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1.
Environ Microbiol ; 22(1): 183-197, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31637819

RESUMO

Ultraviolet-B radiation is known to harm most photosynthetic organisms with the exception of several studies of photosynthetic eukaryotes in which UV-B showed positive effects. In this study, we investigated the effect of acclimation to low UV-B radiation on growth and photosynthesis of the cyanobacterium Nostoc sphaeroides. Exposure to 0.08 W m-2 UV-B plus low visible light for 14 d significantly increased the growth rate and biomass production by 16% and 30%, respectively, compared with those under visible light alone. The UV-B acclimated cells showed an approximately 50% increase in photosynthetic efficiency (α) and photosynthetic capacity (Pmax ), a higher PSI/PSII fluorescence ratio, an increase in PSI content and consequently enhanced cyclic electron flow, relative to those of non-acclimated cells. Both the primary quinone-type acceptor and plastoquinone pool re-oxidation were up-regulated in the UV-B acclimated cells. In parallel, the UV-B acclimated colonies maintained a higher rate of D1 protein synthesis following exposure to elevated intensity of UV-B or visible light, thus functionally mitigating photoinhibition. The present data provide novel insight into photosynthetic acclimation to low UV-B radiation and suggest that UV-B may act as a positive ecological factor for the productivity of some photosynthetic prokaryotes, especially during twilight periods or in shaded environments.

2.
Mar Pollut Bull ; 146: 225-235, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31426151

RESUMO

Ocean acidification is known to affect primary producers differentially in terms of species and environmental conditions, with controversial results obtained under different experimental setups. In this work we examined the physiological performances of the coccolithophore Gephyrocapsa oceanica that had been acclimated to 1000 µatm CO2 for ~400 generations, and then exposed to multiple drivers, light intensity, light fluctuating frequency, temperature and UV radiation. Here, we show that increasing light intensity resulted in higher non-photochemical quenching and the effective absorption cross-section of PSII. The effective photochemical efficiency (Fv'/Fm') decreased with increased levels of light, which was counterbalanced by fluctuating light regimes. The greenhouse condition acts synergistically with decreasing fluctuating light frequency to increase the Fv'/Fm' and photosynthetic carbon fixation rate. Our data suggest that the coccolithophorid would be more stressed with increased exposures to solar UV irradiances, though its photosynthetic carbon fixation could be enhanced under the greenhouse condition.


Assuntos
Haptófitas/fisiologia , Aclimatação , Dióxido de Carbono/metabolismo , Luz , Processos Fotoquímicos , Fotossíntese , Água do Mar/química , Estresse Fisiológico , Temperatura Ambiente , Raios Ultravioleta
3.
Sci Total Environ ; 680: 79-90, 2019 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-31102831

RESUMO

Diatoms and other phytoplankton groups are exposed to abrupt changes in pCO2, in waters in upwelling areas, near CO2 seeps, or during their blooms; or to more gradual pCO2 rise through anthropogenic CO2 emissions. Gradual CO2 rises have, however, rarely been included in ocean acidification (OA) studies. We therefore compared how small (Thalassiosira pseudonana) and larger (Thalassiosira weissflogii) diatom cell isolates respond to gradual pCO2 rises from 180 to 1000 µatm in steps of ~40 µatm with 5-10 generations at each step, and whether their responses to gradual pCO2 rise differ when compared to an abrupt pCO2 rise imposed from ambient 400 directly to 1000 µatm. Cell volume increased in T. pseudonana but decreased in T. weissflogii with an increase from low to moderate CO2 levels, and then remained steady under yet higher CO2 levels. Growth rates were stimulated, but Chl a, particulate organic carbon (POC) and cellular biogenic silica (BSi) decreased from low to moderate CO2 levels, and then remained steady with further CO2 rise in both species. Decreased saturation light intensity (Ik) and light use efficiency (α) with CO2 rise in T. pseudonana indicate that the smaller diatom becomes more susceptible to photoinhibition. Decreased BSi/POC (Si/C) in T. weissflogii indicates the biogeochemical cycles of both silicon and carbon may be more affected by elevated pCO2 in the larger diatom. The different CO2 modulation methods resulted in different responses of some key physiological parameters. Increasing pCO2 from 180 to 400 µatm decreased cellular POC and BSi contents, implying that ocean acidification to date has already altered diatom contributions to carbon and silicon biogeochemical processes.


