In h?heren Pflanzen vermittelt der Blaulicht-sensitive Photorezeptor Phototropin verschiedene Reaktionen wie Phototropismus, Chloroplastendrehung und die ?ffnung von Schlie?zellen. Alle Reaktionen haben mit der Optimierung der pflanzlichen Lichtaufnahme und damit einer angepa?ten Photosynthese sowie der Vermeidung von Lichtsch?digung zu tun. In C.reinhardtii haben alle Phototropinreaktionen mit dem Sexualleben dieser Alge zu tun, d.h. Gametogenese, sexueller Kompetenz sowie der Keimung von Zygoten. Diese Doktorarbeit wurde Ende 2001 begonnen und verlief parallel zu den Arbeiten von Huang. Im Unterschied zu den Ergebnissen von Huang war das Chlamydomonas Phototropin in meinen H?nden unl?slich. Das Protein war nicht komplett membranassoziiert, sondern ein Teil des Proteins blieb immer l?slich. Die Phototropinmenge sowie die Verteilung waren in vegetativen Zellen, die unter Stark- oder Schwachlicht gewachsen waren, unterschiedlich. Deshalb wurde fš¹r diesen Unterschied Licht als wesentlicher Faktor verantwortlich gemacht. Jedoch zeigen verschiedene St?mme bei vegetativem Wachstum unter identischen Lichtbedingungen unterschiedliche Phototropinmengen. Das deutet auf weitere Faktoren hin, die Konzentration und Verteilung von Phototropin beeinflussen. In Chlamydomonas wurde neben dem Volll?ngenprodukt noch eine c-terminal verkš¹rzte Phototropinvariante gefunden. Licht wurde als Verursacher der Verkš¹rzung identifiziert. Aber nur lange Belichtungen von ca. 48 h fš¹hrten je nach Intensit?t zu klaren Abbaumustern. Fš¹r das Studium der Beteiligung des Phototropins am Sexualleben von Chlamydomonas, sollte ein Phot- Stamm generiert werden. Dazu wurde ein RNAi-Konstrukt hergestellt, mit dem es m?glich war, im Stamm cw15 arg- A das Phototropin bis auf 10% des Originalniveaus zu reduzieren. Leider funktionierte das Konstrukt in anderen St?mmen nicht zuverl?ssig. Im Stamm CC32pab1mt(+) konnte nur ein Klon mit einer Reduktion auf 15% des Originalniveaus erreicht werden. Au?erdem war die Silencing-Effizienz stark von den Wachstumsbedingungen abh?ngig. Die beste Reduktion wurde bei niedrigen Lichtintensit?ten gefunden. Es wurde ein weiterer Kreuzungstest etabliert, der fš¹r die Analyse der Zygotenkeimung verschiedene Vorteile gegenš¹ber bekannten Tests liefert. Aus den durchgefš¹hrten Tests konnte geschlossen werden, dass Licht auch ein wesentlicher Faktor fš¹r die Zygotenkeimung ist. Bei mittleren Lichtintensit?ten keimen Zygoten mit wenig Phototropin sp?ter. Starklicht kann diesen Mangel weitgehend kompensieren. Zur biochemischen Analyse des Phototropins in vitro war die Expression eines markierten Phototropins notwendig. Zur Analyse des Phototropinabbaus und fš¹r die sp?tere Reinigung wurde auch versucht, Phototropin in verschiedenen Gastorganismen zu exprimieren. In dieser Arbeit wurde Phototropin in Xenopus Oocyten und Diatom?en exprimiert. Diese Versuche haben best?tigt, dass das Phototropinabbauprodukt vom selben Gen wie das Volll?ngenprotein resultiert. Durch Expression der Phot-Mutante S57S/C250S konnte auch gezeigt werden, dass die Aktivierung des Phototropins keine Voraussetzung fš¹r den Abbau ist. Erstmalig konnte auch Phototropin als Fusionsprotein in Chlamydomonas exprimiert werden. Das Fusionsprotein wurde gereinigt und die Identit?t massenspektrometrisch verifiziert. Es wurde ein Stamm gefunden, der nur eine verkš¹rzte Variante des Phototropins exprimiert. Das Produkt war besser l?slich als die Volll?ngenversion. Eine Gro?produktion sollte fš¹r die Reinigung und nachfo! lgende Kristallisation angesetzt werden. Tandem Affinit?tsreinigungen sollten fš¹r die Identifizierung von Reaktionspartnern durchgefš¹hrt werden. / Abstract In higher plants, phototropin is in charge of phototropism (Liscum, 2002), chloroplast relocation (Wada et al., 2003) and stomatal opening (Schroeder et al., 2001). All its functions are connected with plants' modulation to the surrounding light conditions so that plants can make the best use of light for photosynthesis and dodge harmful strong light. In C.reinhardtii, all its reported functions are connected to the sexual life of this green alga, i.e. gametogenesis, maintenance of gamete competence and zygote germination. This PhD work started at the end of 2001 and went on in parallel with Huang's work. Different from Huang's observation that phototropin was insoluble (Huang et al., 2002), it was found that phototropin existed not only as a membrane associated protein, a portion of phototropin always remained soluble. Phototropin levels and distributions were different between vegetative cells grown in strong light or in darkness. Light was thought to be the essential factor that caused this difference. But, different strains grown vegetatively under same light conditions showed that the levels of phototropin and its distributions varied. This suggested the existence of other factors in the determination of its level and distribution. A C-terminus degradation product of phototropin was found as a stable component in C. reinhardtii. Light was found as a reason that caused the degradation. However, short time of illumination with strong light (up to 2 h) did not evoke the degradation machinery. In light gradient experiment, long time illumination (~48h) with different light intensity showed a clear degradation pattern. To study phototropin involvement in Chlamydomonas sexual life, a Phot1- strain was needed. An RNAi phototropin construct was made. It managed to reduce the level of phototropin in strain cw15 arg- A down to 10% of its original level. However, the construct did not work properly in other strains. Only one transformant of strain CC32pab1mt(+) with a reduction of the phototropin level to around 15% of the original level was found. Under different growth conditions, the silencing efficiency varied. The best silencing result appeared when cells were grown under low light conditions. A new mating assay was established in this work, which has many benefits over the traditional way of studying zygote germination. The conclusion was drawn from this assay that light was the primary factor that determines zygote germination; under moderate light conditions, zygotes with higher phototropin level would germinate earlier; strong illumination could compensate the difference caused by the low phototropin level in zygote germination. For phototropin function analysis in vitro, a Chlamydomonas strain that over-expressed phototropin was in need. To prove that the suspected degradation product originated from the phototropin gene and to purify phototropin for crystallization, trials to express C.r. phototropin cDNA in different organisms were also made. Phototropin was expressed in Xenopus oocytes and diatom in this work. The expression pattern confirmed that both the full-length and the suspected degradation product did originate from the same phototropin gene. It was also found that the degradation was independent on phototropin activation state by expressing C.r. Phot1 (C57S, C250S) in oocytes. For the first time, recombinant phototropin got expressed in Chlamydomonas by fusion expression strategy. The fusion product was purified and the identity was confirmed by Mass Spectrometry analysis. One strain which expressed only a C-terminus truncation version of the fusion product was found. Compared with the full length product, this mutant had better solubility and was easier to be purified. Large scale of purification should be performed to obtain enough material for crystallographic studies. Tandem affinity purification (TAP) tag should also be performed in Chlamydomonas proteomic studies about phototropin.

