scholarly journals Toxic Effects of Ethyl Cinnamate on the Photosynthesis and Physiological Characteristics ofChlorella vulgarisBased on Chlorophyll Fluorescence and Flow Cytometry Analysis

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Yang Jiao ◽  
Hui-Ling Ouyang ◽  
Yu-Jiao Jiang ◽  
Xiang-Zhen Kong ◽  
Wei He ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Chlorophyll Fluorescence ◽  
Photochemical Efficiency ◽  
Physiological Characteristics ◽  
Toxic Effects ◽  
Total Biomass ◽  
Flow Cytometry Analysis ◽  
Average Cell Size ◽  
Average Cell ◽  
Photochemical Efficiency Of Psii

The toxic effects of ethyl cinnamate on the photosynthetic and physiological characteristics ofChlorella vulgariswere studied based on chlorophyll fluorescence and flow cytometry analysis. Parameters, including biomass,Fv/Fm(maximal photochemical efficiency of PSII), ФPSII(actual photochemical efficiency of PSII in the light), FDA, and PI staining fluorescence, were measured. The results showed the following: (1) The inhibition on biomass increased as the exposure concentration increased. 1 mg/L ethyl cinnamate was sufficient to reduce the total biomass ofC. vulgaris. The 48-h and 72-h EC50 values were 2.07 mg/L (1.94–2.20) and 1.89 mg/L (1.82–1.97). (2) After 24 h of exposure to 2–4 mg/L ethyl cinnamate, the photosynthesis ofC. vulgarisalmost ceased, manifesting in ФPSIIbeing close to zero. After 72 h of exposure to 4 mg/L ethyl cinnamate, theFv/FmofC. vulgarisdropped to zero. (3) Ethyl cinnamate also affected the cellular physiology ofC. vulgaris, but these effects resulted in the inhibition of cell yield rather than cell death. Exposure to ethyl cinnamate resulted in decreased esterase activities inC. vulgaris, increased average cell size, and altered intensities of chlorophyll a fluorescence. Overall, esterase activity was the most sensitive variable.

scholarly journals THE INFLUENCE OF BIO-ALGEEN S90 ON THE GROWTHOF MULTIFLORA ROSE SEEDLINGS (Rosa multiflora Thunb.)

2019 ◽  
Vol 18 (3) ◽  
pp. 35-43
Author(s):  
Mariusz Szmagara ◽  
Krystyna Pudelska ◽  
Wojciech Durlak ◽  
Barbara Marcinek ◽  
Kamila Rojek
Keyword(s):  
Chlorophyll Fluorescence ◽  
Photochemical Efficiency ◽  
Morphological Characteristics ◽  
Rosa Multiflora ◽  
Plant Growth And Development ◽  
Agent Based ◽  
Photochemical Efficiency Of Psii ◽  
Stimulate Plant Growth ◽  
Maximum Photochemical Efficiency ◽  
Natural Agent

Striving to intensify horticultural production, new and more effective bio-preparations are being sought to stimulate plant growth and development. Bio-algeen S90 is a natural agent based on sea algae, the high bi- ological activity of which results from the high content of natural growth regulators. The aim of the study was to verify the influence of Bio-algeen S90 on the growth, morphological characteristics and chlorophyll fluorescence of Rosa multiflora seedlings. The bio-preparation was applied one, two and three times at con- centrations: 0.1, 0.2, 0.4 and 0.6 mg.dm−3. Following parameters were measured to evaluate the response of plants to the bio-preparation: F0 – initial fluorescence, Fm – maximal fluorescence in the dark-adapted state, Fv/Fm – maximum photochemical efficiency of PSII. All concentrations of the bio-preparation and frequency of its application stimulated the number of shoots in a bush, the length of shoots and the diameter of the root crown of plants intended for budding. The most beneficial was the two-fold bio-preparation application at a concentration of 0.4 mg.dm–3. Bio-algeen also positively influenced the chlorophyll fluorescence parame- ters. The highest mean F0 and Fm values were recorded with the two-fold preparation treatment. There was no significant effect of the bio-preparation on the Fv/Fm index, which was within the range of 0.75–0.66.

scholarly journals Differences in photosynthetic capacity, chlorophyll fluorescence, and antioxidant system between invasive Alnus formosana and its native congener in response to different irradiance levels

