scholarly journals Effect of light on N<sub>2</sub> fixation and net nitrogen release of <i>Trichodesmium</i> in a field study

2018 ◽  
Vol 15 (1) ◽  
pp. 1-12 ◽  
Author(s):  
Yangyang Lu ◽  
Zuozhu Wen ◽  
Dalin Shi ◽  
Mingming Chen ◽  
Yao Zhang ◽  
...  
Keyword(s):  
Light Intensity ◽  
Carbon Fixation ◽  
Physiological State ◽  
Light Stress ◽  
Light Response ◽  
Light Change ◽  
Filamentous Cyanobacterium ◽  
Light Saturation ◽  
Net Release ◽  
Effect Of Light

Abstract. Dinitrogen fixation (NF) by marine cyanobacteria is an important pathway to replenish the oceanic bioavailable nitrogen inventory. Light is the key to modulating NF; however, field studies investigating the light response curve (NF-I curve) of NF rate and the effect of light on diazotroph-derived nitrogen (DDN) net release are relatively sparse in the literature, hampering prediction using models. A dissolution method was applied using uncontaminated 15N2 gas to examine how the light changes may influence the NF intensity and DDN net release in the oligotrophic ocean. Experiments were conducted at stations with diazotrophs dominated by filamentous cyanobacterium Trichodesmium spp. in the western Pacific and the South China Sea. The effect of light on carbon fixation (CF) was measured in parallel using the 13C tracer method specifically for a station characterized by Trichodesmium bloom. Both NF-I and CF-I curves showed a Ik (light saturation coefficient) range of 193 to 315 µE m−2 s−1, with light saturation at around 400 µE m−2 s−1. The proportion of DDN net release ranged from ∼ 6 to ∼ 50 %, suggesting an increasing trend as the light intensity decreased. At the Trichodesmium bloom station, we found that the CF ∕ NF ratio was light-dependent and the ratio started to increase as light was lower than the carbon compensation point of 200 µE m−2 s−1. Under low-light stress, Trichodesmium physiologically preferred to allocate more energy for CF to alleviate the intensive carbon consumption by respiration; thus, there is a metabolism tradeoff between CF and NF pathways. Results showed that short-term (< 24 h) light change modulates the physiological state, which subsequently determined the C ∕ N metabolism and DDN net release by Trichodesmium. Reallocation of energy associated with the variation in light intensity would be helpful for prediction of the global biogeochemical cycle of N by models involving Trichodesmium blooms.

scholarly journals The effect of light on N<sub>2</sub> fixation and net nitrogen release of field <i>Trichodesmium</i>

2017 ◽  
Author(s):  
Yangyang Lu ◽  
Zuozhu Wen ◽  
Dalin Shi ◽  
Mingming Chen ◽  
Yao Zhang ◽  
...  
Keyword(s):  
Light Intensity ◽  
Model Prediction ◽  
Carbon Fixation ◽  
Physiological State ◽  
Light Stress ◽  
Light Response ◽  
Light Change ◽  
Filamentous Cyanobacterium ◽  
Net Release ◽  
Effect Of Light

Abstract. Dinitrogen fixation (NF) by marine cyanobacteria is a crucial pathway to replenish the oceanic bioavailable nitrogen inventory. Light is the key to modulate NF, however, field studies regarding light response curve (NF-I curve) of NF rate and the effect of light on diazotroph derived nitrogen (DDN) net release are missing that may hamper an accurate nitrogen model prediction. Uncontaminated 15N2 gas dissolution method was applied to examine how the light change may influence the NF intensity and DDN net release in the oligotrophic ocean. Experiments were conducted at stations with diazotrophs dominated by filamentous cyanobacterium Trichodesmium spp. in the Western Pacific and the South China Sea. The light effect on carbon fixation (CF) was measured in parallel using the 13C labelling method specifically for a station characterized by Trichodesmium bloom. Both NF-I and CF-I curves showed Ik (light saturation coefficient) range of 328 to 509 μE m−2 s−1 with saturation light at around 600 μE m−2 s−1. The proportion of DDN net release ranged from ~6% to ~50% revealing an increasing trend as the light intensity decreased. At the Trichodesmium bloom station, we found CF/NF ratio was light-dependent and the ratio started to increase as light was lower than the carbon compensation point of 300 μE m−2 s−1. NF pathway was likely preferentially blocked under low light to conserve energy for photosynthesis, thus, there is a metabolism tradeoff between carbon and nitrogen fixation pathways under light stress. Results showed that short-term light change modulates the physiological state, which subsequently determined the C/N metabolism and DDN net release of field Trichodesmium. Energy reallocation associated with the variations of field light intensity would be helpful for model prediction of global biogeochemical cycle involved with Trichodesmium.