Blue light filters have become commonplace in modern technology. While there has been a substantial amount of research into their effects on sleep, there has been little into the effect on the media perceived through them. This study sought to examine whether the mechanisms responsible for the adaptation to ambient light conditions would counteract this effect. To do so, a digital survey was conducted in which participants rated 30 colors on 3 different emotional attributes: warmth, weight, and activity. Participants took the survey with or without a blue light filter active, and with or without external light. The external light was intended to eliminate or reduce the level of adaptation to the screen’s altered colors. After comparison between the groups, it was revealed that no significant subjective difference appeared between either of the test conditions. However, with external light, there was a difference in perceived warmth with and without the blue light filter. This implies that some sort of adaptation is involved, and is interfered with by qualities of ambient light. The prevalence of these usage conditions is left to future research, as is whether the specific extent of the difference caused by blue light filters is significant enough to design around. / Blåljusfilter har blivit vanliga i modern teknik. Även om det har gjorts en betydande mängd forskning om deras effekter på sömn, har det varit lite om effekten på media som uppfattas genom dem. Denna studie försökte undersöka om de mekanismer som är ansvariga för anpassningen till omgivande ljusförhållanden skulle motverka denna effekt. För att göra det genomfördes en digital undersökning där deltagarna betygsatte 30 färger på 3 olika känslomässiga egenskaper: värme, vikt och aktivitet. Deltagarna gjorde undersökningen med eller utan ett aktivt blåljusfilter och med eller utan externt ljus. Det yttre ljuset var avsett att eliminera eller minska nivån av anpassning till skärmens ändrade färger. Efter jämförelse mellan grupperna avslöjades att ingen signifikant subjektiv skillnad förekom mellan någon av testbetingelserna. Men med externt ljus var det skillnad i upplevd värme med och utan blåljusfiltret. Detta innebär att någon form av anpassning är inblandad och störs av egenskaperna hos omgivande ljus. Förekomsten av dessa användningsförhållanden överlämnas till framtida forskning, liksom om den specifika omfattningen av skillnaden som orsakas av blåljusfilter är tillräckligt stor för att kunna designas runt.

