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Journal articles on the topic 'Marine photosynthetic plants'
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1
Beer, Sven. "THE ACQUISITION OF INORGANIC CARBON IN MARINE MACROPHYTES." Israel Journal of Plant Sciences 46, no. 2 (May 13, 1998): 83–87. http://dx.doi.org/10.1080/07929978.1998.10676714.
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The low diffusion rates of solutes in water call for a separation of photosynthetic carbon acquirement in aquatic plants into carbon transport and the subsequent photosynthetic reduction of CO2. This paper will focus on the transport of inorganic carbon from the external medium to the site of fixation in marine macrophytes. In accord with the much higher concentration of HCO3− than of CO2 in seawater, most marine macrophytes can utilize the ionic carbon form for their photosynthetic needs. The two known ways of HCO, utilization are (a) via extracellular, carbonic anhydrase catalyzed dehydration of HCO3− to form CO2, which then diffuses into the photosynthesizing cells, and (b) by direct uptake via a transporter. While the first way may be sufficient to support low rates of photosynthesis in temperate regions, it is viewed as futile under situations where high temperatures and irradiances would cause a high pH to form close to the uptake site of carbon and where, consequently, the CO2/HCO3− ratio would be very low. Therefore, it may well be that the direct HCO3− uptake mechanism described for Ulva from more tropical regions confers an adaptational advantage under conditions conducive to higher photosynthetic rates.
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Rasmusson, Lina M., Aekkaraj Nualla-ong, Tarawit Wutiruk, Mats Björk, Martin Gullström, and Pimchanok Buapet. "Sensitivity of Photosynthesis to Warming in Two Similar Species of the Aquatic Angiosperm Ruppia from Tropical and Temperate Habitats." Sustainability 13, no. 16 (August 23, 2021): 9433. http://dx.doi.org/10.3390/su13169433.
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Climate change-related events, such as marine heatwaves, are increasing seawater temperatures, thereby putting pressure on marine biota. The cosmopolitan distribution and significant contribution to marine primary production by the genus Ruppia makes them interesting organisms to study thermal tolerance and local adaptation. In this study, we investigated the photosynthetic responses in Ruppia to the predicted future warming in two contrasting bioregions, temperate Sweden and tropical Thailand. Through DNA barcoding, specimens were determined to Ruppia cirrhosa for Sweden and Ruppia maritima for Thailand. Photosynthetic responses were assessed using pulse amplitude-modulated fluorometry, firstly in short time incubations at 18, 23, 28, and 33 °C in the Swedish set-up and 28, 33, 38, and 43 °C in the Thai set-up. Subsequent experiments were conducted to compare the short time effects to longer, five-day incubations in 28 °C for Swedish plants and 40 °C for Thai plants. Swedish R. cirrhosa displayed minor response, while Thai R. maritima was more sensitive to both direct and prolonged temperature stress with a drastic decrease in the photosynthetic parameters leading to mortality. The results indicate that in predicted warming scenarios, Swedish R. cirrhosa may sustain an efficient photosynthesis and potentially outcompete more heat-sensitive species. However, populations of the similar R. maritima in tropical environments may suffer a decline as their productivity will be highly reduced.
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Economou, G., E. D. Christou, A. Giannakourou, E. Gerasopoulos, D. Georgopoulos, V. Kotoulas, D. Lyra, et al. "Eclipse effects on field crops and marine zooplankton: the 29 March 2006 total solar eclipse." Atmospheric Chemistry and Physics 8, no. 16 (August 12, 2008): 4665–76. http://dx.doi.org/10.5194/acp-8-4665-2008.
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Abstract. Some effects in the biosphere from the Total Solar Eclipse of 29 March 2006 were investigated in field crops and marine zooplankton. Taking into account the decisive role of light on plant life and productivity, measurements of photosynthesis and stomatal behaviour were conducted on seven important field-grown cereal and leguminous crops. A drop in photosynthetic rates, by more than a factor of 5 in some cases, was observed, and the minimum values of photosynthetic rates ranged between 3.13 and 10.13 μmol CO2 m−2 s−1. The drop in solar irradiance and the increase in mesophyll CO2-concentration during the eclipse did not induce stomatal closure thus not blocking CO2 uptake by plants. Light effects on the photochemical phase of photosynthesis may be responsible for the observed depression in photosynthetic rates. Field studies addressing the migratory responses of marine zooplankton (micro-zooplankton (ciliates), and meso-zooplankton) due to the rapid changes in underwater light intensity were also performed. The light intensity attenuation was simulated with the use of accurate underwater radiative transfer modeling techniques. Ciliates, responded to the rapid decrease in light intensity during the eclipse adopting night-time behaviour. From the meso-zooplankton assemblage, various vertical migratory behaviours were adopted by different species.
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Economou, G., E. D. Christou, A. Giannakourou, E. Gerasopoulos, D. Georgopoulos, V. Kotoulas, D. Lyra, et al. "Eclipse effects on field crops and marine zooplankton: the 29 March 2006 Total Solar Eclipse." Atmospheric Chemistry and Physics Discussions 8, no. 1 (January 25, 2008): 1291–320. http://dx.doi.org/10.5194/acpd-8-1291-2008.
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Abstract. The effects in the biosphere from the Total Solar Eclipse of 29 March 2006 were investigated in field crops and marine zooplankton. Taking into account the decisive role of light on the photoenergetic and photoregulatory plant processes, measurements of photosynthesis and stomatal behaviour were conducted on seven important field-grown cereal and leguminous crops. A drop in photosynthetic rates, by more than a factor of 5 in some cases, was observed, and the minimum values of photosynthetic rates ranged between 3.13 and 10.13 μmol CO2 m−2 s−1. However, since solar irradiance attenuation has not at the same time induced stomatal closure thus not blocking CO2 uptake by plants, it is probably other endogenous factors that has been responsible for the observed fall in photosynthetic rates. Field studies addressing the migratory responses of marine zooplankton (micro-zooplankton (ciliates), and meso-zooplankton) due to the rapid changes in underwater light intensity were also performed. The light intensity attenuation was simulated with the use of accurate underwater radiative transfer modeling techniques. Ciliates, responded to the rapid decrease in light intensity during the eclipse adopting night-time behaviour. From the meso-zooplankton assemblage, various vertical migratory behaviours were adopted by different species.
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Genç, Yasin, Hilal Bardakci, Çiğdem Yücel, Gökçe Şeker Karatoprak, Esra Küpeli Akkol, Timur Hakan Barak, and Eduardo Sobarzo-Sánchez. "Oxidative Stress and Marine Carotenoids: Application by Using Nanoformulations." Marine Drugs 18, no. 8 (August 13, 2020): 423. http://dx.doi.org/10.3390/md18080423.
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Carotenoids are natural fat-soluble pigments synthesized by plants, algae, fungi and microorganisms. They are responsible for the coloration of different photosynthetic organisms. Although they play a role in photosynthesis, they are also present in non-photosynthetic plant tissues, fungi, and bacteria. These metabolites have mainly been used in food, cosmetics, and the pharmaceutical industry. In addition to their utilization as pigmentation, they have significant therapeutically applications, such as improving immune system and preventing neurodegenerative diseases. Primarily, they have attracted attention due to their antioxidant activity. Several statistical investigations indicated an association between the use of carotenoids in diets and a decreased incidence of cancer types, suggesting the antioxidant properties of these compounds as an important factor in the scope of the studies against oxidative stress. Unusual marine environments are associated with a great chemical diversity, resulting in novel bioactive molecules. Thus, marine organisms may represent an important source of novel biologically active substances for the development of therapeutics. Marine carotenoids (astaxanthin, fucoxanthin, β-carotene, lutein but also the rare siphonaxanthin, sioxanthin, and myxol) have recently shown antioxidant properties in reducing oxidative stress markers. Numerous of bioactive compounds such as marine carotenoids have low stability, are poorly absorbed, and own very limited bioavailability. The new technique is nanoencapsulation, which can be used to preserve marine carotenoids and their original properties during processing, storage, improve their physiochemical properties and increase their health-promoting effects. This review aims to describe the role of marine carotenoids, their potential applications and different types of advanced nanoformulations preventing and treating oxidative stress related disorders.
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Raven, John A., and John Beardall. "Energizing the plasmalemma of marine photosynthetic organisms: the role of primary active transport." Journal of the Marine Biological Association of the United Kingdom 100, no. 3 (April 13, 2020): 333–46. http://dx.doi.org/10.1017/s0025315420000211.
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AbstractGeneration of ion electrochemical potential differences by primary active transport can involve energy inputs from light, from exergonic redox reactions and from exergonic ATP hydrolysis. These electrochemical potential differences are important for homoeostasis, for signalling, and for energizing nutrient influx. The three main ions involved are H+, Na+ (efflux) and Cl− (influx). In prokaryotes, fluxes of all three of these ions are energized by ion-pumping rhodopsins, with one archaeal rhodopsin pumping H+into the cells; among eukaryotes there is also an H+ influx rhodopsin in Acetabularia and (probably) H+ efflux in diatoms. Bacteriochlorophyll-based photoreactions export H+ from the cytosol in some anoxygenic photosynthetic bacteria, but chlorophyll-based photoreactions in marine cyanobacteria do not lead to export of H+. Exergonic redox reactions export H+ and Na+ in photosynthetic bacteria, and possibly H+ in eukaryotic algae. P-type H+- and/or Na+-ATPases occur in almost all of the photosynthetic marine organisms examined. P-type H+-efflux ATPases occur in charophycean marine algae and flowering plants whereas P-type Na+-ATPases predominate in other marine green algae and non-green algae, possibly with H+-ATPases in some cases. An F-type Cl−-ATPase is known to occur in Acetabularia. Some assignments, on the basis of genomic evidence, of P-type ATPases to H+ or Na+ as the pumped ion are inconclusive.