Assuntos
Dióxido de Carbono/análise , Diatomáceas/fisiologia , Monitoramento Ambiental , Concentração de Íons de Hidrogênio , Fitoplâncton , Água do Mar/química
4.
Mar Pollut Bull ; 141: 462-471, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30955757

RESUMO

Ocean acidification (OA) has potential to affect marine phytoplankton in ways that are partly understood, but there is less knowledge about how it may alter the coupling to secondary producers. We investigated the effects of OA on phytoplankton primary production, and its trophic transfer to zooplankton in a subtropical eutrophic water (Wuyuan Bay, China) under present day (400 µatm) and projected end-of-century (1000 µatm) pCO2 levels. Net primary production was unaffected, although OA did lead to small decreases in growth rates. OA had no measurable effect on micro-/mesozooplankton grazing rates. Elevated pCO2 had no effect on phytoplankton fatty acid (FA) concentrations during exponential phase, but saturated FAs increased relative to the control during declining phase. FA profiles of mesozooplankton were unaffected. Our findings show that short-term exposure of plankton communities in eutrophic subtropical waters to projected end-of-century OA conditions has little effect on primary productivity and trophic linkage to mesozooplankton.


Assuntos
Monitoramento Ambiental/métodos , Fitoplâncton/crescimento & desenvolvimento , Água do Mar/química , Zooplâncton/crescimento & desenvolvimento , Animais , Ciclo do Carbono , Dióxido de Carbono/análise , China , Eutrofização , Ácidos Graxos/análise , Concentração de Íons de Hidrogênio , Oceanos e Mares , Fitoplâncton/química , Zooplâncton/química
6.
Mar Environ Res ; 141: 159-166, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30180993

RESUMO

Coastal and offshore waters in the South China Sea are warming and becoming acidified due to rising atmospheric levels of carbon dioxide (CO2), yet the combined effects of these two stressors are poorly known. Here, we carried out shipboard incubations at ambient (398 µatm) and elevated (934 µatm) pCO2 at in situ and in situ+1.8 °C temperatures and we measured primary productivity at two coastal and two offshore stations. Both warming and increased CO2 levels individually increased phytoplankton productivity at all stations, but the combination of high temperature and high CO2 did not, reflecting an antagonistic effect. Warming decreased Chl a concentrations in off-shore waters at ambient CO2, but had no effect in the coastal waters. The high CO2 treatment increased night time respiration in the coastal waters at ambient temperatures. Our findings show that phytoplankton assemblage responses to rising temperature and CO2 levels differ between coastal and offshore waters. While it is difficult to predict how ongoing warming and acidification will influence primary productivity in the South China Sea, our data imply that predicted increases in temperature and pCO2 will not boost surface phytoplankton primary productivity.

7.
J Cell Mol Med ; 22(9): 4076-4084, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-29961269

RESUMO

Endogenous circular RNAs (circRNAs) have been reported in various diseases. However, their role in active TB remains unknown. The study was aimed to determine plasma circRNA expression profile to characterize potential biomarker and improve our understanding of active TB pathogenesis. CircRNA expression profiles were screened by circRNA microarrays in active TB plasma samples. Dysregulated circRNAs were then verified by qRT-PCR. CircRNA targets were predicted based on analysis of circRNA-miRNA-mRNA interaction. GO and KEGG pathway analyses were used to predict the function of circRNA. ROC curve was calculated to evaluate diagnostic value for active TB. A total of 75 circRNAs were significantly dysregulated in active TB plasma. By further validation, hsa_circRNA_103571 exhibited significant decrease in active TB patients and showed potential interaction with active TB-related miRNAs such as miR-29a and miR-16. Bioinformatics analysis revealed that hsa_circRNA_103571 was primarily involved in ras signalling pathway, regulation of actin cytoskeleton, T- and B-cell receptor signalling pathway. ROC curve analysis suggested that hsa_circRNA_103571 had significant value for active TB diagnosis. Circulating circRNA dysregulation may play a role in active TB pathogenesis. Hsa_circRNA_103571 may be served as a potential biomarker for active TB diagnosis, and hsa_circRNA_103571-miRNA-mRNA interaction may provide some novel mechanism for active TB.


