| 1. |
- Carlsson, F., et al.
(författare)
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A comparative study including Clamydomonas reinhardtii and Chlamydomonas raudensis Ettl. strains SAG 49.72 and UWO 241 focusing on phototaxis.
- 2005
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Ingår i: Proceedings of the 6th European Workshop Biotechnology of Microalgae.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Phototaxis is movement induced by light; this phenomenon has been detected in several solitary green algae species and generally works as a balancing force against gravitaxis, creating a system for optimum vertical placing in relation to irradiance, (energy -demands/restrictions). We study phototaxis in the mesophilic green algae, Chlamydomonas reinhardtii and C. raudensis SAG 49.72, relative to phototaxis in the from Antarctica newly isolated obligate psychrophilic strain of C. Raudensis (UWO 241) (henceforth called UWO 241). This species has some unusual movement patterns (Pocock et. al 2004) which function is yet to be revealed. Phototactic movement has not earlier been monitored in the normal conditions (high salinity, low temperature) for this strain, though when exposed to extreme temperatures (25C) the organism displays movement patterns interpreted as positive phototaxis. (Pocock et. al 2004). This behaviour should lead to a more rapid destruction of the organism due to the damaging high light (high energy input). The study shows that the three species responds different to light stimuli, when temperature is set to 12 C (culturing temperature) or the respective optimum culture temperatures. Light response curves of phototaxis in the range of 0,5 to 3000 μmol quanta m-2 s-1, shows that C. raudensis SAG 49.72 produce positive phototaxis over the entire range while C. reinhardtii mainly shows negative reactions. UWO 241 seem to be unaffected by irradiance, thus showing only nondirectional behaviour. In a second set of experiments the cells were kept in Petri dishes and exposed to 3000 μmol quanta m-2 s-1 under 40 min, in a temperature range of 5C to 25C for each sample. The results show that C. reinhardtii was negatively phototactic at 5C, switching to positive phototaxis at 25C.
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| 2. |
- Carstensen, Anna-Maria, 1982, et al.
(författare)
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Remote light stress detection for greenhouse LED lighting control
- 2015
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Ingår i: Proceedings 19th Nordic Process Control Workshop. ; , s. 20:1-6
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The illumination in greenhouses is in general still controlled manually by on/off control because of the type of lamps (High Pressure Sodium) that are traditionally used. With High Brightness LEDs being introduced on the market today, sufficiently high power for greenhouse grown crops can be achieved, which opens up for advanced lighting control since both light spectrum and intensity can be controlled then. For the growers, maximizing production in order to meet customer demand and economically optimize the production, often imply a high light intensity and a high level of artificial light complementing the natural sunlight. However, a too high intensity causes light stress and a photo inhibition that can significantly reduce the photosynthetic yield and hence, production. A key issue to address is therefore to detect when this level is reached. Here we present new results on how to diagnose the plants remotely based on transient and frequency analysis, system identification and frequency function properties.
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| 3. |
- Clendinning, Kirk, et al.
(författare)
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Method for controlling a growth cycle for growing plants using state oriented control
- 2013
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The present invention relates to a method for controlling a growth cycle for growing plants. Such a method may be implemented in a greenhouse, a walk-in chamber or a growth cabinet. The invention also relates to a corresponding system, use of the system and a computer program product. The invention allows for improvements in operating a greenhouse, such as in relation to reduced energy consumption and increased predictability of the growth process.
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| 4. |
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| 5. |
- Gylle, A. Maria, 1965-, et al.
