published_or_final_version / Zoology / Master / Master of Philosophy

An infusion technique was used with an aqueous radiocalcium ( 45CaCl2) solution during the seed-filling stage of well-watered and moisture-stressed soybean in a greenhouse. The kinetics of infusion volume showed a quadratic reduction in absorption which approached zero on the sixth day for non-irrigated plants. The concentration of 45Ca increased quadratically from the point of injection towards the apex independent of both water status and plant parts. The difference in concentration of 45Ca between irrigated and non-irrigated plants was significant (P < 0.05) and concentrations attained the maximum values at the sixth node from the plant base. Seeds contained considerably less 45Ca than either stem or leaves. / The effects of a long (LD, 16h) and a short (SD, 12h) photoperiod with two water stress levels (SL) of stress (ST) and no stress (NS) on the distribution of 45Ca in plant organs (PO) of leaves, petioles, and stem at different node number (NN) of soybean were studied during the seed-filling stage. The univariate and Manova analyses showed the main effects of photoperiod (PP), SL, and PO to be highly significant (P < 0.001) on Ca distribution. The long PP increased Ca concentration in top leaves compared with the short PP regardless of SL. Water stress significantly (P < 0.001) modified the Ca distribution and reduced its concentration in PO within NN irrespective of the photoperiod (a measure of light stress). A possible mechanism for the regulation of Ca distribution is discussed in terms of nitrate reduction. / Ca uptake was also studied by immersing the central tip of a trifoliate leaf in various concentrations of 45CaCl2 solutions and drought conditions during the seed-filling period of soybean. The beta-ray gauging and the diurnal leaf temperature variation showed similar characteristics for leaf water status. The activities of 45Ca were significantly higher (P < 0.0001) at 5, 10, 20, and 30 mM concentrations for water-stressed and non-stressed leaves compared with the control. 45Ca activities at 5, 10, and 20 mM Ca concentrations between stressed and non-stressed leaves were not significant, but the difference in their mean values at 30 mM Ca concentration was significant (P = 0.0159). The relationship between 45Ca uptake and Ca concentration was parabolic for both stressed (R 2 = 0.77) and non-stressed (R2 = 0.81) leaves. Autoradiograms indicated Ca movement through the mid-rib and veins of the tip-immersed trifoliate leaf but showed no activity in other plant parts. An activity gradient developed between seeds when a pod-tip was immersed in the radioactive solution. Solutions of ruthenium red (RR, 0.01 mM), Ethylene Glycol-bis-(beta-aminoethyl ether)- N,N,N,N-Tetraacetic Acid (EGTA, 0.1 mM), calcium (Ca, 1 mM), and double distilled water (control) were fed through a bottom branch of soybean with (ST) and without (NS) water stress. The volume absorptions and transpiration rates were significantly higher for NS than ST plants and decreased almost linearly with time for all treatments. The transpiration rates of Ca-feeding ST plants and the control overlapped while the NS plants approached the same rate of transpiration by the third week. Ca was implicated in stomatal closure for the reduction in the transpiration rates. The relative amounts of chlorophyll decreased with time but chlorophyll was least affected for Ca-absorbing plants for both ST and NS plants. The use of RR (Ca transport blocker), and EGTA (Ca chelator) indicated the role of intracellular Ca conce

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The present investigation is concerned with determining the role of calcium, phospholipids, and phospholipid metabolites on transepithelial sodium and water transport in response to antidiuretic hormone (ADH). These studies utilize the frog skin for determining sodium transport and amphibian urinary bladder for water flow measurements and scanning electron microscopy of cell surface morphology. The results demonstrate that phospholipids and phospholipid metabolites containing arachidonic acid stimulate transepithelial sodium transport through amiloride sensitive channels and the action of these lipids involves the synthesis of prostaglandins. These lipids also inhibited the increase in water flow induced by ADH, and this effect was prevented with prostaglandin synthesis inhibitors. Prostaglandins alter intracellular calcium concentrations and agents effecting calcium metabolism alter cell surface morphology and the changes in surface substructure induced by ADH. These observations support the hypothesis that alterations in membrane permeability to water and ions may involve metabolism of membrane phospholipids and prostaglandin biosynthesis.

