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Studies on carotenoid biosynthesis and carotenoproteins of Corynebacterium poinsettiae ATCC 9682

Description: Thin layer chromatography and high performance liquid chromatography were used to compare pigments of the wild type streptomycin resistant strain of C. poinsettiae with those of mutants derived from it. Possible biosynthetic pathways in carotenoid biosynthesis of the wild type were postulated on the basis of observed blocks in pigment synthesis.
Date: August 1983
Creator: Wariso, Benjamin A.
Partner: UNT Libraries

Research in Photosynthesis

Description: The determination of the specific radioactivities of the chlorophylls and carotenoids of algae after photosynthesis with C/sup 14/O/sub 2/ is a formidable task, due to the extreme lability of these compounds. The whole success of the method depends on adequate chromatographic separations of the pigments from the colorless contaminants which are closely associated with them, and yet the time involved for such separations is sufficient for marked decomposition of the pigments to occur. It is suggested that the techniques of column chromatography, followed by centrifugallyaccelerated paper chromatography of the spectroscopically pure pigments, may resolve this problem. In an investigation of the action of cyanide on photosynthesis, green algae have been treated with radioactive cyanide. A multitude of products have been found to be formed in very short exposure times. One of these was identified with a material formed when algae are given radioactive CO/sub 2/ and nonradioactive KCN. This material has been identified as the cyanide addition product of ribulose-1,5- diphosphate. Upon hydrolysis it gives a branched-chain sugar acid (or mixture of isomers) closely related to hamamelonic acid. Perhaps the most important aspect of this work is the demonstration of the chemlcal role of cyanide. (auth)
Date: September 1, 1959
Creator: Anderson, Joan Mary
Partner: UNT Libraries Government Documents Department

The intracellular location of carotenoid pigments in the yeast- phase of Wangiella dermatitidis

Description: Carotenoids in W. dermatitids were found to be associated with membranes of lipid globules and/or proteins dispersed in the lipids in the yeast-phase of the organism. The lipid globules increase in size and the pigment concentrations increase with age of the cell. Electron micrographs show these organelles to be surrounded by a single unit membrane. The free carotenoids are extractable with ethyl ether from pigmented fractions of osmotically ruptured protoplasts only after the sample has been treated with acetone, indicating the pigment is non-covalently bound, presumably to a protein.
Date: August 1985
Creator: Foster, Linda Ann
Partner: UNT Libraries

Studies on the mechanism of protection by carotenoids against photodynamic killing in Curtobacterium flaccumfaciens pathover poinsettiae

Description: The mechanism of protection by carotenoids against photodynamic killing in Curtobacterium flaccumfaciens pathover poinsettiae (C. poinsettae)was studied using pigment mutants isolated by treatment with nitrosuguandine and DNA gyrase inhibitors.
Date: August 1992
Creator: Abusada, Gabi M. (Gabi Michael)
Partner: UNT Libraries

Characterization of the pigment-protein complex in Corynebacterium poinsettiae

Description: The purpose of this study was to completely characterize the protein moiety in the caroteno complex in C. poinsettae, determine if the distribution and level of protein in the pigment-protein complex in membranes of the wild type and in a colorless mutant could account for the differences in the stability of the membrane, and to determine if this protein is common to other pigmented and non-pigmented organisms.
Date: May 1986
Creator: Ebadati, Nasrollah D.
Partner: UNT Libraries

Effect of Light and Other Environmental Factors on Growth and Carotenogenesis of Corynebacterium Species Strain 7E1C

Description: This investigation studies effects of environmental factors on growth and carotenogenesis in Corynebacterium strain 7ElC. Changes in pH were found to effect growth more than carotenogenesis. However, certain nutrients or long incubation periods stimulated carotenoid formation more than growth. Dark conditions in a mineral salts-glucose medium stimulated growth, but minimized carotenogenesis. Tryptic soy broth or yeast extract elicited carotenogenesis in darkness. Although brief light exposure during inoculation was photoinductive, continuous exposure to light following inoculation was required for maximum pigment synthesis. Dark grown stationary phase cells required 24-hours of light for maximum pigment synthesis. Chloramphenicol inhibition of carotenogenesis in dark grown cells exposed to light showed that enzymes needed for carotenoid synthesis were absent from dark grown cultures.
Date: August 1974
Creator: Howard, Marta E.
Partner: UNT Libraries