Performance and reliability of solid state laser diodes in the IR region exceeds those in the visible and UV part of the light spectrum. Single frequency visible and UV laser diodes with higher than 500 mW power are not available commercially. However we successfully stabilized a multi-longitudinal mode IR laser to 860 mW single frequency. This means high efficiency harmonic generation using this laser can produce visible and UV laser light not available otherwise. In this study we examined three major leading nonlinear crystals: PPMgO:SLN, PPKTP and PPMgO:SLT to generate blue light by second harmonic generation. We achieved record high net conversion efficiencies 81.3% using PPMgO:SLT (~500 mW out), and 81.1% using PPKTP (~700 mW out). In both these cases an external resonance buildup cavity was used. We also studied a less complicated single pass waveguide configuration (guided waist size of ~ 5 um compared to ~60 um) to generate blue. With PPMgO:SLN we obtained net 40.4% and using PPKT net 6.8% (110mW and 10.1 mW respectively).

Die Arbeit umreißt das Krankheitsbild der Myopie (Kurzsichtigkeit) und deren unterschiedliche Ausprägungen, im Speziellen der progressiven und pathologischen Myopie. Hierbei wird ein Einblick in die Symptomatik, die anatomischen Ursachen und die heutigen medizinischen Interventionen gegeben. Hierdurch wird die Problematik einer zu „weichen“ Sklera (Lederhaut des Auges) und des damit einhergehenden fortschreitenden Augenwachstums deutlich. Im Zentrum der Arbeit steht ein neuer therapeutischer Ansatz zur vorbeugenden Behandlung der pathologischen Myopie; das Riboflavin/Blaulicht Cross-Linking der Sklera des Kaninchenauges. Dessen Wirkungsweise ermöglicht die biomechanische Versteifung von kollagenem Gewebe. Aus diesem Sachverhalt ergibt sich die Fragestellung der Arbeit: Ist das sklerale Riboflavin/Blaulicht Cross Linking geeignet das Augenwachstum im Tiermodell (junge Kaninchen) verträglich zu hemmen? Operationsbeeinflussende Parameter wie die Riboflavin-Durchdringungsdauer der Sklera und die sklerale Lichtdurchlässigkeit werden untersucht und für die Optimierung der Operationsmethode herangezogen und diskutiert. Zur Einschätzung des Versuchsansatzes werden die im Methodikteil dargelegten Anwendungen an adulten und jungen Kaninchen/Kaninchenaugen durchgeführt. In Tierversuchen wird die Schadensschwelle in Abhängigkeit der Blaulichtintensität, des Alters und der Pigmentierung untersucht, wobei histologische, immunhistochemische und elektronenmikroskopische Verfahren angewendet werden. Der inhibitorische Einfluss des Riboflavin/Blaulicht Cross-Linkings auf das Augenwachstum kann im Jungtiermodell durch verschiedene metrische Verfahren und MRT-Untersuchungen belegt werden.

