by Cheung Yeuk Siu. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2000. / Includes bibliographical references (leaves 141-153). / Abstracts in English and Chinese. / Acknowledgments --- p.i / Abstract --- p.ii / 摘要 --- p.iv / List of abbreviations --- p.v / Table of contents --- p.viii / Chapter Chapter 1 --- Introduction / Chapter 1.1 --- Prolactin (PRL) --- p.1 / Chapter 1.1.1 --- General introduction --- p.1 / Chapter 1.1.2 --- Genomic organization of teleost PRL gene --- p.2 / Chapter 1.1.3 --- Conserved domains of fish PRL --- p.3 / Chapter 1.1.4 --- Structure of teleost PRL --- p.6 / Chapter 1.1.5 --- Tissue sources of PRL --- p.8 / Chapter 1.2 --- Prolactin receptor (PRLR) --- p.9 / Chapter 1.2.1 --- Tissue distribution in teleosts --- p.9 / Chapter 1.2.2 --- Receptor structure and multiple forms of PRLR --- p.11 / Chapter 1.2.3 --- Possible action mechanisms of PRL --- p.14 / Chapter 1.3 --- Control of PRL release --- p.17 / Chapter 1.4 --- Biological functions of PRL in vertebrates --- p.19 / Chapter 1.4.1 --- Biological effects on teleosts --- p.19 / Chapter 1.4.1.1 --- Osmoregulatory roles --- p.20 / Chapter 1.4.1.2 --- Non-osmoregulatory roles --- p.29 / Chapter 1.5 --- Aim of the present study --- p.32 / Chapter Chapter 2 --- "Recombinant goldfish (Carassius auratus) prolactin: subcloning, expression, purification and refolding of the recombinant protein" / Chapter 2.1 --- Introduction --- p.35 / Chapter 2.2 --- Materials --- p.38 / Chapter 2.3 --- Methods --- p.48 / Chapter 2.3.1 --- Subcloning of the gfPRL cDNA --- p.48 / Chapter 2.3.1.1 --- PCR cloning of gfPRL cDNA --- p.48 / Chapter 2.3.1.2 --- DNA sequencing of the subcloned fragment --- p.51 / Chapter 2.3.1.3 --- Subcloning of the gfPRL cDNA fragment into the expression vector --- p.52 / Chapter 2.3.2 --- Expression and purification of rgfPRL --- p.53 / Chapter 2.3.2.1 --- Transformation of pRSETA/gfPRL into BL21(DE3)pLysS cells --- p.53 / Chapter 2.3.2.2 --- Prokaryotic expression of rgfPRL --- p.53 / Chapter 2.3.2.3 --- Affinity purification of rgfPRL --- p.55 / Chapter 2.3.2.4 --- Western blot analysis of the purified rgfPRL --- p.57 / Chapter 2.3.2.5 --- Protein concentration determination of the rgfPRL --- p.59 / Chapter 2.3.3 --- Protein refolding --- p.60 / Chapter 2.4 --- Results --- p.61 / Chapter 2.4.1 --- Subcloning and DNA sequencing of the gfPRL --- p.61 / Chapter 2.4.2 --- Expression and purification of rgfPRL --- p.63 / Chapter 2.4.2.1 --- Prokaryotic expression of rgfPRL --- p.63 / Chapter 2.4.2.2 --- Affinity purification of rgfPRL --- p.66 / Chapter 2.4.2.3 --- Western blot analysis of the purified rgfPRL --- p.68 / Chapter 2.4.2.4 --- Protein concentration determination of the rgfPRL --- p.68 / Chapter 2.4.3 --- Protein refolding --- p.70 / Chapter 2.5 --- Discussion --- p.72 / Chapter Chapter 3 --- Production of polyclonal antibodies against rgfRPL / Chapter 3.1 --- Introduction --- p.81 / Chapter 3.2 --- Materials --- p.82 / Chapter 3.3 --- Methods --- p.84 / Chapter 3.3.1 --- Immunization of rabbits --- p.84 / Chapter 3.3.2 --- Collection of the polyclonal antisera --- p.85 / Chapter 3.3.3 --- Purification of IgG from the polyclonal antisera --- p.86 / Chapter 3.3.4 --- Enzyme linked immunosorbent assay (ELISA) --- p.87 / Chapter 3.3.5 --- Western blot analysis for cross-reactivity --- p.88 / Chapter 3.4 --- Results --- p.90 / Chapter 3.4.1 --- Isolation and purification of IgG from the polyclonal antisera --- p.90 / Chapter 3.4.2 --- ELISA --- p.93 / Chapter 3.4.3 --- Western blot analysis for cross-reactivity --- p.96 / Chapter 3.5 --- Discussion --- p.98 / Chapter Chapter 4 --- Isolation of native PRL from goldfish pituitaries / Chapter 4.1 --- Introduction --- p.100 / Chapter 4.2 --- Materials --- p.101 / Chapter 4.3 --- Methods --- p.103 / Chapter 4.3.1 --- Alkaline extraction --- p.103 / Chapter 4.3.2 --- Size exclusion chromatography --- p.104 / Chapter 4.3.3 --- Anion exchange chromatography --- p.104 / Chapter 4.4 --- Results --- p.106 / Chapter 4.4.1 --- Size exclusion chromatography --- p.106 / Chapter 4.4.2 --- Anion exchange chromatography --- p.109 / Chapter 4.4.3 --- SDS-PAGE analysis and immuno-detection of the purified protein --- p.112 / Chapter 4.5 --- Discussion --- p.114 / Chapter Chapter 5 --- Receptor binding assays / Chapter 5.1 --- Introduction --- p.115 / Chapter 5.2 --- Materials --- p.117 / Chapter 5.3 --- Methods --- p.119 / Chapter 5.3.1 --- Gill membrane preparation --- p.119 / Chapter 5.3.2 --- Radioactive labelling of the primary ligand --- p.120 / Chapter 5.3.3 --- Determination of