Isolation and Partial Characterization of Pigment Mutants of Corynebacterium poinsettie ATCC 9682

Description: Carotenoid pigments were extracted from Corynebacteriuma poinsettiae (wild type) ATCC 9682, and from 108 mutants obtained by exposure of a streptomycin resistant strain of C. poinsettiae to ultra-violet light irradiation and N-methyl- N'-nitro-N-nitrosoguanidine. The pigments were characterized by their absorption maxima, Rf-values, and partition ratios in petroleum ether and methanol. Thin layer chromatography was used to compare pigments of the wild type with those of the mutants. Possible biosynthetic pathways in carotenoid synthesis of the wild type were postulated on the basis of the observed genetic blocks. Mutants were found which suggested the existence of a linear pathway in carotenoid synthesis from the aliphatic C4 0 molecule to the bi-cyclic C50-diol. Other mutants suggested possible alternative pathways in the biosynthesis of these pigments or the presence of intermediates not detectable by thin layer chromatography.
Date: August 1980
Creator: Wariso, Benjamin A.
Partner: UNT Libraries

Effect of Amino Acids on Growth and Cartenogenesis in Corynebacterium Species Strain 7E1C

Description: Studies were evaluated on the effects of known growth factors on the growth and carotenogenesis of Corynebacterium species strain 7ElC. The complex medium, Tryptic Soy Broth,was found to stimulate growth and production of more pigment in the light and in the dark than did a mineral salts-glucose medium. A complete amino acid mixture added to LSG enhanced carotenogenesis in the dark in Corynebacterium 7ElC, while B-vitamins retarded carotenogenesis. No absolute requirement for one or more amino acids was found,indicating a multiple amino acid requirement. The fewest amino acids found to stimulate carotenogenesis in the dark were a combination of those in the Serine and Histidine families which include serine, glycine, cysteine, and histidine.
Date: May 1977
Creator: Coughran, Carolyn S.
Partner: UNT Libraries

The Genetics of Pigmentation in Corynebacterium poinsettiae ATCC 9682

Description: Corynebacterium poinsettiae mutant strains blocked in carotenoid biosynthesis were obtained by treatment with the mutagen N-methyl-N1-nitro-N-nitrosoguanidine. Additional carotenoid (Crt) mutant strains were obtained from a previous study conducted in our laboratory. Fifty-nine Crt mutants affected in carotenoid biosynthesis were examined by a normal phase high performance liquid chromatography (HPLC) system. Pigment extracts of Crt mutants and C. poinsettiae wild type strains were resolved by an isocratic system with hexane:acetone:dicholoromethane, 11.35:1.73:1.00 (by vol.) as the eluting solvent. In addition to the five major peaks, twelve minor peaks were observed in the wild type C. poinsettiae strain used in this study. Crt mutant and wild type strain peak heights were measured from the individual chromatograms and the peak height data set created was analyzed using the Statistical Analysis System program to perform a cluster analysis. The cluster analysis revealed five carotenoid mutant groups. Carotenoid pigments which accumulated or were absent in each of the cluster groups are reported. Cluster group 1 mutants (CrtA) are blocked in the dehydrogenase(s) which is(are) responsible for the dehydrogenations between phytoene and lycopene. Cluster group 2 mutants (CrtB) appear to be blocked at a second dehydrogenase specific for the dehydrogenation from C.p. 470 to C.p. 496. Cluster group 3 mutants (CrtC) are blocked at a cyclization step in the pathway which involves cyclization of C.p. 496 to C.p. 470 and which may cyclize C.p. 473 to C.p. 450. The genes CrtA and CrtB map only 0.5 map units from each other while CrtA and CrtC map 2.1 map units from one another. Mutants which accumulate end products but which lack certain precursors indicate a branched pathway for pigment biosynthesis exists in this organism. Media for the formation, fusion and regeneration of C. poinsettiae protoplasts are reported and a protocol for the use of these media in genetic ...
Date: August 1986
Creator: Campbell, Alan L. (Alan Lee)
Partner: UNT Libraries

