• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 831
  • 472
  • 143
  • 129
  • 21
  • 21
  • 21
  • 21
  • 21
  • 21
  • 21
  • 21
  • 15
  • 15
  • 14
  • Tagged with
  • 2080
  • 355
  • 241
  • 239
  • 227
  • 149
  • 134
  • 111
  • 106
  • 105
  • 103
  • 100
  • 97
  • 96
  • 95
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
291

Control analysis of adrenal Sseroidogenesis

Genade, Tyrone 12 1900 (has links)
Thesis (MSc (Biochemistry))--University of Stellenbosch, 2004. / This study describes: 1. Investigation of product inhibition regarding the metabolism of progesterone in ovine adrenal micosomes. 2. The employment of novel cell culture techniques to study the effect of CYP17 and CYP21 concentration on adrenal progesterone metabolism. 3. The formulation of a mathematical model describing the behaviour of the observed results in point 2.
292

An investigation into the molecular mechanism of action of the progestins, medroxyprogesterone acetate and norethisterone acetate

Koubovec, Dominique J. B. M. 04 1900 (has links)
Thesis (PhD)--Stellenbosch University, 2004. / ENGLISH ABSTRACT: Although the progestins medroxyprogesterone acetate (MPA) and norethisterone acetate (NET-A) are widely used in reproductive therapy, the steroid receptors and their target genes involved in the actions of MPA and NET-A are not well understood. Surprisingly, it had not yet been investigated whether doses of MPA and NET-A used for contraception and HRT cause significant side effects through various target genes via the glucocorticoid receptor (GR). In this thesis results of in vitro studies showed that, MPA, like dexamethasone (dex) and prog, significantly repressed tumour necrosis factor (TN F)-stimulated IL-6 protein production, and IL-6 and IL-8 promoter reporter constructs at the transcriptional level in L929sA cells, via interference with nuclear factor KB (NFKB) and activator protein-1 (AP-1) transcription factors. Like dex and prog, MPA did not affect NFKB DNA-binding activity. Furthermore, unlike dex and prog, MPA did not inhibit mitogen-activated protein kinase (MAPK) activity. The antagonistic effects of the GR and progesterone receptor (PR) antagonist, RU486, as well as the MPAinduced nuclear translocation of the GR, strongly suggest that the actions of MPA in these cells are mediated at least in part via the GR. Although the mechanism was not investigated as extensively as for MPA, NET-A was shown to repress IL-8 promoter reporter activity very weakly relative to dex, MPA and prog in Hek293 cells stably transfected with the rat GR. Furthermore, NET-A, like MPA, dex and prog did not interfere with the DNA-binding activity of NFKB. Significant transactivation of a GRE-driven promoter reporter construct by MPA and dex in L929sA via endogenous GR and COS-1 cells via expressed rat GR, and by MPA, dex and prog in Hek293 cells via expressed rat GR was also observed. In contrast, NET-A, unlike MPA, dex and prog showed no transactivation in Hek293 cells. MPA, NET-A and prog were shown to compete with dex for binding to the endogenous human GR in human lung carcinoma A549 cells. Similarly, MPA and NET-A were shown to compete with dex for binding to expressed rat GR in COS-1 cells. MPA displayed a higher relative binding affinity than NET-A for the GR in both systems, and a higher relative binding affinity than prog in A549 cells. Equilibrium dissociation constants (Ki values) for MPA (Ki = 10.8 ± 1.1 nM), NET-A (Ki = 270 ± 1.3 nM) and prog (Ki = 215 ± 1.1 nM) towards the human GR in A549 cells were also established. Furthermore, dose-response curves showed that MPA displays significantly greater GC agonist potency and efficacy than NET-A and prog for both transactivation of a synthetic GRE-reporter construct and transrepression of a synthetic IL-8 reporter construct via expressed rat GR in Hek293 cells, as NET-A showed no transactivation and very weak partial agonist activity for transrepression. Based