve of zebrafish during gonadal differentiation and maturation --- p.17 / Chapter 2.3.2 --- Gonadal differentiation in the zebrafish --- p.17 / Chapter 2.3.3 --- Puberty onset in female zebrafish --- p.18 / Chapter 2.3.4 --- Relationship of body growth and puberty initiation in female zebrafish --- p.19 / Chapter 2.4 --- Discussion --- p.19 / Chapter Chapter 3 --- Ontogenic Expression Profiles of Gonadotropins (fshb and lhb) and Growth Hormone (gh) During Sexual Differentiation and Puberty Onset in Female Zebrafish / Chapter 3.1 --- Introduction --- p.29 / Chapter 3.2 --- Materials and methods --- p.30 / Chapter 3.2.1 --- Animals --- p.30 / Chapter 3.2.2 --- Sampling --- p.31 / Chapter 3.2.3 --- Histological examination --- p.31 / Chapter 3.2.4 --- Total RNA isolation and reverse transcription --- p.32 / Chapter 3.2.5 --- Fluorescent double-colored in situ hybridization --- p.32 / Chapter 3.2.6 --- Microinjection of morpholino knockdown --- p.32 / Chapter 3.2.7 --- Real-time qPCR quantification of fshb, lhb and gh expression --- p.33 / Chapter 3.2.8 --- Data analysis --- p.34 / Chapter 3.3 --- Results --- p.34 / Chapter 3.3.1 --- Detection of fshb, lhb and gh expression in the pituitary of adult zebrafish --- p.34 / Chapter 3.3.2 --- Expression of fshb, lhb and gh before gonadal differentiation (4-25 dpf) --- p.34 / Chapter 3.3.3 --- Expression of fshb, lhb and gh during gonadal differentiation (22-25 dpf) --- p.35 / Chapter 3.3.4 --- Expression of fshb, lhb and gh during puberty period (~45 dpf) --- p.35 / Chapter 3.3.5 --- Phenotypes of fshb-MO and lhb-MO zebrafish in early development36 --- p.36 / Chapter 3.4 --- Discussion --- p.37 / Chapter Chapter 4 --- Neonatal Exposure to 17β-Estradiol or Bisphenol A Promotes Ovarian Differentiation but Suppresses Its Growth Probably via Inhibiting Follicle-Stimulating Hormone Expression / Chapter 4.1 --- Introduction --- p.55 / Chapter 4.2 --- Materials and methods --- p.57 / Chapter 4.2.1 --- Animals --- p.57 / Chapter 4.2.2 --- In vivo treatment and hormone replacement --- p.57 / Chapter 4.2.3 --- Sampling --- p.58 / Chapter 4.2.4 --- Total RNA isolation and reverse transcription --- p.58 / Chapter 4.2.5 --- Fluorescent double-colored in situ hybridization --- p.58 / Chapter 4.2.6 --- Real-time qPCR quantification --- p.59 / Chapter 4.2.7 --- Protein extraction and quantification --- p.59 / Chapter 4.2.8 --- Two-dimensional electrophoresis --- p.60 / Chapter 4.2.9 --- Staining --- p.61 / Chapter 4.2.10 --- In-gel digestion --- p.61 / Chapter 4.2.11 --- Mass spectrometry --- p.61 / Chapter 4.2.12 --- Data analysis --- p.61 / Chapter 4.3 --- Results --- p.62 / Chapter 4.3.1 --- E2 had distinct effect on the body growth and behavior --- p.62 / Chapter 4.3.2 --- BPA and E2 increased female ratio but suppressed ovarian growth in the zebrafish --- p.62 / Chapter 4.3.3 --- BPA and E2 shut down fshb but increased lhb expression in the pituitary without altering the expression of GnRH and kisspeptin in the hypothalamus --- p.63 / Chapter 4.3.4 --- E2 but not BPA induced hepatic hyperplasia --- p.64 / Chapter 4.4 --- Discussion --- p.65 / Chapter Chapter 5 --- General Discussion
|
104 |
GHRH/PACAP-GH-IGF axis in the ovary of zebrafish, Danio rerio. / CUHK electronic theses & dissertations collectionJanuary 2012 (has links)