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Schorsch, Michael, Manuela Kramer, Tatjana Goss, Marion Eisenhut, Nigel Robinson, Deenah Osman, Annegret Wilde, et al. "A unique ferredoxin acts as a player in the low-iron response of photosynthetic organisms." Proceedings of the National Academy of Sciences 115, no. 51 (December 4, 2018): E12111—E12120. http://dx.doi.org/10.1073/pnas.1810379115.
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Iron chronically limits aquatic photosynthesis, especially in marine environments, and the correct perception and maintenance of iron homeostasis in photosynthetic bacteria, including cyanobacteria, is therefore of global significance. Multiple adaptive mechanisms, responsive promoters, and posttranscriptional regulators have been identified, which allow cyanobacteria to respond to changing iron concentrations. However, many factors remain unclear, in particular, how iron status is perceived within the cell. Here we describe a cyanobacterial ferredoxin (Fed2), with a unique C-terminal extension, that acts as a player in iron perception. Fed2 homologs are highly conserved in photosynthetic organisms from cyanobacteria to higher plants, and, although they belong to the plant type ferredoxin family of [2Fe-2S] photosynthetic electron carriers, they are not involved in photosynthetic electron transport. As deletion offed2appears lethal, we developed a C-terminal truncation system to attenuate protein function. Disturbed Fed2 function resulted in decreased chlorophyll accumulation, and this was exaggerated in iron-depleted medium, where different truncations led to either exaggerated or weaker responses to low iron. Despite this, iron concentrations remained the same, or were elevated in all truncation mutants. Further analysis established that, when Fed2 function was perturbed, the classical iron limitation marker IsiA failed to accumulate at transcript and protein levels. By contrast, abundance of IsiB, which shares an operon withisiA, was unaffected by loss of Fed2 function, pinpointing the site of Fed2 action in iron perception to the level of posttranscriptional regulation.
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Hackenberg, Claudia, Johanna Hakanpää, Fei Cai, Svetlana Antonyuk, Caroline Eigner, Sven Meissner, Mikko Laitaoja, et al. "Structural and functional insights into the unique CBS–CP12 fusion protein family in cyanobacteria." Proceedings of the National Academy of Sciences 115, no. 27 (June 18, 2018): 7141–46. http://dx.doi.org/10.1073/pnas.1806668115.
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Cyanobacteria are important photosynthetic organisms inhabiting a range of dynamic environments. This phylum is distinctive among photosynthetic organisms in containing genes encoding uncharacterized cystathionine β-synthase (CBS)–chloroplast protein (CP12) fusion proteins. These consist of two domains, each recognized as stand-alone photosynthetic regulators with different functions described in cyanobacteria (CP12) and plants (CP12 and CBSX). Here we show that CBS–CP12 fusion proteins are encoded in distinct gene neighborhoods, several unrelated to photosynthesis. Most frequently, CBS–CP12 genes are in a gene cluster with thioredoxin A (TrxA), which is prevalent in bloom-forming, marine symbiotic, and benthic mat cyanobacteria. Focusing on a CBS–CP12 fromMicrocystis aeruginosaPCC 7806 encoded in a gene cluster with TrxA, we reveal that the domain fusion led to the formation of a hexameric protein. We show that the CP12 domain is essential for hexamerization and contains an ordered, previously structurally uncharacterized N-terminal region. We provide evidence that CBS–CP12, while combining properties of both regulatory domains, behaves different from CP12 and plant CBSX. It does not form a ternary complex with phosphoribulokinase (PRK) and glyceraldehyde-3-phosphate dehydrogenase. Instead, CBS–CP12 decreases the activity of PRK in an AMP-dependent manner. We propose that the novel domain architecture and oligomeric state of CBS–CP12 expand its regulatory function beyond those of CP12 in cyanobacteria.
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Levitan, Orly, Muyuan Chen, Xuyuan Kuang, Kuan Yu Cheong, Jennifer Jiang, Melissa Banal, Nikhita Nambiar, et al. "Structural and functional analyses of photosystem II in the marine diatom Phaeodactylum tricornutum." Proceedings of the National Academy of Sciences 116, no. 35 (August 13, 2019): 17316–22. http://dx.doi.org/10.1073/pnas.1906726116.
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A descendant of the red algal lineage, diatoms are unicellular eukaryotic algae characterized by thylakoid membranes that lack the spatial differentiation of stroma and grana stacks found in green algae and higher plants. While the photophysiology of diatoms has been studied extensively, very little is known about the spatial organization of the multimeric photosynthetic protein complexes within their thylakoid membranes. Here, using cryo-electron tomography, proteomics, and biophysical analyses, we elucidate the macromolecular composition, architecture, and spatial distribution of photosystem II complexes in diatom thylakoid membranes. Structural analyses reveal 2 distinct photosystem II populations: loose clusters of complexes associated with antenna proteins and compact 2D crystalline arrays of dimeric cores. Biophysical measurements reveal only 1 photosystem II functional absorption cross section, suggesting that only the former population is photosynthetically active. The tomographic data indicate that the arrays of photosystem II cores are physically separated from those associated with antenna proteins. We hypothesize that the islands of photosystem cores are repair stations, where photodamaged proteins can be replaced. Our results strongly imply convergent evolution between the red and the green photosynthetic lineages toward spatial segregation of dynamic, functional microdomains of photosystem II supercomplexes.
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Bowes, George, Srinath K. Rao, Gonzalo M. Estavillo, and Julia B. Reiskind. "C4 mechanisms in aquatic angiosperms: comparisons with terrestrial C4 systems." Functional Plant Biology 29, no. 3 (2002): 379. http://dx.doi.org/10.1071/pp01219.
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Aquatic C4 photosynthesis probably arose in response to dissolved CO2 limitations, possibly before its advent in terrestrial plants. Of over 7600 C4 species, only about a dozen aquatic species are identified. Amphibious Eleocharis species (sedges) have C3–C4 photosynthesis and Kranz anatomy in aerial, but not submersed, leaves. Aquatic grasses have aerial and submersed leaves with C4 or C3–C4 photosynthesis and Kranz anatomy, but some lack Kranz anatomy in the submersed leaves. Two freshwater submersed monocots, Hydrilla verticillata and possibly Egeria densa, are C4 NADP-malic enzyme (NADP-ME) species. A marine macroalga, Udotea flabellum (Chlorophyta), and possibly a diatom, are C4, so it is not confined to angiosperms. Submersed C4 species differ from terrestrial in that β-carboxylation is cytosolic with chloroplastic decarboxylation and Rubisco carboxylation, so the C4 and Calvin cycles operate in the same cell without Kranz anatomy. Unlike terrestrial plants, Hydrilla is a facultative C4 that shifts from C3 to C4 in low [CO2]. It is well documented, with C4 gas exchange and pulse-chase characteristics, enzyme kinetics and localization, high internal [CO2], relative growth rate, and quantum yield studies. It has multiple phosphoenolpyruvate carboxylase isoforms with C3-like sequences. Hvpepc4 appears to be the photosynthetic form induced in C4 leaves, but it differs from terrestrial C4 isoforms in lacking a C4 signature Serine. The molecular mass of NADP-ME (72 kDa) also resembles a C3 isoform. Hydrilla belongs to the ancient Hydrocharitaceae family, and gives insight to early C4 development. Hydrilla is an excellent ‘minimalist’ system to study C4 photosynthesis regulation without anatomical complexities.
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Dautermann, O., D. Lyska, J. Andersen-Ranberg, M. Becker, J. Fröhlich-Nowoisky, H. Gartmann, L. C. Krämer, et al. "An algal enzyme required for biosynthesis of the most abundant marine carotenoids." Science Advances 6, no. 10 (March 2020): eaaw9183. http://dx.doi.org/10.1126/sciadv.aaw9183.
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Fucoxanthin and its derivatives are the main light-harvesting pigments in the photosynthetic apparatus of many chromalveolate algae and represent the most abundant carotenoids in the world’s oceans, thus being major facilitators of marine primary production. A central step in fucoxanthin biosynthesis that has been elusive so far is the conversion of violaxanthin to neoxanthin. Here, we show that in chromalveolates, this reaction is catalyzed by violaxanthin de-epoxidase–like (VDL) proteins and that VDL is also involved in the formation of other light-harvesting carotenoids such as peridinin or vaucheriaxanthin. VDL is closely related to the photoprotective enzyme violaxanthin de-epoxidase that operates in plants and most algae, revealing that in major phyla of marine algae, an ancient gene duplication triggered the evolution of carotenoid functions beyond photoprotection toward light harvesting.
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Sebök, Stefan, Werner B. Herppich, and Dieter Hanelt. "Outdoor cultivation of Ulva lactuca in a recently developed ring-shaped photobioreactor: effects of elevated CO2 concentration on growth and photosynthetic performance." Botanica Marina 62, no. 2 (April 24, 2019): 179–90. http://dx.doi.org/10.1515/bot-2018-0016.
