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  • 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.
1

The importance of cyclic nucleotides (cyclic GMP and cyclic AMP) in the development of malignant disease

Williams, A. C. January 1987 (has links)
No description available.
2

An investigation of the relationship between cyclic nucleotides and chemotaxis by Escherichia coli

Black, Roy A. January 1982 (has links)
Thesis (Ph. D.)--University of Wisconsin--Madison, 1982. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.
3

Synthesis and characterization of seven thiophosphate analogs of cyclic diguanosine monophosphate

Zhao, Jianwei, January 2009 (has links)
Thesis (Ph. D.)--Rutgers University, 2009. / "Graduate Program in Chemistry and Chemical Biology." Includes bibliographical references.
4

Molecular pathogenicity of disease-associated mutations in cone CNG channel subunits

Liu, Chunming. January 2008 (has links) (PDF)
Thesis (Ph. D.)--Washington State University, May 2008. / Includes bibliographical references.
5

Classical and atypical β-andrenoceptor subtypes mediating relaxation in rat isolated aorta : role of the endothelium/nitric oxide pathway

Brawley, Lee January 2000 (has links)
No description available.
6

Effect of Catecholamines, Methylxanthines and Cyclic Nucleotides on the Morphogenesis of Verticillium Dahliae

Oyofo, Buhari Anthony 01 August 1981 (has links)
The purpose of this investigation is to study the effects of methylxanthines, catecholamines, and cyclic nucleotides on melanin synthesisand conidiation using the technique of phase contrast microscopy. Verticillium wild type (T9) strain was grown in both sucrose nitrate liquid medium and polygalacturonic acid media (SNLM and PGAM). These media allowed rapid production of conidia and synchronous development of microsclerotia respectively. Even though caffeine has a greater effect on conidiation, both caffeine and theophylline promoted melanization. Dibutyl cyclic AMP to lesser extent inhibited conidiation, while cyclic AMP had little to no effect on conidiation. Dibutyl cyclic AMP inhibited melanin production. Cyclic AMP had a stimulatory effect on melanin production. Isoproterenol a stimulant of adenylate cyclase activity, inhibited conidiation the first two days, but had no apparent effect after day 3. Isoproterenol also induced melanin production in the flask. Propranolol, an antagonist of hormonally induced adenylate cyclase activity, did not repress conidiation when compared to the drug-free SNLM. Melanin was not formed in either SNLM and PGAM, suggesting that the effect of propranolol was opposite that of isoproterenol. Propranolol, a beta blocking agent, reversed the isoproterenol induced inhibition of conidiation. This reversal indicates that there is a receptor which isoproterenol attached itself to - the binding beta receptor site. The isoproterenol effect on conidiation and melanin synthesis indicates that, there might be cyclic AMP involvement in development, since this agent affects cyclic AMP level. Since melanin is known to be associated with microsclerotia, it is possible that cyclic AMP might be involved in this development. In this study, the effects of methylxanthines, catecholamines and cyclic nucleotides on melanin synthesis and conidiation was determined. There is every possibility that cyclic AMP might be involved in the regulation of conidiation process and melanin synthesis.
7

Physiological and Molecular Effects of the Cyclic Nucleotides cAMP and cGMP on Arabidopsis thaliana

Herrera, Natalia M. 12 1900 (has links)
The cyclic nucleotide monophosphates (CNs), cAMP and cGMP, are second messengers that participate in the regulation of development, metabolism and adaptive responses. In plants, CNs are associated with the control of pathogen responses, pollen tube orientation, abiotic stress response, membrane transport regulation, stomatal movement and light perception. In this study, we hypothesize that cAMP and cGMP promote changes in the transcription level of genes related to photosynthesis, high light and membrane transport in Arabidopsis thaliana leaves and, that these changes at the molecular level can have functional biological consequences. For this reason we tested if CNs modulate the photosynthetic rate, responses to high light and root ion transport. Real time quantitative PCR was used to assess transcription levels of selected genes and infrared gas analyzers coupled to fluorescence sensors were used to measure the photosynthetic parameters. We present evidence that both cAMP and cGMP modulate foliar mRNA levels early after stimulation. The two CNs trigger different responses indicating that the signals have specificity. A comparison of proteomic and transcriptional changes suggest that both transcriptional and post-transcriptional mechanisms are modulated by CNs. cGMP up-regulates the mRNA levels of components of the photosynthesis and carbon metabolism. However, neither cAMP nor cGMP trigger differences in the rate of carbon assimilation, maximum efficiency of the photosystem II (PSII), or PSII operating efficiency. It was also demonstrated that CN regulate the expression of its own targets, the cyclic nucleotide gated channels - CNGC. Further studies are needed to identify the components of the signaling transduction pathway that mediate cellular changes and their respective regulatory and/or signaling roles.
8

