Accessory Pigments Research Articles

Enhancement of Dunaliella salina growth by using wavelength shifting dyes

The availability of light is one of the key driving factors for photosynthesis. Chlorophyll and accessory pigments absorb light at some of the wavelengths present in the solar spectrum. If all other requirements are available in abundance, introducing more light to the system at wavelengths that can be absorbed will increase the growth rate of microalgae and the final biomass achieved up to the level of photosaturation. Therefore, the effect of shifting the spectrum of light available such that the photons unutilized in photosynthesis are converted to those that can be utilised was investigated. Spectral shifts converting UV light to blue light and green light to red light were carried out using films produced with Coumarin and Solvent Orange respectively. Dunaliella salina (CCAP 19-30) was grown in an airlift photobioreactor (ALB) which was coated with the wavelength shifting films. Dunaliella final biomass in the ALB, as determined by the optical density, were shown to increase by 36.9% for UV to blue light conversion and by 18.8% for green to red light conversion when using a coated ALB compared with an uncoated one.

A new fluorescent oligonucleotide probe for in-situ identification of Microcystis aeruginosa in freshwater

Cyanobacteria colonize different environments and blooms can occur in both contaminated and non-contaminated water bodies (freshwater, brackish and marine areas). Among 150 known cyanobacteria genera, >40 species are able to produce toxins, which are natural compounds that differ from both a chemical and toxicological point of view and are responsible for acute and chronic poisoning in animals and humans. Among the main classes of cyanotoxins, microcystins are frequently found in the environment. Fast and accurate methods for unequivocally identifying microcystin-producing cyanobacteria, such as Microcystis aeruginosa in water bodies, are necessary to distinguish them from other non-toxic cyanobacteria and to manage and monitor algal blooms. For this purpose, we designed, developed and validated an oligonucleotide probe for FISH (Fluorescence In Situ Hybridization) analysis to detect Microcystis aeruginosa at the species level even at relatively low concentrations in freshwater. The FISH probe, MicAerD03, was designed using the ARB software with the Silva database within the framework of the MicroCoKit project, also with the intention of adding it to the microarray from the EU project, μAQUA, for freshwater pathogens, which had only genus level probes for Microcystis.We tested various fixative methods to minimize the natural autofluorescence from chlorophyll-a and certain accessory pigments (viz., phycobilins and carotenoids). The FISH probe was tested on pure cultures of Microcystis aeruginosa, and then successfully applied to water samples collected from different sampling points of the Tiber River (Italy), using a laser confocal microscope. Subsequently, the probe was also conjugated at the 5′ end with horse-radish peroxidase (HRP-MicAerD03) to apply the CAtalysed Reported Deposition-FISH (CARD-FISH) for increasing the fluorescence signal of the mono-fluorescently labelled probe and make it possible to detect M. aeruginosa using an epifluorescence microscope. Samples taken within the EU MicroCokit project indicated that microarray signals for Microcystis were coming from single cells and not colonial cells. We confirmed this with the CARD-FISH protocol used here to validate the microarray signals for Microcystis detected at the genus level in MicroCokit.This paper provides a new early warning tool for investigating M. aeruginosa at the species level even at low cell concentrations in surface water, which can be added to the μAqua microarray for all freshwater pathogens to complete the probe hierarchy for Microcystis aeruginosa.

The influence of bio-optical properties of Emiliania huxleyi and Tetraselmis sp. on biomass and lipid production when exposed to different light spectra and intensities of an adjustable LED array and standard light sources

The effects of bio-optical characteristics on lipid and biomass production rates for Emiliania huxleyi and Tetraselmis sp. were studied under different irradiances and spectra. Biomass and lipid production increased from irradiances of 50–800 μE m−2 s−1 but differed for each spectrum. The highest biomass and neutral lipid production rates for E. huxleyi occurred under a red-blue LED array, which mimicked the absorption spectra of the cell’s chlorophyll a and accessory pigments, especially fucoxanthins. Biomass and neutral lipid production for Tetraselmis sp. were enhanced under broader spectra of cool white and grow lights. Neutral lipids per cell volume were similar for the two species and inversely proportional to chlorophyll a concentrations. High biomass and neutral lipid production rates were associated with high total quantum absorption and low quantum absorption per cell. Generally, quantum efficiencies were highest for high light treatments with high total quantum absorption and high production rates. Using reconstructed quantum absorption by pigments, the bio-optical model showed that photoprotective pigments were dependent on light intensity and spectra. Quantum efficiencies increased when excluding the contribution of photoprotective pigments to total quantum absorption since they did not directly contribute to photosynthesis, but did promote higher production rates.

