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You searched for subject:(Phototropin). Showing records 1 – 3 of 3 total matches.

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Western Kentucky University

1. Forbes=Stovall, Jennifer. Action Spectrum for Photoentrainment of the Circadian Clock in Wild-Type <i>Chlamydomonas reinhardtii</i>.

Degree: MS, Department of Biology, 2011, Western Kentucky University

The circadian clock is an endogenous timer that oscillates with a period of approximately 24 hours and is reset upon environmental time cues such as the daily light/ dark or temperature cycles. Chlamydomonas reinhardtii is an ideal model organism for research on the circadian clock, because it shows several well-characterized behaviors that exhibit a circadian rhythm. Its circadian rhythm of phototaxis (swimming toward light) has been automated. Former action spectrum studies using the circadian phototaxis rhythm as an indicator surprisingly found that pulses of blue light were not effective in resetting the circadian clock of dark-adapted cells. This may have been because of the particular strain used in the study (the cell wall-deficient strain CW15). It may also have been due to the additional phase shift caused by the act of placing the cultures into the monitoring machine at particular times during their circadian cycle. This additional phase shift was most likely the result of the white background light present when monitoring the rhythm of phototaxis. The phototaxis monitoring process was improved by using narrow-wavelength LEDs specific for phototaxis as test lights and by omitting the background light between test light cycles. This study demonstrates that the modifications prevent any phase shifts due to the cultures being placed into the monitoring machine. Using a further improved experimental set-up and the wild-type strain CC124, this study unambiguously shows that blue light of 440nm is effective in resetting the circadian clock in Chlamydomonas reinhardtii. Because of this difference in blue light response to the earlier study, the action spectrum of the entire visible light range was also evaluated. Effective wavelengths for resetting the circadian clock in wild-type C. reinhardtii were found to occur at 400nm, 440nm, 540nm, and 640-660nm, corresponding to near UV-A, blue, green, and red light, respectively. With the exception of 440nm, these findings are congruent with previous action spectrum studies for the cell wall-deficient strain CW15. Advisors/Committee Members: Dr. Sigrid Jacobshagen (Director), Dr. Claire Rinehart, Dr. Nancy Rice.

Subjects/Keywords: phototropin; rhodospin; cryptochrome; phototaxis; algae; Algae; Biology; Organisms

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APA (6th Edition):

Forbes=Stovall, J. (2011). Action Spectrum for Photoentrainment of the Circadian Clock in Wild-Type <i>Chlamydomonas reinhardtii</i>. (Masters Thesis). Western Kentucky University. Retrieved from https://digitalcommons.wku.edu/theses/1094

Chicago Manual of Style (16th Edition):

Forbes=Stovall, Jennifer. “Action Spectrum for Photoentrainment of the Circadian Clock in Wild-Type <i>Chlamydomonas reinhardtii</i>.” 2011. Masters Thesis, Western Kentucky University. Accessed August 11, 2020. https://digitalcommons.wku.edu/theses/1094.

MLA Handbook (7th Edition):

Forbes=Stovall, Jennifer. “Action Spectrum for Photoentrainment of the Circadian Clock in Wild-Type <i>Chlamydomonas reinhardtii</i>.” 2011. Web. 11 Aug 2020.

Vancouver:

Forbes=Stovall J. Action Spectrum for Photoentrainment of the Circadian Clock in Wild-Type <i>Chlamydomonas reinhardtii</i>. [Internet] [Masters thesis]. Western Kentucky University; 2011. [cited 2020 Aug 11]. Available from: https://digitalcommons.wku.edu/theses/1094.

Council of Science Editors:

Forbes=Stovall J. Action Spectrum for Photoentrainment of the Circadian Clock in Wild-Type <i>Chlamydomonas reinhardtii</i>. [Masters Thesis]. Western Kentucky University; 2011. Available from: https://digitalcommons.wku.edu/theses/1094


Duke University

2. Li, Fay-Wei. Seeing the Light: the Origin and Evolution of Plant Photoreceptors .

Degree: 2015, Duke University

Plants use an array of photoreceptors to measure the quality, quantity, and direction of light in order to respond to ever-changing light environments. Photoreceptors not only determine how and when individual plants complete their life cycles, but they also have a profound and long-term macroevolutionary influence on species diversification. Despite their significances, very little is known about photoreceptors across plants as whole, and we lack a comprehensive view of photoreceptor evolution. In my dissertation, I investigate the origin and evolution of three of the most prominent photoreceptor gene families in plants: phytochromes, phototropins and neochromes. Using newly available transcriptomic and genomic data, I completed the first in-depth survey of these photoreceptor families across land plants, green algae, red algae, glaucophytes, cryptophytes, haptophytes, and stramenopiles. Phytochromes are red/far-red photoreceptors that play essential roles in seed germination, seedling photomorphogenesis, shade-avoidance, dormancy, circadian rhythm, phototropism, and flowering. Here, I show that the canonical plant phytochromes originated in a common ancestor of streptophytes (charophyte green algae plus land plants), and I identify the most likely sequence whereby the plant phytochrome structure evolved from its ancestral phytochrome. Phytochromes in charophyte algae are structurally diverse, including canonical and non-canonical forms, whereas in land plants, phytochrome structure is highly conserved. Liverworts, hornworts, and Selaginella apparently possess a single phytochrome gene copy, whereas independent gene duplications occurred within mosses, lycopods, ferns, and seed plants, leading to diverse phytochrome families in these clades. My detailed phylogeny encompasses all of green plants and enables me to not only uncover new phytochrome lineages, but also to make links to our current understanding of phytochrome function in Arabidopsis and Physcomitrella (the major model organism outside of flowering plants). Based on this robust evolutionary framework, I propose new hypotheses and discuss future directions to study phytochrome mechanisms. Phototropins are blue-light photoreceptors that regulate key adaptive physiological responses, including shoot-positive phototropism, root-negative phototropism, chloroplast accumulation/avoidance, stomatal opening, circadian rhythm, leaf expansion, and seedling elongation I show that phototropins originated in the common ancestor of Viridiplantae (all green algae [charophytes, chlorophytes, prasinophytes] plus land plants). Phototropins repeatedly underwent independent duplications in all major plant lineages (mosses, lycopods, ferns and seed plants), except for liverworts and hornworts, where phototropin is a single-copy gene. Following each major duplication event, phototropins subsequently differentiated in parallel, resulting in two specialized (yet partially overlapping) functional forms that primarily mediate either low- or high-light… Advisors/Committee Members: Pryer, Kathleen M (advisor).

