Degradation Of Chlorophyll-a Research Articles

Target of Rapamycin (TOR) negatively regulates chlorophyll degradation and lipid peroxidation and controls responses under abiotic stress in Arabidopsis thaliana

The Target of Rapamycin (TOR) is a conserved multifunctional Serine/ Threonine protein kinase present in all eukaryotes, which controls several important signaling pathways related to growth and development. In the present investigation, we report that TOR overexpressing Arabidopsis plants ATR-1.4.27, and ATR-3.7.32 exhibit enhanced tolerance to osmotic and salt stress treatments. The TOR overexpressing lines ATR-1.4.27, and ATR-3.7.32 treated with mannitol (100 mM), NaCl (150 mM), sorbitol (200 mM), and PEG (7% w/v), showed improved performance in root growth, fresh weight, and lateral root density. The transgenic lines also exhibited increased proline and chlorophyll contents along with the significant upregulation of stress-responsive genes compared with their corresponding treated and untreated wild-type (WT) controls. More than 90% degradation of chlorophyll-a, chlorophyll b, and total chlorophyll contents was observed in WT plants under each stress treatment, whereas the two transgenic lines had very low degradation ranging from 40% to 50%. Stress treated TOR-OE lines also showed decreased malondialdehyde (MDA) content, and high chlorophyll fluorescence of PhotosystemII (PSII; Fv/Fm ratio) compared with the treated WT control. Taken together, our results show that the constitutive overexpression of TOR enhances salt and osmotic stress tolerance in Arabidopsis thaliana.

Pre-oxidation with peracetic acid to degradation of chlorophyll-a from drinking water: A comparative study with calcium hypochlorite

Pre-treatment is a common operation in Water Treatment Plants (WTP) that addresses a pre-oxidation of raw water to remove this phytoplankton matter, before conventional water treatment processes. Currently, the most widely used oxidant is chlorine, but its application can lead to the formation of carcinogenic by-products such as trihalomethanes (THMs), which stimulates the search for substituents that have less toxicity. In this sense, this work used the peracetic acid (PAA) as an alternative to replace chlorine, using chlorophyll-a removal process as a performance parameter. For this study we have been made comparative tests between PAA and calcium hypochlorite using water raw with high concentration of chlorophyll-a. It was observed for the dosage of 4 mg.L−1 of both oxidants a removal of 97.7 % chlorophyll-a in the application of PAA and 98.3 % for calcium hypochlorite application, considering the same contact time (120 min). The use of APA, there was also a reduction in real color by 77 % for a concentration of 3 mg.L−1 and 44 % for a concentration of 4 mg.L−1 of APA. The use of calcium hypochlorite implied an increase in the color of the water from 2 mg.L−1.

One-Step Synthesis of b-N-TiO2/C Nanocomposites with High Visible Light Photocatalytic Activity to Degrade Microcystis aeruginosa

Black TiO2 with doped nitrogen and modified carbon (b-N-TiO2/C) were successfully prepared by sol-gel method in the presence of urea as a source of nitrogen and carbon. The photocatalysts were characterized by field emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman, electron paramagnetic resonance (EPR), and UV-vis diffuse reflectance spectra (DRS). The doped nitrogen, introduced defects, and modified carbon played a synergistic role in enhancing photocatalytic activity of b-N-TiO2/C for the degradation of chlorophyll-a in algae cells. The sample, with a proper amount of phase composition and oxygen vacancies, showed the highest efficiency to degrade chlorophyll-a, and the addition of H2O2 promoted this photocatalysis degradation. Based on the trapping experiments and electron spin resonance (ESR) signals, a photocatalytic mechanism of b-N-TiO2/C was proposed. In the photocatalytic degradation of chlorophyll-a, the major reactive species were identified as OH and O2−. This research may provide new insights into the photocatalytic inactivation of algae cells by composite photocatalysts.

Effect of certain Additives on the Degradation of Chlorophyll-A and Pheophytin-A in Aqueous KOH and Acetonitrile Media: A Kinetic Study

Effect of certain Additives on the Degradation of Chlorophyll-A and Pheophytin-A in Aqueous KOH and Acetonitrile Media: A Kinetic Study

Inhibitory effect and mechanism of linoleic acid sustained-release microspheres on Microcystis aeruginosa at different growth phases