Effects of different UV radiation on photoprotective pigments and antioxidant activity of the hot‐spring cyanobacterium Leptolyngbya cf. fragilis

SUMMARYUV‐induced synthesis/accumulation of photoprotective pigments and antioxidant activity were investigated in the hot‐spring cyanobacterium Leptolyngbya cf. fragilis. The results indicated that UV radiation may induce biosynthesis of carotenoids, allophycocyanin, phycoerythrin, and scytonemin while phycocyanin degrades in response to longtime UV radiation. Moreover, pigment composition of L. cf. fragilis was significantly altered with increasing UV radiation times, probably due to destruction and resynthesis of accessory pigments as an adaptation strategy to UV stress. The in vitro antioxidant analysis of different extracts of UV treated cyanobacteria exhibited concentration‐dependent antioxidant activity. Ethyl acetate extract of 72 h UV treatment showed maximum total antioxidant activity (IC50 = 71.73 ± 5.3 μg mL−1) followed by ethyl acetate control (non‐UV irradiated) extract (IC50 = 109.43 ± 2.76 μg mL−1). This is the first report for the UV‐induced synthesis of photoprotective pigments and their antioxidant activity in L. cf. fragilis.

Phycocyanin Enhances the Cytotoxic Profile of Cisplatin in Platinum‐Resistant Ovarian Cancer Cells by Targeting Focal Adhesion Kinase

Platinum‐based therapy is one of the major treatment approaches in ovarian cancer. Although greater than 80% of advanced stage ovarian cancer patients initially achieve remission with platinum therapy; the majority of this cohort eventually relapse, and develop drug‐resistant disease. Resistance to chemotherapeutic drugs such as cisplatin has been attributed in part to the overexpression of Focal Adhesion Kinase (FAK), which is known to promote cancer cell survival and metastasis. In recent years, there has been heightened interest in targeting focal adhesion kinase in platinum resistant cancer as a new modality in ovarian cancer treatment. In previous studies, we have reported that Phycocyanin (C‐PC), a major accessory pigment in the Limnothrix sp. 37‐2‐1, demonstrates cytotoxicity towards multiple cancer cell lines. Therefore, in the present study we evaluated the ability of C‐PC to sensitize platinum resistant OVCAR3 cells to cisplatin treatment. We also examined the response of FAK activation by phosphorylation, to treatment with cisplatin and CP‐C alone, and in combination (C‐PC +cisplatin). Cell viability was determined by MTT assay, and DNA fragmentation was used to confirm apoptotic cell death. The expression of phosphorylated FAK (pFAK), total FAK, pAKT, as well as the key apoptotic regulators p21, p53, Bax, and Bcl‐2 in response to the treatments were determined through western blotting. The results from our study confirm that C‐PC significantly enhances the cytotoxic profile of cisplatin in OVCAR‐3 cells through the induction of apoptosis as confirmed by the presence of DNA fragmentation patterns in all three treatment groups. The expression of activated pFAK was also significantly reduced in the CPC and CPC + cisplatin treatment groups and this corresponded with increased p53, p21 and Bax expression, while pAkt and Bcl‐2 expression was downregulated. These results confirm a novel effect of CPC on FAK phosphorylation in platinum resistant ovarian cancer, which can be further explored towards the treatment of advanced stage disease through combination strategies.Support or Funding InformationThis project was supported by The Royal Dames of Cancer Research Inc., Ft. Lauderdale, FloridaThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Lidar Monitoring of Chlorophyll a During the XXIX and XXXI Italian Antarctic Expeditions

