Effects of solar ultraviolet radiation on the photochemical efficiency, photosynthetic pigments and biomass production of Spirulina platensis

Effects of solar ultraviolet radiation (UVR) on Spirulina platensis were studied by investigating its photochemical efficiency, photosynthetic pigments and biomass production while exposed to full spectrum solar radiation or depleted of UVR for understanding how and to what extent UVR influences its photosynthe tic physiology and production. It was found that UVR brought about an extra inhibition of photochemical efficiency by 26%—30%. The greatest inhibition of pho tochemical efficiency in S. platensis was observed at noontime, and then recovered to some extent in late afternoon no matter which treatment they were exposed to. The contents of chlorophyll a, phycocyanin and carotenoids increased during initial stage of the exposure, but decreased with elongated exposure. UVR decre ased the biomass yield by about 6%. It indicated that filtering out UVR of solar radiation would raise the productivity of S. platensis, which is an important factor that should be considered in the production.     

Effects of space environment on biological characters of tissue cultured rose seedlings

Tissue cultured rose seedlings were carried into space by SHENZHOU-4 spacecraft and then used as the experimental material to investigate effects of the space environmental conditions on morphology, cytology, physiology and molecular biology of the seedlings. After loaded on the space flight, the plant's height, number of leaves, and fresh weight per seedling were all increased significantly compared to the ground controls. The content of chlorophyll was basically unchanged. In some cells, the ultrastructural changes involved twist, contraction and deformation of cell wall, curvature and loose arrangement of lamellae of some chloroplasts, and a significant increase in number of starch grains per chloroplast. In addition, the number of mitochondria increased, but some mitochondrial outer membrane broke, and some mitochondrial cristae disappeared. The activities of the defense enzymes, such as superoxide dismutase, peroxidase and catalyse, in rose leaves increased and the content of malondialdehyde decreased. In the RAPD analysis with 40 10-mer primers, 36 primers generated 148 DNA bands from both of the space flight treated seedlings and the ground controls, and five primers amplified polymorphic products. The rate of DNA variation was 6.34%.     

Effect of CO2 increase in atmosphere and UV-B intensification on Nostoc commune photosynthetic pigment and UV-B masking materials

Using Nostoc commune as experiment target,the effect of CO 2 with different concentrations in atmosphere and dosage of UV-B on photosynthetic pigment chlorophyll a (Chl a),carotenoids,phycoerythrin,phycocyanin,allophycocyanin and UV-B masking materials was studied.The results showed that high dosage of UV-B radiation inhibited the synthesis process of Chl a,phycoerythrin,phycocyanin and allophycocyanin,but promoted the synthesis of carotenoids,MAAs and scytonemin,thus the negative effect produced by UV-B radiation was reduced and the resistance of Nostoc commune against UV-B radiation was enhanced.     

Improving photosynthesis of microalgae by changing the ratio of light-harvesting pigments

Changing the ratio of light-harvesting pigments was regarded as an efficient way to improve the photosynthesis rate in microalgae, but the underlying mechanism is still unclear. In the present study, a mutant of Anabeana simensis （called SP） was selected from retrieved satellite cultures. Several parameters related with photosynthesis, such as the growth, photosynthesis rate, the content of photosynthetic pigment, low temperature fluorescence spectrum （77K） and electron transport rate, were compared with those of the wild type. It was found that the change in the ratio of light-harvesting pigments in the mutant led to more efficient light energy transfer and usage in mutant than in the wild type. This may be the reason why the mutant had higher photosynthesis and growth rates.     