Action and Emission Spectra of the Luminescence of Green PlantMaterials

Description: The action and emission spectra of the delayed light emission from Chlorella, Nostoc, and spinach chloroplasts have been measured. The action spectra for Chlorella and for spinach chloroplasts are quite similar to the absorption spectra of these materials. The action spectrum for Nostoc, on the other hand, shows a relatively low activity for chlorophyll and carotenoids and a high activity for phycocyanin. The emission spectra of these materials demonstrates that the luminescence is the result of a transition between the first excited singlet state and the ground state of chlorophyll. Low-temperature studies suggest that the triplet state of chlorophyll is not involved at all in the luminescence of spinach chloroplasts. There is some indication that part of the light emitted from Nostoc is due to a phycocyanin transition.
Date: December 29, 1957
Creator: Tollin, G.; Fujimori, E. & Calvin, Melvin
Partner: UNT Libraries Government Documents Department


Description: Although the detailed pathway of carbon, by which carbohydrates are formed from carbon dioxide during photosynthesis, has been established, comparatively little is known about the participation and transport of hydrogen in the complex series of reactions now known to be involved in photosynthesis. The transport of hydrogen may occur concurrently with the redox reactions of photosynthetic electron transport leading to the formation of ATP, as well as in the reduction of carbon dioxide. The participation of the chlorophylls, the carotenoids, the quinones, and other lipoid components in photosynthetic hydrogen transport has been the subject of considerable speculation. In an attempt to elucidate the pathway of hydrogen transport, we are studying the tritium labeling pattern in the lipid extracts of Rhodospirillum rubrum after the bacteria have been illuminated in growth medium containing tritiated water.
Date: July 1, 1967
Creator: Dehner, Thomas R.; Chan, W.-S.; Caple, Marianne B. & Calvin, M.
Partner: UNT Libraries Government Documents Department

Magnetic resonance and optical spectroscopic studies of carotenoids. Progress report, December 1, 1994--November 30, 1995

Description: The fundamental goals of this project are (1) to understand the role of a host matrix in the formation and decay mechanisms of carotenoid cation radical and dication and (2) to determine the special properties of carotenoids that enable them to serve as photoprotective agents in photosynthesis and as possible components in electron transfer processes. Results to date are discussed briefly. Work will continue as outlined in the original proposal with emphasis on using simultaneous electrochemistry EPR, and optical methods, variable temperature electrochemistry using microelectrodes and fast scans to examine the more unstable intermediates formed upon electrochemical oxidation of synthetically prepared carotenoids.
Date: June 1, 1995
Creator: Kispert, L.D.
Partner: UNT Libraries Government Documents Department

The protein's role in triplet energy transfer in bacterial reaction centers.

Description: When photosynthetic organisms are subjected to high-light conditions in nature, electron transfer becomes blocked as the rate of conversion of light into charge-separated states in the reaction center (RC) exceeds the capacity of the soluble carriers involved in cyclic electron transfer. In that event, a well-characterized T{sub 0}-polarized triplet state {sup T}P, is formed on the primary donor, P, from the P{sup +}H{sub A}{sup {minus}} state (reviewed in [1]). In an aerobic or semi-aerobic environment, the major role of the carotenoid (C), also bound by the RC, is to quench {sup T}P prior to its sensitization of the {sup 1}{Delta}{sub g} singlet state of oxygen--a potentially damaging biological oxidant. The carotenoid performs this function efficiently in most bacterial RCs by rapidly accepting the triplet state from P and dissipating this excited-state energy into heat through internal conversion. The lowest-lying triplet states of P and the carotenoid are sufficiently different that {sup T}P can promote oxygen to its excited singlet state whereas {sup T}C can quench the {sup T}P state (reviewed in [2]).
Date: August 14, 1998
Creator: Laible, P. D.
Partner: UNT Libraries Government Documents Department

Is Lutein a Physiologically Important Ligand for Transthyretin in Humans?