Although it is known that the Ross Sea is responsible for more than a quarter of CO2 absorption of the Southern Ocean, more information is needed to model the primary production of this key area. In particular, it is necessary to improve the characterization of the size class distribution, biomass and taxonomic composition of phytoplankton in the Ross Sea. Recently, an innovative compact lidar fluorosensor was deployed for real-time sensing of chlorophyll a, during the Ross Sea Mesoscale Experiment (RoME), conducted in the XXIX (2014) and XXXI (2016) Italian Antarctic expeditions. Furthermore, high-performance liquid chromatography (HPLC) was also performed to provide pigment analysis of in situ samples. Lidar fluorosensors are laser-induced fluorescence (LIF) instruments and have been extensively operated by the Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA) since the 1990s to monitor water bodies. Spectra obtained with LIF contain signatures of phytoplankton pigments, chromophoric dissolved organic matter and dispersed impurities, such as crude oils. The study of algal pigments provides not only the phytoplankton biomass—directly linked to chlorophyll a—but also its taxonomic composition through detection of several accessory pigments. Moreover, some models allow the identification of phytoplankton size classes. Lidar and HPLC mapped the spatiotemporal distribution of algal biomass and showed that during RoME, the phytoplankton assemblage structure was dominated by large-size cells (micro-phytoplankton) and the prevailing algal groups were diatoms.

Photosynthetic pigments and vigour of rice (Oryza sativa L.) seedlings as affected by kinetin and prohexadione-calcium

In the present study effects of exogenous application of Kinetin (Kn @ 10, 20 and 40 mg/l) and Prohexadione calcium (BX-112 @ 5, 10 and 20 mg/l) were studied on rice (Oryza sativa L.) cultivars viz PB-2, PB-3 and PUSA 112. Different levels of Kn and BX-112 were applied to seedlings, five days after sowing (DAS). The content of photosynthetic pigments (total chlorophyll) was recorded at fourteen DAS stage, furthermore application of Kn significantly improved it in selected cultivars with more percent increase at 7 DAS. The content of accessory pigments (carotenoids) was recorded higher in both Kn as well as BX-112 treated sets. Kn application promoted vigour of rice seedlings in the selected cultivars with more pronounced effect in treatments involving higher concentration of Kn. BX-112 decreased both the vigour and relative growth rate (RGR) that led to reduction in growth of seedlings of all the three cultivars. This study revealed that though both Kn and BX-112 improved accumulation of photosynthetic pigments yet Kn application promoted growth and vigour of the seedlingswhile BX-112displayed an inhibitory effect on vigour of rice seedling.

Influence of Selenium on Growth, Antioxidants Production and Physiological Parameters of Rice (<i>Oryza sativa</i> L.) Seedlings and Its Possible Reversal by Coapplication of Sulphate

The effect of selenate (Na2SeO4) and sulphate (Na2SO4) was studied on growth and metabolism in two rice cultivars cv. satabdi and cv. khitish. Selenate at low concentration (2 μM) expressed growth promoting effect on rice seedlings as opposed to its high concentration (≥20 μM) where the test seedlings showed stunted growth with browning at the apices of both roots and shoots. The chlorophyll contents showed a dose dependent effect. Both chlorophyll a and chlorophyll b contents were inhibited with increase in selenate concentrations. The effect was more pronounced in cv. satabdi compared to cv. khitish.The level of accessory pigments was deferentially affected by selenium treatment. Simultaneously, the fluorescence intensity and Hill activity decreased with increase in selenate concentrations in the test seedlings. It is assumed that selenium plays a protective role in plants subjected to stress and prevents the formation of reactive oxygen species (ROS) in the cells. Higher selenate concentrations (≥20 μM) exerted variable effect on the activities of enzymatic antioxidants viz.; superoxide dismutase (SOD), catechol peroxidase (CPX) and catalase (CAT) in the test seedlings. The activity of SOD increased with increase in selenate concentrations, whereas activities of CAT and CPX decreased. Under high selenate concentrations, the levels of oxidative stress markers, viz.; proline, H2O2 and MDA were also enhanced. Selenium induced accumulation of total soluble sugar and increased the level of both reducing and non reducing sugars in both the test cultivars. The starch contents concomitantly decreased with rise in selenate concentrations. Moreover, the nutrient contents of test seedlings were significantly influenced by selenium. The Na and K levels gradually increased whereas Ca, Mg and Fe levels decreased on application of selenate. Joint application of 10 mM sulphate and selenate showed significant alterations on all parameters tested with respect to selenate treatment alone. Partial to complete amelioration occurred in the test seedlings treated with high concentrations of selenate and sulphate. Our study shows that selenium at low concentration had a stimulatory effect on growth and metabolism as against high concentrations which proved to be toxic to the rice seedlings obtained from both the cultivars. Effects were more pronounced in cv. satabdi than in cv. khitish which is considered to be comparatively tolerant to selenium. The dose dependent influence of selenium on the physiological and biochemical responses of test seedlings may be reversed by co-application with sulphate.