on these observations, MPA behaves as a GR agonist whereas NET-A is proposed to be a weak antagonist. These results show that MPA and NET-A are not alike and not the same as prog in their mechanism of action via the GR, which may have serious health implications in vivo. Such insights may provide women and their clinicians with more information to facilitate the selection of contraception or reproductive therapy regimes with fewer side effects. / AFRIKAANSE OPSOMMING: Alhoewel MPA en NET-A algemeen gebruik word in hormoontherapie, is dit nie duidelik watter steroïedreseptore en teikengene betrokke is by die werking van MPA en NET-A nie. Verrassend is dat geen studie nog gedoen is om te bepaal of die dosisse van MPA en NET-A wat gebruik word in voorbehoeding en hormoonvervangingsterapie (HVT), newe-effekte veroorsaak deur die glukokortikoïedreseptor (GR) en verskeie teikengene nie. In hierdie tesis is in L929sA selle aangetoon dat MPA, net soos deksametasoon (dex) en prog, TNF-gestimuleerde IL-6 produksie onderdruk, en dat IL-6 en IL-8 promoter-rapporteerderkonstrukte op transkripsionele vlak onderdruk word deur middel van inmenging met NF-KB en AP-1 transkripsie-faktore. Net soos dex en prog het MPA nie die DNA-bindingsaktiwiteit van NF-KB beïnvloed nie. Anders as dex en prog het MPA egter nie MAPK aktiwiteit onderdruk nie. Die antagonistiese effekte van RU486, asook die MPA-geïnduseerde translokasie van die GR na die selkern, dui sterk daarop dat die effekte van MPA in hierdie selle ten minste gedeeltelik deur die GR geskied. Alhoewel die meganisme vir NET -A nie so breedvoerig bestudeer is as dié van MPA nie, is tog aangetoon dat, in Hek293 selle wat stabiel getransfekteer is met die rot GR, die onderdrukking van die IL-8 promoter deur NET-A baie swakker is as met dex, prog en MPA. Verder is daar ook gevind dat NET-A, net soos MPA, dex en prog, nie kon inmeng met die DNA-bindingsaktiwiteit van NF-KB nie. Beduidende transaktivering van 'n GRE-bevattende promoterrapporteerderkonstruk deur MPA en dex in L929sA en COS-1 selle, en deur MPA, dex en prog in Hek293 selle, is ook gevind. Daarteenoor het NET-A, anders as MPA, dex en prog, geen transaktivering in Hek293 selle getoon nie. Verder moes die relatiewe bindingsaffiniteit (ewewigs-dissosiasiekonstantes) van MPA, NET-A en prog vir die GR, asook die relatiewe sterkte en effektiwiteit vir transaktivering en transonderdrukking van verskeie teikengene deur die GR, ook bepaal word. Daar is gevind dat MPA, NET-A en prog meeding met dex vir binding aan die endogene GR in mens longkarsinoom A549 selle. Soortgelyk hieraan is ook gevind dat MPA en NET-A meeding met dex vir binding aan rot GR wat in COS-1 selle uitgedruk is. MPA het in beide sisteme 'n hoër relatiewe bindingsaffiniteit vir die GR getoon as NET-A, asook 'n hoër relatiewe bindingsaffiniteit as prog in A549 selle. Ewewigs-dissosiasiekonstantes (Ki waardes) vir MPA (Ki = 10.8 ± 1.1 nM), NET- A (Ki = 270 ± 1.3 nM) en prog (Ki = 215 ± 1.1 nM) vir die mens GR in A549 selle is ook bereken. Dosisrespons-grafieke het ook aangedui dat MPA 'n beduidend beter GC sterkte en effektiwiteit as NET-A en prog het, vir beide transaktivering van 'n sintetiese GRE-rapporteerderkonstruk en transonderdrukking van 'n sintetiese IL-8 rapporteerderkonstruk via rot GR wat uitgedruk is in Hek293 selle. Dit kon afgelei word aangesien NET-A geen transaktivering en slegs baie swak gedeeltelike agonisaktiwiteit vir transonderdrukking getoon het. Op grond van hierdie waarnemings tree MPA op as 'n GR agonis, terwyl dit lyk asof NET-A 'n swak antagonis is. Hierdie resultate dui aan dat MPA en NET-A nie dieselfde is nie, en ook nie dieselfde meganisme van werking deur die GR het as prog nie. Dit kan ernstige gesondheidsimplikasies inhou in vivo. Hierdie insigte kan dus meer inligting aan vroue en kliniese personeel verskaf om sodoende die keuse van voorbehoeding of voortplantingsterapie met minder newe-effekte te vergemaklik.
293