生長和繁殖這兩個最主要的生理過程在脊椎動物中是密切相關的。生長主要是由腦-垂體-肝軸,即促生長激素釋放激素/垂體腺苷酸環化酶激活肽(GHRH/ PACAP-生長激素(GH)-胰島素樣生長因子(IGFs)軸所控制。值得一提的是,所有與這個神經內分泌軸相關的基因在卵巢中都有表達。這表明一個有功能的微型軸很可能存在於卵巢中。我們著重研究PACAP,該軸的上游因子,來揭示卵巢中這個微型軸的存在和功能。 / PACAP是一種最初從羊的下丘腦純化出來的夠能刺激cAMP分泌的神經肽,研究表明它也存在於如卵巢在內的其它各種外圍組織中。在斑馬魚中,兩種形式的PACAP(PACAP38-1,adcyap1a; PACAP38-2,adcyap1b)和三個 PACAP受體(PAC1-R,adcyap1r1; VPAC1-R,vipr1和VPAC2-R,vipr2)均在卵巢中表達。為了確定PACAP系統在斑馬魚的卵巢中有重要作用,我們首先對 PACAP的配體和三個受體在濾泡中的空間分佈進行了研究。此外,為了研究PACAP系統的潛在作用,我們還分析了PACAP的配體和受體在濾泡發育和成熟時期的表達情況。PACAP系統在濾泡細胞中時空表達的數據顯示,PACAP可能在調節濾泡發育和成熟中發揮雙重作用,這雙重作用是通過PACAP作用於不同的受體上完成的。卵母細胞體外成熟實驗的結果顯示PACAP可以促進完整的濾泡卵母細胞的成熟,但抑制裸露的卵母細胞體外自發成熟,這也進一步支持了我們的假說。 / 我們以前的研究表明,在原代培養的斑馬魚濾泡細胞中,垂體促性腺激素(HCG)可以顯著提高PACAP(PACAP38-2)的表達。因此,PACAP很可能是垂體促性腺激素控制卵巢功能的下游調節者。我們從幾個方面來驗證我們的假設。首先,由於激活素/結合蛋白系統是公認的垂體促性腺激素(HCG)的下游調節者,我們研究了PACAP對該系統表達的調控。研究結果表明,PACAP不僅能模仿促性腺激素對激活素/結合蛋白系統表達的調控,同時也刺激激活素介導的卵母細胞的成熟。PACAP和hCG選擇同樣的信號通路對激活素/結合蛋白系統進行調控進一步證實 PACAP的下游調節作用。其次,卵巢內源性生長因子,表皮生長因子EGF對PACAP調控激活素/結合蛋白系統表達的影響和其對hCG調控該系統表達的影響是一樣的。表皮生長因子可以作用於其膜上的受體並且使用MEK途徑來調節PACAP對激活素/結合蛋白系統的表達的調控。第三,我們研究了PACAP對激素生成的影響。芳香化酶是激素生成中一個十分重要的酶,它可以將睾酮轉化成雌激素E2。PACAP能刺激斑馬魚濾泡細胞中芳香化酶的表達。cAMP類似物,如forskolin和dbCAMP都可以模仿PACAP對芳香化酶的表達。PKA抑製劑 H89,可以完全抑制 PACAP誘導的芳香化酶的表達,這表明PACAP通過cAMP-PKA依賴性途徑調節芳香化酶的表達。由於促性腺激素也使用相同的cAMP-PKA途徑調節芳香化酶的表達,這進一步證實了PACAP是促性腺激素的下游調節者。 / 我們還研究了PACAP對該軸的其他因子調控,以便確定卵巢中是否存在一個有功能的GHRH/PACAP-GH-IGF軸。我們使用斑馬魚原代培養的濾泡細胞作為研究體系進行了一系列的基因調控的研究。PACA可以刺激gh及其受體 ghra和ghrb的表達。此外,它還增加了igf1表達,但對igf2a和igf2b的表達沒有明顯的影響。鑑於之前的工作證明重組zfGH可以刺激igf1的表達,我們有理由相信,在斑馬魚卵巢中存在一個有功能的GHRH/PACAP-GH-IGF軸。PACAP對此軸的調節作用也主要是通過cAMP-PKA途徑。 / 本研究不僅增加了我們對GHRH/PACAP-GH-IGF軸在卵巢中功能的了解,而且還提供了關於魚類生長和繁殖的協調方面有價值的信息,這必將有利於水產養殖。魚脊椎動物中最原始,最多元化的群體,目前的研究結果為其他生物的研究也提供了重要的參考。 / Growth and reproduction are two major physiological processes, which have been proven to be closely related in vertebrates. The process of growth is governed by the brain-pituitary-liver axis involving growth hormone releasing hormone/ pituitary adenylate cyclase-activating polypeptide (GHRH/PACAP), growth hormone (GH) and insulin-like growth factors (IGFs). Interestingly, the expression of all the genes involved in this axis has been reported in the ovary, which indicates that a functional mini-axis might exist in the ovary. In this study, we focus on the characterization of PACAP, the upstream element of the axis, to reveal the existence and functional roles of this intraovarian mini-axis. / PACAP is a neuropeptide originally purified from ovine hypothalamus for its potent activity to stimulate cAMP production. However, its presence and actions have also been demonstrated in various peripheral tissues including the ovary. In the zebrafish, two forms of PACAP (PACAP₃₈-1, adcyap1a; and PACAP₃₈-2, adcyap1b) and three PACAP receptors (PAC1-R, adcyap1r1; VPAC1-R, vipr1 and VPAC2-R, vipr2) were all expressed in the ovary. To provide clues to the importance of the PACAP system in the function of zebrafish ovary, we first investigated the spatial distribution of both PACAP ligands and the three potential receptors in the somatic follicle layer and denuded oocytes. We also analyzed the temporal expression profiles of PACAP ligands and receptors during follicle growth and maturation. Spatiotemporal expression data of PACAP system suggested that PACAP might play dual roles in regulating follicle growth and maturation through different receptors