Effects of temperature,hypoxia, ammonia and nitrate on the bleaching among three coral species

Coral bleaching, which is defined as the loss of colour in corals due to the loss of their symbiotic algae (commonly called zooxanthellae) or pigments or both, is occurring globally at increasing rates, and its harm becomes more and more serious during these two decades. The significance of these bleaching events to the health of coral reef ecosystems is extreme, as bleached corals exhibited high mortality, reduced fecundity and productivity and increased susceptibility to diseases. This decreased coral fitness is easily to lead to reef degradation and ultimately to the breakdown of the coral reef ecosystems. Recently, the reasons leading to coral bleaching are thought to be as follows: too high or too low temperature, excess ultraviolet exposure, heavy metal pollution, cyanide poison and seasonal cycle. To date there has been little knowledge of whether mariculture can result in coral bleaching and which substance has the worst effect on corals. And no research was conducted on the effect of hypoxia on corals. To address these questions, effects of tem- perature, hypoxia, ammonia and nitrate on bleaching of three coral species were studied through examination of morphology and the measurement of the number of symbiotic algae of three coral species Acropora nobilis, Palythoa sp. and Alveopora verrilliana. Results showed that increase in temperature and decrease in dissolved oxygen could lead to increasing number of symbiotic algae and more serious bleaching. In addition, the concentration of 0.001 mmol/L ammonia or nitrate could increase significantly the expulsion of the symbiotic algae of the three coral species. Except for Acropora nobilis, the numbers of symbiotic algae of other two corals did not significantly increase with the increasing concentration of ammonia and nitrate. Furthermore, different hosts have different stress susceptibilities on coral bleaching.     

Induction of Apoptosis in Purified Nuclei from Tobacco-Suspension Cells by Cytochrome b6／f Complex

An apoptotic cell-free system containing cytosol and nuclei from normally cultured tobacco suspension cells was used to show that a spinach chloroplast preparation can induce apoptosis in nuclei, evidenced by DNA electrophoresis and fluorescence microscopy observations, Further study showed that the chloroplast preparation or its pellet (thylakoid membrane) after hypoosmotic or supersonic treatment still exhibited the apoptosis-inducing activity, but the supernatant had no effect, which indicates that the apoptosisinducing effector in the chloroplast preparation is water-insoluble. The induction of apoptosis by chloroplast preparation could be attenuated by Ac-DEVD-CHO, the specific inhibitor of Caspase-3, implying involvement of a Caspase-3-1ike protease during the process. Furthermore, extensive apoptosis in nuclei was induced by cytochrome b6/f on the thylakoid membrane, indicating that this important cytochrome complex may have an important role in the chloroplast-related apoptotic pathway.     

Deletion of an electron donor-binding subunit of the NDH-1 complex,NdhS, results in a heat-sensitive growth phenotype in Synechocystis sp. PCC 6803

In cyanobacteria and higher plants, NdhS is suggested to be an electron donor-binding subunit of NADPH dehydrogenase （NDH-1） complexes and its absence impairs NDH-l-dependent cyclic electron trans- port around photosystem I （NDH-CET）. Despite significant advances in the study of NdhS during recent years, its functional role in resisting heat stress is poorly understood. Here, our results revealed that the absence of NdhS resulted in a serious heat-sensitive growth phenotype in the uni- cellular cyanobacterium Synechocystis sp. strain PCC 6803. Furthermore, the rapid and significant increase in NDH-CET caused by heat treatment was completely abolished, and the repair of photosystem II under heat stress conditions was greatly impaired when compared to that of other photosynthetic apparatus in the thylakoid membrane. We therefore conclude that NdhS plays an important role in resistance to heat stress, possibly by stabilizing the electron input module of cyanobacterial NDH-1 complexes.     

Effects of five heavy metals at sub-lethal concentrations on the growth and photosynthesis of Chlorella vulgaris

The impact of sub-lethal concentrations(0.05,0.5,5 μmol L 1) of the heavy metals copper(Cu),chromium(Cr),zinc(Zn),cadmium(Cd) and lead(Pb) on the growth and photosynthesis of Chlorella vulgaris was studied during 96 h exposure experiments.The results showed that the effects of these five metals on the growth of Chlorella vulgaris were dependent on both concentration and exposure time.It was found that 5 μmol L 1 treatments of Cu,Cr,Zn,Cd and Pb significantly inhibited the growth of Chlorella vulgaris,and the effect became weaker with an increase in exposure duration.Different effects on chlorophyll fluorescence were found for different metals,with Cu and Cr having an inhibiting effect and Zn and Cd having a promoting effect.The effects of heavy metals upon the growth and photosynthesis of Chlorella vulgaris were independent of each other and not causally related.     