Relationship between serum lipoproteins and sex- and adrenal cortical hormaones in men.

January 1993 (has links)
by Linda Shiou-mei Ooi. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1993. / Includes bibliographical references (leaves 95-109). / Abstract --- p.i / Acknowledgements --- p.iii / List of Figures --- p.viii / Chapter Chapter I. --- Introduction --- p.1 / Objectives --- p.4 / Chapter Chapter II. --- Literature Review --- p.5 / Chapter II. 1. --- Lipoprotein-Lipids --- p.5 / Chapter II.1.1. --- General Concept and Metabolism of Lipoprotein-lipids --- p.5 / Chapter II. 1.2. --- Factors affecting plasma lipoprotein-lipids --- p.11 / Chapter II. 1.2.1. --- Ageing --- p.11 / Chapter II. 1.2.2. --- Obesity --- p.12 / Chapter II. 1.2.3. --- Diet --- p.13 / Chapter II. 1.2.4. --- Alcohol --- p.13 / Chapter II. 1.2.5. --- Cigarette smoking --- p.14 / Chapter II. 1.2.6. --- Exercise --- p.14 / Chapter II. 1.2.7. --- Gender differences --- p.14 / Chapter II.2. --- Sex Hormones --- p.14 / Chapter II.2.1. --- General concepts of sex hormone-production and the metabolism of sex hormones --- p.15 / Chapter II.2.1.1. --- Biosynthesis of testosterone --- p.16 / Chapter II.2.1.2. --- Metabolism of testosterone --- p.17 / Chapter II.2.1.3. --- Dihydrotestosterone (DHT) --- p.18 / Chapter II.2.1.4. --- Androstenedione --- p.18 / Chapter II.2.1.5. --- Biosynthesis of estrogen in men --- p.18 / Chapter II.2.1.6. --- Metabolism of estrogen --- p.19 / Chapter II.2.2. --- Factors affecting sex hormone levels in plasma --- p.19 / Chapter II.2.2.1. --- Sex hormone binding globulin (SHBG) --- p.19 / Chapter II.2.2.2. --- Sampling time --- p.19 / Chapter II.2.2.3. --- Stress and acute or chronic non-endocrine illnesses --- p.20 / Chapter II.2.2.4. --- Ageing --- p.21 / Chapter II.2.2.5. --- Diet and nutrition --- p.21 / Chapter II.2.2.6. --- "Medication, drugs and alcohol" --- p.22 / Chapter II.2.2.7. --- Body composition and obesity --- p.22 / Chapter II.2.2.8. --- Variations in states of sleep-wake cycle --- p.23 / Chapter II.2.2.9. --- Levels of physical and sympathetic nervous system activity --- p.23 / Chapter II. 3. --- The relationship between sex hormones and lipoproteins --- p.24 / Chapter II.3.1. --- "Gender difference in sex hormones, menopause and lipoprotein-lipids" --- p.24 / Chapter II.3.2. --- "Interventional study, exogenous sex hormone and lipoprotein-lipidsin men" --- p.25 / Chapter II.3.3. --- The relationships of endogenous sex hormones and lipoprotein-lipids --- p.26 / Chapter Chapter III. --- Materials and Methods --- p.28 / Chapter III.l. --- Subjects and Sampling Methods --- p.28 / Chapter III.2. --- Quantitation of serum lipoprotein-lipids --- p.29 / Chapter III.2.1 --- Determination of cholesterol and triglyceride --- p.29 / Chapter Table III.2.1.A. --- Intra-assay variations for cholesterol and triglyceride --- p.30 / Chapter Table III.2.1.B. --- Inter -assay variations for Cholesterol and Triglyceride --- p.30 / Chapter III.2.2. --- Determination of HDL-Cholesterol and its subfractions --- p.31 / Chapter Table III.2.2. --- Intra- and inter-assay variation for HDL-cholesterol --- p.31 / Chapter III.2.3. --- Determination of VLDL-C and LDL-C --- p.32 / Chapter III.2.4. --- Quantitative determination of serum