located in different compartments. This hypothesis was further supported by the observation that PACAP promoted maturation of follicle-enclosed oocytes but suppressed spontaneous maturation of denuded oocytes in vitro. / As the expression of PACAP (PACAP₃₈-2) was significantly stimulated by pituitary gonadotropins (hCG) in cultured zebrafish follicle cells, PACAP is therefore likely a downstream mediator or modulator of pituitary gonadotropins in controlling ovarian functions. We illustrated from several aspects to verify our hypothesis. Firstly, we tested the regulation of PACAP on the expression of activin/follistatin system for its well characterized roles in mediating pituitary gonadotropins (hCG). According to our results, PACAP could not only mimic gonadotropin-regulated expression of the activin/follistatin system, but also stimulated activin-mediated oocyte maturation. The same cAMP-dependent signal pathways PACAP and hCG chose towards the differential regulation of activin/follistatin system further confirm PACAP’s role as a mediator or even an amplifier. Secondly, EGF, the ovary-derived growth factor, was administrated to study its effects on PACAP regulated expression of activin/follistatin system. Similar with its influences on hCG regulated genes expression of activin system, EGF could work on its membrane receptors using a MEK pathway to regulate the effects of PACAP. Thirdly, the effect of PACAP on steroidogenesis was also studied. PACAP could stimulate the expression of aromatase, one of the steroidogenic enzymes that could convert testosterone to E2, in cultured zebrafish follicle cells. Its effect on aromatase expression could be mimicked by drugs that increase intracellular cAMP levels such as forskolin and db-cAMP. PACAP induced aromatase expression was totally abolished by a PKA inhibitor H89, which indicated that PACAP worked through a cAMP-PKA dependent pathway to regulate aromatase expression. As gonadotropins also use the same cAMP-PKA pathway to regulate the expression of aromatase, it was further confirmed that PACAP could mediate or amplify the effects of gonadotropins, even in steroidogenesis. / We also studied the regulatory effects of PACAP on other components of this mini-axis to find out whether this hypothetical GHRH/PACAP-GH-IGF axis in the ovary work the same way as the systemic somatotrophic one. We carried out a series of regulatory studies using the primary zebrafish follicle cell culture system. Interestingly, PACAP up-regulated the expression of gh and its receptors ghra and ghrb. In addition, it also increased the expression of igf1 but not igf2a and igf2b. Accompanied with the fact that recombinant zfGH could stimulate the expression of igf1, we have reason to believe that a functional intraovarian axis exited in zebrafish ovary. It seems that the regulatory effects of PACAP on this axis also mediated through a cAMP-PKA pathway. / The present study not only increases our understanding of the GHRH/PACAP- GH-IGFs axis and its actions in the ovary, but also provides valuable information on the coordination of growth and reproduction in fish, which will surely benefit the manipulation of fish growth and breeding in aquaculture. Since fish represent the most primitive and diverse group of vertebrates, the information obtained from the present study will serve as important reference for the studies in other organisms. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Zhou, Rui. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 127-157). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese. / Abstract in English --- p.i / Abstract in Chinese --- p.iv / Acknowledgement --- p.vi / Table of content --- p.viii / List of figures and tables --- p.xiii / Symbols and abbreviation --- p.xvi / Chapter Chapter 1 --- General Introduction / Chapter 1.1 --- Ovary --- p.1 / Chapter 1.1.1 --- Folliculogenesis --- p.1 / Chapter 1.1.2 --- Steroidogenesis --- p.7 / Chapter 1.1.3 --- Endocrine, paracrine and autocrine network of ovarian follicles --- p.8 / Chapter 1.2 --- GHRH/PACAP-GH-IGF axis --- p.11 / Chapter 1.2.1 --- GHRH/PACAP-GH-IGF axis in growth --- p.11 / Chapter 1.2.2 --- GHRH/PACAP-GH-IGF axis in reproduction --- p.13 / Chapter 1.3 --- Pituitary adenylate cyclase-activating polypeptide (PACAP) family --- p.15 / Chapter 1.3.1 --- PACAP ligands --- p.15 / Chapter 1.3.2 --- PACAP receptors --- p.17 / Chapter 1.3.3 --- Function of PACAP system --- p.21 / Chapter 1.4 --- Objective of present study --- p.23 / Chapter Chapter 2 --- Pituitary Adenylate Cyclase-activating Polypeptide (PACAP) and Its Receptors in the Zebrafish Ovary - Evidence for Potential Dual Roles of PACAP in Controlling Final Oocyte Maturation / Chapter 2.1 --- Introduction --- p.27 / Chapter 2.2 --- Materials and method --- p.30 / Chapter 2.2.1 --- Animals and chemicals --- p.30 / Chapter 2.2.2 --- Isolation of ovarian follicles --- p.31 / Chapter 2.2.3 --- Separation of oocyte and follicle layer --- p.32 / Chapter 2.2.4 --- Follicle incubation and oocyte maturation assay --- p.32 / Chapter 2.2.5 --- Primary follicle cell culture --- p.33 / Chapter 2.2.6 --- RNA extraction and reverse transcription --- p.33 / Chapter 2.2.7 --- Semi- quantitative RT-PCR and real-time qPCR --- p.33 / Chapter 2.2.8 --- Data analysis --- p.34 / Chapter 2.3 --- Results --- p.34 / Chapter 2.3.1 --- Spatial distribution of PACAP system within the follicle --- p.34 / Chapter 2.3.2 --- Temporal expression profiles of the PACAP system during folliculogenesis --- p.35 / Chapter 2.3.3 --- Expression profiles of PACAP system in peri-ovulatory period in vivo --- p.35 / Chapter 2.3.4 --- Expression mark change of the PACAP system during in vivo and in vitro maturation --- p.37 / Chapter 2.3.5 --- Effects of PACAP on final maturation of intact follicles and denuded oocytes --- p.38 / Chapter 2.4 --- Discussion --- p.39 / Chapter Chapter 3 --- PACAP Mimics Pituitary Gonadotropin(s) in Regulating Ovarian Activin/Inhibin/Follistatin System / Chapter 3.1 --- Introduction --- p.54 / Chapter 3.2 --- Materials and method --- p.57 / Chapter 3.2.1 --- Animals and chemicals --- p.57 / Chapter 3.2.2 --- Primary culture of ovarian follicle cells --- p.57 / Chapter 3.2.3 --- Total RNA isolation and reverse transcription --- p.58 / Chapter 3.2.4 --- Real-time polymerase chain reaction --- p.58 / Chapter 3.2.5 --- Isolation and incubation of follicles --- p.59 / Chapter 3.2.6 --- Data analysis --- p.59 / Chapter 3.3 --- Result --- p.61 / Chapter 3.3.1 --- PACAP regulation of the expression of activin/inhibin/follistatin system in cultured zebrafish ovarian follicle cells --- p.61 / Chapter 3.3.2 --- Involvement of protein kinase A (PKA) in the differential regulation of activin subunits and follistatin by PACAP --- p.61 / Chapter 3.3.3 --- Potential role of activin in PACAP-induced oocyte maturation --- p.62 / Chapter 3.3.4 --- Interactive effects of EGF and PACAP on the expression of activin subunits and follistatin in the follicle cells --- p.62 / Chapter 3.3.5 --- Potential involvement of EGF-EGFR signaling in PACAP-regulated expression of activin subunits and follistatin in the follicle cells --- p.62 / Chapter 3.4 --- Discussion --- p.63 / Chapter Chapter 4 --- PACAP Regulation of Ovarian GH-IGF System / Chapter 4.1 --- Introduction --- p.78 / Chapter 4.2 --- Materials and methods --- p.81 / Chapter 4.2.1 --- Animals and chemicals --- p.81 / Chapter 4.2.2 --- Primary culture of ovarian follicle cells --- p.81 / Chapter 4.2.3 --- Total RNA isolation and reverse transcription --- p.82 / Chapter 4.2.4 --- Real-time polymerase chain reaction --- p.82 / Chapter 4.2.5 --- Follicle incubation --- p.82 / Chapter 4.2.6 --- Data analysis --- p.83 / Chapter 4.3 --- Result --- p.83 / Chapter 4.3.1 --- PACAP regulation of the expression of growth hormone and growth hormone receptors in cultured zebrafish ovarian follicle cells --- p.83 / Chapter 4.3.2 --- PACAP regulation of the expression of insulin-like growth factors and their receptors in cultured zebrafish ovarian follicle cells --- p.84 / Chapter 4.3.3 --- Self-regulation of PACAP expression in cultured zebrafish ovarian follicle cells --- p.85 / Chapter 4.3.4 --- Evaluation of protein kinase A (PKA) involvement in the PACAP-regulated expression of GH and IGFs family --- p.85 / Chapter 4.3.5 --- Interactive effects of PACAP and EGF on expression of zebrafish GH-IGF axis in cultured follicle cells --- p.86 / Chapter 4.4 --- Discussion --- p.87 / Chapter Chapter 5 --- PACAP regulation of cytochrome P450 aromatase expression in cultured zebrafish ovarian follicle cells / Chapter 5.1 --- Introduction --- p.103 / Chapter 5.2 --- Materials and methods --- p.106 / Chapter 5.2.1 --- Animals and chemicals --- p.106 / Chapter 5.2.2 --- Primary culture of ovarian follicle cells --- p.106 / Chapter 5.2.3 --- Total RNA isolation and reverse transcription --- p.107 / Chapter 5.2.4 --- Real-time polymerase chain reaction --- p.107 / Chapter 5.2.5 --- Data analysis --- p.108 / Chapter 5.3 --- Results --- p.108 / Chapter 5.3.1 --- PACAP regulation of cyp19a1a expression in cultured zebrafish ovarian follicle cells --- p.108 / Chapter 5.3.2 --- Effects of forskolin and db-cAMP on cyp19a1a expression --- p.109 / Chapter 5.3.3 --- Involvement of protein kinase A (PKA) in the regulation of cyp19a1a expression by PACAP --- p.109 / Chapter 5.4 --- Discussion --- p.109 / Chapter Chapter 6 --- General Discussion / Chapter 6.1 --- Potential roles of PACAP in folliculogenesis --- p.120 / Chapter 6.2 --- PACAP mediates gonadotropins’ signaling through activin/follistatin system --- p.123 / Chapter 6.3 --- PACAP regulation of steroidogenesis --- p.124 / Chapter 6.4 --- PACAP regulation of ovarian PACAP-GH-IGF axis --- p.127 / Reference
|
105 |
Cultivation of invasive zebra mussels (Dreissena polymorpha) for the improvement of reservoir water qualityMcLaughlan, Claire January 2015 (has links)
No description available.