Effect of foliar application of Fe and banana peel waste biochar on growth, chlorophyll content and accessory pigments synthesis in spinach under chromium (IV) toxicity

Abstract Chromium (Cr) toxicity is becoming one of a major issue for the cultivation of crops. Toxicity of Cr directly affects synthesis of chlorophyll and restricts Fe intake, which decreases crop growth. It is well documented that the reduction of Cr toxicity through the application of biochar. However, current experiment was carried out to investigate any positive effect of, banana peel waste biochar (BC) and foliar application of Fe (FFe) on growth and chlorophyll content of Spinacia oleracea L. under different levels of Cr toxicity. Seeds of Spinacia oleracea L. were grown under three levels of Cr i.e. control (Cr0), Cr35 (35 mg Cr kg−1 soil) and Cr70 (70 mg Cr kg-1 soil). Analyzed data confirmed that Spinacia oleracea L. seeds grown in 1% BC amended soils and 1000mM FFe, showed significantly better growth, Fe uptake and chlorophyll content as compared to control at Cr35 and Cr70. A significant improvement in shoot length (16.9 and 26.9%), root length (16.3 and 20.9%), plant fresh (15.5 and 28.3%) and dry weight (70.3 and 77.8%) as compared to control under Cr35 and Cr70, respectively, validated the efficacious functioning of 1% BC and FFe to mitigate Cr toxicity in Spinacia oleracea L. It is concluded that both 1% banana peel waste BC and 1000mM FFe have potential but sole application of FFe is more effective to alleviate Cr toxicity in Spinacia oleracea L. Fortification of Fe by foliar application is more effective comparative to banana peel waste biochar for improvement in growth, chlorophyll content and accessory pigments synthesis in spinach under chromium (IV) toxicity.

Effect of Exogenous Application of Several Plant Growth Regulators on Photosynthetic Pigments of Fennel Plants

In order to investigate the effects of some plant growth regulators on photosynthetic pigments and growth of fennel plants, a greenhouse experiment was conducted based on the randomized complete block design with three replicates in 2017. Treatments were the application of methyl jasmonate (25, 50, 100 and 200 μM), putrescine (0.25, 0.5, 1 and 2 mM) and 24-Epibrassinolide at 0.001, 0.01, 0.1 and 1 μM and distilled water as a control. The results indicated that application of 0.5 Mm putrescine, exhibited significant effects on the chlorophyll a (62%), b (104%), total chlorophyll (72%), carotenoids (51%), flavonoids (51%), anthocyanin content (-14%), phenolic compounds (13%) and maximum quantum efficiency (17%) in dark condition and in light condition. Application of 24-Epibrassinolide resulted in a significant increase of chlorophyll a and total chlorophyll, carotenoids, phenol content, maximum quantum efficiency in the dark condition and photochemical quenching of fluorescence. The highest chlorophyll content and carotenoids were observed in treated plants with 0.1 µM 24-Epibrassinolide, while the maximum phenol content was obtained by application of 0.01 µM 24-Epibrassinolide. The application of methyl jasmonate significantly affected the major chlorophyll and accessory pigments (except phenol) of fennel. Plants treated with 50 µM methyl jasmonate exhibited higher concentrations of chlorophyll a (3.25 mg per g FW-1), total chlorophyll (4.35 mg per g FW-1), carotenoids (0.87 mg per g FW-1) and flavonoids (4.75 µg per g FW-1). A significant dry weight increased after the application of methyl jasmonate and it can be concluded that the most effective treatment in this regard for fennel plants was 50 µM methyl jasmonate.