Expressions of cyclic nucleotide-gated ionic conductances in rat cerebellar purkinje neurons =: 大鼠小腦浦肯野細胞環核苷酸門控離子通道的表達. / 大鼠小腦浦肯野細胞環核苷酸門控離子通道的表達 / Expressions of cyclic nucleotide-gated ionic conductances in rat cerebellar purkinje neurons =: Da shu xiao nao pukenye xi bao huan he gan suan men kong li zi tong dao de biao da. / Da shu xiao nao pukenye xi bao huan he gan suan men kong li zi tong dao de biao da

January 2005 (has links)
Tsoi Sze Man. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 82-104). / Text in English; abstracts in English and Chinese. / Tsoi Sze Man. / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Overview of study --- p.1 / Chapter 1.2 --- Cerebellum --- p.2 / Chapter 1.2.1 --- General Structure of cerebellum --- p.3 / Chapter 1.2.2 --- Cell types of cerebellar cortex --- p.4 / Chapter 1.2.2.1 --- Basket cells --- p.5 / Chapter 1.2.2.2 --- Stellate cells --- p.6 / Chapter 1.2.2.3 --- Purkinje cells --- p.6 / Chapter 1.2.2.4 --- Granule cells --- p.7 / Chapter 1.2.2.5 --- Golgi cells --- p.8 / Chapter 1.2.2.6 --- Unipolar brush cells --- p.9 / Chapter 1.2.2.7 --- Deep cerebellar nuclear neurons --- p.11 / Chapter 1.2.3 --- The neuronal circuitry of the cerebellum --- p.12 / Chapter 1.2.4 --- Cerebellar function --- p.14 / Chapter 1.3 --- Cyclic nucleotide-gated (CNG) channels --- p.16 / Chapter 1.3.1 --- Molecular characterization of CNG channels --- p.16 / Chapter 1.3.2 --- Functional properties of CNG channels --- p.19 / Chapter 1.3.3 --- Expression of CNG channels in brain --- p.21 / Chapter 1.3.4 --- CNG channel and neuronal plasticity --- p.23 / Chapter 1.4 --- Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels --- p.26 / Chapter 1.4.1 --- Molecular characterization of HCN channels --- p.27 / Chapter 1.4.2 --- Functional properties of HCN channels and Ih current --- p.29 / Chapter 1.4.3 --- Modulation by cyclic nucleotides --- p.31 / Chapter 1.4.4 --- Expression of HCN channels in brain --- p.33 / Chapter 1.4.5 --- Physiological roles of Ih current in central nervous system --- p.35 / Chapter 1.5 --- Aims of study --- p.38 / Chapter Chapter 2 --- Material and Methods --- p.39 / Chapter 2.1 --- Immunohistochemistry Experiments --- p.39 / Chapter 2.1.1 --- Animal preparation --- p.39 / Chapter 2.1.2 --- Tissue preparation --- p.39 / Chapter 2.1.3 --- Primary and secondary antibodies --- p.40 / Chapter 2.1.4 --- Immunofluroescence staining --- p.41 / Chapter 2.1.5 --- Confocal laser scanning microscopy and data processing --- p.41 / Chapter 2.2 --- Whole cell patch clamp recordings --- p.42 / Chapter 2.2.1 --- Brain slice preparation and identification of the cerebellar Purkinje neurons --- p.42 / Chapter 2.2.2 --- Whole cell voltage- and current-clamp recordings --- p.43 / Chapter 2.2.3 --- Drug solutions and delivery --- p.44 / Chapter 2.2.4 --- Statistical analysis --- p.45 / Chapter Chapter 3 --- Expression of Various Cyclic Nucleotide-Gated (CNG) Channel Subunits in Rat Cerebellum --- p.46 / Chapter 3.1 --- Introduction --- p.46 / Chapter 3.2 --- Results --- p.46 / Chapter 3.2.1 --- Immunoreactivity of CNGA1 in cerebellum --- p.46 / Chapter 3.2.2 --- Immunoreactivity of CNGA2 in cerebellum --- p.47 / Chapter 3.2.3 --- Immunoreactivity of CNGA3 in cerebellum --- p.47 / Chapter 3.3 --- Discussion --- p.48 / Chapter Chapter 4 --- Expression of Various Hyperpolarization-Activated Cyclic Nucleotide-Gated (HCN) Channel Subunits in Rat Cerebellum --- p.53 / Chapter 4.1 --- Introduction --- p.53 / Chapter 4.2 --- Results --- p.53 / Chapter 4.2.1 --- Immunoreactivity of HCN 1 in cerebellum --- p.53 / Chapter 4.2.2 --- Immunoreactivity of HCN2 in cerebellum --- p.55 / Chapter 4.2.3 --- Immunoreactivity of HCN3 in cerebellum --- p.55 / Chapter 4.2.4 --- Immunoreactivity of HCN4 in cerebellum --- p.55 / Chapter 4.3 --- Discussion --- p.55 / Chapter Chapter 5 --- Electrophysiological Recordings of Cyclic Nucleotide-Gated Ionic Conductance in Rat Cerebellar Purkinje Neurons --- p.59 / Chapter 5.1 --- Introduction --- p.59 / Chapter 5.2 --- Results --- p.59 / Chapter 5.2.1 --- Effect of cyclic nucleotides on the membrane potential of cerebellar Purkinje neurons --- p.59 / Chapter 5.2.2 --- Ionic conductance of the cyclic nucleotide-induced inward current --- p.61 / Chapter 5.2.3 --- The mechanism of the cyclic nucleotide-induced inward current --- p.61 / Chapter 5.2.3.1 --- Site of action --- p.62 / Chapter 5.2.3.2 --- Involvement of CNG channels and HCN channels --- p.63 / Chapter 5.2.3.3 --- Involvement of protein kinase A (PKA) and protein kinase G (PKG) --- p.65 / Chapter 5.2.3.4 --- Involvement of inwardly rectifying potassium (Kir) channels and transient receptor potential (TRP) channels --- p.65 / Chapter 5.2.4 --- Effect of cyclic nucleotides on Ih current in Purkinje neurons --- p.67 / Chapter 5.3 --- Discussion --- p.68 / Chapter Chapter 6 --- Concluding remarks References --- p.78 / References --- p.82
9

