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https://www.readbyqxmd.com/read/28646233/identifying-community-thresholds-for-lotic-benthic-diatoms-in-response-to-human-disturbance
#1
Tao Tang, Ting Tang, Lu Tan, Yuan Gu, Wanxiang Jiang, Qinghua Cai
Although human disturbance indirectly influences lotic assemblages through modifying physical and chemical conditions, identifying thresholds of human disturbance would provide direct evidence for preventing anthropogenic degradation of biological conditions. In the present study, we used data obtained from tributaries of the Three Gorges Reservoir in China to detect effects of human disturbance on streams and to identify disturbance thresholds for benthic diatoms. Diatom species composition was significantly affected by three in-stream stressors including TP, TN and pH...
June 23, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28645158/the-potential-for-co-evolution-of-co2-concentrating-mechanisms-and-rubisco-in-diatoms
#2
Jodi N Young, Brian M Hopkinson
Diatoms are a diverse group of unicellular algae that contribute significantly to global photosynthetic carbon fixation and export in the modern ocean, and are an important source of microfossils for paleoclimate reconstructions. Because of their importance in the environment, diatoms have been a focus of study on the physiology and ecophysiology of carbon fixation, in particular their CO2-concentrating mechanisms (CCMs) and Rubisco characteristics. While carbon fixation in diatoms is not as well understood as in certain model aquatic photoautotrophs, a greater number of species have been examined in diatoms...
June 22, 2017: Journal of Experimental Botany
https://www.readbyqxmd.com/read/28645048/phytolith-carbon-sequestration-in-global-terrestrial-biomes
#3
Zhaoliang Song, Hongyan Liu, Caroline A E Strömberg, Xiaomin Yang, Xiaodong Zhang
Terrestrial biogeochemical carbon (C) sequestration is coupled with the biogeochemical silicon (Si) cycle through mechanisms such as phytolith C sequestration, but the size and distribution of the phytolith C sink remain unclear. Here, we estimate phytolith C sequestration in global terrestrial biomes. We used biome data including productivity, phytolith and silica contents, and the phytolith stability factor to preliminarily determine the size and distribution of the phytolith C sink in global terrestrial biomes...
June 19, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28641894/carbon-assimilation-and-losses-during-an-ocean-acidification-mesocosm-experiment-with-special-reference-to-algal-blooms
#4
Nana Liu, Shanying Tong, Xiangqi Yi, Yan Li, Zhenzhen Li, Hangbin Miao, Tifeng Wang, Futian Li, Dong Yan, Ruiping Huang, Yaping Wu, David A Hutchins, John Beardall, Minhan Dai, Kunshan Gao
A mesocosm experiment was conducted in Wuyuan Bay (Xiamen), China, to investigate the effects of elevated pCO2 on bloom formation by phytoplankton species previously studied in laboratory-based ocean acidification experiments, to determine if the indoor-grown species performed similarly in mesocosms under more realistic environmental conditions. We measured biomass, primary productivity and particulate organic carbon (POC) as well as particulate organic nitrogen (PON). Phaeodactylum tricornutum outcompeted Thalassiosira weissflogii and Emiliania huxleyi, comprising more than 99% of the final biomass...
May 27, 2017: Marine Environmental Research
https://www.readbyqxmd.com/read/28637853/trophic-state-changes-can-affect-the-importance-of-methane-derived-carbon-in-aquatic-food-webs
#5
Jos Schilder, Maarten van Hardenbroek, Paul Bodelier, Emiliya P Kirilova, Markus Leuenberger, André F Lotter, Oliver Heiri
Methane-derived carbon, incorporated by methane-oxidizing bacteria, has been identified as a significant source of carbon in food webs of many lakes. By measuring the stable carbon isotopic composition (δ(13)C values) of particulate organic matter, Chironomidae and Daphnia spp. and their resting eggs (ephippia), we show that methane-derived carbon presently plays a relevant role in the food web of hypertrophic Lake De Waay, The Netherlands. Sediment geochemistry, diatom analyses and δ(13)C measurements of chironomid and Daphnia remains in the lake sediments indicate that oligotrophication and re-eutrophication of the lake during the twentieth century had a strong impact on in-lake oxygen availability...