Subjects/Keywords: Biology; Plant biology; ferns; horizontal gene transfer; hornworts; neochrome; phototropin; phytochrome

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Li, F. (2015). Seeing the Light: the Origin and Evolution of Plant Photoreceptors . (Thesis). Duke University. Retrieved from http://hdl.handle.net/10161/9904

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Li, Fay-Wei. “Seeing the Light: the Origin and Evolution of Plant Photoreceptors .” 2015. Thesis, Duke University. Accessed August 11, 2020. http://hdl.handle.net/10161/9904.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Li, Fay-Wei. “Seeing the Light: the Origin and Evolution of Plant Photoreceptors .” 2015. Web. 11 Aug 2020.

Vancouver:

Li F. Seeing the Light: the Origin and Evolution of Plant Photoreceptors . [Internet] [Thesis]. Duke University; 2015. [cited 2020 Aug 11]. Available from: http://hdl.handle.net/10161/9904.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Li F. Seeing the Light: the Origin and Evolution of Plant Photoreceptors . [Thesis]. Duke University; 2015. Available from: http://hdl.handle.net/10161/9904

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

3. Thamarath Surendran, Smitha. Towards photo-CIDNP MAS NMR as a generally applicable enhancement method.

Degree: 2014, Solid State NMR/Biophysical Organic Chemistry Group, Leiden Institute of Chemistry (LIC), Faculty of Science, Leiden University

Solid-state photochemically induced dynamic polarisation (photo-CIDNP) is one of the hyperpolarization techniques that tremendously enhances the sensitivity and selectivity of solid state NMR. Photo-CIDNP MAS NMR studies on entire cells of heliobacteria Hb. mobilis in both anaerobic and aerobic forms are presented in Chapter 2. This chapter demonstrates that photo-CIDNP MAS NMR can be applied as an analytical tool directly on to cells and bacteria even if no further purification is known or possible. To improve the knowledge of the solid-state photo-CIDNP effect, field dependencies are measured over large ranges (Chapter 3). The electron spin density distribution in the 3P donor triplet state is constructed here using the analysis of differential relaxation mechanism and this stresses the versatility of photo-CIDNP MAS NMR as hyperpolarization method. Chapter 4 describes the first observation of photo-CIDNP MAS NM R in phototropin LOV1-C57S, overcoming an old limitation of this method to natural photosynthetic RCs. The first analytical studies on the LOV1 system in Chapter 5 provides the potential to develop photo-CIDNP MAS NMR into an enhancement method generally applicable to electron transfer proteins. In Chapter 6 this leads to a new paradigm, expecting plenty of photo-CIDNP hyperpolarization if the experiment is optimized for the LOV1 system.

Subjects/Keywords: Heliobacteria; Solid-state photo-CIDNP effect; Phototropin; Reaction Center; Three spin mechanism; Differential decay; Purple bacteria; Differential relaxation; Heliobacteria; Solid-state photo-CIDNP effect; Phototropin; Reaction Center; Three spin mechanism; Differential decay; Purple bacteria; Differential relaxation

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Thamarath Surendran, S. (2014). Towards photo-CIDNP MAS NMR as a generally applicable enhancement method. (Doctoral Dissertation). Solid State NMR/Biophysical Organic Chemistry Group, Leiden Institute of Chemistry (LIC), Faculty of Science, Leiden University. Retrieved from http://hdl.handle.net/1887/23855

Chicago Manual of Style (16th Edition):

Thamarath Surendran, Smitha. “Towards photo-CIDNP MAS NMR as a generally applicable enhancement method.” 2014. Doctoral Dissertation, Solid State NMR/Biophysical Organic Chemistry Group, Leiden Institute of Chemistry (LIC), Faculty of Science, Leiden University. Accessed August 11, 2020. http://hdl.handle.net/1887/23855.

MLA Handbook (7th Edition):

Thamarath Surendran, Smitha. “Towards photo-CIDNP MAS NMR as a generally applicable enhancement method.” 2014. Web. 11 Aug 2020.

Vancouver:

Thamarath Surendran S. Towards photo-CIDNP MAS NMR as a generally applicable enhancement method. [Internet] [Doctoral dissertation]. Solid State NMR/Biophysical Organic Chemistry Group, Leiden Institute of Chemistry (LIC), Faculty of Science, Leiden University; 2014. [cited 2020 Aug 11]. Available from: http://hdl.handle.net/1887/23855.

Council of Science Editors:

Thamarath Surendran S. Towards photo-CIDNP MAS NMR as a generally applicable enhancement method. [Doctoral Dissertation]. Solid State NMR/Biophysical Organic Chemistry Group, Leiden Institute of Chemistry (LIC), Faculty of Science, Leiden University; 2014. Available from: http://hdl.handle.net/1887/23855

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