Assuntos
Regulação da Expressão Gênica , MicroRNAs/genética , RNA/genética , Tuberculose Pulmonar/diagnóstico , Tuberculose Pulmonar/genética , Linfócitos B/imunologia , Linfócitos B/microbiologia , Sequência de Bases , Biomarcadores/sangue , Estudos de Casos e Controles , Ontologia Genética , Humanos , MicroRNAs/sangue , MicroRNAs/imunologia , Anotação de Sequência Molecular , Mycobacterium tuberculosis/patogenicidade , Mycobacterium tuberculosis/fisiologia , Análise de Sequência com Séries de Oligonucleotídeos , RNA/sangue , RNA/imunologia , Curva ROC , Receptores de Antígenos de Linfócitos B/sangue , Receptores de Antígenos de Linfócitos B/genética , Receptores de Antígenos de Linfócitos B/imunologia , Receptores de Antígenos de Linfócitos T/sangue , Receptores de Antígenos de Linfócitos T/genética , Receptores de Antígenos de Linfócitos T/imunologia , Transdução de Sinais , Linfócitos T/imunologia , Linfócitos T/microbiologia , Transcriptoma , Tuberculose Pulmonar/imunologia , Tuberculose Pulmonar/microbiologia
8.
PeerJ ; 6: e4608, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29666762

RESUMO

Background: The globally abundant coccolithophore, Emiliania huxleyi, plays an important ecological role in oceanic carbon biogeochemistry by forming a cellular covering of plate-like CaCO3 crystals (coccoliths) and fixing CO2. It is unknown how the cells arrange different-sized coccoliths to maintain full coverage, as the cell surface area of the cell changes during daily cycle. Methods: We used Euler's polyhedron formula and CaGe simulation software, validated with the geometries of coccoliths, to analyze and simulate the coccolith topology of the coccosphere and to explore the arrangement mechanisms. Results: There were only small variations in the geometries of coccoliths, even when the cells were cultured under variable light conditions. Because of geometric limits, small coccoliths tended to interlock with fewer and larger coccoliths, and vice versa. Consequently, to sustain a full coverage on the surface of cell, each coccolith was arranged to interlock with four to six others, which in turn led to each coccosphere contains at least six coccoliths. Conclusion: The number of coccoliths per coccosphere must keep pace with changes on the cell surface area as a result of photosynthesis, respiration and cell division. This study is an example of natural selection following Euler's polyhedral formula, in response to the challenge of maintaining a CaCO3 covering on coccolithophore cells as cell size changes.

9.
Photochem Photobiol ; 94(5): 994-1002, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-29701244

RESUMO

The physiological performance of calcified and non-calcified cells of Gephyrocapsa oceanica (NIES-1318) and their short-term responses to UV radiation were compared for cultures grown under present-day (LC, 400 µatm) and high pCO2 (HC, 1000 µatm) conditions. Similar growth rates and Fv /Fm values were observed in both types of cell under LC conditions, indicating that the loss of calcification in the non-calcified cells did not lead to a competitive disadvantage under such conditions. Detrimental effects of elevated pCO2 were observed in both cell types, with the growth rate of non-calcified cells decreasing more markedly, which might reflect a negative impact of higher cytoplasmic H+ . When exposed to short-term UV radiation, similar trends in effective quantum yield were observed in both cell types acclimated to LC conditions. Elevated pCO2 and associated seawater chemical changes strongly reduced effective quantum yield in non-calcified cells but no significant influence was observed in calcified cells. Based on these findings and comparisons with previous studies, we suggest that the negative impact of elevated cytoplasmic H+ would exacerbate the detrimental effects of UV radiation while the possession of calcification attenuated this influence.


Assuntos
Calcificação Fisiológica , Dióxido de Carbono/metabolismo , Haptófitas/efeitos da radiação , Raios Ultravioleta , Citoplasma/metabolismo , Haptófitas/crescimento & desenvolvimento , Haptófitas/fisiologia , Prótons , Teoria Quântica , Água do Mar
10.
Sci Total Environ ; 633: 618-629, 2018 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-29597159