Botany ◽  
2016 ◽  
Vol 94 (12) ◽  
pp. 1087-1101 ◽  
Author(s):  
Shi-liang Liu ◽  
Rong-jie Yang ◽  
Bo Ren ◽  
Mao-hua Wang ◽  
Ming-dong Ma
Keyword(s):  
Invasive Species ◽  
Chlorophyll Fluorescence ◽  
Antioxidant System ◽  
Photosynthetic Rate ◽  
Native Species ◽  
Antioxidant Activities ◽  
Photochemical Efficiency ◽  
High Irradiance ◽  
Invasion Success ◽  
Photochemical Efficiency Of Psii

We compared the invasive Alnus formosana (Burk.) Makino with its native congener (Alnus cremastogyne Burk.) at three irradiances in terms of photosynthesis, chlorophyll fluorescence, and antioxidant system. The increased light-saturated photosynthetic rate (Amax) and light saturation point (LSP) contributed directly to the increased performance of the invasive. The invasive species had also higher plasticity in carotenoid and total chlorophyll than the native species at 100% irradiance, potentially contributing to invasion success in high-irradiance locations via photoprotection. Moreover, the diurnal photoinhibition of photosynthesis, as judged by the maximum photochemical efficiency of PSII (Fv/Fm) of dark-adapted leaves, was more severe in the native species than in the invasive species. With increasing irradiance, the invasive exhibited increased antioxidant activities and higher antioxidant levels to support the adverse conditions of both low- and high-irradiance acclimation. In contrast, the intercellular CO2 concentration (Ci) and stomatal limitation (Ls) decreased with increases in the net photosynthetic rate (An), stomatal conductance (Gs), and transpiration rate (Tr). We speculated that Ls was the main factor inhibiting the An for both studied species. These results first indicated that the invasive may occupy new habitats successfully through tolerating shading at low irradiance and out-compete native species through higher Amax and antioxidant levels when irradiance is increased.

scholarly journals Chlorophyll fluorescence as a tool to select salinity-tolerant cowpea genotypes

2019 ◽  
Vol 10 (2) ◽  
pp. 319-324
Author(s):  
Jaima Ribeiro de Andrade ◽  
Sebastião De Oliveira Maia Júnior ◽  
José Wilson Da Silva Barbosa ◽  
Aryadne Ellen Vilar de Alencar ◽  
Raphael Silva Jovino ◽  
...  
Keyword(s):  
Chlorophyll Fluorescence ◽  
Saline Water ◽  
Photochemical Efficiency ◽  
Fluorescence Analysis ◽  
Stem Diameter ◽  
Stem Length ◽  
Photochemical Efficiency Of Psii ◽  
Randomized Design ◽  
Irrigation Water Salinity ◽  
Efficient Selection

The use of saline water reduces the growth and productivity of crops, so the need for techniques that make possible the use of this resource such as the use of salinity tolerant genotypes and efficient selection methods are of great importance. Thus, this study aimed to evaluate the tolerance of cowpea (Vigna unguiculata L. Walp.) genotypes to salt stress, through the chlorophyll fluorescence analysis. The experiment was conducted in a protected environment at the Federal University of Campina Grande, Paraíba, Brazil, using a completely randomized design in a 2 x 10 factorial arrangement, with three replications, consisting of two levels of irrigation water salinity (0.6 and 5.1 dS m-1) and ten cowpea genotypes: (G1: MNCO1-649F-2-1, G2: MNCO3-736F-2, G3: PINGO DE OURO-1-2, G4: BRS GURGUÉIA, G5: BRS MARATAOÃ, G6: MNCO2-676F-3, G7: MNCO2-683F-1, G8: MNCO3-737F-5-4, G9: MNCO3-737F-5-9, and G10: BRS TUMUCUMAQUE). The stem length, stem diameter, SPAD index, and chlorophyll fluorescence transients were evaluated. The G2 and G4 genotypes had the lowest reductions in the growth, stem diameter, initial fluorescence, and primary and maximum photochemical efficiency of PSII, proving to be tolerant to salinity. Chlorophyll fluorescence is a tool that can be used in the selection of salinity-tolerant cowpea genotypes.

Thermostability and Photostability of Photosystem II of the Resurrection Plant Haberlea rhodopensis Studied by Chlorophyll Fluorescence

2006 ◽  
Vol 61 (3-4) ◽  
pp. 234-240 ◽  
Author(s):  
Katya Georgieva ◽  
Liliana Maslenkova
Keyword(s):  
Chlorophyll Fluorescence ◽  
Electron Transport ◽  
Quantum Yield ◽  
Photochemical Efficiency ◽  
Resurrection Plant ◽  
Haberlea Rhodopensis ◽  
Photochemical Efficiency Of Psii ◽  
Light Intensities ◽  
Psii Photochemistry ◽  
Quantum Yield Of Psii