This thesis contains quantum chemical models and force field calculations for the RuBisCO isotope effect, the spectral characteristics of the blue-light sensor BLUF and the light harvesting complex II. The work focuses on the influence of the environment on the corresponding systems. For RuBisCO, it was found that the isotopic effect is almost unaffected by the environment. In case of the BLUF domain, an amino acid was found to be important for the UV/vis spectrum, but unaccounted for in experiments so far (Ser41). The residue was shown to be highly mobile and with a systematic influence on the spectral shift of the BLUF domain chromophore (flavin). Finally, for LHCII it was found that small changes in the geometry of a Chlorophyll b/Violaxanthin chromophore pair can have strong influences regarding the light harvesting mechanism. Especially here it was seen that the proper description of the environment can be critical. In conclusion, the environment was observed to be of often unexpected importance for the molecular properties, and it seems not possible to give a reliable estimate on the changes created by the presence of the environment. / Diese Arbeit beinhaltet quantenchemische und molekularmechanische Modelle zum Isotopeneffekt des Enzyms RuBisCO, der spektralen Charakterisierung des Blaulicht-Rezeptors BLUF und dem Lichtsammelkomplex II (LHCII). Es wurden vor allem die Einflüsse der Umgebung auf die entsprechenden Systeme untersucht. Für RuBisCO wurde gefunden, dass der Isotopeneffekt nur marginal von der Umgebung abhängt. Im Falle der BLUF Domäne wurde eine Aminosäure charakterisiert (Ser41), die bis dato experimentell noch nicht beschrieben war. Es wurde festgestellt, dass Ser41 hochmobil ist und einen systematischen Einfluss auf die spektrale Verschiebung des BLUF Chromophors (Flavin) hat. Schließlich wurde bei LHCII festgestellt, dass kleine Veränderungen in der Geometrie eines Chlorophyll b/Violaxanthin Chromophorenpaares bereits massive Einflüsse auf den Mechanismus des Lichtsammelprozesses haben können. Insbesondere hier zeigt sich, wie kritisch die genaue Beschreibung der Umgebung ist. Zusammenfassend wurde beobachtet, dass sich die Umgebung in oft unerwarteter Weise auf die molekularen Eigenschaften auswirken kann und es daher nicht möglich zu sein scheint, die entsprechenden Effekte vorher abzuschätzen.

Abstract The elongation response of Scots pine (Pinus sylvestris L.) seedlings to the removal of blue light (400–500 nm) was studied in field experiments in northern Finland. The seedlings were grown in orange or transparent plexiglass chambers or in ambient control plots. The orange plexiglass removed the blue wavelengths from sunlight, while the others served as controls. The experiment was conducted at sub-arctic (69°N) and mid-boreal (64°N) latitudes with three- and two-year-old seedlings originating from 67°N latitude. The response to blue light depletion was also investigated at the 69°N latitude in the following plant subjects: one-year-old Scots pine seedlings of northern (67°N) and southern (62°N) provenances, deciduous Betula pubescens ssp. czerepanovii and Betula pubescens f. rubra seedlings and herbaceous Epilobium angustifolium and Glechoma hederacea plants. Additionally, diurnal change in light quality at the 69°N latitude during the summer was measured. The elongation of Scots pine seedlings was increased by the removal of blue wavelengths. The increase was more pronounced at the 69°N latitude, while at the 64°N latitude the response was smaller or absent. This is due to increased amount of scattered growth-inhibiting blue light during the nights at the high latitude. The removal of blue light increased stem elongation in northern origin Scots pine seedlings much more compared to the southern origin seedlings, which suggests that the northern provenance is more sensitive to blue light. Irrespective of that, southern origins also suffer from reduced elongation in the north as they migrate according to climatic change scenarios. However, it is obvious that they grow longer than local origins in the north. Morphological variables and photosynthetic pigments confirm that the increased elongation of Scots pine seedlings under blue light depletion is not a result of etiolation or it is only a marginal factor. Also, it was neither dependent on temperature nor photosynthesis and growth resources. Instead, the increased elongation is probably a photomorphogenic regulation response of metabolism. In addition, shade intolerant Scots pine, Betula seedlings and herbaceous Epilobium angustifolium responded stronger to blue light removal compared to the more shade-tolerant herbaceous Glechoma hederacea.