apolipoproteins and Lp(a) --- p.32 / Chapter III.2.4.1. --- Determination of Apolipoproteins A-I and B --- p.33 / Chapter III.2.4.2. --- Determination of Lipoprotein (a) --- p.33 / Chapter III. 3. --- Quantitative determination of sex hormones --- p.33 / Chapter III.3.1. --- For urinary unconjugated and serum total testosterone --- p.34 / Chapter III.3.1.1 --- Experimental Procedures --- p.35 / Determination of the optimal antibody titre --- p.35 / Establishment of a standard curve and quality controls --- p.35 / Preparation of standards --- p.35 / Purification of radioactively-labelled 3H-testosterone --- p.37 / Preparation of charcoal- stripped urine as zero calibrator (blank) --- p.37 / Preparation of spiked urine or plasma --- p.38 / Preparation of samples for RIA --- p.38 / RIA --- p.39 / Calculation --- p.40 / Chapter III.3.1.2. --- Characteristics of the radioimmunoassay for testosterone --- p.40 / Sensitivity --- p.40 / Precision studies --- p.42 / Within- and between- batch imprecisions --- p.42 / Chapter Table III.3.1.2.A. --- Within-run variation --- p.42 / Chapter Table III.3.1.2.B. --- Between-run variation --- p.42 / Recoveries --- p.43 / Chapter Table III.3.1.2.C. --- "The recoveries of known amounts of testosterone added to charcoal-stripped urine, between immunoassays" --- p.43 / Test of linearity --- p.43 / Comparison with another procedure --- p.43 / Cross reactivity of the antiserum --- p.44 / Procedure --- p.46 / Chapter Table III.3.1.2.D. --- Cross reactivity of some naturally occurring steroids with testosterone antiserum --- p.47 / Chapter III.3.2 --- For urinary total testosterone --- p.47 / Test of linearity and recovery --- p.48 / Chapter III.3.3. --- For urinary unconjugated and serum total 17β-Estradiol --- p.50 / Chapter III.3.3.1 --- Experimental procedure --- p.50 / Determination of the optimal antibody titre --- p.50 / Establishment of a standard curve and quality controls --- p.52 / Preparation of standards --- p.52 / Preparation of tracer 3H-estradiol and construction of a standard curve --- p.52 / Preparation of spiked control urine or plasma --- p.52 / Preparation of samples for RIA --- p.53 / Chapter III.3.3.2. --- Characteristics of the radioimmunoassay for E2 --- p.53 / Sensitivity --- p.54 / Precision studies --- p.54 / Within- and between- batch imprecisions --- p.54 / Chapter Table III.3.3.2.A. --- Within-run variation of known amount of E2 added to charcoal- stripped urine --- p.54 / Chapter Table III.3.3.2.B. --- Between-run variation of known amount of e2 added to charcoal- stripped urine --- p.54 / Recoveries --- p.56 / Chapter Table III.3.3.2.C. --- "The recoveries of known amount of e2 added to charcoal- stripped urine, between immunoassays" --- p.56 / Test of linearity --- p.56 / Comparison with another procedure --- p.56 / Chapter III.3.4. --- For urinary total estradiol --- p.58 / Test of linearity and recovery --- p.58 / Chapter III.4. --- Determination of serum sex hormone-binding globulin (SHBG) --- p.60 / Chapter III.5. --- Determination of urinary unconjugated Cortisol --- p.60 / Chapter III.6. --- Statistical methods --- p.62 / Chapter III.6.1. --- Biological Variations --- p.62 / Chapter III.6.2. --- Univariate and multivariate correlations --- p.62 / Chapter Chapter