RESUMO

Increases of atmospheric CO2 concentrations due to human activity and associated effects on aquatic ecosystems are recognized as an environmental issue at a global scale. Growing attention is being paid to CO2 enrichment effects under multiple stresses or fluctuating environmental conditions in order to extrapolate from laboratory-scale experiments to natural systems. We carried out a mesocosm experiment in coastal water with an assemblage of three model phytoplankton species and their associated bacteria under the influence of elevated CO2 concentrations. Net community production and the metabolic characteristics of the phytoplankton and bacteria were monitored to elucidate how these organisms responded to CO2 enrichment during the course of the algal bloom. We found that CO2 enrichment (1000µatm) significantly enhanced gross primary production and the ratio of photosynthesis to chlorophyll a by approximately 38% and 39%, respectively, during the early stationary phase of the algal bloom. Although there were few effects on bulk bacterial production, a significant decrease of bulk bacterial respiration (up to 31%) at elevated CO2 resulted in an increase of bacterial growth efficiency. The implication is that an elevation of CO2 concentrations leads to a reduction of bacterial carbon demand and enhances carbon transfer efficiency through the microbial loop, with a greater proportion of fixed carbon being allocated to bacterial biomass and less being lost as CO2. The contemporaneous responses of phytoplankton and bacterial metabolism to CO2 enrichment increased net community production by about 45%, an increase that would have profound implications for the carbon cycle in coastal marine ecosystems.


Assuntos
Poluentes Atmosféricos/toxicidade , Dióxido de Carbono/toxicidade , Ecossistema , Eutrofização/efeitos dos fármacos , Fitoplâncton/efeitos dos fármacos , Água do Mar/microbiologia , Poluentes Atmosféricos/análise , Bactérias/efeitos dos fármacos , Bactérias/crescimento & desenvolvimento , Dióxido de Carbono/análise , Clorofila/análise , Clorofila/metabolismo , Clorofila A , Fotossíntese , Fitoplâncton/metabolismo , Água do Mar/química
11.
Int J Mol Med ; 41(5): 2885-2892, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29436601

RESUMO

Cell wall deficient (CWD) forms of Mycobacterium tuberculosis (Mtb) confers a marked resistance to immune system of the host. However, there is limit data on the effect of intracellular CWD-Mtb infection on macrophages. In the study, effects of CWD-Mtb on cell viability, cytokine response and miRNA expression of macrophages were analyzed. Cell viability was reduced, levels of interleukin-1α (IL-1α), IL-1ß, IL-6, IL-10 and interferon-γ (IFN-γ) were also significantly changed after infection of RAW264.7 cells with CWD-Mtb. A total of 105 miRNAs were deregulated between CWD-Mtb and wild Mtb group, and among them, miR-29b was upregulated in CWD-Mtb group. Downregulation of miR-29b resulted in significant elevation level of IFN-γ mRNA. Involved signaling pathways of potential target genes of differentially expressed miRNAs mainly focused on T cell receptor signaling pathway, MAPK signaling pathway, neurotrophin signaling pathway, and regulation of actin cytoskeleton. Taken together, the results showed that cytokine production of CWD-Mtb infected macrophages was altered and many miRNAs were involved in regulation of macrophage response to CWD-Mtb infection, which probably determined the differential outcome following different phenotype Mtb infection. These findings open up a new and interesting avenue for an improved understanding of pathogenesis of CWD-Mtb.


Assuntos
Regulação da Expressão Gênica , Macrófagos/microbiologia , MicroRNAs/genética , Mycobacterium tuberculosis/fisiologia , Tuberculose/genética , Animais , Sobrevivência Celular , Parede Celular/genética , Parede Celular/imunologia , Parede Celular/fisiologia , Interleucinas/análise , Interleucinas/imunologia , Macrófagos/imunologia , Macrófagos/metabolismo , Camundongos , Mycobacterium tuberculosis/genética , Mycobacterium tuberculosis/imunologia , Células RAW 264.7 , Transdução de Sinais , Tuberculose/imunologia , Tuberculose/microbiologia
12.
Glob Chang Biol ; 24(6): 2239-2261, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-29476630

RESUMO

Marine life is controlled by multiple physical and chemical drivers and by diverse ecological processes. Many of these oceanic properties are being altered by climate change and other anthropogenic pressures. Hence, identifying the influences of multifaceted ocean change, from local to global scales, is a complex task. To guide policy-making and make projections of the future of the marine biosphere, it is essential to understand biological responses at physiological, evolutionary and ecological levels. Here, we contrast and compare different approaches to multiple driver experiments that aim to elucidate biological responses to a complex matrix of ocean global change. We present the benefits and the challenges of each approach with a focus on marine research, and guidelines to navigate through these different categories to help identify strategies that might best address research questions in fundamental physiology, experimental evolutionary biology and community ecology. Our review reveals that the field of multiple driver research is being pulled in complementary directions: the need for reductionist approaches to obtain process-oriented, mechanistic understanding and a requirement to quantify responses to projected future scenarios of ocean change. We conclude the review with recommendations on how best to align different experimental approaches to contribute fundamental information needed for science-based policy formulation.