The stability of PSII in leaves of the resurrection plant Haberlea rhodopensis to high temperature and high light intensities was studied by means of chlorophyll fluorescence measurements. The photochemical efficiency of PSII in well-hydrated Haberlea leaves was not significantly influenced by temperatures up to 40 °C. F0 reached a maximum at 50 °C, which is connected with blocking of electron transport in reaction center II. The intrinsic efficiency of PSII photochemistry, monitored as Fv/Fm was less vulnerable to heat stress than the quantum yield of PSII electron transport under illumination (ΦPSII). The reduction of ΦPSII values was mainly due to a decrease in the proportion of open PSII centers (qP). Haberlea rhodopensis was very sensitive to photoinhibition. The light intensity of 120 μmol m−2 s−1 sharply decreased the quantum yield of PSII photochemistry and it was almost fully inhibited at 350 μmol m−2 s−1. As could be expected decreased photochemical efficiency of PSII was accompanied by increased proportion of thermal energy dissipation, which is considered as a protective effect regulating the light energy distribution in PSII. When differentiating between the three components of qN it was evident that the energy-dependent quenching, qE, was prevailing over photoinhibitory quenching, qI, and the quenching related to state 1-state 2 transitions, qT, at all light intensities at 25 °C. However, the qE values declined with increasing temperature and light intensities. The qI was higher than qE at 40 °C and it was the major part of qN at 45 °C, indicating a progressing photoinhibition of the photosynthetic apparatus.

Change of Photosynthetic Gas Exchange and Chlorophyll Fluorescence of Cd-Sensitive Mutant Rice in Response to Cd Stress

2013 ◽  
Vol 807-809 ◽  
pp. 336-341 ◽  
Author(s):  
Jun Yu He ◽  
Yan Fang Ren ◽  
Cheng Zhu ◽  
Dean Jiang
Keyword(s):  
Chlorophyll Fluorescence ◽  
Gas Exchange ◽  
Photochemical Efficiency ◽  
Dry Mass ◽  
Photochemical Quenching ◽  
Reaction Centre ◽  
Cd Stress ◽  
Wild Type ◽  
Photosynthetic Gas Exchange ◽  
Photochemical Efficiency Of Psii

The growth, photosynthetic gas exchange and chlorophyll fluorescence were investigated in wild type and mutant rice plants treated with 50 μmol L-1 Cd. The results showed that plant height, dry mass, and chlorophyll content decreased by Cd treatment, and the mutant showed more severe reduction than wild type rice. Net photosynthetic rate (Pn), transpiration rate (E), stomatal conductance (Gs), maximal photochemical efficiency of PSII (Fv/Fm), effective PSII quantum yield (ΦPS2), and photochemical quenching (qP) were decreased and intercellular CO2 concentration (Ci) and and non-photochemical quenching (qN) were enhanced in Cd-treated plants with the increasing of Cd exposure time, with changes in the mutant being more evident. The results suggest that Cd inhibits photosynthesis due to non-stomatal limitations and the response of PSII reaction centre and the mutant has less capacity of acclimation to Cd stress.

Cell structure properties during in situ creep experiments in the H.V.E.M.

1978 ◽  
Vol 36 (1) ◽  
pp. 574-575
Author(s):  
D. Caillard ◽  
J.L. Martin
Keyword(s):  
Tensile Axis ◽  
Cell Structure ◽  
Image Intensifier ◽  
Foil Thickness ◽  
Average Cell Size ◽  
Average Cell ◽  
Voltage Electron ◽  
Steady Stage ◽  
Stationary Creep

The behaviour of the dislocation substructure during the steady stage regime of creep, as well as its contribution to the creep rate, are poorly known. In particular, the stability of the subboundaries has been questioned recently, on the basis of experimental observations |1||2| and theoretical estimates |1||3|. In situ deformation experiments in the high voltage electron microscope are well adapted to the direct observation of this behaviour. We report here recent results on dislocation and subboundary properties during stationary creep of an aluminium polycristal at 200°C.During a macroscopic creep test at 200°C, a cell substructure is developed with an average cell size of a few microns. Microsamples are cut out of these specimens |4| with the same tensile axis, and then further deformed in the microscope at the same temperature and stain rate. At 1 MeV, one or a few cells can be observed in the foil thickness |5|. Low electron fluxes and an image intensifier were used to reduce radiation damage effects.

scholarly journals Morphological, thermal and mechanical properties of recycled HDPE foams via rotational molding

2021 ◽  
pp. 0021955X2110137
Author(s):  
Yao Dou ◽  
Denis Rodrigue
Keyword(s):  
Cell Density ◽  
Morphological Analysis ◽  
Mechanical Characterization ◽  
Gradual Increase ◽  
Thermal And Mechanical Properties ◽  
Rotational Molding ◽  
Average Cell Size ◽  
Average Cell ◽  
The Impact ◽  
Recycled Hdpe