Kwok, Po Lam. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 124-130). / Abstracts in English and Chinese. / Thesis/Assessment Committee --- p.i / Abstract --- p.ii / 中文摘要 --- p.v / Acknowledgements --- p.vii / List of Figures --- p.viii / List of Tables --- p.x / Table of Abbreviations --- p.xii / Contents --- p.xix / Chapter Chapter 1 --- General Introduction --- p.1 / Chapter Chapter 2 --- The Biology of Human Umbilical Cord Perivascular Cells (HUCPVs) and Their Potential Applications in Tissue Regeneration / Chapter 2.1 --- INTRODUCTION --- p.5 / Chapter 2.1.1 --- Stem cells --- p.5 / Chapter 2.1.2.1 --- Embryonic stem cells --- p.6 / Chapter 2.1.2.2 --- iPS cells --- p.7 / Chapter 2.1.2.3 --- Somatic stem cells --- p.8 / Chapter 2.1.3 --- Mesenchymal stem cells --- p.9 / Chapter 2.1.4 --- Pericytes --- p.11 / Chapter 2.1.5 --- CD146 positive MSCs --- p.12 / Chapter 2.1.6 --- Human umbilical cord perivascular cells (HUCPVs) --- p.13 / Chapter 2.1.7 --- The biology of stem cell microenvironment (niche) --- p.14 / Chapter 2.1.8 --- Current applications of HUCPVs --- p.17 / Chapter 2.1.9 --- Regenerative medicine --- p.17 / Chapter 2.1.10 --- Applications of stem cells in bone regeneration --- p.19 / Chapter 2.2 --- MATERIALS AND METHODS --- p.22 / Chapter 2.2.1 --- Cell culture --- p.22 / Chapter 2.2.2 --- Preparation of Human Umbilical Cord Perivascular (HUCPV) cells --- p.22 / Chapter 2.2.2.1 --- Isolation of Human Umbilical Cord Perivascular (HUCPV) cells from human umbilical cord --- p.22 / Chapter 2.2.2.2 --- Purification of HUCPV cells --- p.23 / Chapter 2.2.3 --- Immunocytochemsitry --- p.24 / Chapter 2.2.4 --- Semi-quantitative reverse transcription polymerase chain reaction (RT-PCR) --- p.25 / Chapter 2.2.4.1 --- Isolation of total cellular RNA --- p.25 / Chapter 2.2.4.2 --- Complementary DNA (cDNA) synthesis --- p.26 / Chapter 2.2.4.3 --- Polymerase chain reaction (PCR) --- p.26 / Chapter 2.2.5 --- Quantitative real-time reverse transcriptionpolymerase chain reaction (qRT-PCR) --- p.30 / Chapter 2.2.6 --- In vitro differentiation assays --- p.33 / Chapter 2.2.6.1 --- Osteogenic differentiation --- p.33 / Chapter 2.2.6.2 --- Adipogenic differentiation --- p.33 / Chapter 2.2.6.3 --- Chondrogenic differentiation --- p.34 / Chapter 2.2.6.4 --- In vitro chondrogenic differentiation on gelfoam® --- p.34 / Chapter 2.2.7 --- Cytochemistry staining --- p.35 / Chapter 2.2.7.1 --- Alkaline Phosphatase staining --- p.35 / Chapter 2.2.7.2 --- Alizarin Red S staining --- p.35 / Chapter 2.2.7.3 --- Oil Red O staining --- p.36 / Chapter 2.2.7.4 --- Alcian Blue staining --- p.36 / Chapter 2.2.8 --- Scanning electron microscopy (SEM) --- p.37 / Chapter 2.2.9 --- Transmission electron microscopy (TEM) --- p.37 / Chapter 2.2.10 --- Paraffin tissue embedding --- p.38 / Chapter 2.2.10 --- Haematoxylin and Eosin staining --- p.38 / Chapter 2.3 --- RESULTS --- p.40 / Chapter 2.3.1 --- Isolation and purification of HUCPVs --- p.40 / Chapter 2.3.2 --- Osteogenic differentiation of HUCPVs under normoxia --- p.41 / Chapter 2.3.3 --- Osteogenic differentiation of HUCPVs under hypoxia --- p.42 / Chapter 2.3.4 --- Adipogenic differentiation of HUCPVs --- p.43 / Chapter 2.3.5 --- Chondrogenic differentiation of HUCPVs --- p.43 / Chapter 2.3.6 --- Chondrogenic differentiation of HUCPVs on gelfoam® --- p.44 / Chapter 2.4 --- DISCUSSION --- p.59 / Chapter Chapter 3 --- Calcium and Calcium-sensing Receptor (CaSR) in osteogenesis / Chapter 3.1 --- INTRODUCTION --- p.62 / Chapter 3.1.1 --- Metabolism of calcium --- p.62 / Chapter 3.1.2 --- Calcium-sensing receptor --- p.64 / Chapter 3.1.2.1 --- The molecular structure of calcium-sensing Receptor (CaSR) --- p.64 / Chapter 3.1.2.2 --- The expression pattern of calciumsensing receptor (CaSR) --- p.67 / Chapter 3.1.2.3 --- The physiological function of calcium-sensing receptor in different tissues or organs --- p.68 / Chapter 3.1.2.4 --- Regulatory role of calcium-sensing receptor in calcium sensing and homeostasis --- p.71 / Chapter 3.1.2.5 --- The role of calcium-sensing receptor in diseases --- p.72 / Chapter 3.1.2.6 --- Genetic animal models targeting calciumsensing receptor --- p.73 / Chapter 3.1.2.7 --- Calcium-sensing receptor in mesenchymal lineage Differentiation --- p.76 / Chapter 3.1.2.8 --- The role of calcium-sensing receptor in the skeleton --- p.76 / Chapter 3.1.3 --- Calcium-sensing receptor related pathway --- p.78 / Chapter 3.1.3.1 --- Cyclic AMP pathway --- p.78 / Chapter 3.1.3.2 --- Cyclic AMP response element-binding protein (CREB) --- p.80 / Chapter 3.2 --- MATERIALS AND METHODS --- p.83 / Chapter 3.2.1 --- Preparation of primary mouse osteoblasts (MOB) from long bone --- p.83 / Chapter 3.2.2 --- Preparation of primary mouse osteoblasts (CMOB) from calvaria --- p.84 / Chapter 3.2.3 --- Immunocytochemistry --- p.84 / Chapter 3.2.4 --- Osteogenic differentiation --- p.85 / Chapter 3.2.3 --- Quantitative real-time reverse transcriptionpolymerase chain reaction (qRT-PCR) --- p.85 / Chapter 3.2.4 --- Cell proliferation measurement by BrdU ELISA (colorimetric) assay --- p.85 / Chapter 3.2.5 --- Western blotting analysis --- p.86 / Chapter 3.2.5.1 --- Preparation of the protein lysate --- p.86 / Chapter 3.2.5.2 --- Protein quantitation --- p.86 / Chapter 3.2.5.3 --- SDS-PAGE --- p.87 / Chapter 3.2.5.4 --- Protein transfer --- p.87 / Chapter 3.2.5.5 --- Immunodetection --- p.88 / Chapter 3.2.6 --- cAMP EIA assay --- p.89 / Chapter 3.3 --- RESULTS --- p.91 / Chapter 3.3.1 --- "Expression of CD 146 and CaSR in HUCPVs, primary mouse long bone osteoblasts and MC3T3-E1 cell line" --- p.91 / Chapter 3.3.2 --- The effect of calcium treatment on the osteogenic differentiation potential of MC3T3-E1 cells under normoxia --- p.91 / Chapter 3.3.3 --- The effect of calcium treatment on the osteogenic differentiation potential of MC3T3-E1 cells under hypoxia --- p.92 / Chapter 3.3.4 --- The effect of calcium treatment on cell proliferation in primary mouse long bone osteoblasts --- p.93 / Chapter 3.3.5 --- The effect of calcium treatment on calcium-sensing receptor expression in primary mouse long bone osteoblasts --- p.94 / Chapter 3.3.6 --- The effect of calcium treatment on calcium-sensing receptor expression in HUCPVs --- p.95 / Chapter 3.3.7 --- The effect of calcium treatment on calcium-sensing receptor expression in primary mouse calvarian osteoblasts --- p.96 / Chapter 3.3.8 --- The effect of calcium treatment on cyclic AMP levels in primary mouse long bone osteoblasts --- p.97 / Chapter 3.4 --- DISCUSSION --- p.117 / Chapter Chapter 4 --- General Discussions --- p.121 / References --- p.124 / Appendices --- p.131