Flaking and degradation of polyurethane coatings after 2 years of outdoor exposure in Lhasa

The exposure of a high gloss polyurethane aircraft topcoat system with polyurethane intermediate coating and epoxy primer to strong ultraviolet radiation in Lhasa, Tibet was studied by using scanning electron microscopy (SEM), atomic force microscopy (AFM), attenuated total reflectance Fourier-transform infrared (ATR-FTIR), and X-ray photoelectron spectroscopy (XPS). Micro-flakes were found to form on the topcoat surface after exposure and the size and quantity of the flakes increased with the increase of the exposure time. The magnitude of micro-bulges and the topcoat roughness increased after a long exposure to sunlight. Flakes and micro-bulges resulted in the loss of the topcoat gloss. ATR-FTIR and XPS analysis indicated that chain scissions of the polyurea C==O group and the polyurethane C―O―C and CO―NH groups occurred, and the degradation products of NH and carbonyl groups formed due to the exposure. The breaking of the chemical structure of the polyurethane resulted in a decrease in its elasticity and in the adhesion of the flakes to its surface.     

Effects of ultraviolet radiation B （UV-B） on photosynthesis of natural phytoplankton assemblages in a marine bay in Southern China

Solar ultraviolet radiation B (UVB) is known to have inhibitive effects on phytoplankton photosynthesis. UVB light decreases rapidly with increasing depth in the water column and exerts different degrees of UVB inhibitive effects on phytoplankton photosynthesis. In this study, the objectives were to quantify effects of UVB on phytoplankton photosynthesis and quantum yield, and to examine UVB effects on phytoplankton photosynthesis when light varies. The insitu experiments were conducted in Da Ya Bay, which is a semienclosed area in the subtropical South China. The results showed a significant reduction of photosynthetic rates and quantum yield in the presence of UVB. Maximum photosynthetic rates (Pmax) and maximum quantum yield (Φmax) were 11%-22% and 17%-49% less under solar radiation with UVB than without UVB. A simplified model was developed to describe the UVB biologically effective fluence rate (E*inh) as an exponential decay function of depth. Light-shift experiments, in which water samples from the surface and at depth of 4 m were divided into several subsamples, and each subsamples were then incubated at different depths with and without UVB in the water column, showed that phytoplankton from the deeper water (4 m) had more inhibitive rates by UVB than that from the surface when exposed to the same light condition.     

Increase in electron transfer activity in photosystem Ⅱ of spinach thylakoids caused by conversion of phosphatidyl- glycerol to phosphatidic acid molecules

The techniques of oxygen electrode polarography, sodium dodecyl sulfate-polyacryamide gel electrophoresis (SDS-PAGE) and thin layer chromatography (TLC) were employed to investigate the effect of phospholipase D treatment on physiological function of spinach thylakoids. It was shown that the phospholipase D treatment on thylakoid resuited in the degradation of phosphatidylglycerol (PG) and occurrence of phosphatidic acid (PA). The changes of PG to PA molecules caused an increase in oxygen evolution in photosystem Ⅱ (PS Ⅱ), which was accompanied by an uncoupling effect on thylakoid membrane. It was revealed that the head-groups of PG molecules play an important role in themaintenance of the appropriate physiological activity of thylakoid membrane.     

Influence of prolonged optic flow stimuli on spontaneous activities of cat PMLS neurons

Changes in neuronal spontaneous activities after prolonged optic flow stimulation (using the three basic flow modes: translation, radiation and rotation) were investigated by extracellular single-unit recording in cortical area PMLS of the cat. The results showed that the evoked responses decreased with the prolongation of visual stimuli,and the spontaneous activities usually dropped to a lower level after the stimuli were withdrawn. Generally, the reduction in spontaneous activities was larger after adaptation in the preferred direction than in the non-preferred direction.This difference was much pronounced to translation stimuli,but relatively insignificant to radiation and rotation. These points suggest that non-specific fatigue may act as the key factor in adaptation to simple translation, while some kinds of more complicated, direction-specific mechanism may be involved in adaptation to the complex optic flow patterns. In addition, PMLS may play an important role in perception and adaptation to complex motion and the relevant motion after-effects.     