June 28, 2017: Proceedings. Biological Sciences
https://www.readbyqxmd.com/read/28634653/assessing-the-combined-toxicity-of-bmaa-and-its-isomers-2-4-dab-and-aeg-in-vitro-using-human-neuroblastoma-cells
#6
Brendan J Main, Kenneth J Rodgers
The non-protein amino acid (NPAA) ß-methylamino-L-alanine (BMAA) is produced by a diverse range of cyanobacteria, diatoms and dinoflagellates, and is present in both aquatic and terrestrial ecosystems globally. Exposure to BMAA has been implicated in the development of neurodegenerative diseases including amyotrophic lateral sclerosis (ALS), Alzheimer's disease (AD) and Parkinson's disease (PD). BMAA is often found in nature along with its structural isomers 2,4-diaminobutyric acid (2,4-DAB) and aminoethylglycine (AEG); however, the toxicity of these NPAAs in combination has not been examined...
June 20, 2017: Neurotoxicity Research
https://www.readbyqxmd.com/read/28633304/molecular-aspects-of-the-biophysical-co2-concentrating-mechanism-and-its-regulation-in-marine-diatoms
#7
Yoshinori Tsuji, Kensuke Nakajima, Yusuke Matsuda
Diatoms operate a CO2-concentrating mechanism (CCM) that drives upwards of 20% of annual global primary production. Recent progress in CCM research in the marine pennate diatom Phaeodactylum tricornutum revealed that this diatom directly takes up HCO3- from seawater through low-CO2-inducible plasma membrane HCO3- transporters, which belong to the solute carrier (SLC) 4 family. Apart from this, studies of carbonic anhydrases (CAs) in diatoms have revealed considerable diversity in classes and localization among species...
June 13, 2017: Journal of Experimental Botany
https://www.readbyqxmd.com/read/28631733/plastid-thylakoid-architecture-optimizes-photosynthesis-in-diatoms
#8
Serena Flori, Pierre-Henri Jouneau, Benjamin Bailleul, Benoit Gallet, Leandro F Estrozi, Christine Moriscot, Olivier Bastien, Simona Eicke, Alexander Schober, Carolina Río Bártulos, Eric Maréchal, Peter G Kroth, Dimitris Petroutsos, Samuel Zeeman, Cécile Breyton, Guy Schoehn, Denis Falconet, Giovanni Finazzi
Photosynthesis is a unique process that allows independent colonization of the land by plants and of the oceans by phytoplankton. Although the photosynthesis process is well understood in plants, we are still unlocking the mechanisms evolved by phytoplankton to achieve extremely efficient photosynthesis. Here, we combine biochemical, structural and in vivo physiological studies to unravel the structure of the plastid in diatoms, prominent marine eukaryotes. Biochemical and immunolocalization analyses reveal segregation of photosynthetic complexes in the loosely stacked thylakoid membranes typical of diatoms...
June 20, 2017: Nature Communications
https://www.readbyqxmd.com/read/28631440/recognition-cascade-and-metabolite-transfer-in-a-marine-bacteria-phytoplankton-model-system
#9
Bryndan P Durham, Stephen P Dearth, Shalabh Sharma, Shady A Amin, Christa B Smith, Shawn R Campagna, E Virginia Armbrust, Mary Ann Moran
The trophic linkage between marine bacteria and phytoplankton in the surface ocean is a key step in the global carbon cycle, with almost half of marine primary production transformed by heterotrophic bacterioplankton within hours to weeks of fixation. Early studies conceptualized this link as the passive addition and removal of organic compounds from a shared seawater reservoir. Here we analyzed transcript and intracellular metabolite patterns in a two-member model system and found that the presence of a heterotrophic bacterium induced a potential recognition cascade in a marine phytoplankton species that parallels better-understood vascular plant response systems...
June 19, 2017: Environmental Microbiology
https://www.readbyqxmd.com/read/28630429/marine-diatoms-change-their-gene-expression-profile-when-exposed-to-microscale-turbulence-under-nutrient-replete-conditions
#10
Alberto Amato, Gianluca Dell'Aquila, Francesco Musacchia, Rossella Annunziata, Ari Ugarte, Nicolas Maillet, Alessandra Carbone, Maurizio Ribera d'Alcalà, Remo Sanges, Daniele Iudicone, Maria I Ferrante
Diatoms are a fundamental microalgal phylum that thrives in turbulent environments. Despite several experimental and numerical studies, if and how diatoms may profit from turbulence is still an open question. One of the leading arguments is that turbulence favours nutrient uptake. Morphological features, such as the absence of flagella, the presence of a rigid exoskeleton and the micrometre size would support the possible passive but beneficial role of turbulence on diatoms. We demonstrate that in fact diatoms actively respond to turbulence in non-limiting nutrient conditions...