Assuntos
Evolução Biológica , Mudança Climática , Monitoramento Ambiental/métodos , Oceanos e Mares , Animais
13.
Glob Chang Biol ; 24(7): 3055-3064, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-29356310

RESUMO

Coccolithophores are important oceanic primary producers not only in terms of photosynthesis but also because they produce calcite plates called coccoliths. Ongoing ocean acidification associated with changing seawater carbonate chemistry may impair calcification and other metabolic functions in coccolithophores. While short-term ocean acidification effects on calcification and other properties have been examined in a variety of coccolithophore species, long-term adaptive responses have scarcely been documented, other than for the single species Emiliania huxleyi. Here, we investigated the effects of ocean acidification on another ecologically important coccolithophore species, Gephyrocapsa oceanica, following 1,000 generations of growth under elevated CO2 conditions (1,000 µatm). High CO2 -selected populations exhibited reduced growth rates and enhanced particulate organic carbon (POC) and nitrogen (PON) production, relative to populations selected under ambient CO2 (400 µatm). Particulate inorganic carbon (PIC) and PIC/POC ratios decreased progressively throughout the selection period in high CO2 -selected cell lines. All of these trait changes persisted when high CO2 -grown populations were moved back to ambient CO2 conditions for about 10 generations. The results suggest that the calcification of some coccolithophores may be more heavily impaired by ocean acidification than previously predicted based on short-term studies, with potentially large implications for the ocean's carbon cycle under accelerating anthropogenic influences.


Assuntos
Adaptação Fisiológica/genética , Dióxido de Carbono/administração & dosagem , Dióxido de Carbono/farmacologia , Haptófitas/efeitos dos fármacos , Seleção Genética , Carbono/metabolismo , Carbonatos/metabolismo , Haptófitas/genética , Haptófitas/crescimento & desenvolvimento , Concentração de Íons de Hidrogênio , Nitrogênio/metabolismo , Fotossíntese/efeitos dos fármacos , Água do Mar/química
14.
Photosynth Res ; 137(1): 41-52, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-29322482

RESUMO

Cell size has implications for the package effect in photon absorption as well as for metabolic scaling of metabolism. In this study, we have avoided species-related differences by using isolates of the marine planktonic diatom Coscinodiscus granii with cells of different sizes and grown at different light intensities to investigate their energy allocation strategies. To make full use of incident light, several fold variations in cellular chlorophyll a content were employed across cell size. This modulation of pigment-related light absorbance was deemed effective as similar light absorbing capacities were found in all treatments. Unexpected low values of O2 evolution rate at the highest irradiance level of 450 µmol photons m-2 s-1 were found in medium and large cells, regardless of more photons being absorbed under these conditions, suggesting the operation of alternative electron flows acting as electron sinks. The growth rate was generally larger at higher irradiance levels except for the large cells, in which growth slowed at 450 µmol photons m-2 s-1, suggesting that larger cells achieved a balance between growth and photoprotection by sacrificing growth rate when exposed to high light. Although the ratio of carbon demand to rates of uncatalysed CO2 diffusion to the cell surface reached around 20 in large cells grown under higher irradiance, the carbon fixation rate was not lowered, due to the presence of a highly effective carbon dioxide concentrating mechanism.


Assuntos
Diatomáceas/citologia , Diatomáceas/fisiologia , Fotossíntese/fisiologia , Dióxido de Carbono/metabolismo , Clorofila/metabolismo , Clorofila A , Diatomáceas/crescimento & desenvolvimento , Transferência de Energia , Oxigênio/metabolismo , Luz Solar
15.
Front Microbiol ; 9: 3342, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30692981