Description: Lutein and zeaxanthin are the only carotenoids accumulated in the macula of the human retina and are known as the macular pigments (MP). These pigments account for the yellow color of the macula and appear to play an important role in protecting against age-related macular degeneration (AMD). The uptake of lutein and zeaxanthin in human eyes is remarkably specific. It is likely that specific transport or binding proteins are involved. The objective is to determine whether transthyretin (TTR) is a transport protein in human plasma and could thus deliver lutein from the blood to the retina. In this study, they used a biosynthetic {sup 13}C-lutein tracer and gas chromatography-combustion interfaced-isotope ratio mass spectrometry (GCC-IRMS) to gain the requisite sensitivity to detect the minute amounts of lutein expected as a physiological ligand for human transthyretin. The biosynthetic {sup 13}C-labeled lutein tracer was purified from algae. Healthy women (n = 4) each ingested 1 mg of {sup 13}C-labeled lutein daily for 3 days and a blood sample was collected 24 hours after the final dose. Plasma TTR was isolated by retinol-binding protein (RBP)-sepharose affinity chromatography and extracted with chloroform. The {sup 13}C/{sup 12}C ratio in the TTR extract was measured by GCC-IRMS. There was no {sup 13}C-lutein enrichment in the pure TTR extract. This result indicated that lutein is not associated with TTR in human plasma after ingestion in physiological amounts. Some hydrophobic compounds with yellow color may bind to human TTR in the plasma. However, this association needs to be further proved by showing specificity. The study provides a new approach for carotenoid-binding protein studies using a stable isotope tracer method combined with the high precision of GCC-IRMS. The mechanism of selective transport, uptake, and accumulation of lutein in human macula remain to be determined.
Date: May 31, 2003
Creator: Chen, Liwei
Partner: UNT Libraries Government Documents Department

Excited State Structural Dynamics of Carotenoids and ChargeTransfer Systems

Description: This dissertation describes the development andimplementation of a visible/near infrared pump/mid-infrared probeapparatus. Chapter 1 describes the background and motivation ofinvestigating optically induced structural dynamics, paying specificattention to solvation and the excitation selection rules of highlysymmetric molecules such as carotenoids. Chapter 2 describes thedevelopment and construction of the experimental apparatus usedthroughout the remainder of this dissertation. Chapter 3 will discuss theinvestigation of DCM, a laser dye with a fluorescence signal resultingfrom a charge transfer state. By studying the dynamics of DCM and of itsmethyl deuterated isotopomer (an otherwise identical molecule), we areable to investigate the origins of the charge transfer state and provideevidence that it is of the controversial twisted intramolecular (TICT)type. Chapter 4 introduces the use of two-photon excitation to the S1state, combined with one-photon excitation to the S2 state of thecarotenoid beta-apo-8'-carotenal. These 2 investigations show evidencefor the formation of solitons, previously unobserved in molecular systemsand found only in conducting polymers Chapter 5 presents an investigationof the excited state dynamics of peridinin, the carotenoid responsiblefor the light harvesting of dinoflagellates. This investigation allowsfor a more detailed understanding of the importance of structuraldynamics of carotenoids in light harvesting.
Date: September 1, 2006
Creator: Van Tassle, Aaron Justin
Partner: UNT Libraries Government Documents Department

Structural Determinats Underlying Photoprotection in the Photoactive Orange Carotenoid Protein of Cyanobacteria

Description: The photoprotective processes of photosynthetic organisms involve the dissipation of excess absorbed light energy as heat. Photoprotection in cyanobacteria is mechanistically distinct from that in plants; it involves the Orange Carotenoid Protein (OCP), a water-soluble protein containing a single carotenoid. The OCP is a new member of the family of blue light photoactive proteins; blue-green light triggers the OCP-mediated photoprotective response. Here we report structural and functional characterization of the wildtype and two mutant forms of the OCP, from the model organism Synechocystis PCC6803. The structural analysis provides highresolution detail of the carotenoidprotein interactions that underlie the optical properties of the OCP, unique among carotenoid-proteins in binding a single pigment per polypeptide chain. Collectively, these data implicate several key amino acids in the function of the OCP and reveal that the photoconversion and photoprotective responses of the OCP to blue-green light can be decoupled.
Date: April 1, 2010
Creator: Wilson, Adjele; Kinney, James N.; Zwart, Petrus H.; Punginelli, Claire; D'Haene, Sandrine; Perreau, Francois et al.
Partner: UNT Libraries Government Documents Department