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Abstract Land-based cultivation of marine macroalgae may open up the possibility to produce high quality algal biomass as required in various application areas all year round. In this context, the potential of a recently developed ring-shaped cultivation system with algae moving in a circular way, simulating the movement pattern in a standard tank cultivation vessel was evaluated using the green alga Ulva lactuca. Plants were cultivated under outdoor conditions at ambient (37 μmol CO2 kg−1 seawater) and increased CO2 concentration (152 μmol CO2 kg−1 seawater). Biomass growth and photosynthetic performance of algae were analyzed over a test period of 7 d. Elevated CO2 concentration significantly stimulated algal growth and also helped to compensate the effects of environmental stress conditions. This was indicated by the predominant stability of photosynthetic competence and represented by maximum photosynthetic electron transport rates, efficiency of light-harvesting and photon fluence rates (PFR) saturating photosynthetic electron transport at low PFR. At high PFR, no difference in photosynthetic competence was detected between algae cultivated at the high CO2-concentration and those grown at ambient CO2. Under elevated CO2 concentrations, photochemical energy dissipation decreased more distinctly at low PFR. This may reflect a declining energy demand necessary to maintain photosynthetic capacity. Under elevated CO2, the apparent changes in the quantum yields of regulated and unregulated non-photochemical energy dissipation of PS II at high PFR possibly reflected the enhanced capacity of photoprotection under the prevailing environmental conditions.
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Doyle, Jason R., James N. Burnell, Dianne S. Haines, Lyndon E. Llewellyn, Cherie A. Motti, and Dianne M. Tapiolas. "A Rapid Screening Method to Detect Specific Inhibitors of Pyruvate Orthophosphate Dikinase as Leads for C₄ Plant-Selective Herbicides." Journal of Biomolecular Screening 10, no. 1 (February 2005): 67–75. http://dx.doi.org/10.1177/1087057104269978.
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Plants using the C4 photosynthetic pathway are highly represented among the world’s worst weeds, with only 4 C4 species being agriculturally productive (maize, sorghum, millet, and sugar cane). With the C4 acid cycle operating as a biochemical appendage of C3 photosynthesis, the additional enzymes involved in C4 photosynthesis represent an attractive target for the development of weed-specific herbicides. The rate-limiting enzyme of this metabolic pathway is pyruvate orthophosphate dikinase (PPDK). PPDK, coupled with phosphoenolpyruvate carboxylase and nicotinamide adenine dinucleotide-malate dehydrogenase, was used to develop a microplate-based assay to detect inhibitors of enzymes of the C4 acid cycle. The resulting assay had a Z′ factor of 0.61, making it a high-quality assay able to reliably identify active test samples. Organic extracts of 6679 marine macroscopic organisms were tested within the assay, and 343 were identified that inhibited the 3 enzyme-coupled reaction. A high confirmation rate was achieved, with 95% of these hit extracts proving active again upon retesting. Sequential addition of phosphoenolpyruvate and oxaloacetate to the assay facilitated identification of 83 extracts that specifically inhibited PPDK. ( Journal of Biomolecular Screening 2005:67-75)
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Forster, R. M., and M. J. Dring. "Influence of blue light on the photosynthetic capacity of marine plants from different taxonomic, ecological and morphological groups." European Journal of Phycology 29, no. 1 (February 1994): 21–27. http://dx.doi.org/10.1080/09670269400650441.
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Deng, Shuyuan, Bo Wang, Wenda Zhang, Sanbao Su, Hao Dong, Ibrahim M. Banat, Shanshan Sun, et al. "Elucidate microbial characteristics in a full-scale treatment plant for offshore oil produced wastewater." PLOS ONE 16, no. 8 (August 12, 2021): e0255836. http://dx.doi.org/10.1371/journal.pone.0255836.
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Oil-produced wastewater treatment plants, especially those involving biological treatment processes, harbor rich and diverse microbes. However, knowledge of microbial ecology and microbial interactions determining the efficiency of plants for oil-produced wastewater is limited. Here, we performed 16S rDNA amplicon sequencing to elucidate the microbial composition and potential microbial functions in a full-scale well-worked offshore oil-produced wastewater treatment plant. Results showed that microbes that inhabited the plant were diverse and originated from oil and marine associated environments. The upstream physical and chemical treatments resulted in low microbial diversity. Organic pollutants were digested in the anaerobic baffled reactor (ABR) dominantly through fermentation combined with sulfur compounds respiration. Three aerobic parallel reactors (APRs) harbored different microbial groups that performed similar potential functions, such as hydrocarbon degradation, acidogenesis, photosynthetic assimilation, and nitrogen removal. Microbial characteristics were important to the performance of oil-produced wastewater treatment plants with biological processes.
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Eriksson, K. M., A. K. Clarke, L. G. Franzen, M. Kuylenstierna, K. Martinez, and H. Blanck. "Community-Level Analysis of psbA Gene Sequences and Irgarol Tolerance in Marine Periphyton." Applied and Environmental Microbiology 75, no. 4 (December 16, 2008): 897–906. http://dx.doi.org/10.1128/aem.01830-08.
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ABSTRACT This study analyzes psbA gene sequences, predicted D1 protein sequences, species relative abundance, and pollution-induced community tolerance in marine periphyton communities exposed to the antifouling compound Irgarol 1051. The mechanism of action of Irgarol is the inhibition of photosynthetic electron transport at photosystem II by binding to the D1 protein. The metagenome of the communities was used to produce clone libraries containing fragments of the psbA gene encoding the D1 protein. Community tolerance was quantified with a short-term test for the inhibition of photosynthesis. The communities were established in a continuous flow of natural seawater through microcosms with or without added Irgarol. The selection pressure from Irgarol resulted in an altered species composition and an inducted community tolerance to Irgarol. Moreover, there was a very high diversity in the psbA gene sequences in the periphyton, and the composition of psbA and D1 fragments within the communities was dramatically altered by increased Irgarol exposure. Even though tolerance to this type of compound in land plants often depends on a single amino acid substitution (Ser264→Gly) in the D1 protein, this was not the case for marine periphyton species. Instead, the tolerance mechanism likely involves increased degradation of D1. When we compared sequences from low and high Irgarol exposure, differences in nonconserved amino acids were found only in the so-called PEST region of D1, which is involved in regulating its degradation. Our results suggest that environmental contamination with Irgarol has led to selection for high-turnover D1 proteins in marine periphyton communities at the west coast of Sweden.
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Sánchez-Baracaldo, Patricia, John A. Raven, Davide Pisani, and Andrew H. Knoll. "Early photosynthetic eukaryotes inhabited low-salinity habitats." Proceedings of the National Academy of Sciences 114, no. 37 (August 14, 2017): E7737—E7745. http://dx.doi.org/10.1073/pnas.1620089114.
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The early evolutionary history of the chloroplast lineage remains an open question. It is widely accepted that the endosymbiosis that established the chloroplast lineage in eukaryotes can be traced back to a single event, in which a cyanobacterium was incorporated into a protistan host. It is still unclear, however, which Cyanobacteria are most closely related to the chloroplast, when the plastid lineage first evolved, and in what habitats this endosymbiotic event occurred. We present phylogenomic and molecular clock analyses, including data from cyanobacterial and chloroplast genomes using a Bayesian approach, with the aim of estimating the age for the primary endosymbiotic event, the ages of crown groups for photosynthetic eukaryotes, and the independent incorporation of a cyanobacterial endosymbiont by Paulinella. Our analyses include both broad taxon sampling (119 taxa) and 18 fossil calibrations across all Cyanobacteria and photosynthetic eukaryotes. Phylogenomic analyses support the hypothesis that the chloroplast lineage diverged from its closet relative Gloeomargarita, a basal cyanobacterial lineage, ∼2.1 billion y ago (Bya). Our analyses suggest that the Archaeplastida, consisting of glaucophytes, red algae, green algae, and land plants, share a common ancestor that lived ∼1.9 Bya. Whereas crown group Rhodophyta evolved in the Mesoproterozoic Era (1,600–1,000 Mya), crown groups Chlorophyta and Streptophyta began to radiate early in the Neoproterozoic (1,000–542 Mya). Stochastic mapping analyses indicate that the first endosymbiotic event occurred in low-salinity environments. Both red and green algae colonized marine environments early in their histories, with prasinophyte green phytoplankton diversifying 850–650 Mya.
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Serôdio, João, William Schmidt, Jörg C. Frommlet, Gregor Christa, and Matthew R. Nitschke. "An LED-based multi-actinic illumination system for the high throughput study of photosynthetic light responses." PeerJ 6 (September 4, 2018): e5589. http://dx.doi.org/10.7717/peerj.5589.
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The responses of photosynthetic organisms to light stress are of interest for both fundamental and applied research. Functional traits related to the photoinhibition, the light-induced loss of photosynthetic efficiency, are particularly interesting as this process is a key limiting factor of photosynthetic productivity in algae and plants. The quantitative characterization of light responses is often time-consuming and calls for cost-effective high throughput approaches that enable the fast screening of multiple samples. Here we present a novel illumination system based on the concept of ‘multi-actinic imaging’ of in vivo chlorophyll fluorescence. The system is based on the combination of an array of individually addressable low power RGBW LEDs and custom-designed well plates, allowing for the independent illumination of 64 samples through the digital manipulation of both exposure duration and light intensity. The illumination system is inexpensive and easily fabricated, based on open source electronics, off-the-shelf components, and 3D-printed parts, and is optimized for imaging of chlorophyll fluorescence. The high-throughput potential of the system is illustrated by assessing the functional diversity in light responses of marine macroalgal species, through the fast and simultaneous determination of kinetic parameters characterizing the response to light stress of multiple samples. Although the presented illumination system was primarily designed for the measurement of phenotypic traits related to photosynthetic activity and photoinhibition, it can be potentially used for a number of alternative applications, including the measurement of chloroplast phototaxis and action spectra, or as the basis for microphotobioreactors.