IV. --- Results --- p.64 / Chapter IV. 1. --- The characteristics of the experimental subjects and their lipoprotein-lipids profiles --- p.64 / Chapter Table IV. 1. A. --- The anthropometric and biochemical characteristics of the experimental male subjects --- p.64 / Chapter Table IV.1.B. --- The lipoprotein-lipids profiles in 46 healthy Hong Kong Chinese men --- p.65 / Chapter IV. 2. --- "Levels of sex hormones in serum and urine, and urinary free Cortisol" --- p.65 / Chapter Table IV.2. --- The sex hormones at serum and urinary levels and urinary free Cortisol in 46 healthy Hong Kong Chinese men --- p.66 / Chapter Table IV.2.A. --- Formula for the indirect calculation of unbound (free) testosterone levels in plasma --- p.67 / Chapter Table IV.2.B. --- Formula for the indirect calculation of unbound (free) 17β-estradiol levels in plasma --- p.68 / Chapter IV. 3. --- Biological variations --- p.69 / Chapter Table IV. 3. --- "The biological variations of serum lipoprotein-lipids, serum sex hormones and urinary sex hormones and Cortisol in 46 healthy Hong Kong Chinese men" --- p.69 / Chapter Table IV.3.A. --- Correlations of serum lipoprotein-lipids between short-term (3- week) variations --- p.70 / Chapter Table IV.3.B. --- Correlations of serum and urinary sex hormones and urinary unconjugated Cortisol between short-term (3-week) variations --- p.70 / Chapter IV. 4. --- Univariate correlation --- p.71 / Chapter Table IV.4. --- The univariate correlation table --- p.72 / Chapter IV.4.1. --- Inter-relationship among serum and urinary sex hormones --- p.73 / Chapter IV.4.2. --- Urinary free Cortisol and sex hormones and serum lipoprotein-lipids --- p.73 / Chapter IV.4.3. --- Correlation between urinary sex hormones and serum lipoprotein- lipids --- p.73 / Chapter IV.4.4. --- Correlations among serum lipoprotein-lipids --- p.74 / Chapter IV.4.5. --- Correlations between serum lipoprotein-lipids and sex hormones --- p.74 / Chapter IV.4.6. --- "Correlations between anthropometric variables, sex hormones and lipoprotein-lipids" --- p.75 / Chapter IV.4.7. --- Correlation of the ratio of HDL2 and HDL3 and other variables --- p.76 / Chapter IV. 5. --- Multiple linear stepwise regression --- p.77 / Chapter Table IV.5. --- "Stepwise multiple linear regression of lipoprotein-lipids on BMI, W/H Ratio, and Age" --- p.77 / Chapter Table IV.5. A. --- "Stepwise multiple linear regression of lipoprotein-lipids on BMI, W/H Ratio, Age, SHBG, and serum and urinary Sex Hormones" --- p.80 / Chapter Table IV.5.B. --- "Stepwise multiple linear regression of lipoprotein-lipids on BMI, W/H Ratio, Age, SHBG, Triglyceride and serum and urinary Sex Hormones" --- p.81 / Chapter Chapter V. --- Discussion --- p.82 / Chapter V. l. --- Experimental subjects and their lipoprotein-lipids profiles --- p.82 / Chapter V. 2. --- Levels of sex hormones in serum and urine --- p.84 / Chapter Table V.2. --- Values of sex steroids in 46 healthy Hong Kong Chinese men compared to others cited in literature --- p.85 / Chapter V. 3. --- "17β-Estradiol,atherogenic lipoprotein-lpids and HDL3" --- p.88 / Chapter V. 4. --- "Testosterone, and HDL-C and its subfractions" --- p.90 / Chapter Chapter VI. --- Conclusions --- p.92 / References --- p.95 / Appendices --- p.110
294