Kinetics of Beta-14[14C] Carotene in a Human Subject Using Accelerator Mass Spectrometry

Description: {beta}-Carotene is a tetraterpenoid distributed widely throughout the plant kingdom. It is a member of a group of pigments referred to as carotenoids that have the distinction of serving as metabolic precursors to vitamin A in humans and many animals [1,2]. We used Accelerator Mass Spectrometry (AMS) [3] to determine the metabolic behavior of a physiologic oral dose of {beta}-[{sup 14}C]carotene (200 nanoCuries; 0.57 {micro}mol) in a healthy human subject. Serial blood specimens were collected for 210-d and complete urine and feces were collected for 17 and 10-d, respectively. Balance data indicated that the dose was 42% bioavailable. The absorbed {beta}-carotene was lost slowly via urine in accord with the slow body turnover of {beta}-carotene and vitamin A [4]. HPLC fractionation of plasma taken at early time points (0-24-h) showed the label was distributed between {beta}-carotene and retinyl esters (vitamin A) derived from intestinal metabolism.
Date: January 31, 2000
Creator: Dueker, S.R.; Lin, Y.; Follett, J.R.; Clifford, A.J. & Buchholz, B.A.
Partner: UNT Libraries Government Documents Department

Supramolecular structures for photochemical energy conversion. Technical progress report, 1993--1996

Description: This research project is concerned with the design, synthesis and study by photochemical and spectroscopic methods of complex molecular devices that mimic some important aspects of photosynthetic electron and energy transfer. Properly engineered molecules of this type can functionally mimic photosynthetic light harvesting (singlet-singlet energy transfer between chromophores), photoprotection from light-initiated singlet oxygen damage (triplet-triplet energy transfer from chlorophylls to carotenoid polyenes), and, most importantly, photoinduced multistep electron transfer to generate charge-separated states that preserve some of the photon energy as chemical potential. During the last three years, progress has been made on several fronts, all of which are related to the overall goal. A biomimetic system based on carotenoid-porphyrin-quinone triads has been constructed that demonstrates photoinduced transmembrane charge separation which in turn drives transmembrane proton transfer. Another investigation has focused on the use of proton transfer reactions to stabilize the initial products of photoinduced electron transfer and thereby increase the yield of long-lived charge separation. A third study has investigated the influence of rigid molecular geometries and short donor-acceptor separations on photoinduced electron transfer reactions. Finally, generation and quenching of singlet molecular oxygen by chlorophyll aggregates has been studied. All four studies are described and results are discussed.
Date: June 1, 1996
Partner: UNT Libraries Government Documents Department

Adaptive Advantages of Carotenoid Pigments in Alpine and Subalpine Copepod Responses to Polycyclic Aromatic Hydrocarbon Induced Phototoxicity

Description: Alpine zooplankton are exposed to a variety of stressors in their natural environment including ultraviolet radiation. Physiological coping mechanisms such as the accumulation of photoprotective compounds provide these zooplankton protection from many of these stressors. Elevated levels of carotenoid compounds such as astaxanthin have been shown to help zooplankton survive longer when exposed to ultraviolet radiation presumably due to the strong antioxidant properties of carotenoid compounds. This antioxidant capacity is important because it may ameliorate natural and anthropogenic stressor-induced oxidative stress. While previous researchers have shown carotenoid compounds impart increased resistance to ultraviolet radiation in populations of zooplankton, little work has focused on the toxicological implications of PAH induced phototoxicity on zooplankton containing high levels of carotenoid compounds. This thesis discusses research studying the role that carotenoid compounds play in reducing PAH induced phototoxicity. By sampling different lakes at elevations ranging from 9,500' to 12,700' in the front range of the Colorado Rocky Mountains, copepod populations containing different levels of carotenoid compounds were obtained. These populations were then challenged with fluoranthene and ultraviolet radiation. Results discussed include differences in survival and levels of lipid peroxidation among populations exhibiting different levels of carotenoid compounds, and the toxicological and ecological implications of these results.
Date: May 2010
Creator: Kovach, Matthew James
Partner: UNT Libraries