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Quigg, Antonietta, John Beardall, and Tom Wydrzynski. "Photoacclimation involves modulation of the photosynthetic oxygen-evolving reactions in Dunaliella tertiolecta and Phaeodactylum tricornutum." Functional Plant Biology 30, no. 3 (2003): 301. http://dx.doi.org/10.1071/fp02140.
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Net energy accumulation by marine microalgae at very low photon fluxes involves modulation of several attributes related to both the growth and photosynthetic physiology of these organisms. Here we studied flash-induced oscillatory patterns in oxygen evolution by previously dark-adapted cells of the green alga Dunaliella tertiolecta (Butcher) and the diatom Phaeodactylum tricornutum (Bohlin). The activity of the oxygen-evolving complex was found to be species-specific and influenced by photoacclimation. Results from measurements of oxygen flash yield obtained for these organisms grown under light-saturating conditions are directly comparable to those previously reported in the literature for other microalgae and higher plants. However, similar measurements on cells grown in low-light and/or light-starved conditions indicate an increased level of backward transitions (double misses) leading to the formation of super-reduced states (i.e. S–1 and S–2). Thus, in this communication, we present the first evidence that super-reduced states can be generated in vivo and speculate, on how they may be physiologically important.
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Abels, H. A., V. Lauretano, A. van Yperen, T. Hopman, J. C. Zachos, L. J. Lourens, P. D. Gingerich, and G. J. Bowen. "Carbon isotope excursions in paleosol carbonate marking five early Eocene hyperthermals in the Bighorn Basin, Wyoming." Climate of the Past Discussions 11, no. 3 (May 18, 2015): 1857–85. http://dx.doi.org/10.5194/cpd-11-1857-2015.
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Abstract. Transient greenhouse warming events in the Paleocene and Eocene were associated with the addition of isotopically-light carbon to the exogenic atmosphere–ocean carbon pool, leading to substantial environmental and biotic change. The magnitude of an accompanying carbon isotope excursion (CIE) can be used to constrain both the sources and amounts of carbon released during an event, as well as to correlate marine and terrestrial records with high precision. The Paleocene Eocene Thermal Maximum (PETM) is well documented, but CIE records for the subsequent warming events are still rare especially from the terrestrial realm. Here, we provide new CIE records for two of the smaller hyperthermal events, I1 and I2, in paleosol carbonate, as well as two additional records of ETM2 and H2 in the Bighorn Basin. Stratigraphic comparison of this expanded, high-resolution terrestrial carbon isotope record to the deep-sea benthic foraminifera records from ODP Sites 1262 and 1263, Walvis Ridge, in the southern Atlantic Ocean corroborates that the Bighorn Basin fluvial sediments record global atmospheric change. The stratigraphic thicknesses of the eccentricity-driven hyperthermals in these archives are in line with precession-forcing of the 7 m thick fluvial overbank-avulsion sedimentary cycles. Using the CALMAG bulk oxide mean annual precipitation proxy, we reconstruct similar or slightly wetter than background soil moisture contents during the four younger hyperthermals, in contrast to drying observed during the PETM. Soil carbonate CIEs vary in magnitude proportionally with the marine CIEs for the four smaller early Eocene hyperthermals. This relationship breaks down for the PETM, with the soil carbonate CIE ~ 2–4‰ less than expected if all five linearly relate to marine CIEs. If the PETM CO2 forcing was similar but scaled to the younger hyperthermals, photosynthetic isotope fractionation or soil environmental factors are needed to explain this anomaly. We use sensitivity testing of experimentally determined photosynthetic isotope discrimination relationships to show that factors other than the recently demonstrated pCO2 sensitivity of C3 plants carbon isotope fractionation are required to explain this anomaly.
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Hesslein, R. H., M. J. Capel, D. E. Fox, and K. A. Hallard. "Stable Isotopes of Sulfur, Carbon, and Nitrogen as Indicators of Trophic Level and Fish Migration in the Lower Mackenzie River Basin, Canada." Canadian Journal of Fisheries and Aquatic Sciences 48, no. 11 (November 1, 1991): 2258–65. http://dx.doi.org/10.1139/f91-265.
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Stable isotopes of sulfur, carbon, and nitrogen were used to investigate the incorporation of nutrients into food chains (fish, invertebrates, and plants) and the influence of migration on the nutritional origins of fish in two freshwater systems in the Mackenzie Delta region. Sulfur isotope analyses of fish muscle showed that broad whitefish (Coregonus nasus) in Travaillant Lake and lake whitefish (Coregonus clupeaformis) in the Kukjuktuk Creek system were migrant populations which had grown mostly on sources outside the local food base. A marine food source was indicated for the lake whitefish, while no specific source was determined for the broad whitefish. The δ15N clearly defined the trophic levels in the local food chains in both systems. Fish were in three levels in Travaillant Lake. Amphipods were in a level below the lowest fish and sediments and macrophytes were in the lowest level. The Kukjuktuk Creek fish were in two levels above a level including macrophytes, amphipods, and zooplankton. The δ13C varied widely even within single fish species local to Travaillant Lake. The δ13C did not differentiate migrants from local fish. Plants of both the C3 and C4 photosynthetic pathway were indicated by carbon isotopes.
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Lopez, Pascal Jean. "Silicomics: Silicon enters the 'omics arena." Biochemist 33, no. 3 (June 1, 2011): 26–28. http://dx.doi.org/10.1042/bio03303026.
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Silicon is the second most abundant element in the Earth's crust, making up about onequarter of the crust by mass. In the modern surface waters of recent oceans, silicon is undersaturated, but it is estimated that its concentration was much higher before the rise of the diatoms during the Jurassic–Cretaceous periods. Since silicon is everywhere, it is not surpris ing that, over time, a large number of marine and terrestrial organisms have acquired or developed the ability to use or to transform silicon. It is generally known that many organisms accumulate and/or use silicon to construct inter nal or external skeletons. One such organism is diatoms, a class of photosynthetic microalgae capable of creating beautiful threedimensional silica structures, called frustules. The importance of silicon has also been demonstrated by numerous studies in plants showing that silicon improves the resistance to diseases and mitigates other biotic or abiotic stresses. In this article, I highlight selected studies that aimed to understand the meta bolism of silicon, with a particular emphasis on the diatoms.
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Wang, Zongshuai, Shuxin Li, Shengqun Liu, Fahong Wang, Lingan Kong, Xiangnan Li, and Marian Brestic. "Effects of Elevated Atmospheric CO2 Concentration on Phragmites australis and Wastewater Treatment Efficiency in Constructed Wetlands." Water 13, no. 18 (September 12, 2021): 2500. http://dx.doi.org/10.3390/w13182500.
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Elevated atmospheric CO2 concentration (e[CO2]) has been predicted to rise to more than 400 ppm by the end of this century. It has received extensive attention with regard to the pros and cons of e[CO2] effects in terrestrial and marine ecosystems, while the effects of e[CO2] on wastewater treatment efficiency in constructed wetlands (CWs) are rarely known. In this study, the atmospheric CO2 concentration was set as 400 ppm (that is, ambient [CO2]) and 800 ppm (that is, e[CO2]). The physiological performance of Phragmites australis and microbial enzyme activities in constructed wetlands in response to e[CO2] were tested. Significantly higher net photosynthetic rate and plant growth were found under e[CO2]. The concentrations of nitrate, total anions, and total ions in the xylem sap of Phragmites australis were reduced, while the uptake of N and P in plants were not affected under e[CO2] condition. In addition, the ammonia monooxygenase activity was reduced, while the phosphatase activity was enhanced by e[CO2]. The increased removal efficiency of chemical oxygen demand and total nitrogen in CWs could be ascribed to the changes in physiological performance of Phragmites australis and activities of microbial enzymes under e[CO2]. These results suggested that the future atmospheric CO2 concentration could affect the wastewater treatment efficiency in CWs, due to the direct effects on plants and microorganisms.
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Tang, Lei, Liping Qiu, Cong Liu, Guoying Du, Zhaolan Mo, Xianghai Tang, and Yunxiang Mao. "Transcriptomic Insights into Innate Immunity Responding to Red Rot Disease in Red Alga Pyropia yezoensis." International Journal of Molecular Sciences 20, no. 23 (November 27, 2019): 5970. http://dx.doi.org/10.3390/ijms20235970.
