Near-Infrared 810 nm Light Affects Porifera Chondrosia reniformis (Nardo, 1847) Regeneration: Molecular Implications and Evolutionary Considerations of Photobiomodulation–Animal Cell Interaction (original) (raw)
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Marine Biotechnology, 2006
The unicellular green alga Dunaliella salina is an attractive model organism for studying photoacclimation responses and the photosystem II (PSII) damage and repair process in the photosynthetic apparatus. Irradiance during cell growth defines both the photoacclimation and the PSII repair status of the cells. To identify genes specific to these processes, a cDNA library was created from irradiance-stressed D. salina. From the cDNA library, 1112 randomly selected expressed sequence tags (ESTs) were analyzed. Because ESTs constitute the expressed part of the genome, the strategy of randomly sequencing cDNA clones at their 5'-ends allowed us to obtain information about the transcript level of numerous genes in light-stressed D. salina. The results of a BLASTX search performed on the obtained total set of ESTs showed that approximately 1% of the ESTs could be assigned to genes coding for proteins that are known to be upregulated in response to high-light stress. Specifically, after 48 h of high-light exposure of the cells, an increase in the expression level of antioxidant genes, such as Fe-SOD and APX, was observed, as well as elevated levels of the Cbr transcript, a lightharvesting Chl-protein homolog. Further, the ATPdependent Clp protease gene was also up-regulated in D. salina cells after 48 h of exposure to high light. The results provide initial insight into the global gene regulation process in response to irradiance.
PHOTOBIOSTIMULATION AS A FUNCTION OF DIFFERENT WAVELENGTHS
2001
In the current study we compare the effect of different light sources in the visible and near infra-red (IR) range on cell stimulation. It is obvious that in order to interact with the living cell, light has to be absorbed by intracellular chromophores. In a search for chromophores responsible for photobiostimulation, endogenous porphyrins, mitochondrial and membranal cytochromes were found to be suitable candidates, as they possess absorption bands in the visible and near I.R. ranges. The above-mentioned chromophores are photosensitizers that generate reactive oxygen species (ROS) following irradiation. In our opinion the first step in photobiostimulation might be ROS formation. To confirm ROS formation by various light sources, we used the electron paramagnetic resonance (EPR) associated with spin trapping techniques. , including a broad band in the visible range (400-800nm), stimulated hydroxyl radical formation in sperm cells. Measuring the amount of OH radicals as a function of the irradiating wavelength shows that shorter wavelengths might be more effective on the cell than longer ones.
We investigated the systems response of metabolism and growth after an increase in irradiance in the nonsaturating range in the algal model Chlamydomonas reinhardtii. In a three-step process, photosynthesis and the levels of metabolites increased immediately, growth increased after 10 to 15 min, and transcript and protein abundance responded by 40 and 120 to 240 min, respectively. In the first phase, starch and metabolites provided a transient buffer for carbon until growth increased. This uncouples photosynthesis from growth in a fluctuating light environment. In the first and second phases, rising metabolite levels and increased polysome loading drove an increase in fluxes. Most Calvin-Benson cycle (CBC) enzymes were substrate-limited in vivo, and strikingly, many were present at higher concentrations than their substrates, explaining how rising metabolite levels stimulate CBC flux. Rubisco, fructose-1,6-biosphosphatase, and seduheptulose-1,7-bisphosphatase were close to substrate saturation in vivo, and flux was increased by posttranslational activation. In the third phase, changes in abundance of particular proteins, including increases in plastidial ATP synthase and some CBC enzymes, relieved potential bottlenecks and readjusted protein allocation between different processes. Despite reasonable overall agreement between changes in transcript and protein abundance (R 2 = 0.24), many proteins, including those in photosynthesis, changed independently of transcript abundance.
Inhibition of Respiration in Prototheca zopfii by Light
Plant Physiology, 1970
Irradiation of cells of Prototheca zopfii with blue light inhibited the respiratory capacity of the cells. The inhibition of respiration was correlated with a photodestruction of cytochrome c(551), cytochrome b(559), and cytochrome a3. Cytochrome c(549), cytochrome b(555), and cytochrome b(564) were unaffected by the irradiation treatment. The a-band of reduced cytochrome a was shifted from 599 to 603 nm by irradiation, an effect similar to that observed when methanol was added to nonirradiated cells. The presence of oxygen was required during irradiation for both photoinhibition of respiration and photodestruction of the cytochromes. Cytochrome a3 was protected against photodestruction by cyanide. Photodestruction of these same cytochromes also occurred when washed mitochondria of P. zopfii were irradiated.
