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White Light Irradiation (white + light_irradiation)
Selected AbstractsSporulation of Plasmopara viticola: Differentiation and Light RegulationPLANT BIOLOGY, Issue 3 2002J. Rumbolz Abstract: The development of grape downy mildew (Plasmopara viticola) was followed histologically during the entire latent period until the appearance of mature sporangia. Production of sporangiophores and sporangia was assessed using low-temperature scanning electron (LTSEM) and fluorescent light microscopy. Time-course studies using attached leaves of Vitis vinifera cv. Müller-Thurgau revealed that the production of sporangiophores and sporangia is a highly coordinated process and is completed within 7 h. As this differentiation is assumed to occur only in darkness, the influence of light was investigated. For this purpose, different light regimes were applied to infected leaf discs of V. viniferacv. Müller-Thurgau. White light irradiation prevented formation of sporangia, although the growth of the mycelium was not affected. Many sporangiophores were observed that were abnormally shaped, i.e., short hyphae in clusters or thin, extremely elongated hyphae. For the formation of mature sporangia, a prolonged dark period was necessary. Light experiments suggest photosensitivity at the end of the latent period. A terminal white light irradiation caused an inhibitory effect, whereas a final phase of darkness promoted sporangium development. Different light qualities were tested, revealing an inhibition of sporangium development by blue light whereas neither red nor far-red light were effective. [source] Mitigating Photosensitivity of Erythropoietic Protoporphyria Patients by an Agonistic Analog of ,-Melanocyte Stimulating Hormone,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 6 2009Juergen H. Harms Erythropoietic protoporphyria (EPP) is a rare hereditary disorder characterized by dermal accumulation of the photosensitizer protoporphyrin IX. Following sunlight exposure, the resulting photosensitivity is manifested first as pain, later as erythema, edema and dermal lesions. Afamelanotide (Nle4 -d-Phe7 -,-MSH), a synthetic analog of ,-melanocyte stimulating hormone and agonist of the melanocortin-1-receptor, promotes melanin synthesis, increasing skin pigmentation. This study examines the efficacy of afamelanotide in preventing symptoms in patients with EPP. A sustained-release subcutaneous implant of 20 mg afamelanotide was administered twice, with a 60-day interval to five EPP patients. Therapeutic efficacy was assessed by a photoprovocation test using standardized white light irradiation, melanin density (MD) determination and daily recording of sunlight exposure and symptoms. From Day 30 to Day 120 tolerance to photoprovocation significantly increased compared with baseline (P = 0.007) and skin MD was significantly higher than that recorded at baseline (P = 0.004). Except for two low-grade pain episodes, patients recorded no phototoxic events past Day 4 of treatment. Tolerance to natural sunlight was up to 24 times longer than prior to therapy. The findings demonstrate beneficial effects of afamelanotide in patients with EPP. Due to the limited number of patients enrolled and the design being an open-label study, confirmation by a large-scale trial is required. [source] Up to 30 times enhancement of deep UV emission at room temperature by prolonged excitation of localized exciton in NaCl:I crystalPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 1 2009Ikuko Akimoto Abstract A material emitting DUV light at room temperature is promising for an application to a new laser action. We report the remarkable phenomena that deep ultra-violet (DUV) emission at 220 nm, so-called NE emission, in NaCl:I crystal is enhanced up to 30 times at room temperature by prolonged excitation of the localized exciton. Such an accumulated effect is kept even if the excitation is interuped for a few minutes but is completely reset by white light irradiation at room temperature. The phenomena are discussed considering thermal ionization of iodine anion by the VUV light excitation, trapping of dissociated electrons in hole centers and recombination of electrons and iodine hole centers. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Sporulation of Plasmopara viticola: Differentiation and Light RegulationPLANT BIOLOGY, Issue 3 2002J. Rumbolz Abstract: The development of grape downy mildew (Plasmopara viticola) was followed histologically during the entire latent period until the appearance of mature sporangia. Production of sporangiophores and sporangia was assessed using low-temperature scanning electron (LTSEM) and fluorescent light microscopy. Time-course studies using attached leaves of Vitis vinifera cv. Müller-Thurgau revealed that the production of sporangiophores and sporangia is a highly coordinated process and is completed within 7 h. As this differentiation is assumed to occur only in darkness, the influence of light was investigated. For this purpose, different light regimes were applied to infected leaf discs of V. viniferacv. Müller-Thurgau. White light irradiation prevented formation of sporangia, although the growth of the mycelium was not affected. Many sporangiophores were observed that