Concentrations of Multiple Phytoplankton Pigments in the Global Oceans Obtained from Satellite Ocean Color Measurements with MERIS

The remote sensing of chlorophyll a concentration from ocean color satellites has been an essential variable quantifying phytoplankton in the past decades, yet estimation of accessory pigments from ocean color remote sensing data has remained largely elusive. In this study, we validated the concentrations of multiple pigments (Cpigs) retrieved from in situ and MEdium Resolution Imaging Spectrometer (MERIS) measured remote sensing reflectance (Rrs(λ)) in the global oceans. A multi-pigment inversion model (MuPI) was used to semi-analytically retrieve Cpigs from Rrs(λ). With a set of globally optimized parameters, the accuracy of the retrievals obtained with MuPI is quite promising. Compared with High-Performance Liquid Chromatography (HPLC) measurements near Bermuda, the concentrations of chlorophyll a, b, c ([Chl-a], [Chl-b], [Chl-c]), photoprotective carotenoids ([PPC]), and photosynthetic carotenoids ([PSC]) can be retrieved from MERIS data with a mean unbiased absolute percentage difference of 38%, 78%, 65%, 36%, and 47%, respectively. The advantage of the MuPI approach is the simultaneous retrievals of [Chl-a] and the accessory pigments [Chl-b], [Chl-c], [PPC], [PSC] from MERIS Rrs(λ) based on a closure between the input and output Rrs(λ) spectra. These results can greatly expand scientific studies of ocean biology and biogeochemistry of the global oceans that are not possible when the only available information is [Chl-a].

Parameterization of phytoplankton spectral absorption coefficients in the Baltic Sea: general, monthly and two-component variants of approximation formulas

Abstract. This paper presents approximate formulas (empirical equations) for parameterizing the coefficient of light absorption by phytoplankton aph(λ) in Baltic Sea surface waters. Over a thousand absorption spectra (in the 350–750 nm range), recorded during 9 years of research carried out in different months of the year and in various regions of the southern and central Baltic, were used to derive these parameterizations. The empirical material was characterized by a wide range of variability: the total chlorophyll a concentration (Tchl a) varied between 0.31 and 142 mg m−3, the ratio of the sum of all accessory pigment concentrations to chlorophyll a (∑Ci/Tchla) ranged between 0.21 and 1.5, and the absorption coefficients aph(λ) at individual light wavelengths varied over almost 3 orders of magnitude. Different versions of the parameterization formulas were derived on the basis of these data: a one-component parameterization in the “classic” form of a power function with Tchl a as the only variable and a two-component formula – the product of the power and exponential functions – with Tchl a and ∑Ci/Tchla as variables. We found distinct differences between the general version of the one-component parameterization and its variants derived for individual months of the year. In contrast to the general variant of parameterization, the new two-component variant takes account of the variability of pigment composition occurring throughout the year in Baltic phytoplankton populations.