Preparation of Modified Poly( ethylene terephthalate) Fibers and Their Properties of Ultraviolet Radiation Protection

Protection against solar ultraviolet radiation (UVR) among the general public has been increasing steadily. Poly(ethylene terephthalate) (PET) was blended with UVR protection agent and was spun into the modified fibers with the properties of UVR protection. An investigation on the properties using an ultraviolet spectrophotometer showed that the modified PET fabrics could be resistant to UVR more than 90% in the band of UV-B. The effect of the heat insulation and the mechanical properties of the fibers were also studied.     

Distribution and partition of polybrominated diphenyl ethers （PBDEs） in water of the Zhujiang River Estuary

The spatial, temporal, and vertical distributions of polybrominated diphenyl ethers （PBDEs） in water columns from the Zhujiang River Estuary were examined, and the partition behavior of PBDEs between particle and dissolved phases was investigated in the present study. The results show that the distributions of PBDEs concentrations in the water varied with the sampling seasons. The PBDEs concentrations in water samples were lower in May 2005, when the brackish water was dominant in the estuary, than in October 2005, when fresh water from river runoff dominated the estuary. The spatial distribution of PBDEs in October 2005 indicated that the river runoff was the major mode to input PBDEs to the estuary, and the concentration of PBDEs in water might be dissolved organic carbon （DOC） dependence. The spatial and vertical distributions of PBDEs in May 2005 were relatively homogeneous, and SPM was the major factor on controlling the levels of PBDEs in this sampling time. Both DOC and POC could play certain roles in determining the distribution and partition of PBDEs between particle and dissolved phases, but their effects varied with the water properties.     

海滨钛磁铁矿精矿直接还原制备钛酸镁纯度的因素分析

Magnesium titanate was prepared directly through external coal reduction of seashore titanomagnetite concentrate and magnesium oxide (MgO). The effects of roasting temperature and the type and dosage of reductants on the purity of generated magnesium titanate particles were systematically investigated. Scanning electron microscopy and energy-dispersive spectroscopy analyses were performed to characterize the magnesium titanate particles and observe their purity under different conditions. Results showed that the roasting temperature remarkably influenced the purity of magnesium titanate. At 1200, 1300, and 1400°C, some magnesium ferrite and magnesium aluminate spinel were dissolved in magnesium titanate. However, as the roasting temperature increased to 1500°C, relatively pure magnesium titanate particles were generated because no magnesium ferrite was dissolved in them. The type and dosage of the reductants also remarkably affected the purity of magnesium titanate. The amount of fine metallic iron disseminated in the magnesium titanate particles obviously decreased when lignite was used as a reductant at a dosage of 70wt%. Thus, high-purity magnesium titanate particles formed. At a roasting temperature of 1500°C and with 70wt% lignite, the magnesium titanate product with a yield of 30.63% and an iron content of 3.01wt% was obtained through magnetic separation.     

Effect of UV-B Radiation on Ingesting and Nutritional Selecting Behavior of Rotifer Brachionus urceus

Effect of UV-B radiation on ingesting and nutritional selecting behavior of the roifer Brachionus urceus on 5 species of microlgae were studied under controlled laboratory conditions. Restdts showed that enhanced UV-B radiation significantly inhibited ingesting of the rotifer B. urceus when it was fed with 5 species of micro-algae （p〈0.05）. The ingesting selectivity rate varied with the UV-B radiation enhancement when it was fed with 5 species micro-algal mixture. Results indicated that the enhanced UV-B radiation could affect ingesting and nutritional selectivity of B. urceus.     