|
106 |
Developmental profile of aromatase expression in the zebrafish ovary and its regulation.January 2003 (has links)
Yung Cheuk Man. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (leaves 89-113). / Abstracts in English and Chinese. / Abstract (in English) --- p.i / Abstract (in Chinese) --- p.iii / Acknowledgement --- p.v / Table of content --- p.vii / List of figures --- p.xi / Symbols and abbreviations --- p.xiii / Scientific names --- p.xv / Chapter Chapter 1 --- General Introduction --- p.1 / Chapter 1.1 --- Structure of ovarian follicles --- p.2 / Chapter 1.2 --- Steroidogenesis in the ovary --- p.3 / Chapter 1.2.1 --- Two-cell-type model --- p.5 / Chapter 1.2.2 --- Steroidogenic shift --- p.8 / Chapter 1.3 --- Aromatase --- p.8 / Chapter 1.3.1 --- Structure --- p.8 / Chapter 1.3.2 --- Function --- p.9 / Chapter 1.3.3 --- Mechanism of aromatase action --- p.11 / Chapter 1.3.4 --- Expression --- p.13 / Chapter 1.3.5 --- Regulation --- p.14 / Chapter 1.3.5.1 --- Gonadotropins --- p.15 / Chapter 1.3.5.2 --- Insulin-like growth factor-I --- p.17 / Chapter 1.3.5.3 --- Activin --- p.19 / Chapter 1.4 --- Objectives of the present study --- p.23 / Chapter Chapter 2 --- Expression profiles of the ovarian aromatase in the zebrafish --- p.25 / Chapter 2.1 --- Introduction --- p.25 / Chapter 2.2 --- Materials and Methods --- p.27 / Chapter 2.2.1 --- Animals --- p.27 / Chapter 2.2.2 --- Total RNA extraction from intact ovaries and ovarian follicles --- p.27 / Chapter 2.2.3 --- Validation of semi-quantitative RT-PCR assays for aromatase and GAPDH --- p.28 / Chapter 2.2.4 --- Data analysis --- p.29 / Chapter 2.3 --- Results --- p.30 / Chapter 2.3.1 --- Validation of the semi-quantitative RT-PCR assays for aromatase and GAPDH --- p.30 / Chapter 2.3.2 --- Developmental expression profile of aromatase in the whole ovary during sexual maturation --- p.32 / Chapter 2.3.3 --- Stage-dependent expression of aromatase in the ovarian follicles of mature gravid zebrafish --- p.35 / Chapter 2.4 --- Discussion --- p.37 / Chapter Chapter 3 --- Regulation of aromatase expression in vitro --- p.42 / Chapter 3.1 --- Introduction --- p.42 / Chapter 3.2 --- Materials and Methods --- p.45 / Chapter 3.2.1 --- Animals --- p.45 / Chapter 3.2.2 --- Chemicals and hormones --- p.45 / Chapter 3.2.3 --- Preparation of goldfish pituitary extract --- p.45 / Chapter 3.2.4 --- Primary follicle cell culture --- p.46 / Chapter 3.2.5 --- Preparation of freshly isolated mid-vitellogenic follicles --- p.46 / Chapter 3.2.6 --- Preparation of ovarian fragments --- p.47 / Chapter 3.2.7 --- "Total RNA extraction from cultured follicle cells, ovarian follicles and ovarian fragments" --- p.47 / Chapter 3.2.8 --- Validation of semi-quantitative RT-PCR assays --- p.48 / Chapter 3.2.9 --- Data analysis --- p.48 / Chapter 3.3 --- Results --- p.49 / Chapter 3.3.1 --- Validation of the semi-quantitative RT-PCR assays for aromatase and GAPDH --- p.49 / Chapter 3.3.2 --- Expression of aromatase in the zebrafish primary follicle cell culture system --- p.52 / Chapter 3.3.3 --- Gonadotropin regulation of aromatase expression in the zebrafish ovarian fragments and freshly isolated intact follicles --- p.54 / Chapter 3.3.4 --- Effects of db-cAMP and forskolin on aromatase expression in cultured zebrafish follicle cells --- p.59 / Chapter 3.3.5 --- Involvement of protein kinase A (PKA) in the regulation of aromatase expression