Biophysical oceanography of tidally-extreme waters of the southern Kimberley coast, Western Australia

The continental shelf of the South Kimberley region of Western Australia is wide (~300 km) and interactions with the Indian Ocean culminate in extreme tides. This results in some of the largest tropical tides in the world (reaching 11 m on spring tide) measured in King Sound (KS), a large embayment which opens to the Indian Ocean. This remote area of Australia is very rich in natural resources and under increasing developmental pressures, but despite this the marine environment has been poorly studied. In Austral autumn (April/May) 2010, we examined phytoplankton biomass and production across four onshore-offshore transects from coastal waters (also within KS) to the 1000 m isobath, and their responses to physical and chemical environmental variables associated with tidal forces during a four week voyage aboard the RV Southern Surveyor. Using temperature and salinity relationships we found three distinct water masses; KS, Kimberley Shelf, and Kimberley Shelf break waters. The highest chlorophyll-a biomass in the study area was measured in a band along the 200 m isobath (27–46 mg Chl a m−2), and associated with greater concentrations of nutrients (332–392 mmol NO3- m−2, 650–823 mmol Si m−2, 21–39 mmol PO43- m−2). Phytoplankton biomass inside KS was dominated by large diatoms (as determined from accessory pigment analyses), shifting to a community largely comprised of picophytoplankton offshore. Rates of primary production (PP) on the shelf, via measurements of phytoplankton carbon (14C) uptake from photosynthesis versus irradiance incubations, decreased from coastal areas (222–560 mg C m−2 d−1) to offshore waters (45–78 mg C m−2 d−1). In KS, PP was highest (1692 mg C m−2 d−1) despite low standing stock nutrient concentrations (0.02–1.5 mmol NO3- m−2) and relatively high concentrations of suspended particulate material reducing light availability (Kd = 0.27 m−1).

Phytoplankton pigment pattern in the subsurface chlorophyll maximum in the South Java coastal upwelling system, Indonesia

Upwelling occurs on the coast of Java between June and October, forced by local alongshore winds associated with the southeasterly monsoon. This causes variations in phytoplankton community composition in the upwelling zone compared with the surrounding offshore area. Based on pigments analysis with subsequent calculations of group contributions to total chlorophyll a (Chl a) using CHEMTAX, we studied the distribution and composition of phytoplankton assemblages in the subsurface chlorophyll maximum along the south coast of Java and the influence of upwelling. Nineteen phytoplankton pigments were identified using high-performance liquid chromatography, and CHEMTAX analysis associated these to ten major phytoplankton groups. The phytoplankton community in the coastal area influenced by upwelling was characterized by high Chl a and fucoxanthin concentrations, indicating the dominance of diatoms. In contrast, in the offshore area, the Chl a and fucoxanthin concentrations declined to very low levels and the community was dominated by haptophytes represented by 19′-Hexanoyloxyfucoxanthin. Accordingly, microphytoplankton was found to be the major size class in the coastal area influenced by upwelling, while nanophytoplankton was most abundant in the offshore area. Low concentrations of other accessory pigments indicated less contribution from dinoflagellates, prasinophytes, chlorophytes and cryptophytes. Photo-pigment indices revealed that photosynthetic carotenoids (PSCs) were the largest component of the pigment pool, exceeding the proportion of Chl a, with the average PSCTP up to 0.62. These distribution trends can mainly be explained by phytoplankton adaption strategies to upwelling and subsurface conditions by changing species composition and adjusting the pigment pool.

A comparative study of phycobilliprotein production in two strains of Pseudanabaena isolated from Arctic and tropical regions in relation to different light wavelengths and photoperiods

Phycobiliproteins, which include phycocyanin, allophycocyanin and phycoerythrin, are the group of coloured accessory photosynthetic pigments present in cyanobacteria (blue-green algae). Pseudanabaena is a genus of microscopic cyanobacteria, cosmopolitan in distribution and known to be rich in phycoerythrins. Cyanobacteria are photosynthetic organisms, thus, one of the factors that influences their metabolism is the quality and quantity of incident light. In order to determine the production of phycobiliproteins (mainly phycocyanin and phycoerythrin) in this genus, the quantity of these pigments was investigated in two different strains of Pseudanabaena, P. catenata USMAC16 isolated from an Arctic location (Svalbard) and P. amphigranulata USMAC18 from a tropical location (Tasik Harapan, USM, Malaysia). The aims of this study were twofold. First, to determine the influence of different light wavelengths (white, green and red) and exposure duration (photoperiod of 12–24 h (h)) on phycocyanin and phycoerythrin production in the two strains. Second, to compare the production of phycobiliprotein between the two strains. Highest phycocyanin production was obtained under red light, while phycoerythrin production was highest under green light. Highest production was achieved with photoperiod 24:00 h L:D (L: light, D: dark) in the polar strain and 12:12 h L: D in the tropical strain. P. catenata (Arctic strain) was a good producer of phycoerythrin when grown under green light.