Photocatalysis is a robust synthetic tool capable of breaking and assembling chemical bonds using single electron chemistry. This is achieved through the catalytic conversion of light energy to chemical energy in situ, such that the photons being delivered are themselves reagents. Herein, an inexpensive and environmentally-benign platform for scaling up photocatalytic reaction is disclosed, harnessing blue light naturally emitted by deep-sea bioluminescent bacteria. Photobacterium angustum GB-1 was demonstrated to photoexcite both polypyridyl organometallic chromophores and organic dyes at short molecular distances, enabling photocatalysis without any external energy-consuming lamps.While improving the eco-friendliness of photocatalysis itself, we also present a method to use photocatalysis for environmental remediation. Using visible light, a nontoxic organic photosensitizer, and oxygen, we demonstrate the controlled oxidative depolymerization of polystyrene—including polystyrene retrieved from waste receptacles in Havemeyer—to acetophenone. This method is based on results obtained in the controlled aerobic deannulation of cycloalkanes, which is also discussed herein. Lastly, a means by which catalysis itself can be made more cost, resource, and time effective is presented. An innovative computational platform in development predicts new catalysts for reactions currently energetically inaccessible. In collaboration with the developers, we present experimental validation of their theoretical predictions, as well as perform the synthesis of a de novo fluorinated thiazolium precatalyst calculated to significantly lower the energetic barrier of an otherwise energetically prohibitive Stetter reaction.

No description available.

Wheat (triticum aestivum, L.) plants were exposed to three different levels of phytochrome photoequilibria (φ), two different photoperiods, end-of-day far-red radiation, two different levels of blue (400-500 nm) light, three levels of photosynthetic photon flux (PPF), and two types of high intensity discharge lamp types. Tillering was reduced by lowered φ, by reduced amounts on blue light and by end-of-day far-red. Main culm development was increased by lowered φ, by increased PPF, and was reduced by shortened photoperiod and by reduced blue light. Leaf length was increased by increased PPF, lowered φ, and reduced blue light but was not affected by photoperiod, end-of-day far-red or lamp type. Dry-mass accumulation increased under increasing PPF but was unaffected by other treatment in these experiments.

Short height and high yield per unit energy in controlled environments are essential to the success of a food production system for spaceflight. Temperature and light quality can be manipulated in controlled environments to reduce plant height and increase yield. Although the effects of temperature on height and yield are well studied at ambient CO2, temperature effects at elevated CO2 with a hydroponic root zone are not well characterized. We studied soybean yield and height under two lamp types over a broad range of temperatures. Temperature had little effect on yield or height, but lamp type had a significant effect on canopy height. This first study highlighted the importance of understanding spectral quality in controlling plant growth, especially canopy height. Numerous studies have compared lamp types and suggested that profound differences in leaf area, canopy height, yield, and total dry mass responses were due to blue light differences. Unfortunately, the most energy-efficient light sources have the least blue light. We have a poor understanding of the specific morphological and histological effects of blue light on leaves and stems. Three species, soybeans, wheat, and lettuce, were grown at five blue light fractions (0, 2, 6, 12, and 26%) and two light levels (200 and 500 μmol m-2 s-1). Phytochrome photoequilibria were constant among treatments. Blue light responses were species dependent. Wheat leaf area, dry mass, and stem length were insensitive to blue light fraction. Increasing blue light to 26% decreased soybean stem length, but leaf area was greatest at 6% blue. Lettuce leaf area, stem length, and dry mass were highly sensitive to blue light fraction between 0% and 6% under high pressure sodium lamps, but were insensitive between 6% and 26% under metal halide lamps. These results may be complicated by sensitivity to other wavelengths . The decrease in soybean stem length with increasing blue light was caused by an inhibition of cell division, while the decrease in leaf area was caused primarily by a decrease in cell expansion. Increased lettuce leaf area with increasing blue light fraction was caused by both cell division and expansion. This research indicates that lamps high in blue photons are not only energetically wasteful, but do not benefit, and in some cases reduce, plant growth. However, some blue light is necessary for controlling plant height in soybean and even required for proper growth and development in lettuce.