Effect of light intensity on the ultrastructure of the filamentous cyanobacterium, Anabaena variabilis

1988 ◽  
Vol 46 ◽  
pp. 300-301
Author(s):  
C. S. Bricker ◽  
S. R. Barnum ◽  
B. Huang ◽  
J. G. Jaworskl
Keyword(s):  
Fatty Acid ◽  
Light Intensity ◽  
Acid Content ◽  
Fatty Acid Content ◽  
Anabaena Variabilis ◽  
Chloroplast Envelope ◽  
Major Constituent ◽  
Filamentous Cyanobacterium ◽  
Photosynthetic Membrane ◽  
Effect Of Light

Cyanobacteria are Gram negative prokaryotes that are capable of oxygenic photosynthesis. Although there are many similarities between eukaryotes and cyanobacteria in electron transfer and phosphorylation during photosynthesis, there are two features of the photosynthetic apparatus in cyanobacteria which distinguishes them from plants. Cyanobacteria contain phycobiliproteins organized in phycobilisomes on the surface of photosynthetic membrane. Another difference is in the organization of the photosynthetic membranes. Instead of stacked thylakolds within a chloroplast envelope membrane, as seen In eukaryotes, IntracytopIasmlc membranes generally are arranged in three to six concentric layers. Environmental factors such as temperature, nutrition and light fluency can significantly affect the physiology and morphology of cells. The effect of light Intensity shifts on the ultrastructure of Internal membrane in Anabaena variabilis grown under controlled environmental conditions was examined. Since a major constituent of cyanobacterial thylakolds are lipids, the fatty acid content also was measured and correlated with uItrastructural changes. The regulation of fatty acid synthesis in cyanobacteria ultimately can be studied if the fatty acid content can be manipulated.

scholarly journals Physiological response of Monimopetalum chinense to light stress under habitat fragmentation

2010 ◽  
Vol 56 (No. 12) ◽  
pp. 551-556 ◽  
Author(s):  
C. Hao ◽  
R. Fan ◽  
X. Zhang ◽  
L. Wang ◽  
W. Chen ◽  
...  
Keyword(s):  
Antioxidant Enzymes ◽  
Habitat Fragmentation ◽  
Light Intensity ◽  
Physiological Responses ◽  
Light Stress ◽  
Strong Light ◽  
Malondialdehyde Content ◽  
Antioxidant Enzymes Activities ◽  
Intense Light ◽  
Effect Of Light

To determine the effect of light stress under fragmental habitat on the physiology, this paper investigated the physiological responses of Monimopetalum chinense with different light intensities in the Xianyu Mountains (Anhui, China). The study showed that both weak and intense light brought about by habitat fragmentation could improve antioxidant enzymes activities, and promote electrical conductivity and malondialdehyde content of M. chinense leaves. However, too strong light could inhibit photosynthesis rates, superoxide dismutase, catalase, and ascorbate peroxidase activities. In addition, the characteristics of leaves were affected by light intensity at the fragmental habitat. Specifically, intense light was disadvantageous to photosynthesis and antioxidant enzymes of the species. Our results suggest that the biodiversity conservation of M. chinense is necessary, and that light intensity should be considered carefully when implementing conservation efforts. &nbsp;