Nitric Oxide Binds to and Modulates the Activity of a Pollen Specific Arabidopsis Diacylglycerol Kinase

Wong, Aloysius Tze 06 1900 (has links)
Nitric oxide (NO) is an important signaling molecule in plants. In the pollen of Arabidopsis thaliana, NO causes re-orientation of the growing tube and this response is mediated by 3′,5′-cyclic guanosine monophosphate (cGMP). However, in plants, NO-sensors have remained somewhat elusive. Here, the findings of an NO-binding candidate, Arabidopsis thaliana DIACYLGLYCEROL KINASE 4 (ATDGK4; AT5G57690) is presented. In addition to the annotated diacylglycerol kinase domain, this molecule also harbors a predicted heme-NO/oxygen (H-NOX) binding site and a guanylyl cyclase (GC) catalytic domain which have been identified based on the alignment of functionally conserved amino acid residues across species. A 3D model of the molecule was constructed, and from which the locations of the kinase catalytic center, the ATP-binding site, the GC and H-NOX domains were estimated. Docking of ATP to the kinase catalytic center was also modeled. The recombinant ATDGK4 demonstrated kinase activity in vitro, catalyzing the ATP-dependent conversion of sn-1,2-diacylglycerol (DAG) to phosphatidic acid (PA). This activity was inhibited by the mammalian DAG kinase inhibitor R59949 and importantly also by the NO donors diethylamine NONOate (DEA NONOate) and sodium nitroprusside (SNP). Recombinant ATDGK4 also has GC activity in vitro, catalyzing the conversion of guanosine-5'-triphosphate (GTP) to cGMP. The catalytic domains of ATDGK4 kinase and GC may be independently regulated since the kinase but not the GC, was inhibited by NO while Ca2+ only stimulates the GC. It is likely that the DAG kinase product, PA, causes the release of Ca2+ from the intracellular stores and Ca2+ in turn activates the GC domain of ATDGK4 through a feedback mechanism. Analysis of publicly available microarray data has revealed that ATDGK4 is highly expressed in the pollen. Here, the pollen tubes of mis-expressing atdgk4 recorded slower growth rates than the wild-type (Col-0) and importantly, they showed altered NO responses. Specifically, the mis-expressing atdgk4 pollen tubes have growth rates that were less affected by NO and showed reduced bending angles when challenged by an NO source. Further works on atdgk4 knockout/knockdown mutants will reveal the biological functions of ATDGK4 in NO and/or cGMP signaling in the pollen, and in the broader fertilization process.
10

Structural and Functional Studies of CNG channels

Hu, Zhengshan January 2023 (has links)
Ion channels are fundamental to the functioning of life, regulating processes as diverse as neural signaling, homeostasis, and environmental sensing, across the complexities of life from bacteria to the most advanced organisms. Among this vast diversity of ion channels, cyclic-nucleotide gated (CNG) channels hold particular significance and play a pivotal role in the sensory transduction across a variety of species. They transduce chemical signals into electrical signals, linking the external environment and our sensory perceptions. CNG channels were discovered almost 40 years ago and much knowledge has been gained on their physiological roles, biophysical properties, molecular characteristics, and channelopathies. However, the structural details of these channels remained elusive for a long time, mainly due to the lack of a full-length channel structure. It was only recently that atomic-resolution structures of full-length CNG channels became available, and structures of native mammalian CNG channels were only determined within the last two years. In my thesis, I use single particle cryogenic electron microscopy (cryo-EM) to determine the structures of native human cone CNGA3/CNGB3 channel in different biochemical environments and in different states, spanning the full spectrum of channel activation by its natural ligand cGMP. In addition, I use cryo-EM, electrophysiology, calcium imaging, and other biochemical techniques to characterize both wild-type and disease-associated mutant (DAM) CNG channels. Collectively, my thesis work contributes to a deeper understanding of the structural determinants of CNG channel properties, provides a detailed dissection of the CNG channel gating mechanism, demonstrates a potential CNG channel pathogenic mechanism, and calls for an interdisciplinary reevaluation of CNG channel DAMs.

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