June 19, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28629881/cell-mediated-immune-response-of-postmetamorphic-sea-urchin-juveniles-against-infectious-stages-of-diatom-cylindrotheca-closterium-bacillariophyceae
#11
Adriano Magesky, Claude Belzile, Émilien Pelletier
In this study, successive infectious stages by diatom Cylindrotheca closterium (Bacillariophyceae) are described for the first time during the early development of sea urchin at low temperature (8°C). Diatom cell-types enclosed or not by typical theca were capable of infection. As an immune response, red spherulocytes and amoebocytes migrated towards infested areas and restrained the infection spreading over shells in 2- and 3-month old urchins. Only amoebocyte cells appeared to be involved in the immune reaction of 1-month old specimens which turned out to be a less effective fence to stop infestation...
June 16, 2017: Journal of Invertebrate Pathology
https://www.readbyqxmd.com/read/28628993/the-impact-of-silver-nanoparticles-on-marine-plankton-dynamics-dependence-on-coating-size-and-concentration
#12
Anastasia Tsiola, Paraskevi Pitta, Agnès Junyer Callol, Margarita Kagiorgi, Ioanna Kalantzi, Kyriaki Mylona, Ioulia Santi, Claudio Toncelli, Spyros Pergantis, Manolis Tsapakis
During this study, three microcosm experiments were carried out with natural coastal seawater, collected in the Eastern Mediterranean Sea, in order to assess the effect of silver nanoparticle (AgNP) exposure to natural plankton communities. The impact of coating (branched-polyethyleneimine: BPEI vs. poly-vinylpyrrolidone: PVP), size (40 vs. 60nm), concentration (200, 500, 2000, 5000 and 10,000ng Ag L(-1)) and silver form (dissolved Ag(+) vs. AgNPs) were tested. The results of chlorophyll a concentration revealed that PVP AgNPs caused a higher toxicity than BPEI AgNPs, and this was possibly related to the measured higher dissolution rate...
June 14, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28627710/oil-and-eicosapentaenoic-acid-production-by-the-diatom-phaeodactylum-tricornutum-cultivated-outdoors-in-green-wall-panel-gwp%C3%A2-reactors
#13
Liliana Rodolfi, Natascia Biondi, Alessia Guccione, Niccolò Bassi, Massimo D'Ottavio, Gimena Arganaraz, Mario R Tredici
Phaeodactylum tricornutum is a widely studied diatom and has been proposed as a source of oil and polyunsaturated fatty acids (PUFA), particularly eicosapentaenoic acid (EPA). Recent studies indicate that lipid accumulation occurs under nutritional stress. Aim of this research was to determine how changes in nitrogen availability affect productivity, oil yield and fatty acid (FA) composition of P. tricornutum UTEX 640. After preliminary laboratory trials, outdoor experiments were carried out in 40-L GWP® reactors under different nitrogen regimes in batch...
June 19, 2017: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/28627163/molecular-structures-and-functions-of-chlorophylls-a-esterified-with-geranylgeranyl-dihydrogeranylgeranyl-and-tetrahydrogeranylgeranyl-groups-at-the-17-propionate-residue-in-a-diatom-chaetoceros-calcitrans
#14
Tadashi Mizoguchi, Megumi Isaji, Nami Yamano, Jiro Harada, Ritsuko Fujii, Hitoshi Tamiaki
The 17-propionate ester group of chlorophyll(Chl)-a in some oxygenic phototrophs was investigated using HPLC. Chls-a esterified with partially dehydrogenated forms of a phytyl group were found in fully grown cells of a diatom, Chaetoceros calcitrans: geranylgeranyl (GG), dihydrogeranylgeranyl (DHGG), and tetrahydrogeranylgeranyl (THGG). Chls-a bearing such esterifying groups were reported to be found only in greening processes of higher plants, and thus these Chls-a have been thought to be biosynthetic precursors for phytylated Chl-a...
June 19, 2017: Biochemistry
https://www.readbyqxmd.com/read/28624939/additive-effect-of-calcium-depletion-and-low-resource-quality-on-gammarus-fossarum-crustacea-amphipoda-life-history-traits
#15
Marc Rollin, Romain Coulaud, Michael Danger, Bénédicte Sohm, Justine Flayac, Alexandre Bec, Arnaud Chaumot, Olivier Geffard, Vincent Felten
Gammarus fossarum is an often-abundant crustacean detritivore that contributes importantly to leaf litter breakdown in oligotrophic, mainly heterotrophic, headwater streams. This species requires large amounts of Ca to moult, thus allowing growth and reproduction. Because resource quality is tightly coupled to the organism's growth and physiological status, we hypothesised that low Ca concentration [Ca] and low food resource quality (low phosphorus [P] and/or reduced highly unsaturated fatty acid [HUFA] contents) would interactively impair molecular responses (gene expression) and reproduction of G...