Environment-friendly algaecides based on allelopathy have been extensively studied to control harmful algal blooms (HABs). The inhibitory effects of linoleic acid (LA) sustained-release microspheres on different cell densities of Microcystis aeruginosa (M. aeruginosa) at different growth phases were studied. The results showed that the growth of M. aeruginosa could be inhibited within 4 days and the constant inhibitory rate with initial algal density of 8 × 105 cells∙mL−1 (exponential phase) was up to 96% compared with control. The chlorophyll-a content in the treatment group had the same change trend with the algal density and declined significantly at day 20th, which suggested that the microspheres could promote the degradation of chlorophyll-a. The activities of superoxide dismutase (SOD) and catalase (CAT) increased gradually within 5 days but then declined sharply, which indicated that LA microspheres could cause oxidative damage to M. aeruginosa during the process of inhibition and reduce the activities of antioxidant enzymes. In addition, the concentration of oxygen free radical (O2−) increased at day 10th and rose constantly, and the content of malodialdehyde (MDA) increased to 2.7 times as much as control at day 20th. Furthermore, the content of protein, nucleic acid and the conductivity in culture solution showed a significant rise. These results showed that algal cell membrane lipid peroxidation occurred and the membrane permeability increased, accompanied by the damage of cell membrane. To sum up, the destruction of algal cell membrane is the main mechanism of LA microspheres inhibiting algal growth.

Isolation and Characterization of <i>Microcystis</i>-Grazing Protozoa P1 from Lake Dianchi

The incidence of algae blooms is increasing in China and worldwide, causing serious environmental problem. A protozoan P1 was isolated from the water samples of Lake Dianchi, which had potent grazing effect on some kind of cyanobacteria. It should be belonged to Ciliophore, Oligohymenophorea, Philasterida based on morphological characters observed by the optical microscope. The main influencing factors of the protozoan grazing properties including: algae species, protozoan density, culture temperature, time and pH value were investigated in batch experiments. The results showed that the protozoan P1 had strong ability to graze the cells of Microcystis wesenbergii. The greater the initial protozoan density, the faster the degradation of chlorophyll-a. The removal rate of chlorophyll-a after 4 days was 78% at the optimum temperature 25°C, pH 7 when using a lower inoculation quantity of 2%. The protozoan P1 was easy to cultivate and reproduce rapidly. It could be applied in the ecological environment to control the Microcystis water bloom.

Chlorophyll-a and pheopigments as tracers of labile organic carbon at the central equatorial Pacific seafloor

High rates of primary production and fast sinking rates lead to the deposition of phytodetritus and highly reactive organic matter to the sediments of the central equatorial Pacific. These substances are responsible for driving important chemical fluxes and fueling benthic organisms. Chloropigments have proven useful as tracers of similar highly reactive organic carbon components in lacustrine and nearshore marine sediments. In this study we investigate the degradation of chlorophyll-a and pheopigments-a at four abyssal sites on the JGOFS equatorial Pacific transect along 140°W and explore the usefulness of these chloropigments as tracers of the most-reactive component of the deep-sea particulate organic carbon (POC) rain. First-order reaction rate constants ( k = 1–75 yr −1, half-life 3–250 d) and relative reactivities (chlorophyll-a > allomer and pheophorbide-a > pheophytin-a) derived from most of the sedimentary profiles are similar to those found in laboratory and other field (lake and coastal marine) studies. However, in some profiles, the rate constants determined by fitting data below 0.5 cm are slower by up to 3 orders of magnitude despite an apparent abundance of bacteria, macrofauna, and porewater oxygen. Model results assuming multi-G kinetics suggest that these chloropigments degrade as two components: one, which accounts for at least 99% of the degradation and 11–57% of the sediment inventory, degrades with a half-life of 4–120 days. The other component degrades with a half-life of up to 440 years. These results suggest that some otherwise labile POC may be protected and escape rapid degradation near the sediment-water interface. If phytodetritus is deposited continuously throughout the year, our model-calculated chlorophyll-a fluxes indicate that it could account for 25–100% of the annual POC flux at sites close to the equator.

Degradation of chlorophyll-a by heating experiments : Implications for its early diagenesis in sediments

Degradation of chlorophyll-a by heating experiments : Implications for its early diagenesis in sediments

Correlations between the concentration of adenosine tri phosphate, chlorophyll degradation and the amounts of airborne heavy metals and sulphur in a transplanted lichen

The lichenRamalina duriaei (De Not.) Bagl. was transplanted to 12 biomonitoring sites during the period July1984–July 1985. The amounts of Ni, Cr, Cu, Zn, and Pb detected in the lichen thalli after the period of exposure, were compared with the ATP concentrations and the chlorophyll degradation in the same material. An inverse correlation between Pb, Cu, and ATP concentrations was found in the studied lichen. The degradation of chlorophylla to phaeophytina, as expressed by the ratio OD435/OD415 was inversely correlated with the amounts of Pb, Zn, Cu, and S in the lichen thallus. The amounts of the five heavy metals studied, were compared with those detected inR. duriaei transplanted to eight biomonitoring sites during the period 1979–1980. It is suggested that a regional increase in the amounts of Cr in the lichen exposed during the 1984/85 period is causally linked with emissions of Cr from the stacks of a new coal-fired power plant. The OD435/OD415 ratio was inversely correlated with the amounts of S in the lichen only in the material transplanted around the coal-fired power plant but not in the Tel Aviv area. No significant correlation was obtained between ATP and the amounts of S in the lichen.