Gas Exchange of Four Cassava Cultivars in Relation to Light Intensity

1982 ◽  
Vol 18 (4) ◽  
pp. 375-382 ◽  
Author(s):  
Jairo A. Palta
Keyword(s):  
Gas Exchange ◽  
Light Intensity ◽  
Flux Density ◽  
Direct Effect ◽  
Photosynthetic Rate ◽  
Photosynthetic Apparatus ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Light Saturation ◽  
Effect Of Light

SUMMARYGas exchange measurements were carried out on four cassava cultivars, M. COL22, M. MEX59, M. COL638, and M. VEN218, under a range of light intensities, to investigate possible differences in photosynthesis and transpiration. Over the range of photon flux density 100–1500 μE m−2 s−1 leaves showed a light saturation response typical of C-3 plants with little increase in photosynthetic rate above 1000–1500 μE m−2 s−1 (200–300 Wm−2 PAR). At light saturation there were significant differences in photosynthetic rates between cultivars, with the highest 10% greater than the lowest. Part of the response could be attributed to increased stomatal aperture, and a greater part to a direct effect of light intensity on the photosynthetic apparatus. Transpiration increased with light intensity levels, but no significant differences were observed between cultivars.

CHYTRIDS AND ALGAE: II. FACTORS INFLUENCING PARASITISM OF RHIZOPHYDIUM SPHAEROCARPUM ON SPIROGYRA

1967 ◽  
Vol 45 (4) ◽  
pp. 431-440 ◽  
Author(s):  
D. J. S. Barr ◽  
C. J. Hickman
Keyword(s):  
Light Intensity ◽  
Pure Culture ◽  
Optimum Temperature ◽  
Light Saturation ◽  
Light Intensities ◽  
Alkaline Side ◽  
Culture Growth ◽  
Ph Range ◽  
Host Parasite ◽  
Effect Of Light

Host–parasite interrelationship studies showed that temperature was the most important environmental factor associated with epidemics of Rhizophydium sphaerocarpum (Zopf) Fischer on Spirogyra. Certain highly susceptible spring species of Spirogyra grew poorly or not at all at 30 C, the optimum temperature for R. sphaerocarpum, while resistant summer species grew well at 30 C, and even at 35 C. Both pure-culture growth of R. sphaerocarpum and infection of Spirogyra were optimal at approximately pH 7.0–7.5, falling off markedly below pH 6.0 and above pH 8.5. Spirogyra itself grew over a wider pH range, especially on the alkaline side. Infection of Spirogyra was negligible in darkness but a light intensity of 40 ft-c permitted some infection. No difference in infection occurred over a range of light intensities from 65 to 980 ft-c or in day lengths varying from 8 to 16 hours at a light intensity of 600 ft-c. Light saturation for Spirogyra was 400 ft-c. In contrast to the effect of light upon infection, pure culture growth of R. sphaerocarpum was considerably greater in total darkness than at light intensities of 20 ft-c or higher.

scholarly journals Effect of Light Intensity on the Rate of Apparent Photosynthesis in Coffee Leaves

1969 ◽  
Vol 46 (3) ◽  
pp. 159-166 ◽  
Author(s):  
Marco A. Tió
Keyword(s):  
Light Intensity ◽  
Photosynthetic Activity ◽  
High Light ◽  
Light Saturation ◽  
Arabica Coffee ◽  
Light Intensities ◽  
Effect Of Light

The rate of apparent photosynthesis relative to light intensity was determined for Bourbon variety of Arabica coffee. A curve for the effect of light-saturation on apparent photosynthesis of coffee showed that saturation was reached at a maximum of 2,000 foot-candles and that maximum apparent photosynthesis was maintained up to 6,000 foot-candle intensity, after which it decreased. Evidence is also presented to demonstrate that high light intensities may cause an impairment of the photosynthetic activity.