(författare)
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Photosynthesis and relative amounts of photosynthetic proteins (D1, PsaA and Rubisco) in marine and brackish water ecotypes of Fucus vesiculosus and Fucus radicans (Phaeophyceae) : Photosynthesis and proteins in Fucus
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- This study investigated if the photosynthetic maximum capacity (Pmax) is related to the relative amounts of D1 (PsbA), PsaA proteins and ribulose-1.5-bisphosphate carboxylase/ oxygenase (Rubisco) in the marine, Norwegian Sea (34-35 practical salinity units, psu) and the brackish, Bothnian Sea (4-5 psu) ecotypes of Fucus vesiculosus and in Fucus radicans. The results revealed higher Pmax in the marine ecotype of F. vesiculosus compared to the brackish Fucus species. The relative amounts of PsaA proteins or D1/PsaA (photosystem II/photosystem I; PSII/PSI) ratio did not indicate any differences between the Fucus strains whereas the relative amount of D1 was higher in the marine F. vesiculosus compared to F. radicans. The PSII/PSI ratios confirm an overweight of PSI in all three Fucus strains. The analyses of the relative amount of Rubisco indicated a greater amount in both ecotypes of F. vesiculosus compared to F. radicans, whereas no differences could be detected between the two ecotypes of F. vesiculosus. Therefore, we suggest that the amount of Rubisco contributed to the differences of Pmax between the marine ecotype of F. vesiculosus and F. radicans. The lower Pmax in the brackish ecotype of F. vesiculosus compared to the marine ecotype however must have another origin and we suggest further investigations of the CO2 fixation rate of Rubisco. The study also included an investigation of the effects of salinity on Pmax and the relative amount of D1, PsaA and Rubisco in the brackish ecotype of F. vesiculosus. Treatment of the algae for one week in 5, 10, 20 and 35 psu resulted in a higher Pmax at higher salinities and a maximum at 10 psu. These results were not reflected in the amount of D1 or Rubisco whereas analyses of the amount of PsaA revealed the highest amount of PsaA in algae treated in 10 psu. We suggest a need of more ATP by cyclic ATP formation to supply a greater Rubisco activity as an explanation.
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| 6. |
- Gylle, A. Maria, et al.
(författare)
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Photosynthesis in relation to D1, PsaA and Rubisco in marine and brackish water ecotypes of Fucus vesiculosus and Fucus radicans (Phaeophyceae)
- 2013
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Ingår i: Hydrobiologia. - : Springer Science and Business Media LLC. - 0018-8158 .- 1573-5117. ; 700:1, s. 109-119
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to investigate photosynthetic differences between the marine, Norwegian Sea ecotype and the brackish, Bothnian Sea ecotype of F. vesiculosus and F. radicans and to see whether photosynthetic differences could be connected with the relative amounts of D1 protein (PSII), PsaA (PSI) protein and/or Rubisco. For this purpose, we tested if a higher photosynthetic maximum (P (max)) in the Atlantic Ocean ecotype of F. vesiculosus relative to the Baltic Sea ecotype, and an increase of the P (max) in Baltic Sea ecotype of F. vesiculosus at higher salinity, could be due to an increase in the relative amounts of Rubisco. The proteins have been evaluated on a relative basis. Immunoblot signals showed that the amount of Rubisco was higher in both ecotypes of F. vesiculosus than in F. radicans, but no differences could be detected between the two ecotypes of F. vesiculosus. The results suggest an uneven photosystem protein stoichiometry in Fucus, with more of the PSI protein PsaA relative to the PSII protein D1. The difference in P (max) between the two ecotypes of F. vesiculosus might be related to the difficulties for the algae to adapt to the environment in Bothnian Sea.
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| 7. |
- Gylle, A. Maria, et al.
(författare)
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Salinity effect on oxygen evolution and the relative amount of RuBisCO in the brackish Fucus vesiculosus L. (Phaeophyceae)
- 2007
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Ingår i: Pysiological responses of marine and brackish Fucuc vesiculosus L with respect to salinity. - Sundsvall : Mittuniversitetet. - 9789185317417 ; , s. 1-8
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- The sublittoral Fucus vesiculosus from the brackish Bothnian Sea is adapted to a salinity of 4-5 practical salinity units (psu). This study investigated the effect of different salinities (5, 10, 20 and 35 psu) on maximum photosynthetic capacity (Pmax) and the relative amount of ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco). The results revealed a higher Pmax at higher salinities with the maximum at 10 psu. Higher salinities also resulted in increased relative amounts of Rubisco but this was not well correlated with the increased Pmax. Therefore, the amount of Rubisco doesn�t appear to be the main reason for the increased Pmax in higher salinities.