Characterisation of AtPNP-A - A novel Arabidopsis thaliana gene with a role in water and salt homeostasis.

Bastian, René. January 2009 (has links)
<p>Plant natriuretic peptides (PNPs) are a novel class of extracellular, systemically mobile molecules that elicit a number of plant responses important in homeostasis and growth. Natriuretic peptides were first identified in vertebrates where they play a role in the regulation of salt and water balance. Subsequent experimental investigations have identified the presence of a natriuretic peptide hormone system in plants. While PNPs have been implicated in various physiological responses such as stomatal guard cell movements and regulation of net water uptake, its biological role has remained elusive. Here we have used co-expression and promoter content analysis tools to understand the biological role of the Arabidopsis thaliana PNP (AtPNP-A). The analysis of AtPNP-A and its co-expressed genes revealed that genes annotated as part of the systemic acquired resistance (SAR) pathway were over-represented, thus suggesting that AtPNP-A may function as a component of plant defense responses and specifically, SAR. The results further show that AtPNP-A shares many characteristics with pathogenesis related (PR) proteins in that its transcription is strongly induced in response to pathogen challenges, thus implying a newly described role for AtPNP-A in pathogen attack. Additional tissue expression analysis also indicated distinct localization of PNP activity in sepals and transcriptional meta-analysis showed that AtPNP-A may play a role in starch breakdown. Therefore, together with the finding that AtPNP-A plays a role in regulating phloem transport, we also hypothesize that AtPNP-A may play a role in phloem unloading in sepals to assist processes such as seed formation in plants. In plants, the second messenger, guanosine 3&rsquo / ,5&rsquo / -cyclic monophosphate (cGMP) mediates a whole range of important processes including salinity tolerance, disease resistance, drought tolerance and responses to light. Since PNPs regulate water and salt homeostasis via a cGMP-dependent signaling pathways, it is thus important to analyse the transcriptome induced by the second messenger (cGMP) in Arabidopsis thaliana to give a better understanding of its mechanism of action. This study was also supplemented by the analysis of the gibberellic acid (GA) dependent transcriptome, since cGMP also plays a role its transcription pathway. This data analysis, together with promoter content investigation, revealed that genes upregulated after cGMP treatment and down-regulated in the GA insensitive mutant (ga1-3) were enriched with a GA response element (GARE), while no GARE enrichment were observed in genes up-regulated in the ga1-3 mutant. These findings suggest that GARE is indicative of GA-induced and cGMP-dependent transcriptional up-regulation. Gene ontology analysis confirmed previous reports that cGMP is involved in ion homeostasis and indicated that the transcriptional cGMP response is bi-polar in the sense that both genes up- and down-regulated in response to cGMP is involved in cation transport. Additionally, ab initio analysis of genes transcriptionally dependent on cGMP identified CHX8 as a hub gene and promoter content of CHX8 co-expressed genes show enrichment of the GARE motif. The fact that CHX8 has its highest expression levels during male gametogenesis and pollen tube growth, together with our findings, suggest that GA-induced and cGMP- dependent genes may play a key role in ion and water homeostasis in the male gametophyte. Finally, we propose that the type of analysis undertaken here can yield new insights into gene regulation networks and inform experimental strategies to unravel complex transcription regulatory systems under different developmental and stimulus specific conditions.</p>
295

Molecular cloning and functional characterization of a goldfish pituitary adenylate cyclase activating polypeptide receptor

謝齡祥, Shea, Ling-cheung, William. January 1998 (has links)
published_or_final_version / Zoology / Master / Master of Philosophy
296

Characterisation of AtPNP-A - A novel Arabidopsis thaliana gene with a role in water and salt homeostasis.