by db-cAMP in cultured zebrafish follicle cells --- p.64 / Chapter 3.3.6 --- Effects of insulin-like growth factor I (IGF-I) on aromatase expression in zebrafish ovarian fragments --- p.66 / Chapter 3.3.7 --- Effects of activin on aromatase expression in zebrafish ovarian fragments --- p.68 / Chapter 3.4 --- Discussion --- p.71 / Chapter Chapter 4 --- General Discussion --- p.78 / Chapter 4.1 --- Expression profiling of aromatase in the zebrafish ovarian and follicle development --- p.81 / Chapter 4.2 --- Mechanisms for the dynamic expression of aromatase --- p.84 / Chapter 4.3 --- Contribution of the present study --- p.87 / Chapter 4.3 --- Future prospects --- p.88 / References --- p.89
|
107 |
Growth and differentiation factor 9 (GDF9) in the ovary of zebrafish, danio rerio. / CUHK electronic theses & dissertations collectionJanuary 2006 (has links)
Liu Lin. / "January 2006." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (p. 117-135). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese.
|
108 |
Caracterização de marcadores de espermatogônias tronco e sua regulação endócrina e parácrina em zebrafish (Danio rerio)Doretto, Lucas Benites. January 2018 (has links)
Orientador: Rafael Henrique Nóbrega / Resumo: As células tronco são classificadas em dois grandes grupos de acordo com sua origem e capacidade de diferenciação. Células tronco embrionárias (CTE) são originadas do zigoto, e podem ser classificadas como totipotentes, isto é, capazes de originar um indivíduo inteiro, ou pluripotentes, quando originam os três folhetos embrionários (ecto, meso e endoderme). As células tronco adultas (CTA) são as células tronco encontradas nos tecidos fetais e adultos; classificadas como uni, oligo ou multipotentes dependendo da variedade de tecidos originados a partir delas. Marcadores de células tronco, como antígenos de superfície específicos, fatores de trancrição como OCT4 e NANOG são expressos em CTE e algumas CTA, mas são rapidamente reprimidos à medida que as células se diferenciam. O presente trabalho tem como objetivo identificar marcadores de células tronco e com isso, os efeitos do hormônio endócrino Fsh e do fator parácrino GDNF na atividade proliferativa e gênica dessas populações de células e também de células de Sertoli. Foi observado que os marcadores Pou5f3 e Gfra1a são principalmente expressos em espermatogônias tronco indiferenciadas e que sua expressão reduz significativamente sob efeito do recombinante zebrafish Fsh. Por outro lado, genes como o igf3, nanos3 e nanog tiveram sua expressão aumentada significativamente. O recombinante humano GDNF não altera significativamente a expressão desses genes, porém estimula a proliferação de espermatogônias tipo Aund e Adiff e célul... (Resumo completo, clicar acesso eletrônico abaixo) / Mestre
|
109 |
Investigating the Role of Genomic Variation in Susceptibility to Environmental Chemicals across PopulationsHolden, Lindsay Adrian 15 May 2018 (has links)
No two individuals are identical. This is true at the genetic level and at the phenotypic level. One of the traits that varies between populations is toxicant susceptibility: some individuals are sensitive to the effects of environmental chemical exposure, and others are resistant. This body of work aims to address the impact of genomic copy number variants (CNV)--large (>1 Kb) duplications or deletions across the genome--on the toxicant-susceptibility phenotype.