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| 8. |
- Morgan-Kiss, RM, et al.
(författare)
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Adaptation and acclimation of photosynthetic microorganisms to permanently cold environments
- 2006
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Ingår i: Microbiology and molecular biology reviews. - 1092-2172 .- 1098-5557. ; 70:1, s. 222-252
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Forskningsöversikt (refereegranskat)abstract
- Persistently cold environments constitute one of our worlds largest ecosystems, and microorganisms dominate the biomass and metabolic activity in these extreme environments. The stress of low temperatures on life is exacerbated in organisms that rely on photoautrophic production of organic carbon and energy sources. Phototrophic organisms must coordinate temperature-independent reactions of light absorption and photochemistry with temperature-dependent processes of electron transport and utilization of energy sources through growth and metabolism. Despite this conundrum, phototrophic microorganisms thrive in all cold ecosystems described and (together with chemoautrophs) provide the base of autotrophic production in low-temperature food webs. Psychrophilic (organisms with a requirement for low growth temperatures) and psychrotolerant (organisms tolerant of low growth temperatures) photoautotrophs rely on low-temperature acclimative and adaptive strategies that have been described for other low-temperature-adapted heterotrophic organisms, such as cold-active proteins and maintenance of membrane fluidity. In addition, photoautrophic organisms possess other strategies to balance the absorption of light and the transduction of light energy to stored chemical energy products (NADPH and ATP) with downstream consumption of photosynthetically derived energy products at low temperatures. Lastly, differential adaptive and acclimative mechanisms exist in phototrophic microorganisms residing in low-temperature environments that are exposed to constant low-light environments versus high-light- and high-UV-exposed phototrophic assemblages.
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| 9. |
- Morgan-Kiss, R M, et al.
(författare)
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The Antarctic psychrophile, Chlamydomonas raudensis Ettl (UWO241) (Chlorophyceae, Chlorophyta), exhibits a limited capacity to photoacclimate to red light
- 2005
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Ingår i: Journal of Phycology. - : Wiley. - 0022-3646 .- 1529-8817. ; 41:4, s. 791-800
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Tidskriftsartikel (refereegranskat)abstract
- The psychrophilic Antarctic alga, Chlamydomonas raudensis Ettl (UWO241), grows under an extreme environment of low temperature and low irradiance of a limited spectral quality (blue-green). We investigated the ability of C. raudensis to acclimate to long-term imbalances in excitation caused by light quality through adjustments in photosystem stoichiometry. Log-phase cultures of C. raudensis and C. reinhardtii grown under white light were shifted to either blue or red light for 12 h. Previously, we reported that C. raudensis lacks the ability to redistribute light energy via the short-term mechanism of state transitions. However, similar to the model of mesophilic alga, C. reinhardtii, the psychrophile retained the capacity for long-term adjustment in energy distribution between PSI and PSII by modulating the levels of PSI reaction center polypeptides, PsaA/PsaB, with minimal changes in the content of the PSII polypeptide, D1, in response to changes in light quality. The functional consequences of the modulation in PSI/PSII stoichiometry in the psychrophile were distinct from those observed in C. reinhardtii. Exposure of C. raudensis to red light caused 1) an inhibition of growth and photosynthetic rates, 2) an increased reduction state of the intersystem plastoquinone pool with concomitant increases in nonphotochemical quenching, 3) an uncoupling of the major light-harvesting complex from the PSII core, and 4) differential thylakoid protein phosphorylation profiles compared with C. reinhardtii. We conclude that the characteristic low levels of PSI relative to PSII set the limit in the capacity of C. raudensis to photoacclimate to an environment enriched in red light.
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| 10. |
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