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Pyropia yezoensis, one of the most economically important marine algae, suffers from the biotic stress of the oomycete necrotrophic pathogen Pythium porphyrae. However, little is known about the molecular defensive mechanisms employed by Pyr. yezoensis during the infection process. In the present study, we defined three stages of red rot disease based on histopathological features and photosynthetic physiology. Transcriptomic analysis was carried out at different stages of infection to identify the genes related to the innate immune system in Pyr. yezoensis. In total, 2139 up-regulated genes and 1672 down-regulated genes were identified from all the infected groups. Pathogen receptor genes, including three lectin genes (pattern recognition receptors (PRRs)) and five genes encoding typical plant R protein domains (leucine rich repeat (LRR), nucleotide binding site (NBS), or Toll/interleukin-1 receptor (TIR)), were found to be up-regulated after infection. Several defense mechanisms that were typically regarded as PAMP-triggered immunity (PTI) in plants were induced during the infection. These included defensive and protective enzymes, heat shock proteins, secondary metabolites, cellulase, and protease inhibitors. As a part of the effector-triggered immunity (ETI), the expression of genes related to the ubiquitin-proteasome system (UPS) and hypersensitive cell death response (HR) increased significantly during the infection. The current study suggests that, similar to plants, Pyr. yezoensis possesses a conserved innate immune system that counters the invasion of necrotrophic pathogen Pyt. porphyrae. However, the innate immunity genes of Pyr. yezoensis appear to be more ancient in origin compared to those in higher plants.
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Nicastro, Silvia, Anna M. Innocenti, and Nicodemo G. Passalacqua. "Histo-anatomical leaf variations related to depth in Posidonia oceanica." Functional Plant Biology 42, no. 4 (2015): 418. http://dx.doi.org/10.1071/fp14111.
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The purpose of our study is to explore the acclimation of Neptune seagrass (Posidonia oceanica (L.) Delile) to depth by characterising the histo-anatomical leaf modifications. P. oceanica is the dominant seagrass and main habitat constructor of seagrass meadows in the Mediterranean Sea. Meadows play an important biological and ecological role in marine ecosystems, serving as a habitat for a large diversity of species and an efficient erosion protection system for our coasts. Seagrasses are very sensitive to change in light availability and small changes can have significant effects on growth, abundance and distribution. In this study, we analyse changes in P. oceanica leaves collected at –5 m, –15 m and –25 m depth in the Cirella meadow (Tyrrhenian coast, Southern Italy) in order to determine their depth-related histo-anatomical variation. Two main changes were observed at depth: (1) photosynthetic epidermal cells showed smaller chloroplasts but in the same number; and (2) leaves showed smaller epidermal cells and in greater number. Hence, the photosynthetic surface of P. oceanica leaves remains the same at different depths but pigment absorption efficiency can be significantly enhanced with depth. This response supports the differential photoacclimatory response of seagrasses with respect to terrestrial plants previously documented. Mesophyll cells are smaller with depth and more numerous, with a consequent increase in leaf density. The number of vascular bundles also increases, which allows improved functional efficiency of the transport system and solute exchange. Our study is a new contribution to the morpho-functional implications of the histo-anatomy of P. oceanica.
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Holbrook, Gabriel P., Sven Beer, William E. Spencer, Julia B. Reiskind, Joseph S. Davis, and George Bowes. "Photosynthesis in marine macroalgae: evidence for carbon limitation." Canadian Journal of Botany 66, no. 3 (March 1, 1988): 577–82. http://dx.doi.org/10.1139/b88-083.
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During a shipboard expedition to Andros Island (Bahamas), photosynthetic measurements for the macroalgae Cladophoropsis membranacea (Chlorophyta), Dilophus guineensis, Turbinaria turbinata, and Lobophora variegata (Phaeophyta), and Laurencia papillosa (Rhodophyta), taken directly from their marine habitat, showed that only Cladophoropsis was saturated at seawater inorganic carbon levels (2.5 mM). The photosynthetic k0.5 values for inorganic carbon ranged from 1.1 to 3.2 mM. Decreasing the pH at 2.5 mM inorganic carbon, and thus enhancing the CO2 by 30-fold, only slightly increased photosynthesis, suggesting that bicarbonate was the major assimilated form of inorganic carbon. At 2.5 mM inorganic carbon, only Lobophora exhibited a Warburg effect on photosynthesis (49%), but at 0.5 mM, Turbinaria and Laurencia were also inhibited by O2. Ribulosebisphosphate carboxylase–oxygenase appeared to be the predominant carboxylation enzyme, but in Dilophus and Laurencia extracts, its activity was rivaled by phosphoenolpyruvate carboxylase and carboxykinase. Malate pools were detected in Turbinaria and Laurencia, and in the latter they were greater at night than during the day. However, this diel fluctuation was too small to implicate crassulacean acid metabolism. The data indicate that the bicarbonate concentration in seawater is insufficient to overcome O2 inhibition effects on photosynthesis, unless the macroalga has some form of CO2 concentrating system, based on bicarbonate uptake or C4 acid metabolism. In addition, the inorganic carbon in seawater may be a nutrient limiting the photosynthesis and productivity of certain macroalgae.
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Tchernov, Dan, Miriam Hassidim, Assaf Vardi, Boaz Luz, Assaf Sukenik, Leonora Reinhold, and Aaron Kaplan. "Photosynthesizing marine microorganisms can constitute a source of CO2 rather than a sink." Canadian Journal of Botany 76, no. 6 (June 1, 1998): 949–53. http://dx.doi.org/10.1139/b98-084.
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The unexpected finding that certain major marine photosynthetic microorganisms can serve as a source of CO2 rather than a sink emerged during measurements of inorganic carbon fluxes associated with the CO2-concentrating mechanism. During steady-state photosynthesis, CO2 was evolved at sustained rates up to 5-fold that of photosynthesis; the steady-state external CO2 concentration reached was significantly higher than that at CO2-HCO3- equilibrium. The evolved CO2 originated from HCO3- taken up and intracellularly converted to CO2 in a light-dependent process. Our results bear implications for carbon cycling in the marine environment; the use of naturally-observed stable carbon isotope fractionations as paleobarometer and productivity probe; and for intracellular energy balance and pH regulation.Key words: carbonic anhydrase, CO2 evolution, cyanobacteria, photosynthesis, Synechococcus.
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Liang, Hongping, Tong Wei, Yan Xu, Linzhou Li, Sunil Kumar Sahu, Hongli Wang, Haoyuan Li, et al. "Phylogenomics Provides New Insights into Gains and Losses of Selenoproteins among Archaeplastida." International Journal of Molecular Sciences 20, no. 12 (June 20, 2019): 3020. http://dx.doi.org/10.3390/ijms20123020.
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Selenoproteins that contain selenocysteine (Sec) are found in all kingdoms of life. Although they constitute a small proportion of the proteome, selenoproteins play essential roles in many organisms. In photosynthetic eukaryotes, selenoproteins have been found in algae but are missing in land plants (embryophytes). In this study, we explored the evolutionary dynamics of Sec incorporation by conveying a genomic search for the Sec machinery and selenoproteins across Archaeplastida. We identified a complete Sec machinery and variable sizes of selenoproteomes in the main algal lineages. However, the entire Sec machinery was missing in the Bangiophyceae-Florideophyceae clade (BV) of Rhodoplantae (red algae) and only partial machinery was found in three species of Archaeplastida, indicating parallel loss of Sec incorporation in different groups of algae. Further analysis of genome and transcriptome data suggests that all major lineages of streptophyte algae display a complete Sec machinery, although the number of selenoproteins is low in this group, especially in subaerial taxa. We conclude that selenoproteins tend to be lost in Archaeplastida upon adaptation to a subaerial or acidic environment. The high number of redox-active selenoproteins found in some bloom-forming marine microalgae may be related to defense against viral infections. Some of the selenoproteins in these organisms may have been gained by horizontal gene transfer from bacteria.
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Thapa, Puja. "Application of micro algae in poultry nutrition; a review." Journal of Agriculture and Natural Resources 3, no. 2 (October 30, 2020): 241–56. http://dx.doi.org/10.3126/janr.v3i2.32512.
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In this review, we unveil the the use of microalgae as a feed ingredient in poultry nutrition. Microalgae are small-sized algae, unicellular, photosynthetic aquatic plants which have been studied as a natural marine resource for a number of economically applications, including animal feed. They are introduced to poultry diets mainly as a rich source of n-3 long chain polyunsaturated fatty acids, including docohexaenoic and eicosapentaenoic acid, but they can also serve as a protein, microelement, vitamin and antioxidants source, as well as a pigmentation agent for skin and egg yolks. The majority of experiments have shown that microalgae, mainly Spirulina and Chlorella sourced as a defatted biomass from biofuel production, can be successfully used as a feed ingredient in poultry nutrition. They can have beneficial effects on meat and egg quality, through an increased concentration of n-3 polyunsaturated fatty acids and carotenoids, and in regards to performance indices and immune function. Positive results were obtained when fresh microalgae biomass was used to replace antibiotic growth promoters in poultry diets. Because of their chemical composition, microalgae can be efficiently used in poultry nutrition to enhance the pigmentation and nutritional value of meat and eggs, as well as partial replacement of conventional dietary protein sources.
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Raven, John A., and Ramon D. Wolstencroft. "Constraints on Photosynthesis on Earth and Earth-Like Planets." Symposium - International Astronomical Union 213 (2004): 305–8. http://dx.doi.org/10.1017/s0074180900193453.
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We discuss how the spectral mismatch between solar radiation at the Earth's surface and the two absorption maxima (440 and 680 nm) of the dominant chlorophyll pigments can be explained as an evolutionary accident of the marine habitat in which photosynthesis evolved on Earth. The geometric rigidity and great stability of chlorophyll make it a likely “universal pigment” given this, together with the spectral absorption properties of water, the evolution of photosynthesis on Earth-like planets (ELPs) orbiting in the habitable zones of A, F and G stars should be relatively straightforward. However for ELPs orbiting cool K and M stars, the effects of variable UV emission from the ELP at earlier epochs and the high absorption of red light by water could lead to a “feast and famine” existence for photosynthetic organisms in the ELP ocean. Pull exploitation of the cool star radiation when UV activity has declined may lead to an evolution of the photosynthetic machinery from the terrestrial two photon to a three photon system.