June 17, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28624904/the-effect-of-light-on-bacterial-activity-in-a-seaweed-holobiont
#16
Sergio A Coelho-Souza, Stuart R Jenkins, Antonio Casarin, Maria Helena Baeta-Neves, Leonardo T Salgado, Jean R D Guimaraes, Ricardo Coutinho
Holobionts are characterized by the relationship between host and their associated organisms such as the biofilm associated with macroalgae. Considering that light is essential to macroalgae survival, the aim of this study was to verify the effect of light on the heterotrophic activity in biofilms of the brown macroalgae Sargassum furcatum during its growth cycle. Measurements of heterotrophic activity were done under natural light levels at different times during a daily cycle and under an artificial extinction of natural light during the afternoon...
June 17, 2017: Microbial Ecology
https://www.readbyqxmd.com/read/28624246/uv-c-irradiation-accelerates-neutral-lipid-synthesis-in-the-marine-oleaginous-diatom-fistulifera-solaris
#17
Atsushi Arakaki, Takuya Matsumoto, Takuma Tateishi, Mitsufumi Matsumoto, Daisuke Nojima, Yoshino Tomoko, Tsuyoshi Tanaka
This study investigated the induction of oil synthesis in the oleaginous diatom, Fistulifera solaris, following irradiation with small doses of UV-C. A rapid induction of oil accumulation was confirmed within 6h following UV-C radiation of the diatom cells, with increases in cell oil body volumes after 24h of approximately 4- to 6-fold from the initial volume. Reactive oxygen species (ROS), which can be generated by a UV-C-mediated reaction, were detected in irradiated cells and the correlation between ROS generation and oil accumulation was confirmed...
June 1, 2017: Bioresource Technology
https://www.readbyqxmd.com/read/28623567/molecular-identification-and-comparative-evaluation-of-tropical-marine-microalgae-for-biodiesel-production
#18
Sanyo Sabu, I S Bright Singh, Valsamma Joseph
Marine microalgae have emerged as important feedstock for liquid biofuel production. The identification of lipid-rich native microalgal species with high growth rate and optimal fatty acid profile and biodiesel properties is the most challenging step in microalgae-based biodiesel production. In this study, attempts have been made to bio-prospect the biodiesel production potential of marine and brackish water microalgal isolates from the west coast of India. A total of 14 microalgal species were isolated, identified using specific molecular markers and based on the lipid content; seven species with total lipid content above 20% of dry cell weight were selected for assessing biodiesel production potential in terms of lipid and biomass productivities, nile red fluorescence, fatty acid profile and biodiesel properties...
June 16, 2017: Marine Biotechnology
https://www.readbyqxmd.com/read/28623275/influences-of-temperature-and-salinity-on-physicochemical-properties-and-toxicity-of-zinc-oxide-nanoparticles-to-the-marine-diatom-thalassiosira-pseudonana
#19
Mana M N Yung, Kevin W H Kwok, Aleksandra B Djurišić, John P Giesy, Kenneth M Y Leung
Climate change is predicted to result in rising average temperature of seawater with more extreme thermal events, and frequent rainfalls in some coastal regions. It is imperative to understand how naturally mediated changes in temperature and salinity can modulate toxicity of chemical contaminants to marine life. Thus, this study investigated combined effects of temperature and salinity on toxicity of zinc oxide nanoparticles (ZnO-NPs) to the marine diatom Thalassiosira pseudonana. Because ZnO-NPs formed larger aggregations and released less zinc ions (Zn(2+)) at greater temperature and salinity, toxicity of ZnO-NPs to T...
June 16, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28622375/identification-of-benthic-diatoms-isolated-from-the-eastern-tidal-flats-of-the-yellow-sea-comparison-between-morphological-and-molecular-approaches
#20
Sung Min An, Dong Han Choi, Jung Ho Lee, Howon Lee, Jae Hoon Noh
Benthic diatoms isolated from tidal flats in the west coast of Korea were identified through both traditional morphological method and molecular phylogenetic method for methodological comparison. For the molecular phylogenetic analyses, we sequenced the 18S rRNA and the ribulose bisphosphate carboxylase large subunit coding gene, rbcL. Further, the comparative analysis allowed for the assessment of the suitability as a genetic marker for identification of closely related benthic diatom species and as potential barcode gene...
2017: PloS One
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