Abstract not available

Presenilin-1 (PS1) mutations caused by the PSEN1 gene mutations are the major cause of early onset familial Alzheimer’s disease (EOFAD). Two Chinesespecific EOFAD related PS1 mutations, V97L and A136G, have been found. Studies suggested that V97L mutation lead to the overexpression of Aβ42 and tau hyperphosphorylation, which are the major hallmarks of Alzheimer’s disease (AD), while properties of A136G were unclear. Since calcium dysregulation was suggested to play an important role in AD, the research project investigated if V97L and A136G mutations also lead to altered endoplasmic reticulum (ER) 〖Ca〗^(2+) regulation. SH-SY5Y cells transduced with retrovirus carrying V97L mutant or A136 mutant PSEN1 were used as the experiment models. In Western blotting, while the PS1 expression level was unaffected in V97L mutant, the expression level was significantly lower in A136G mutant. In carbachol (CCh) perfusion experiment, V97L mutant was found to exaggerate ER 〖Ca〗^(2+) release when stimulated by higher concentration (30, 100 and 300 μM) CCh, while A136G mutant exaggerated ER Ca2+ release when stimulated by 30 μM and 300 μM CCh, but not 100 μM CCh. In 5% fetal bovine serum (FBS) perfusion experiment, both V97L and A136G mutants were found to sensitize 〖Ca〗^(2+) oscillation, which the sensitization effect of V97L was 3 folds of A136G. The results suggested that V97L mutation exaggerates ER 〖Ca〗^(2+) release, possibly via interaction with IP3R. However the results of A136G were inconclusive and contradicting, therefore further investigation is needed. / published_or_final_version / Physiology / Master / Master of Medical Sciences

M.Sc. / Please refer to full text to view abstract