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1	EXPRESSION OF THE CNGB3 SUBUNIT IN RETINA OF ACHROMATOPSIA-AFFECTED DOGS Gonzalez, Amaliris January 2015 (has links) Light energy is converted into an electrical signal by a set of proteins in the phototransduction cascade in photoreceptors. In this work, I focus on two critical elements of the phototransduction cascade in canine, the opsin molecules and CNG channels of cone photoreceptors. Canines are dichromats possessing two types of cone photoreceptors with different opsin molecules that detect either long and medium wavelengths (L/M) or short wavelengths (S). The L/M- and S-opsin genes were cloned from an Alaskan Malamute and used to investigate key amino acids that are responsible for tuning the spectral properties of the 11-cis retinal chromophore. Cone CNG channels are composed of CNGA3 and CNGB3 subunits. I characterized antibodies to detect cone CNG channel subunits to investigate expression of mutations in CNGB3 subunit on two canine models for achromatopsia. One model contains a missense CNGB3 mutation D262N (CNGB3m/m) and the other is a complete deletion of all exons of the CNGB3 gene (CNGB3-/-). Studies presented in this thesis show CNGB3 is expressed later in cone during retinal development compared to CNGA3. It also presents evidence for the necessity of CNGB3 in cone outer segment targeting of CNGA3. / Biology Biology Achromatopsia Cngb3 Cyclic Nucleotide Gated Channels L/m Opsin
2	Investigation of Structure-function and Signal Transduction of Plant Cyclic Nucleotide-gated Ion Channels Chin, Kimberley 07 January 2014 (has links) Cyclic nucleotide-gated channels (CNGCs) are non-selective cation channels that were first identified in vertebrate photosensory and olfactory neurons. Although the physiological roles and biophysical properties of animal CNGCs have been well studied, much less is known about these channels in plants. The Arabidopsis genome encodes twenty putative CNGC subunits that are postulated to form channel complexes that mediate various physiological processes involving abiotic and biotic stress responses, ion homeostasis and development. The identification of Arabidopsis autoimmune CNGC mutants, such as defense no death class (dnd1 and dnd2), and the constitutive expressor of pathogenesis related genes 22 (cpr22) implicate AtCNGC2, 4, 11 and 12 in plant immunity. Here, I present a comprehensive study of the molecular mechanisms involved in CNGC-mediated signaling pathways with emphasis on pathogen defense. Previously, a forward genetics approach aimed to identify suppressor mutants of the rare gain-of-function autoimmune mutant, cpr22, identified key residues that are important for CNGC subunit interactions and channel function. First, I present a structure-function analysis of one of these suppressor mutants (S58) that revealed a key residue in the cyclic nucleotide binding domain involved in the stable regulation of CNGCs. Second, I present a new suppressor screen using AtCNGC2 T-DNA knockout mutants that specifically aimed to identify novel downstream components of CNGC-mediated pathogen defense signaling. In this screen, I successfully isolated and characterized the novel Arabidopsis mutant, repressor of defense no death 1 (rdd1), and expanded this study to demonstrate its involvement in AtCNGC2 and AtCNGC4-mediated signal transduction. Additionally, I demonstrated for the first time, the physical interaction of AtCNGC2 and AtCNGC4 subunits in planta. The findings presented in this thesis broaden our current knowledge of CNGCs in plants, and provide a new foundation for future elucidation of the structure-function relationships and signal transduction mediated by these channels. Arabidopsis thaliana cyclic nucleotide gated channels plant immunity plant disease resistance plant pathogen resistance CNGC calcium signaling bimolecular fluorescence complementation ion channel signal transduction calcium map based cloning plant autoimmune mutant plant lesion mimic mutant calmodulin floral transition rdd1 cpr22 dnd1 dnd2 CNGC11 CNGC12 CNGC2 CNGC4 suppressor screen 0309 0817 0307
3	Investigation of Structure-function and Signal Transduction of Plant Cyclic Nucleotide-gated Ion Channels Chin, Kimberley 07 January 2014 (has links) Cyclic nucleotide-gated channels (CNGCs) are non-selective cation channels that were first identified in vertebrate photosensory and olfactory neurons. Although the physiological roles and biophysical properties of animal CNGCs have been well studied, much less is known about these channels in plants. The Arabidopsis genome encodes twenty putative CNGC subunits that are postulated to form channel complexes that mediate various physiological processes involving abiotic and biotic stress responses, ion homeostasis and development. The identification of Arabidopsis autoimmune CNGC mutants, such as defense no death class (dnd1 and dnd2), and the constitutive expressor of pathogenesis related genes 22 (cpr22) implicate AtCNGC2, 4, 11 and 12 in plant immunity. Here, I present a comprehensive study of the molecular mechanisms involved in CNGC-mediated signaling pathways with emphasis on pathogen defense. Previously, a forward genetics approach aimed to identify suppressor mutants of the rare gain-of-function autoimmune mutant, cpr22, identified key residues that are important for CNGC subunit interactions and channel function. First, I present a structure-function analysis of one of these suppressor mutants (S58) that revealed a key residue in the cyclic nucleotide binding domain involved in the stable regulation of CNGCs. Second, I present a new suppressor screen using AtCNGC2 T-DNA knockout mutants that specifically aimed to identify novel downstream components of CNGC-mediated pathogen defense signaling. In this screen, I successfully isolated and characterized the novel Arabidopsis mutant, repressor of defense no death 1 (rdd1), and expanded this study to demonstrate its involvement in AtCNGC2 and AtCNGC4-mediated signal transduction. Additionally, I demonstrated for the first time, the physical interaction of AtCNGC2 and AtCNGC4 subunits in planta. The findings presented in this thesis broaden our current knowledge of CNGCs in plants, and provide a new foundation for future elucidation of the structure-function relationships and signal transduction mediated by these channels. Arabidopsis thaliana cyclic nucleotide gated channels plant immunity plant disease resistance plant pathogen resistance CNGC calcium signaling bimolecular fluorescence complementation ion channel signal transduction calcium map based cloning plant autoimmune mutant plant lesion mimic mutant calmodulin floral transition rdd1 cpr22 dnd1 dnd2 CNGC11 CNGC12 CNGC2 CNGC4 suppressor screen 0309 0817 0307

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