PLoS ONE, 2010
The filamentous cyanobacterium Microcoleus vaginatus, a major primary producer in desert biological sand crusts, is exposed to frequent hydration (by early morning dew) followed by desiccation during potentially damaging excess light conditions. Nevertheless, its photosynthetic machinery is hardly affected by high light, unlike ''model'' organisms whereby light-induced oxidative stress leads to photoinactivation of the oxygen-evolving photosystem II (PSII). Field experiments showed a dramatic decline in the fluorescence yield with rising light intensity in both drying and artificially maintained wet plots. Laboratory experiments showed that, contrary to ''model'' organisms, photosynthesis persists in Microcoleus sp. even at light intensities 2-3 times higher than required to saturate oxygen evolution. This is despite an extensive loss (85-90%) of variable fluorescence and thermoluminescence, representing radiative PSII charge recombination that promotes the generation of damaging singlet oxygen. Light induced loss of variable fluorescence is not inhibited by the electron transfer inhibitors 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), 2,5-dibromo-3-methyl-6-isopropylbenzoquinone (DBMIB), nor the uncoupler carbonyl cyanide-p-trifluoromethoxyphenylhydrazone (FCCP), thus indicating that reduction of plastoquinone or O 2 , or lumen acidification essential for non-photochemical quenching (NPQ) are not involved. The rate of Q A 2 reoxidation in the presence of DCMU is enhanced with time and intensity of illumination. The difference in temperatures required for maximal thermoluminescence emissions from S 2 /Q A 2 (Q band, 22uC) and S 2,3 /Q B 2 (B band, 25uC) charge recombinations is considerably smaller in Microcoleus as compared to ''model'' photosynthetic organisms, thus indicating a significant alteration of the S 2 /Q A 2 redox potential. We propose that enhancement of non-radiative charge recombination with rising light intensity may reduce harmful radiative recombination events thereby lowering 1 O 2 generation and oxidative photodamage under excess illumination. This effective photo-protective mechanism was apparently lost during the evolution from the ancestor cyanobacteria to the higher plant chloroplast.
The response of five marine macroalgae from the temperate region against ultraviolet radiation (UVR) was determined in this study. The algae were exposed to a 35 Wm–2 –38 Wm–2 UVA, 1.2 Wm–2 – 1.7 Wm–2 UVB and 129 Wm–2 – 148 Wm–2 photosynthetically active radiation under four different lights/UV conditions for 5 h in a sun simulator. After 5 h of light stress, the algae were transferred to dim light for an 18 h recovery period. The maximum quantum yield (Fv/Fm) of the algae was measured to determine the degree of photoinhibition. In addition, the content of stress proteins (i.e. hsp60 and hsp70) was also determined as an indicator for the presence of protective mechanisms. In general, Fv/Fm of the algae dramatically declined indicating that the algae experienced high photoinhibitory stress. Induction of both the stress proteins was observed in the irradiated algae especially under the presence of UVB. The induction of hsp70 was stronger than hsp60 in most of the algae. However, after...
Role of protective and repair mechanisms in the inhibition of photosynthesis in marine macroalgae
Photochemical & Photobiological Sciences, 2002
The mechanism of photoinhibition was investigated in three representative macroalgal species growing on the coast of Patagonia: the chlorophyte Ulva rigida C. Agardh, the rhodophyte Porphyra columbina Montagne and the phaeophyte Dictyota dichotoma (Huds.) Lamour. Dark adapted specimens were exposed to 15 min unfiltered solar radiation to induce photoinhibition, and subsequently the recovery of the photosynthetic quantum yield was followed for up to 6 h. Photoinhibition is believed to be due to the damage and proteolysis of the D1 protein in the reaction center of Photosystem II. During recovery this protein is resynthesized. In order to prove this hypothesis, inhibitors of the chloroplast protein synthesis, streptomycin and chloramphenicol were applied. Both retarded the repair process indicating an inhibition of the D1 protein resynthesis during recovery after the damage they experienced during light exposure. Some algal groups use the xanthophyll cycle to ameliorate the inhibition by excessive light. Dithiothreitol, an inhibitor of violaxanthin de-epoxidase, was administered, to impair the xanthophyll cycle. It strongly affected both photoinhibition and recovery even in the red algal species, which do not have the xanthophyll cycle, indicating that this drug has significant side effects and should be used with caution for the study of the involvement of this protective cycle in algae. Pigmentation was followed in the three species using absorption spectroscopy of thallus extracts at 665 nm during continuous exposure to natural solar radiation or radiation deprived of the UV component during two days. The results indicated a pronounced variation in pigmentation over time due to bleaching and resynthesis. Solar radiation was monitored during the experiments in three channels (UV-B, UV-A and PAR) using an ELDONET instrument on site.
Algae and UV irradiation: Effects on ultrastructure and related metabolic functions
Micron, 2006
The effects of ultraviolet radiation in the biological relevant wavebands of UV-A (315-400 nm) and UV-B (280-315 nm) on algae have become an important issue as a man-made depletion of the protecting ozone layer has been reported. However, experimental designs to investigate this issue are manifold and the target organisms are extremely diverse. Data are included from the prokaryotic cyanobacteria, haptophytes, diatoms, brown algae to green algae (fresh water, snow algae and marine species) including different habitats from marine littoral and open ocean to freshwater ponds, lakes and snow fields. A broad overview on UV effects on algae is given, with a focus on structurally visible changes. Here we report on destruction in chloroplasts, mitochondria, and the occurrence of structures that are likely to be related to the UV stress. In addition several new data are presented from organisms that have to face naturally high UV irradiation due to their habitats. As no disturbances are reported in these organisms, they obviously have a set of protective mechanisms allowing survival in extreme habitats such as snow fields. Physiological changes as a consequence of UV irradiation are included, effects on the DNA level are summarized, and avoidance strategies are discussed. Every effort has been made to summarize the diverse observations and critically evaluate and compare the different experimental strategies to study UV effects in algae.