Bastian, René. January 2009 (has links)
<p>Plant natriuretic peptides (PNPs) are a novel class of extracellular, systemically mobile molecules that elicit a number of plant responses important in homeostasis and growth. Natriuretic peptides were first identified in vertebrates where they play a role in the regulation of salt and water balance. Subsequent experimental investigations have identified the presence of a natriuretic peptide hormone system in plants. While PNPs have been implicated in various physiological responses such as stomatal guard cell movements and regulation of net water uptake, its biological role has remained elusive. Here we have used co-expression and promoter content analysis tools to understand the biological role of the Arabidopsis thaliana PNP (AtPNP-A). The analysis of AtPNP-A and its co-expressed genes revealed that genes annotated as part of the systemic acquired resistance (SAR) pathway were over-represented, thus suggesting that AtPNP-A may function as a component of plant defense responses and specifically, SAR. The results further show that AtPNP-A shares many characteristics with pathogenesis related (PR) proteins in that its transcription is strongly induced in response to pathogen challenges, thus implying a newly described role for AtPNP-A in pathogen attack. Additional tissue expression analysis also indicated distinct localization of PNP activity in sepals and transcriptional meta-analysis showed that AtPNP-A may play a role in starch breakdown. Therefore, together with the finding that AtPNP-A plays a role in regulating phloem transport, we also hypothesize that AtPNP-A may play a role in phloem unloading in sepals to assist processes such as seed formation in plants. In plants, the second messenger, guanosine 3&rsquo / ,5&rsquo / -cyclic monophosphate (cGMP) mediates a whole range of important processes including salinity tolerance, disease resistance, drought tolerance and responses to light. Since PNPs regulate water and salt homeostasis via a cGMP-dependent signaling pathways, it is thus important to analyse the transcriptome induced by the second messenger (cGMP) in Arabidopsis thaliana to give a better understanding of its mechanism of action. This study was also supplemented by the analysis of the gibberellic acid (GA) dependent transcriptome, since cGMP also plays a role its transcription pathway. This data analysis, together with promoter content investigation, revealed that genes upregulated after cGMP treatment and down-regulated in the GA insensitive mutant (ga1-3) were enriched with a GA response element (GARE), while no GARE enrichment were observed in genes up-regulated in the ga1-3 mutant. These findings suggest that GARE is indicative of GA-induced and cGMP-dependent transcriptional up-regulation. Gene ontology analysis confirmed previous reports that cGMP is involved in ion homeostasis and indicated that the transcriptional cGMP response is bi-polar in the sense that both genes up- and down-regulated in response to cGMP is involved in cation transport. Additionally, ab initio analysis of genes transcriptionally dependent on cGMP identified CHX8 as a hub gene and promoter content of CHX8 co-expressed genes show enrichment of the GARE motif. The fact that CHX8 has its highest expression levels during male gametogenesis and pollen tube growth, together with our findings, suggest that GA-induced and cGMP- dependent genes may play a key role in ion and water homeostasis in the male gametophyte. Finally, we propose that the type of analysis undertaken here can yield new insights into gene regulation networks and inform experimental strategies to unravel complex transcription regulatory systems under different developmental and stimulus specific conditions.</p>
297

Endocrine correlates of fecundity in the ewe /

Ralph, Meredith Margaret. January 1984 (has links) (PDF)
Thesis (Ph. D.)--University of Adelaide, 1985. / Includes bibliographical references (leaves 182-210).
298

Molecular cloning and functional characterization of a goldfish pituitary adenylate cyclase activating polypeptide receptor /

Shea, Ling-cheung, William. January 1998 (has links)
Thesis (M. Phil.)--University of Hong Kong, 1998. / Includes bibliographical references (leaves 77-85).
299

Thyroid hormones are required during long-day photoperiods for the establishment of estradiol-sensitive afferent input to and activation of, dopaminergic neurons in the A15 area of the ovine hypothalamus

Griffith, Ronald D. January 2000 (has links)
Thesis (M.S.)--West Virginia University, 2000. / Title from document title page. Document formatted into pages; contains viii, 46 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 33-38).
300

Cloning and characterization of PAC1 receptor splice variants in goldfish (Carassius auratus)

Kwok, Yuen-yuen. January 2004 (has links)
Thesis (M. Phil.)--University of Hong Kong, 2005. / Title proper from title frame. Also available in printed format.

Page generated in 0.0513 seconds