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Rosic, Nedeljka N., and Sophie Dove. "Mycosporine-Like Amino Acids from Coral Dinoflagellates." Applied and Environmental Microbiology 77, no. 24 (October 14, 2011): 8478–86. http://dx.doi.org/10.1128/aem.05870-11.
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ABSTRACTCoral reefs are one of the most important marine ecosystems, providing habitat for approximately a quarter of all marine organisms. Within the foundation of this ecosystem, reef-building corals form mutualistic symbioses with unicellular photosynthetic dinoflagellates of the genusSymbiodinium. Exposure to UV radiation (UVR) (280 to 400 nm) especially when combined with thermal stress has been recognized as an important abiotic factor leading to the loss of algal symbionts from coral tissue and/or a reduction in their pigment concentration and coral bleaching. UVR may damage biological macromolecules, increase the level of mutagenesis in cells, and destabilize the symbiosis between the coral host and their dinoflagellate symbionts. In nature, corals and other marine organisms are protected from harmful UVR through several important photoprotective mechanisms that include the synthesis of UV-absorbing compounds such as mycosporine-like amino acids (MAAs). MAAs are small (<400-Da), colorless, water-soluble compounds made of a cyclohexenone or cyclohexenimine chromophore that is bound to an amino acid residue or its imino alcohol. These secondary metabolites are natural biological sunscreens characterized by a maximum absorbance in the UVA and UVB ranges of 310 to 362 nm. In addition to their photoprotective role, MAAs act as antioxidants scavenging reactive oxygen species (ROS) and suppressing singlet oxygen-induced damage. It has been proposed that MAAs are synthesized during the first part of the shikimate pathway, and recently, it has been suggested that they are synthesized in the pentose phosphate pathway. The shikimate pathway is not found in animals, but in plants and microbes, it connects the metabolism of carbohydrates to the biosynthesis of aromatic compounds. However, both the complete enzymatic pathway of MAA synthesis and the extent of their regulation by environmental conditions are not known. This minireview discusses the current knowledge of MAA synthesis, illustrates the diversity of MAA functions, and opens new perspectives for future applications of MAAs in biotechnology.
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Nisbet, Euan G., and R. Ellen R. Nisbet. "Methane, oxygen, photosynthesis, rubisco and the regulation of the air through time." Philosophical Transactions of the Royal Society B: Biological Sciences 363, no. 1504 (May 16, 2008): 2745–54. http://dx.doi.org/10.1098/rstb.2008.0057.
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Rubisco I's specificity, which today may be almost perfectly tuned to the task of cultivating the global garden, controlled the balance of carbon gases and O 2 in the Precambrian ocean and hence, by equilibration, in the air. Control of CO 2 and O 2 by rubisco I, coupled with CH 4 from methanogens, has for the past 2.9 Ga directed the global greenhouse warming, which maintains liquid oceans and sustains microbial ecology. Both rubisco compensation controls and the danger of greenhouse runaway (e.g. glaciation) put limits on biological productivity. Rubisco may sustain the air in either of two permissible stable states: either an anoxic system with greenhouse warming supported by both high methane mixing ratios as well as carbon dioxide, or an oxygen-rich system in which CO 2 largely fulfils the role of managing greenhouse gas, and in which methane is necessarily only a trace greenhouse gas, as is N 2 O. Transition from the anoxic to the oxic state risks glaciation. CO 2 build-up during a global snowball may be an essential precursor to a CO 2 -dominated greenhouse with high levels of atmospheric O 2 . Photosynthetic and greenhouse-controlling competitions between marine algae, cyanobacteria, and terrestrial C3 and C4 plants may collectively set the CO 2 : O 2 ratio of the modern atmosphere (last few million years ago in a mainly glacial epoch), maximizing the productivity close to rubisco compensation and glacial limits.
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Joli, Nathalie, Thomas Lacour, Nastasia J. Freyria, Sarah-Jeanne Royer, Marcel Babin, and Connie Lovejoy. "Two versions of short-term phytoplankton ecophysiology and taxonomic assemblages in the Arctic Ocean’s North Water (Canada, Greenland)." Journal of Plankton Research 43, no. 2 (March 2021): 126–41. http://dx.doi.org/10.1093/plankt/fbab009.
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Abstract Photosynthetic performance in open marine waters is determined by how well phytoplankton species are adapted to their immediate environment and available light. Although there is light for 24 h a day during the Arctic summer, little is known about short-term (h) temporal variability of phytoplankton photosynthetic performance in Arctic waters. To address this, we sampled the North Water (76.5°N) every 4 h over 24 h at two stations on the East and West sides that are influenced by different water masses and current conditions. We specifically investigated phytoplankton pigments, the xanthophyll cycle (XC), which is an indication of photoprotective capacity, and photosynthesis–irradiance (PE) response curves, at the surface and 20 m depth. The photophysiological parameters on the two sides differed along with the taxonomic signal derived from accessory pigments. On both sides, surface XC pigments showed high photoprotection capacity with the dinodinoxanthin–diatoxanthin (DD) and the violaxanthin, antheraxanthin and zeaxanthin cycles correlated with incoming radiation. The PE results showed that communities dominated by small flagellates on the western side performed better compared to diatom dominated communities on the eastern side. We conclude that phytoplankton and photosynthetic capacity differed consistent with known hydrography, with implications for a changing Arctic.
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Ahmad, Ahmad, Archana Tiwari, and Shireesh Srivastava. "A Genome-Scale Metabolic Model of Thalassiosira pseudonana CCMP 1335 for a Systems-Level Understanding of Its Metabolism and Biotechnological Potential." Microorganisms 8, no. 9 (September 11, 2020): 1396. http://dx.doi.org/10.3390/microorganisms8091396.
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Thalassiosira pseudonana is a transformable and biotechnologically promising model diatom with an ability to synthesise nutraceuticals such as fucoxanthin and store a significant amount of polyglucans and lipids including omega-3 fatty acids. While it was the first diatom to be sequenced, a systems-level analysis of its metabolism has not been done yet. This work presents first comprehensive, compartmentalized, and functional genome-scale metabolic model of the marine diatom Thalassiosira pseudonana CCMP 1335, which we have termed iThaps987. The model includes 987 genes, 2477 reactions, and 2456 metabolites. Comparison with the model of another diatom Phaeodactylum tricornutum revealed presence of 183 unique enzymes (belonging primarily to amino acid, carbohydrate, and lipid metabolism) in iThaps987. Model simulations showed a typical C3-type photosynthetic carbon fixation and suggested a preference of violaxanthin–diadinoxanthin pathway over violaxanthin–neoxanthin pathway for the production of fucoxanthin. Linear electron flow was found be active and cyclic electron flow was inactive under normal phototrophic conditions (unlike green algae and plants), validating the model predictions with previous reports. Investigation of the model for the potential of Thalassiosira pseudonana CCMP 1335 to produce other industrially useful compounds suggest iso-butanol as a foreign compound that can be synthesized by a single-gene addition. This work provides novel insights about the metabolism and potential of the organism and will be helpful to further investigate its metabolism and devise metabolic engineering strategies for the production of various compounds.
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Retallack, Gregory J. "Were the Ediacaran fossils lichens?" Paleobiology 20, no. 4 (1994): 523–44. http://dx.doi.org/10.1017/s0094837300012975.
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Ediacaran fossils are taphonomically similar to impressions of fossil plants common in quartz sandstones, and the relief of the fossils suggests that they were as resistant to compaction during burial as some kinds of Pennsylvanian tree trunks. Fossils of jellyfish are known from siderite nodules and fine-grained limestone, and even in these compaction-resistant media were more compressed during burial than were the Vendobionta. Vendobionta were constructed of materials that responded to burial compaction in a way intermediate between conifer and lycopsid logs. This comparative taphonomic study thus falsifies the concept of Vendobionta as thin soft-bodied creatures such as worms and jellyfish.Lichens, with their structural chitin, present a viable model for the observed preservational style of Vendobionta, as well as for a variety of other features that now can be reassessed from this new perspective. The diversity of Ediacaran body plans can be compared with the variety of form in fungi, algae, and lichens. The large size (ca. 1 m) of some Ediacaran fossils is reasonable for sessile photosynthetic symbioses, and much bigger than associated burrows of metazoans not preserved. Microscopic tubular structures and darkly pigmented cells in permineralized late Precambrian fossils from Namibia and China are also compatible with interpretation as lichens. The presumed marine habitat of Ediacaran fossils is not crucial to interpretation as lichens, because fungi and lichens live in the sea as well as on land.
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Bar-On, Yinon M., and Ron Milo. "The global mass and average rate of rubisco." Proceedings of the National Academy of Sciences 116, no. 10 (February 19, 2019): 4738–43. http://dx.doi.org/10.1073/pnas.1816654116.