Herein copy number variants were characterized across three commonly used laboratory strains of zebrafish (Danio rerio) and mRNA expression phenotypes were identified in the same strains. It was found that males and females have only a 14% overlap in differentially expressed mRNA transcripts across three common laboratory strains, congruent with the growing body of work identifying sex- and strain-specific phenotypes in zebrafish. Furthermore, identified were two strain-specific response quantitative trait loci (QTL) that explain about a third of the variation in susceptibility to PCB and tested the response QTL using targeted CRISPR-Cas9 editing of the CNV involved. Overall, this body of work defines CNV and mRNA expression variation across zebrafish strains, identifies CNV causal in the PCB-susceptibility phenotype, and confirms the PCB-susceptibility QTL using targeted genomic editing.
|
110 |
Zebrafish as a model of genetic disease.Tucker, Ben January 2008 (has links)
The zebrafish is rapidly becoming a vital tool in studies of genetic disease. Use of the zebrafish embryo as an experimental model combines the efficiency of techniques specific to invertebrates with the human applicability of vertebrate studies, along with a number of other advantages such as optical transparency and high spawn number. Sequencing maps and mutant screen data are available, and gene ontology annotation is progressing. Furthermore, a number of highly important projects are underway to expand the utility of the zebrafish still further (eg. Mutant screens and TILLING projects; see (Lieschke and Currie, 2007) for review). As such the zebrafish has become a vital model organism for study of a variety of genetic defects, toxicology and pharmacological screens etc. These papers trace the development of zebrafish embryos as a model organism for both genetic disease and, as part of this, the development of a relatively high throughput approach to analysing relative levels of apoptosis. The first paper describes the fmr1 gene family in zebrafish (fmr1, and its orthologs fxr1 and fxr2). This paper includes a phylogenetic analysis of the gene family that demonstrates the high conservation between human and zebrafish, in the context of Drosophila. We then describe expression of the genes in the embryo (using in situ hybridisation) and adult (using real time pcr). The conclusions are that the zebrafish is an appropriate model in which to study Fragile X Mental Retardation genetic disease. The second paper builds upon this conclusion and further establishes the appropriateness of the model by recapitulating elements of the disease that had already been modelled in other model organisms. The research is validated using a number of controls. We describe a number of original findings that extended the body of knowledge regarding pharmacological rescue of the FMRP loss phenotypes. A craniofacial phenotype is identified, the first such discovery in a model of Fragile X syndrome. These findings are a vital step toward understanding the pathway from gene, to molecular phenotype, to cellular morphology, to gross morphology. As part of these studies, we found it necessary to analyse apoptosis. The technique developed to facilitate this analysis is described in our third paper. Given the highly stochastic nature of the apoptotic patterns we developed a method to take full advantage of the characteristics of zebrafish embryos, primarily their transparency and availability in large numbers. As the zebrafish becomes more widely accepted as a model for a diverse range of scientific questions, the development of such a technique is doubly important given the necessity of a cheap, reliable and simple generalizable method of analysing processes affecting cell viability in fish. This has clear importance for pharmacological studies, but is also a long overdue addition to the battery of controls available for highly invasive techniques such as microinjection, in which apoptosis is regularly found among its non specific effects. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1311173 / Thesis (Ph.D.) -- University of Adelaide, School of Molecular and Biomedical Science, 2008
|
Page generated in 0.0264 seconds