the percentage of 125I incorporation and specific radioactivity of the radioligand --- p.121 / Chapter 5.3.4 --- Membrane protein dependence assay --- p.122 / Chapter 5.3.5 --- Receptor binding study using rgfPRL --- p.124 / Chapter 5.4 --- Results --- p.125 / Chapter 5.4.1 --- Radioactive labelling of the primary ligand --- p.125 / Chapter 5.4.2 --- Determination of the percentage of 125I incorporation and specific radioactivity of the radioligand --- p.127 / Chapter 5.4.3 --- Membrane protein dependence assay --- p.129 / Chapter 5.4.4 --- Receptor binding study using rgfPRL --- p.131 / Chapter 5.5 --- Discussion --- p.133 / Chapter Chapter 6 --- General discussion and conclusion --- p.136 / References --- p.141

A macroprolactinemia é condição freqüente na hiperprolactinemia e em geral, sem impacto clínico. Os dados sobre a atividade biológica da macroprolactina (bbPRL) são controversos e baseados em bioensaio heterólogo com células de rato Nb2. A atividade biológica da bbPRL é observada in vitro e não in vivo, provavelmente porque seu alto peso molecular evita sua passagem pelos capilares. A bioatividade da bbPRL talvez varie de acordo com a especificidade do receptor de prolactina (PRLR). Avaliamos a bioatividade da bbPRL de indivíduos macroprolactinêmicos (Grupo I, n = 18) e da PRL monomérica (mPRL) de pacientes hiperprolactinêmicos sem bbPRL (Grupo II, n = 5) em Nb2 e em células Ba/F-LLP, transfectadas com o PRLR humano. Enquanto ambos ensaios apresentam resultados similares para a atividade de mPRL, nossos resultados indicam que a atividade da bbPRL é presente em ensaio heterólogo e não em ensaio homólogo. O ensaio Ba/F-LLP é sensível e apresenta melhor correlação com a atividade in vivo da bbPRL / Macroprolactinemia is a frequent finding in hyperprolactinemic individuals, usually without clinical impact. Data on biological activity of macroprolactin (bbPRL) is mostly based on a heterologous bioassay (Nb2 cell). Biological activity of bbPRL observed in vitro but not in vivo maybe due to its high molecular weight preventing its passage through capillary barrier. Alternatively, bbPRL bioactivity may differ depending on the PRL receptor species specificity. BbPRL from macroprolactinemic individuals and monomeric PRL (mPRL) from hyperprolactinemic patients without macroprolactinemia were tested in two bioassays: Nb2 and in Ba/F-LLP, which expresses human prolactin receptor. While both bioassays achieve similar results considering mPRL activity, our results indicate that bbPRL displays activity in a heterologous but not in a homologous bioassay, consistently with the apparent absence of bbPRL bioactivity in vivo

A macroprolactinemia é condição freqüente na hiperprolactinemia e em geral, sem impacto clínico. Os dados sobre a atividade biológica da macroprolactina (bbPRL) são controversos e baseados em bioensaio heterólogo com células de rato Nb2. A atividade biológica da bbPRL é observada in vitro e não in vivo, provavelmente porque seu alto peso molecular evita sua passagem pelos capilares. A bioatividade da bbPRL talvez varie de acordo com a especificidade do receptor de prolactina (PRLR). Avaliamos a bioatividade da bbPRL de indivíduos macroprolactinêmicos (Grupo I, n = 18) e da PRL monomérica (mPRL) de pacientes hiperprolactinêmicos sem bbPRL (Grupo II, n = 5) em Nb2 e em células Ba/F-LLP, transfectadas com o PRLR humano. Enquanto ambos ensaios apresentam resultados similares para a atividade de mPRL, nossos resultados indicam que a atividade da bbPRL é presente em ensaio heterólogo e não em ensaio homólogo. O ensaio Ba/F-LLP é sensível e apresenta melhor correlação com a atividade in vivo da bbPRL / Macroprolactinemia is a frequent finding in hyperprolactinemic individuals, usually without clinical impact. Data on biological activity of macroprolactin (bbPRL) is mostly based on a heterologous bioassay (Nb2 cell). Biological activity of bbPRL observed in vitro but not in vivo maybe due to its high molecular weight preventing its passage through capillary barrier. Alternatively, bbPRL bioactivity may differ depending on the PRL receptor species specificity. BbPRL from macroprolactinemic individuals and monomeric PRL (mPRL) from hyperprolactinemic patients without macroprolactinemia were tested in two bioassays: Nb2 and in Ba/F-LLP, which expresses human prolactin receptor. While both bioassays achieve similar results considering mPRL activity, our results indicate that bbPRL displays activity in a heterologous but not in a homologous bioassay, consistently with the apparent absence of bbPRL bioactivity in vivo