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Photosynthetic carbon assimilation enables energy storage in the living world and produces most of the biomass in the biosphere. Rubisco (d-ribulose 1,5-bisphosphate carboxylase/oxygenase) is responsible for the vast majority of global carbon fixation and has been claimed to be the most abundant protein on Earth. Here we provide an updated and rigorous estimate for the total mass of Rubisco on Earth, concluding it is ≈0.7 Gt, more than an order of magnitude higher than previously thought. We find that >90% of Rubisco enzymes are found in the ≈2 × 1014m2of leaves of terrestrial plants, and that Rubisco accounts for ≈3% of the total mass of leaves, which we estimate at ≈30 Gt dry weight. We use our estimate for the total mass of Rubisco to derive the effective time-averaged catalytic rate of Rubisco of ≈0.03 s−1on land and ≈0.6 s−1in the ocean. Compared with the maximal catalytic rate observed in vitro at 25 °C, the effective rate in the wild is ≈100-fold slower on land and sevenfold slower in the ocean. The lower ambient temperature, and Rubisco not working at night, can explain most of the difference from laboratory conditions in the ocean but not on land, where quantification of many more factors on a global scale is needed. Our analysis helps sharpen the dramatic difference between laboratory and wild environments and between the terrestrial and marine environments.
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Huertas, I. Emma, and Luis M. Lubián. "Comparative study of dissolved inorganic carbon utilization and photosynthetic responses in Nannochloris (Chlorophyceae) and Nannochloropsis (Eustigmatophyceae) species." Canadian Journal of Botany 76, no. 6 (June 1, 1998): 1104–8. http://dx.doi.org/10.1139/b98-068.
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Four species of marine microalgae with similar morphology and life cycle, namely Nannochloris atomus Butcher, Nannochloris maculata Butcher, Nannochloropsis gaditana Lubian, and Nannochloropsis oculata (Droop) Hibberd, have been examined with respect to their affinity for different sources of dissolved inorganic carbon. External carbonic anhydrase activity was not found in any of these species, but the cell affinity for dissolved inorganic carbon (DIC) in Nannochloris species was affected by the inhibitor acetazolamide at a concentration of 400 µM. Measurement of photosynthetic rates and CO2 compensation points at different pH values showed that the Nannochloris species had a greater capacity for CO2 rather than HCO3- utilization. In contrast, the observed rates of photosynthetic oxygen evolution in Nannochloropsis species were greater than could be accounted for by the theoretical rate of CO2 supply from the spontaneous dehydration of bicarbonate in the external medium. This indicates that these algae were able to transport bicarbonate across the plasmalemma. Furthermore, the K0.5 (DIC) value at acidic pH showed that Nannochloropsis oculata could also use CO2 as an exogenous carbon source for photosynthesis. Although the species of marine phytoplankton used in this study possess similar morphological characteristics and life cycle, there exist many differences in the mode of inorganic carbon utilization between these microalgae.Key words: Nannochloris, Nannochloropsis, inorganic carbon utilization, bicarbonate transport, CO2 compensation point, photosynthesis.
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Wu, Hongyan, and Kunshan Gao. "Ultraviolet radiation stimulated activity of extracellular carbonic anhydrase in the marine diatom Skeletonema costatum." Functional Plant Biology 36, no. 2 (2009): 137. http://dx.doi.org/10.1071/fp08172.
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Previous studies have shown that reduced levels of solar UV radiation (280–400 nm) can enhance photosynthetic carbon fixation of marine phytoplankton, but the mechanisms are not known. The supply of CO2 for photosynthesis is facilitated by extracellular (periplasmic) carbonic anhydrase (CAe) in most marine phytoplankton species. The present study showed that the CAe activity of Skeletonema costatum (Greville) Cleve was stimulated when treated with UV-A (320–395 nm) or UV-A + UV-B (295–320 nm) in addition to visible radiation. The presence of UV-A and UV-B enhanced the activity by 28% and 24%, respectively, at a low irradiance (PAR 161, UV-A 28, UV-B 0.9 W m−2) and by 21% and 19%, respectively, at a high irradiance (PAR 328, UV-A 58, UV-B 1.9 W m−2) level after exposure for 1 h. Ultraviolet radiation stimulated CAe activity contributed up to 6% of the photosynthetic carbon fixation as a result of the enhanced supply of CO2, as revealed using the CAe inhibitor (acetazolamide). As a result, there was less inhibition of photosynthetic carbon fixation compared with the apparent quantum yield of PSII. The UV radiation stimulated CAe activity coincided with the enhanced redox activity at the plasma membrane in the presence of UV-A and/or UV-B. The present study showed that UV radiation can enhance CAe activity, which plays an important role in counteracting UV inhibition of photosynthesis.
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Liang, Dayong, Xiaodong Wang, Yiping Huo, Yan Wang, and Shaoshan Li. "Differences in the Formation Mechanism of Giant Colonies in Two Phaeocystis globosa Strains." International Journal of Molecular Sciences 21, no. 15 (July 29, 2020): 5393. http://dx.doi.org/10.3390/ijms21155393.
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Phaeocystis globosa has become one of the primary causes of harmful algal bloom in coastal areas of southern China in recent years, and it poses a serious threat to the marine environment and other activities depending upon on it (e.g., aquaculture, cooling system of power plants), especially in the Beibu Gulf. We found colonies of P. globosa collected form Guangxi (China) were much larger than those obtained from Shantou cultured in lab. To better understand the causes of giant colonies formation, colonial cells collected from P. globosa GX strain (GX-C) and ST strain (ST-C) were separated by filtration. Morphological observations, phylogenetic analyses, rapid light-response curves, fatty acid profiling and transcriptome analyses of two type cells were performed in the laboratory. Although no differences in morphology and 18S rRNA sequences of these cells were observed, the colonies of GX strain (4.7 mm) are 30 times larger than those produced by the ST strain (300 μm). The rapid light-response curve of GX-C was greater than that of ST-C, consistent with the upregulated photosynthetic system, while the fatty acid content of GX-C was lower than that of ST-C, also consistent with the downregulated synthesis of fatty acids and the upregulated degradation of fatty acids. In summary, the increased energy generated by GX-C is allocated to promote the secretion of extracellular polysaccharides for colony formation. We performed a physiological and molecular assessment of the differences between the GX-C and ST-C strains, providing insights into the mechanisms of giant colonies formation in P. globosa.
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Israel A., Alvaro, and Michael Friedlander. "INORGANIC CARBON UTILIZATION AND GROWTH ABILITIES IN THE MARINE RED MACROALGA GELIDIOPSIS SP." Israel Journal of Plant Sciences 46, no. 2 (May 13, 1998): 117–24. http://dx.doi.org/10.1080/07929978.1998.10676718.
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We studied the effects of NH4+, photosynthetic photon flux (PPF), and temperature on growth rates, together with inorganic carbon (Ci) utilization properties of Gelidiopsis sp. cultivated in tanks. At 25% sunlight, weekly growth rates and dry weight yields increased up to 6-fold with increasing NH4+(0–2 mM); however, at 5% or 100% sunlight the effects were much lower. Contents of photosynthetic pigments (chlorophyll a and phycoerythrin) increased in correlation with increases of NH4+. Maximal chlorophyll a concentrations occurred under high PPF, while phycoerythrin concentrations were higher at low PPF. Ash amounts in Gelidiopsis sp. did not vary significantly with different NH4+ or PPF levels. Optimal temperatures and PPFs for growth were 20–25 °C and 170–320 μmol m−2 s−1, respectively, correlating with short-term photosynthetic O2 evolution measurements. The pH of both thallus surface and bulk medium increased during photosynthesis, reaching average values of 8.75, and resulting in low rates of O2 evolution. Activities of carbonic anhydrase (CA) were detected inside and outside the cells and were apparently involved in the Ci uptake system of Gelidiopsis sp. since both acetazolamide (membrane-impermeable) and ethoxyzolamide (membrane-permeable) inhibited photosynthetic O2 evolution by 89% on average. Half-maximal rates of photosynthetic O2 evolution (K0.5) were reached at 17 μM CO2 at pH 5.0 and 2–3 mM Ci at pH 8.0, indicating high affinity for CO2 and close to saturated photosynthesis at Ci levels of seawater. Thus the Ci uptake system of Gelidiopsis sp. probably uses an extracellular CA catalyzed conversion of HCO3− to yield CO2, which could diffuse into the cells, and an intracellular CA catalyzed HCO3− ↔ CO2 interconversion which may assure CO2 for Rubisco. Direct uptake of HCO3− may also be required based on the K0.5 (CO2) estimated for Gelidiopsis sp. and the pH generated at the thallus surface at which CO2 concentrations would only be approximately 10 μM. Therefore, in addition to limitations of low NH4+ concentrations and high temperatures during the summer, growth of Gelidiopsis sp. from the Israeli Mediterranean may also be restricted by its limited Ci utilization system and the low CO2 concentrations prevailing in seawater.
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Dason, Jeffrey S., and Brian Colman. "Inhibition of growth in two dinoflagellates by rapid changes in external pH." Canadian Journal of Botany 82, no. 4 (April 1, 2004): 515–20. http://dx.doi.org/10.1139/b04-023.