The inhibitory effect of light on seed and burr development in several species of Trifolium

1979 ◽  
Vol 30 (5) ◽  
pp. 895 ◽  
Author(s):  
GB Taylor
Keyword(s):  
Light Intensity ◽  
Seed Development ◽  
Subterranean Clover ◽  
Light Response ◽  
Inhibitory Effect ◽  
Low Light ◽  
Effect Of Light

The effect of light on seed and burr development was studied in 20 genotypes from four species of Trifolium. Burrs produced from spaced laterals were enclosed in plastic tubes variously shaded to produce a range of light treatments. Light inhibited seed development to varying degrees in a range of subterranean clovers, which included strains of T. israeliticum and of all three subspecies of T. subterraneum. In four strains studied intensively the weight of seeds per burr decreased linearly with increases in the logarithm of the light intensity. Light had no effect on seed development in two other geocarpic species, T. batmanicum and T. globosum, which do not actually bury their burrs. The weight of both the pod walls (pericarps) and the sterile calyces was reduced by light in all strains of T. subterraneum. Light also reduced the weight of pod walls in T. israeliticum but had little effect on the production of sterile calyces. Variation in the pattern of light response between plants of the Seaton Park strain of T. subterraneum was found to be associated with genetically distinct lines. Four of the subterranean clover strains commonly produced twin-seeded pods in dark and low light treatments. The incidence of twinning in these strains appeared to be greater than that normally encountered in buried burrs. The ranking of strains of T. subterraneum for susceptibility to light agreed reasonably well with the ranking of the same strains, by others, for seed development above ground. Seaton Park and, to a lesser extent, Dinninup were exceptions in that they were more severely inhibited by light than by lack of burr burial. It is suggested that another factor in addition to light may be involved in the response to burr burial.

scholarly journals Lipidomics Analysis Reveals the Effect of Light Intensity on Lipid Metabolism and Leaf Color in Light-Sensitive Albino Tea Plant (Camellia Sinensis cv. Baijiguan)

2020 ◽  
Author(s):  
Zhe Zhou ◽  
Mingjie Chen ◽  
Lin Lin ◽  
Zhidan Chen ◽  
Quanjin Wu ◽  
...  
Keyword(s):  
Light Intensity ◽  
Camellia Sinensis ◽  
Lipid Content ◽  
Thylakoid Membrane ◽  
Membrane Structure ◽  
Light Stress ◽  
Leaf Color ◽  
Lipid Species ◽  
Normal Light ◽  
Effect Of Light

Abstract Background: Camellia sinensis cv. Baijiguan is a light-sensitive albino tea germplasm. Under light stress, the development of thylakoid membrane structure is not complete, leading to the white color of leaves. Previous studies have shown that the change of lipid can cause the change of thylakoid membrane structure. However, there is no study on the effect of lipid on the leaf color of light-sensitive albino tea germplasm. Thus, we hypothesized that the changes of lipid composition in Baijiguan could affect the leaf color.Results: In order to understand the mechanisms of its light sensitivity, Baijiguan and Rougui were grown under three different conditions: normal light, shading, shading followed by the resuming of light. The total lipids were isolated from the second leaf， 156 lipid species were identified and analyzed by lipidomics. We found that under normal light condition，the newly-developed leaves showed the yellow color with incomplete development of thylakoid membrane, the defense enzyme activity was maintained at a high level, accelerated degradation of chlorophyll. The ratio of MGDG to DGDG of Baijiguan was lower than that of Rougui which kept normal green leaf color. The shading treatment, reduced the content of MGDG and DGDG; meanwhile chlorophyll accumulated, and the thylakoid membrane formed, the leaves turned into green color. When shade-treated leaves were reexposed to light, the MGDG to DGDG ratio increased significantly, the lipid content decreased significantly, and the albinism emerged again. Conclusion: Our data demonstrated that the effect of light intensity on Baijiguan leaf color was realized by changing the lipid content and components in the leaves, and offered a new insight about the mechanisms of its leaf albinism.

Effect of light intensity and water aging on surface hardness of dental resin-composites

2019 ◽  
Vol 64 (11) ◽  
pp. 1007-1014
Author(s):  
Tong XU ◽  
◽  
Jia-Hui ZHANG ◽  
Zhao-Ying LIU ◽  
Xuan LI ◽  
...  
Keyword(s):  
Light Intensity ◽  
Surface Hardness ◽  
Resin Composites ◽  
Dental Resin ◽  
Dental Resin Composites ◽  
Effect Of Light
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