Antioxidant activity of N-acetyl-glucosamine based thiazolidine derivative

N-acetyl-glucosamine,the monomer of chitin,was cyclo-condensed with L-cysteine to prepare thiazolidine derivative2-N-acetyl-glucosamine-thiazolidine-4(R)-carboxylic acid(GlcNAcCys).The stability of GlcNAcCys was evaluated by high performance liquid chromatography(HPLC)measurement.The results showed that GlcNAcCys Was more stable than other TCA derivatives,especially in alkaline condition.The direct in vitro antioxidative properties of GlcNAcCys were investigated by using UV radiation-induced lipid peroxidation(LPO)in mitochondria and nuclei and.OH-induced LPO in red blood cell (RBC)ghosts models.UV radiation caused dose-dependent LPO in both mitochondria and nuclei,this effect Was catalvzed by addition of Fd2 while prevented by co-incubation with GlcNAcCys.When nuclei and mitochondria Was treated with 100μl,300μl,500μl of GlcNAcCys and co-incubated at 37℃ for 30min,LPO was decreased to 96%,72%,68%in nuclei and 95%,72%,68% in mitochondria when compared to the UV radiation group respectively.Hydroxyl radicals(.OH)generated by Fenton reaction induced LPO in RBC ghosts.Pretreatment of RBC ghosts with GlcNAcCys could induce antioxidant RBC ghosts and inhibit concentration-dependent malondialdehyde(MDA)formation in antioxidant RBC ghosts.Its inhibition percent Was 14%,35%,36%,42%at 10,20,30,40ms/ml respectively.In a conclusion,the data suggest that GlcNAcCys has antioxidant ability and can significantly inhibit lipid peroxidation in biological samples tested in vitro.     

Study on the effect of highway construction on photosynthetic rate of roadsides plant in Longitudinal Range-Gorge Region

A case study was conducted on Dabao （from Dali city to Baoshan city） and Sixiao （from Simao city to Xiaomengyang town） highways in Longitudinal Range-Gorge Region to investigate the effect of highway construction on photosynthetic rate of roadsides plants. The dominant species in the plant communities were selected to measure the variation of their photosynthetic rate with the distance to the highway, so as to analyze the effect of highway construction on photosynthesis and growth of roadside plants by using mathematic methods including contrast analysis, regress analysis and so on. Results indicate： （1） Highway construction reduced the plant photosynthetic rate of the arbor and crop, and improved the plant photosynthetic rate of the shrub and herbage; （2） highway construction directly affected the plant photosynthetic rate through changing the structure of plant community and living state of plant, and indirectly affected the plant photosynthetic rate through changing its environmental factors; （3） the location and topography of road are also important factors affecting plant photosynthetic rate on roadsides, the influencing incidence and intensity on plant photosynthetic rate under different topographies caused by the two selected highways were obviously different.     

The biogeochemical behavior of dissolved aluminum in the southern Yellow Sea: Influence of the spring phytoplankton bloom

Many recent studies have investigated the nutrient-type profiles of dissolved aluminum(Al) in the ocean.Significant scavenging of dissolved Al can occur during phytoplankton blooms,but the mechanism remains unclear.The distribution of dissolved Al in the southern Yellow Sea(SYS) was investigated in winter and spring 2009.Following measurements at grid stations during the spring sampling cruise,two drifting anchor surveys of more than 100 h were conducted to trace the variation of dissolved Al concentration during the spring phytoplankton bloom(SPB).The concentration of dissolved Al in the SYS decreased from 40 nmol/L in February to 30 nmol/L in March and 10-20 nmol/L in April,while the concentration of Chl a increased from < 2 μg/L in March to > 4 μg/L in April.The concentration of dissolved Al in the SYS decreased significantly with the development of the phytoplankton bloom,which indicated biological scavenging of dissolved Al from water column.The proportion of dissolved Al scavenged from water column by different phytoplankton species differed at the two drifting stations,with greater removal efficiency demonstrated by diatoms than dinoflagellates.Phytoplankton samples collected from the Chl a maximum layer were washed with trace metal clean reagent(oxalate-EDTA-citrate,abbreviate as oxalate solution,Tovar-Sanchez et al.,2003) to enable the surface-scavenged(extracellular) and intracellular Al pools associated with phytoplankton to be differentiated.Thirty-nine to ninetysix percent of the total Al was found to be existed in the interior pools,which indicated that biological absorption was the important way to scavenge dissolved Al during phytoplankton blooms in the SYS.