RESUMO

Understanding of the molecular responses underpinning diatom responses to ocean acidification is fundamental for predicting how important primary producers will be shaped by the continuous rise in atmospheric CO2. In this study, we have analyzed global transcriptomic changes of the model diatom Phaeodactylum tricornutum following growth for 15 generations in elevated pCO2 by strand-specific RNA sequencing (ssRNA-seq). Our results indicate that no significant effects of elevated pCO2 and associated carbonate chemistry changes on the physiological performance of the cells were observed after 15 generations whereas the expression of genes encoding histones and other genes involved in chromatin structure were significantly down-regulated, while the expression of transposable elements (TEs) and genes encoding histone acetylation enzymes were significantly up-regulated. Furthermore, we identified a series of long non-protein coding RNAs (lncRNAs) specifically responsive to elevated pCO2, suggesting putative regulatory roles for these largely uncharacterized genome components. Taken together, our integrative analyses reveal that epigenetic elements such as TEs, histone modifications and lncRNAs may have important roles in the acclimation of diatoms to elevated pCO2 over short time scales and thus may influence longer term adaptive processes in response to progressive ocean acidification.

16.
Mar Environ Res ; 132: 51-62, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-29108676

RESUMO

Ocean Acidification (OA) effects on marine plankton are most often considered in terms of inorganic carbon chemistry, but decreasing pH may influence other aspects of cellular metabolism. Here we present the effects of OA on the fatty acid (FA) content and composition of an artificial phytoplankton community (Phaeodactylum tricornutum, Thalassiosira weissflogii, and Emiliania huxleyi) in a fully replicated, ∼4 m3 mesocosm study in subtropical coastal waters (Wuyuan Bay, China, 24.52°N, 117.18°E) at present day (400 µatm) and elevated (1000 µatm) pCO2 concentrations. Phytoplankton growth occurred in three phases during the 33-day experiment: an initial exponential growth leading to senescence and a subsequent decline phase. Phytoplankton sampled from these mesocosms were fed to mesozooplankton collected by net haul from Wuyuan Bay. Concentrations of saturated fatty acids (SFA) in both phytoplankton and mesozooplankton remained high under acidified and non-acidified conditions. However, polyunsaturated fatty acids (PUFA) and monounsaturated fatty acids (MUFA) increased significantly more under elevated pCO2 during the late exponential phase (Day 13), indicating increased nutritional value for zooplankton and higher trophic levels. Indeed, uptake rates of the essential FA docosahexaenoic acid (C20:5n3, DHA) increased in mesozooplankton under acidified conditions. However, mesozooplankton grazing rates decreased overall with elevated pCO2. Our findings show that these selected phytoplankton species have a relatively high tolerance to acidification in terms of FA production, and local mesozooplankton in these subtropical coastal waters can maintain their FA composition under end of century ocean acidification conditions.


Assuntos
Monitoramento Ambiental , Ácidos Graxos/metabolismo , Plâncton/fisiologia , Dióxido de Carbono , China , Ecossistema , Concentração de Íons de Hidrogênio , Água do Mar/química
17.
Sci Rep ; 7(1): 6868, 2017 07 31.
Artigo em Inglês | MEDLINE | ID: mdl-28761136

RESUMO

There is a growing consensus that the ongoing increase in atmospheric CO2 level will lead to a variety of effects on marine phytoplankton and ecosystems. However, the effects of CO2 enrichment on eutrophic coastal waters are still unclear, as are the complex mechanisms coupled to the development of eutrophication. Here, we report the first mesocosm CO2 perturbation study in a eutrophic subtropical bay during summer by investigating the effect of rising CO2 on a model artificial community consisting of well-characterized cultured diatoms (Phaeodactylum tricornutum and Thalassiosira weissflogii) and prymnesiophytes (Emiliania huxleyi and Gephyrocapsa oceanica). These species were inoculated into triplicate 4 m3 enclosures with equivalent chlorophyll a (Chl-a) under present and higher partial pressures of atmospheric CO2 (pCO2 = 400 and 1000 ppmv). Diatom bloom events were observed in all enclosures, with enhanced organic carbon production and Chl-a concentrations under high CO2 treatments. Relative to the low CO2 treatments, the consumption of the dissolved inorganic nitrogen and uptake ratios of N/P and N/Si increased significantly during the bloom. These observed responses suggest more extensive and complex effects of higher CO2 concentrations on phytoplankton communities in coastal eutrophic environments.