Effects of Astaxanthin on the Proliferation and Migration of Breast Cancer Cells In Vitro.

Astaxanthin (ASX) is a marine-based ketocarotenoid; an accessory pigment in plants in that it has many different potential functions. ASX is an antioxidant that is notably more potent than many other antioxidants. Antioxidants have anti-inflammatory and oxidative stress-reducing properties to potentially reduce the incidence of cancer or inhibit the expansion of tumor cells. In this study, we tested the hypothesis that ASX would inhibit proliferation and migration of breast cancer cells in vitro. We found that application of ASX significantly reduced proliferation rates and inhibited breast cancer cell migration compared to control normal breast epithelial cells. Based on these results, further investigation of the effects of ASX on not only breast cancer cells, but other forms of tumor cells, should be carried out.

Morphology, ultrastructure, and molecular phylogeny of Wangodinium sinense gen. et sp. nov. (Gymnodiniales, Dinophyceae) and revisiting of Gymnodinium dorsalisulcum and Gymnodinium impudicum.

The genus Gymnodinium includes many morphologically similar species, but molecular phylogenies show that it is polyphyletic. Eight strains of Gymnodinium impudicum, Gymnodinium dorsalisulcum and a novel Gymnodinium-like species from Chinese and Malaysian waters and the Mediterranean Sea were established. All of these strains were examined with light microscopy, scanning electron microscopy and transmission electron microscopy. SSU, LSU and internal transcribed spacers rDNA sequences were obtained. A new genus, Wangodinium, was erected to incorporate strains with a loop-shaped apical structure complex (ASC) comprising two rows of amphiesmal vesicles, here referred to as a new type of ASC. The chloroplasts of Wangodinium sinense are enveloped by two membranes. Pigment analysis shows that peridinin is the main accessory pigment in W.sinense. Wangodinium differs from other genera mainly in its unique ASC, and additionally differs from Gymnodinium in the absence of nuclear chambers, and from Lepidodinium in the absence of Chl b and nuclear chambers. New morphological information was provided for G.dorsalisulcum and G.impudicum, e.g., a short sulcal intrusion in G.dorsalisulcum; nuclear chambers in G.impudicum and G.dorsalisulcum; and a chloroplast enveloped by two membranes in G.impudicum. Molecular phylogeny was inferred using maximum likelihood and Bayesian inference with independent SSU and LSU rDNA sequences. Our results support the classification of Wangodinium within the Gymnodiniales sensu stricto clade and it is close to Lepidodinium. Our results also support the close relationship among G.dorsalisulcum, G.impudicum, and Barrufeta. Further research is needed to assign these Gymnodinium species to Barrufeta or to erect new genera.

Exogenous application of calcium to 24-epibrassinosteroid pre-treated tomato seedlings mitigates NaCl toxicity by modifying ascorbate\u2013glutathione cycle and secondary metabolites

The present study tested the efficacy of 24-epibrassinolide (EBL) and calcium (Ca) for mediating salinity tolerance in tomato. Salinity stress affected the morphological parameters of tomato as well as leaf relative water content (LRWC), photosynthetic and accessory pigments, leaf gas exchange parameters, chlorophyll fluorescence and the uptake of essential macronutrients. The salt (NaCl) treatment induced oxidative stress in the form of increased Na+ ion concentration by 146%, electrolyte leakage (EL) by 61.11%, lipid peroxidation (MDA) 167% and hydrogen peroxide (H2O2) content by 175%. Salt stress also enhanced antioxidant enzyme activities including those in the ascorbate–glutathione cycle. Plants treated with EBL or Ca after salt exposure mitigated the ill effects of salt stress, including oxidative stress, by reducing the uptake of Na+ ions by 52%. The combined dose of EBL + Ca reversed the salt-induced changes through an elevated pool of enzymes in the ascorbate–glutathione cycle, other antioxidants (superoxide dismutase, catalase), and osmoprotectants (proline, glycine betaine). Exogenously applied EBL and Ca help to optimize mineral nutrient status and enable tomato plants to tolerate salt toxicity. The ability of tomato plants to tolerate salt stress when supplemented with EBL and Ca was attributed to modifications to enzymatic and non-enzymatic antioxidants, osmolytes and metabolites.