were abnormally shaped, i.e., short hyphae in clusters or thin, extremely elongated hyphae. For the formation of mature sporangia, a prolonged dark period was necessary. Light experiments suggest photosensitivity at the end of the latent period. A terminal white light irradiation caused an inhibitory effect, whereas a final phase of darkness promoted sporangium development. Different light qualities were tested, revealing an inhibition of sporangium development by blue light whereas neither red nor far-red light were effective. [source] Phosphatidylinositol 4,5-bisphosphate is important for stomatal openingTHE PLANT JOURNAL, Issue 5 2007Yuree Lee Summary Previously, we demonstrated that a protein that binds phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2] inhibits both light-induced stomatal opening and ABA-induced stomatal closing. The latter effect is due to a reduction in free PtdIns(4,5)P2, decreasing production of inositol 1,4,5-trisphosphate and phosphatidic acid by phospholipases C and D. However, it is less clear how PtdIns(4,5)P2 modulates stomatal opening. We found that in response to white light irradiation, the PtdIns(4,5)P2 -binding domain GFP:PLC,1PH translocated from the cytosol into the plasma membrane. This suggests that the level of PtdIns(4,5)P2 increases at the plasma membrane upon illumination. Exogenously administered PtdIns(4,5)P2 substituted for light stimuli, inducing stomatal opening and swelling of guard cell protoplasts. To identify PtdIns(4,5)P2 targets we performed patch-clamp experiments, and found that anion channel activity was inhibited by PtdIns(4,5)P2. Genetic analyses using an Arabidopsis PIP5K4 mutant further supported the role of PtdIns(4,5)P2 in stomatal opening. The reduced stomatal opening movements exhibited by a mutant of Arabidopsis PIP5K4 (At3g56960) was countered by exogenous application of PtdIns(4,5)P2. The phenotype of reduced stomatal opening in the pip5k4 mutant was recovered in lines complemented with the full-length PIP5K4. Together, these data suggest that PIP5K4 produces PtdIns(4,5)P2 in irradiated guard cells, inhibiting anion channels to allow full stomatal opening. [source] A novel three-stage light irradiation strategy in the submerged fermentation of medicinal Mushroom Ganoderma lucidum for the efficient production of ganoderic acid and Ganoderma polysaccharidesBIOTECHNOLOGY PROGRESS, Issue 6 2008Wei Zhang Abstract A novel three-stage light irradiation strategy in the submerged fermentation of medicinal mushroom Ganoderma lucidum for the efficient production of bioactive metabolites ganoderic acid (GA) and Ganoderma polysaccharides was developed. Significance of light quality, i.e., blue light (390,500 nm, ,max = 470 nm), red light (560,700 nm, ,max = 625 nm), and white light (400,740 nm, ,max = 550 nm), was studied at first. Interestingly, there was a gradual decrease trend of GA content after the culture of day 2 when the maximal GA content was obtained, while GA content decreased slowly under white light irradiation after day 6. The dark environment was favorable to the specific GA biosynthesis (i.e., GA content) before day 6, and after that the optimum was white light irradiation. A relatively lower irradiation density of white light (i.e., 0.94 and 2.82 W/m2) was beneficial for the specific GA biosynthesis before day 6, while GA content was higher under higher irradiation density of white light (i.e., 4.70 and 9.40 W/m2) at the later-stage of cultivation. 4.70 W/m2 white light irradiation culture was the best from the viewpoint of GA accumulation. Therefore, a two-stage light irradiation strategy by combing the first 2 days dark culture with the following 4.70 W/m2 white light irradiation culture was developed. The highest GA production in the two-stage culture was 276.0 ± 12.5 mg/L, which was increased by 19% compared to 4.70 W/m2 white light irradiation culture (i.e., 232.4 ± 15.8 mg/L) and by 178% compared to the dark culture (i.e., 99.4 ± 1.0 mg/L). Although there still existed a gradual decrease trend of GA content after day 2 when the maximal GA content was obtained in the two-stage culture. Following three-stage light irradiation strategy was further demonstrated in order to turn around the sharp decrease of GA content after day 2. The first-stage was the 2-day dark culture; the second-stage was the following six-day 0.94 W/m2 white light irradiation culture, and the third-stage was 4.70 W/m2 white light irradiation culture until the end of fermentation. During the three-stage culture of G. lucidum, the gradual decrease trend of GA content after day 2 was turned around, which suggested that 0.94 W/m2 white light irradiation was beneficial for the metabolic flux towards the GA biosynthesis. The maximal GA content of 3.1 ± 0.1 mg/100 mg DW was obtained, which was higher by 41% compared to the two-stage culture. The maximal GA production (i.e., 466.3 ± 24.1 mg/L) and productivity (i.e., 38.9 mg/L per day) in the three-stage culture were 69 and 101% higher than those obtained in the two-stage culture. This is the first report investigating the significance of light irradiation on the medicinal mushroom submerged fermentation. Such work is very helpful to other mushroom fermentations for useful metabolite production. [source] | ||||||||||