In this study, foamed recycled high density polyethylene (rHDPE) parts were produced by rotational molding using different concentration (0 to 1% wt.) of a chemical blowing agent (CBA) based on azodicarbonamide. From the samples produced, a complete morphological, thermal and mechanical characterization was performed. The morphological analysis showed a gradual increase in the average cell size, while the cell density firstly increased and then decreased with increasing CBA content. As expected, increasing the CBA content decreased the foam density as well as the thermal conductivity. Although increasing the CBA content decreased both tensile and flexural properties, the impact strength showed a similar trend as the cell density with an optimum CBA content around 0.1% wt. Finally, neat rHDPE samples were also produced by compression molding. The results showed negligible differences between the rotomolded and compression molded properties indicating that optimal rotomolding conditions were selected. These results confirm the possibility of using 100% recycled polymers to produce rotomolded foam parts.

Characterization of microstructures of SAN foam core using micro-computed tomography

2021 ◽  
pp. 026248932110068
Author(s):  
Youming Chen ◽  
Raj Das ◽  
Hui Wang ◽  
Mark Battley
Keyword(s):  
Cell Wall ◽  
Cell Size ◽  
Wall Thickness ◽  
Strain Localization ◽  
Cell Wall Thickness ◽  
Micro Computed Tomography ◽  
Average Cell Size ◽  
Average Cell ◽  
3D Images ◽  
Compressive Tests

In this study, the microstructure of a SAN foam was imaged using a micro-CT scanner. Through image processing and analysis, variations in density, cell wall thickness and cell size in the foam were quantitatively explored. It is found that cells in the foam are not elongated in the thickness (or rise) direction of foam sheets, but rather equiaxed. Cell walls in the foam are significantly straight. Density, cell size and cell wall thickness all vary along the thickness direction of foam sheets. The low density in the vicinity of one face of foam sheets leads to low compressive stiffness and strength, resulting in the strain localization observed in our previous compressive tests. For M80, large open cells on the top face of foam sheets are likely to buckle in compressive tests, therefore being another potential contributor to the strain localization as well. The average cell wall thickness measured from 2D slice images is around 1.4 times that measured from 3D images, and the average cell size measured from 2D slice images is about 13.8% smaller than that measured from 3D images. The dispersions of cell wall thickness measured from 2D slice images are 1.16–1.20 times those measured from 3D images. The dispersions of cell size measured from 2D slice images are 1.12–1.36 times those measured from 3D images.

scholarly journals A Synergic Potential of Antimicrobial Peptides against Pseudomonas syringae pv. actinidiae

Molecules ◽  
2021 ◽  
Vol 26 (5) ◽  
pp. 1461
Author(s):  
Nuno Mariz-Ponte ◽  
Laura Regalado ◽  
Emil Gimranov ◽  
Natália Tassi ◽  
Luísa Moura ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Antimicrobial Peptides ◽  
Pseudomonas Syringae ◽  
Pathogenic Bacteria ◽  
High Efficiency ◽  
Bacterial Canker ◽  
Membrane Permeation ◽  
Flow Cytometry Analysis ◽  
Pathogenic Agent ◽  
Peptide Mixtures

Pseudomonas syringae pv. actinidiae (Psa) is the pathogenic agent responsible for the bacterial canker of kiwifruit (BCK) leading to major losses in kiwifruit productions. No effective treatments and measures have yet been found to control this disease. Despite antimicrobial peptides (AMPs) having been successfully used for the control of several pathogenic bacteria, few studies have focused on the use of AMPs against Psa. In this study, the potential of six AMPs (BP100, RW-BP100, CA-M, 3.1, D4E1, and Dhvar-5) to control Psa was investigated. The minimal inhibitory and bactericidal concentrations (MIC and MBC) were determined and membrane damaging capacity was evaluated by flow cytometry analysis. Among the tested AMPs, the higher inhibitory and bactericidal capacity was observed for BP100 and CA-M with MIC of 3.4 and 3.4–6.2 µM, respectively and MBC 3.4–10 µM for both. Flow cytometry assays suggested a faster membrane permeation for peptide 3.1, in comparison with the other AMPs studied. Peptide mixtures were also tested, disclosing the high efficiency of BP100:3.1 at low concentration to reduce Psa viability. These results highlight the potential interest of AMP mixtures against Psa, and 3.1 as an antimicrobial molecule that can improve other treatments in synergic action.

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