Role of glycolytic intermediate in regulation: Improving lycopene production in Escherichia coli by engineering metabolic control

Description: Metabolic engineering in the postgenomic era is expected to benefit from a full understanding of the biosynthetic capability of microorganisms as a result of the progress being made in bioinformatics and functional genomics. The immediate advantage of such information is to allow the rational design of novel pathways and the elimination of native reactions that are detrimental or unnecessary for the desired purpose. However, with the ability to manipulate metabolic pathways becoming more effective, metabolic engineering will need to face a new challenge: the reengineering of the regulatory hierarchy that controls gene expression in those pathways. In addition to constructing the genetic composition of a metabolic pathway, they propose that it will become just as important to consider the dynamics of pathways gene expression. It has been widely observed that high-level induction of a recombinant protein or pathway leads to growth retardation and reduced metabolic activity. These phenotypic characteristics result from the fact that the constant demands of production placed upon the cell interfere with its changing requirements for growth. They believe that this common situation in metabolic engineering can be alleviated by designing a dynamic controller that is able to sense the metabolic state of the cell and regulate the expression of the recombinant pathway accordingly. This approach, which is termed metabolic control engineering, involves redesigning the native regulatory circuits and applying them to the recombinant pathway. The general goal of such an effort will be to control the flux to the recombinant pathway adaptively according to the cell's metabolic state. The dynamically controlled recombinant pathway can potentially lead to enhanced production, minimized growth retardation, and reduced toxic by-product formation. The regulation of gene expression in response to the physiological state is also essential to the success of gene therapy. Here they illustrate an application of this approach for ...
Date: June 1, 2001
Creator: Farmer, W.R. & Liao, J.C.
Partner: UNT Libraries Government Documents Department

[Starch synthesis in the maize endosperm as affected by starch-synthesizing mutants]. [Annual report, March 1994--June 30, 1995]

Description: Progress is reported in several areas relevant to maize endosperm development. These areas are (1) The tentative identification of the enzymatic deficiency in a previously unknown endosperm mutant, sugary3-1 (su3-1). The evidence leading to this conclusion will be presented below. (2) The recognition that the endosperm mutant that produces an interesting starch resembling some starches that have been chemically modified is actually an unusual, hypomorphic allele (8132) at the brittle2 (bt2) locus; (3) The orange endosperm color present in some progenies derived from a cross between the original bt2-8132 and W22N apparently results from an interaction between two genes, one of which behaves as though linked to the bt2 locus. In the orange endosperm derivative, our limited evidence suggests that the quantity of all the carotinoids present in the yellow endosperm stocks appear to be increased proportionally.
Date: July 1, 1995
Creator: Nelson, O.
Partner: UNT Libraries Government Documents Department

Photoinitiated electron transfer in multi-chromophoric species: Synthetic tetrads and pentads. Technical progress report, 1987--1990

Description: This research project involves the design, synthesis and study of the molecules which mimic many of the important aspects of photosynthetic electron and energy transfer. Specifically, the molecules are designed to mimic the following aspects of natural photosynthetic multistep electron transfer: electron donation from a tetrapyrrole excited singlet state, electron transfer between tetrapyrroles, electron transfer from tetrapyrroles to quinones, and electron transfer between quinones with different redox properties. In addition, they model carotenoid antenna function in photosynthesis (singlet-singlet energy transfer from carotenoid polyenes to chlorophyll) and carotenoid photoprotection from singlet oxygen damage (triplet-triplet energy transfer from chlorophyll to carotenoids).
Date: February 14, 1990
Partner: UNT Libraries Government Documents Department