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The effect of external pH and high CO2 were investigated on growth and photosynthesis in two marine dinoflagellates, Amphidinium carterae Hulburt and Heterocapsa oceanica Stein. Exposure of both species to high CO2 caused a rapid decrease in external pH from 8 to 7 and a complete suppression of growth. Both species were able to grow at pH 7 but the Vmax of photosynthesis was significantly lower than in cells grown at pH 8. There was also a significant reduction in the photosynthetic rate of both species after being on high CO2 for 6 h and a complete loss after 24 h. The internal pH of both species was determined by the distribution of [2-14C]5,5-dimethyloxazolidine-2,4-dione between the cells and the surrounding medium. As the external pH was lowered from 8 to 7, there was a decrease in the internal pH of A. carterae cells, grown at pH 8.0, from 7.92 to 7.04 and in H. oceanica from 8.14 to 7.22. When placed on high CO2, the internal pH of A. carterae further declined to 6.90 and to 7.15. in H. oceanica. This inability to maintain internal pH probably caused the suppression of growth and loss of photosynthetic capacity of high-CO2 cells.Key words: Amphidinium carterae, CO2-concentrating mechanism, dinoflagellates, external pH, Heterocapsa oceanica, internal pH.
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Legendre, L., S. Demers, C. Garside, E. M. Haugen, D. A. Phinney, L. P. Shapiro, J. C. Therriault, and C. M. Yentsch. "Circadian photosynthetic activity of natural marine phytoplankton isolated in a tank." Journal of Plankton Research 10, no. 1 (1988): 1–6. http://dx.doi.org/10.1093/plankt/10.1.1.
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Zhu, Xifeng, Dinghui Zou, Yanhua Huang, Junming Cao, Guangcheng Sheng, and Guoxia Wang. "Physiological responses of Hizikia fusiformis (Phaeophyta) to mercury exposure." Botanica Marina 58, no. 2 (April 1, 2015): 93–101. http://dx.doi.org/10.1515/bot-2014-0068.
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Abstract Marine coastal ecosystems are suffering from metal pollution such as mercury. Hizikia fusiformis is a commercially important brown marine macroalga. Entire thalli of H. fusiformis were cultured in media with different mercury concentrations for 7 days to examine the physiological effects of mercury exposure on this species. The relative growth rate of H. fusiformis was significantly reduced at 0.04 mg l-1 mercury. Chlorophyll a and carotenoid contents were not affected by mercury concentrations ≤0.10 mg l-1, but significantly decreased at 0.20 and 0.40 mg l-1. Optimal quantum yield, maximum net photosynthetic rate, and apparent photosynthetic efficiency were reduced with increasing mercury concentrations. Malondialdehyde contents were significantly increased at 0.04–0.40 mg l-1 mercury. Superoxide dismutase activity increased at 0.02–0.10 mg l-1 mercury. Both superoxide dismutase and catalase activity strongly decreased at 0.20 and 0.40 mg l-1. Nitrate reductase activity declined at mercury concentrations ≥0.04 mg l-1. Consequently, the results suggest that H. fusiformis could tolerate mercury stress at very low concentrations but that mercury at high concentrations has toxic effects on H. fusiformis through its negative influence on photosynthesis and related physiology. The results also illuminate the physiological response mechanisms of algae to mercury exposure.
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Shimasaki, Yohei, Koki Mukai, Yuki Takai, Xuchun Qiu, and Yuji Oshima. "Recent Progress in the Study of Peroxiredoxin in the Harmful Algal Bloom Species Chattonella marina." Antioxidants 10, no. 2 (January 22, 2021): 162. http://dx.doi.org/10.3390/antiox10020162.
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Peroxiredoxin (Prx) is a relatively recently discovered antioxidant enzyme family that scavenges peroxides and is known to be present in organisms from biological taxa ranging from bacteria to multicellular eukaryotes, including photosynthetic organisms. Although there have been many studies of the Prx family in higher plants, green algae, and cyanobacteria, few studies have concerned raphidophytes and dinoflagellates, which are among the eukaryotic algae that cause harmful algal blooms (HABs). In our proteomic study using 2-D electrophoresis, we found a highly expressed 2-Cys peroxiredoxin (2-CysPrx) in the raphidophyte Chattonella marina var. antiqua, a species that induces mass mortality of aquacultured fish. The abundance of the C. marina 2-CysPrx enzyme was highest in the exponential growth phase, during which photosynthetic activity was high, and it then decreased by about a factor of two during the late stationary growth phase. This pattern suggested that 2-CysPrx is a key enzyme involved in the maintenance of high photosynthesis activity. In addition, the fact that the depression of photosynthesis by excessively high irradiance was more severe in the 2-CysPrx low-expression strain (wild type) than in the normal-expression strain (wild type) of C. marina suggested that 2-CysPrx played a critical role in protecting the cell from oxidative stress caused by exposure to excessively high irradiance. In the field of HAB research, estimates of growth potential have been desired to predict the population dynamics of HABs for mitigating damage to fisheries. Therefore, omics approaches have recently begun to be applied to elucidate the physiology of the growth of HAB species. In this review, we describe the progress we have made using a molecular physiological approach to identify the roles of 2-CysPrx and other antioxidant enzymes in mitigating environmental stress associated with strong light and high temperatures and resultant oxidative stress. We also describe results of a survey of expressed Prx genes and their growth-phase-dependent behavior in C. marina using RNA-seq analysis. Finally, we speculate about the function of these genes and the ecological significance of 2-CysPrx, such as its involvement in circadian rhythms and the toxicity of C. marina to fish.
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Rasmusson, Lina M., Pimchanok Buapet, Rushingisha George, Martin Gullström, Pontus C. B. Gunnarsson, and Mats Björk. "Effects of temperature and hypoxia on respiration, photorespiration, and photosynthesis of seagrass leaves from contrasting temperature regimes." ICES Journal of Marine Science 77, no. 6 (July 9, 2020): 2056–65. http://dx.doi.org/10.1093/icesjms/fsaa093.
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Abstract In near-future climate change scenarios, elevated ocean temperatures with higher and more frequent peaks are anticipated than at present. Moreover, increased eutrophication and higher primary and secondary productivity will affect the oxygen levels of shallow-water coastal ecosystems, creating hypoxic conditions that can be experienced regularly, especially in dense vegetated systems. These climate-related events may impose detrimental effects on the primary productivity of seagrass. To evaluate such effects, this study combined gas exchange measurements with pulse amplitude-modulated fluorometry to assess the impact of short-time exposure to a range of water temperatures at ambient and low-oxygen levels on mitochondrial respiration, chlorophyll fluorescence (based on the Fv/F0 ratio), photosynthetic oxygen evolution, and photorespiration in leaf segments of the temperate seagrass Zostera marina and the tropical seagrass Thalassia hemprichii. We found that mitochondrial respiration in both Z. marina and T. hemprichii increased with higher temperatures up to 40°C and that low O2 caused significantly reduced respiration rates, particularly in T. hemprichii. Elevated water temperature had a clear negative effect on the Fv/F0 of both seagrass species, indicating damage or inactivation of the photosynthetic apparatus, even when light is not present. Moreover, damage to the photosynthetic apparatus was observed as an effect of elevated temperature combined with low O2 during darkness, resulting in subsequent lower photosynthesis in light. Photorespiration was present, but not promoted by increased temperature alone and will thus not further contribute to productivity losses during warmer events (when not carbon limited). This study demonstrates the negative impact of hypoxic stress and elevated temperatures on seagrass productivity, which may influence the overall health of seagrass plants as well as oxygen and carbon fluxes of shallow-water coastal ecosystems in warmer climate scenarios.
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Goulard, Fabienne, Klaus Lüning, and Sabine Jacobsen. "Circadian rhythm of photosynthesis and concurrent oscillations of transcript abundance of photosynthetic genes in the marine red algaGrateloupia turuturu." European Journal of Phycology 39, no. 4 (November 2004): 431–37. http://dx.doi.org/10.1080/09670260400009908.
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Hallegraeff, G. M., and I. A. N. Lucas. "The marine dinoflagellate genus Dinophysis (Dinophyceae): photosynthetic, neritic and non-photosynthetic, oceanic species." Phycologia 27, no. 1 (March 1988): 25–42. http://dx.doi.org/10.2216/i0031-8884-27-1-25.1.
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Sittmann, John, Munhyung Bae, Emily Mevers, Muzi Li, Andrew Quinn, Ganesh Sriram, Jon Clardy, and Zhongchi Liu. "Bacterial diketopiperazines stimulate diatom growth and lipid accumulation." Plant Physiology 186, no. 2 (February 23, 2021): 1159–70. http://dx.doi.org/10.1093/plphys/kiab080.
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Abstract Diatoms are photosynthetic microalgae that fix a significant fraction of the world’s carbon. Because of their photosynthetic efficiency and high-lipid content, diatoms are priority candidates for biofuel production. Here, we report that sporulating Bacillus thuringiensis and other members of the Bacillus cereus group, when in co-culture with the marine diatom Phaeodactylum tricornutum, significantly increase diatom cell count. Bioassay-guided purification of the mother cell lysate of B. thuringiensis led to the identification of two diketopiperazines (DKPs) that stimulate both P. tricornutum growth and increase its lipid content. These findings may be exploited to enhance P. tricornutum growth and microalgae-based biofuel production. As increasing numbers of DKPs are isolated from marine microbes, the work gives potential clues to bacterial-produced growth factors for marine microalgae.
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Beardall, J. "Photosynthesis and photorespiration in marine phytoplankton." Aquatic Botany 34, no. 1-3 (July 1989): 105–30. http://dx.doi.org/10.1016/0304-3770(89)90052-1.
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Beer, Sven. "Photosynthesis and photorespiration of marine angiosperms." Aquatic Botany 34, no. 1-3 (July 1989): 153–66. http://dx.doi.org/10.1016/0304-3770(89)90054-5.
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