Natural dye extracts from fruit peels as sensitizer in ZnO-based dye-sensitized solar cells

As a result of twin problems of environmental pollution and continuous depletion of fossil fuels, a search for renewable and clean energy sources is necessary. This paper discusses the simple extraction techniques without any further purification of natural dyes from some fruit peels and their performance in DSSCs. Natural dyes extracted from fruit peels of Carica papaya, Citrus lanatus, Persea americana and Solanum melongena were used as sensitizers to fabricate ZnO-based dye-sensitized solar cells (DSSCs). The extracts of the natural dyes were characterized and studied using UV-Vis absorption spectroscopy, Fourier transforms infra-red (FTIR) and Photoluminescence (PL) spectroscopy. The photo-anode semiconductor material was prepared and characterized. The photo-voltaic characteristics of the fabricated DSSCs were measured under simulated solar light (power of incident light 100 mWcm-2 from Air Mass 1.5G). These studies indicated the presence of pheophytin ‘a’ in most of the extracts studied as the main pigments with other accessory pigments. The solar to electric conversion efficiencies for the pheophytin ‘a’ dye based solar cells are estimated as 0.017%, 0.013%, 0.010% and 0.011% for Carica papaya, Citrus lanatus, Persea americana and Solanum melongena, respectively. The dye extracts from Carica papaya exhibits higher photo-sensitized performance compared to the other extracts and this is due to the better charge transfer between the dyes of Carica papaya and ZnO photo-anode surface. Conversion of visible light into electricity was accomplished with natural dyes and ZnO-based DSSCs, resulting in excellent photo-electric properties compared to those in literature.

Karlodinium zhouanum, a new dinoflagellate species from China, and molecular phylogeny of Karenia digitata and Karenia longicanalis (Gymnodiniales, Dinophyceae)

:Little is known about the diversity and biogeography of the toxigenic dinoflagellate genera Karlodinium and Karenia because their cells are unarmoured and often small. We isolated single cells from Chinese waters to establish five Karlodinium cultures, and carried out single-cell polymerase chain reactions of eight cells of Karlodinium and Karenia isolated directly from field samples. We also obtained large-subunit (LSU) ribosomal DNA and internal transcribed spacer (ITS) sequences from the same samples used for descriptions of Karenia digitata and Karenia longicanalis. Five cultures of Karlodinium from the South China Sea and Yellow Sea of China were established and subjected to light, scanning electron, and transmission electron microscopy. These strains had a sulcal intrusion, a short apical groove, and six chloroplasts, each with an internal lenticular pyrenoid, but lacked a ventral pore. Pigment analysis showed that fucoxanthin was the main accessory pigment. On the basis of unique morphology and corroboration by molecular phylogeny, these strains were described as Karlodinium zhouanum sp. nov. LSU or ITS sequences (or both) of another eight cells revealed the presence of Karlodinium australe, Karenia longicanalis, and K. papilionacea in the East China Sea for the first time. LSU sequences showed that Karenia digitata differed from Karlodinium decipiens at only one position (99.86% similarity), and Karenia longicanalis differed from K. umbella at only four positions (99.45% similarity). Maximum-likelihood and Bayesian inference analyses supported the classification of Karenia digitata within Karlodinium, and demonstrated that presence of a ventral pore was not a reliable generic character for Karlodinium. Our results also indicated that LSU sequences might be too conservative to differentiate species of Karenia and Karlodinium.