18.
Mar Environ Res ; 129: 229-235, 2017 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-28641894

RESUMO

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. Mainly through a capacity to tolerate nutrient-limited situations, P. tricornutum showed a powerful sustained presence during the plateau phase of growth. Significant differences between high and low CO2 treatments were found in cell concentration, cumulative primary productivity and POC in the plateau phase but not during the exponential phase of growth. Compared to the low pCO2 (LC) treatment, POC increased by 45.8-101.9% in the high pCO2 (HC) treated cells during the bloom period. Furthermore, respiratory carbon losses of gross primary productivity were found to comprise 39-64% for the LC and 31-41% for the HC mesocosms (daytime C fixation) in phase II. Our results suggest that the duration and characteristics of a diatom bloom can be affected by elevated pCO2. Effects of elevated pCO2 observed in the laboratory cannot be reliably extrapolated to large scale mesocosms with multiple influencing factors, especially during intense algal blooms.


Assuntos
Dióxido de Carbono/análise , Monitoramento Ambiental , Eutrofização/fisiologia , Fitoplâncton/fisiologia , Água do Mar/química , Biomassa , Carbono/análise , Dióxido de Carbono/metabolismo , China , Diatomáceas/fisiologia , Ecossistema , Haptófitas/fisiologia , Concentração de Íons de Hidrogênio , Nitrogênio/análise , Nitrogênio/metabolismo
19.
Ecol Evol ; 7(10): 3362-3371, 2017 05.
Artigo em Inglês | MEDLINE | ID: mdl-28515872

RESUMO

The elemental composition (surface adsorbed and internalized fraction of Cu, Mo and P) in marine phytoplankton was first examined in cultures of the diatom Phaeodactylum tricornutum which were exposed to various levels of Cu concentrations ranging from 0.25 to 16 µmol/L with equivalent free [Cu2+] concentrations of 0.4-26 nmol/L. We observed an acceleration of algal growth rates (20-40%) with increasing ambient Cu levels, as well as slightly increased levels of internalized Cu in cells (2-13 × 10-18 mol/cell) although cellular Cu mostly accumulated onto the cell surface (>50% of the total: intracellular + surface adsorbed). In particular, we documented for the first time that the elemental composition (Mo and P) in algal cells varies dynamically in response to increased Cu levels: (1) Cellular P, predominantly in the intracellular compartment (>95%), shows with a net consumption as indicated by a gradual decrease with increasing [Cu2+] (120→50 × 10-15 mol P/cell) probably due to the fact that P, a backbone bioelement, is largely required in forming biological compartments such as cell membranes; and (2) cellular Mo, predominantly encountered in the intracellular compartment, showed up to tenfold increase in concentration in the cultures exposed to Cu, with a peak accumulation of 1.1 × 10-18 mol Mo/cell occurring in the culture exposed to [Cu2+] at 3.7 nmol/L. Such a net cellular Mo accumulation suggests that Mo might be specifically required in biological processes, probably playing a counteracting role against Cu.

20.
J Cell Biochem ; 118(12): 4275-4284, 2017 12.
Artigo em Inglês | MEDLINE | ID: mdl-28422321

RESUMO

Dysregulated expression of long noncoding RNAs (lncRNAs) has been demonstrated as being implicated in a variety of human diseases. In the study we aimed to determine lncRNA profile in CD8+ T cells response to active tuberculosis (TB). We examined the lncRNA expression by microarray in circulating CD8+ T cells isolated from patients with active TB and healthy controls. Change predictions to analysis was used to address functional roles of the deregulated mRNAs. Real-time quantitative PCR (RT-qPCR) was used to validate the microarray result. In total, 328 lncRNAs and 356 mRNAs were differentially expressed in TB CD8+ T cells. Upregulated mRNAs were mainly enriched in cAMP signaling pathway, calcium signaling pathway, and TGF-beta signaling pathway, while downregulated mRNAs were enriched in antigen processing and presentation and natural killer cell mediated cytotoxicity in TB CD8+ T cells. Interestingly, we found that heme oxygenase 1 (HMOX1) was decreased in active TB CD8+ T cells, while its nearby lincRNA XLOC_014219 was upregulated. Subsequent RT-qPCR results confirmed the changes. This is the first research addressing lncRNA expression profiles in active TB CD8+ T cells. The aberrantly expressed lncRNAs observed in the study may provide clues to the dysfunction of CD8+ T cells and so to the pathophysiological properties of active TB. Further studies should focus on the function of lncRNAs involved in active TB. J. Cell. Biochem. 118: 4275-4284, 2017. © 2017 Wiley Periodicals, Inc.


Assuntos
Linfócitos T CD8-Positivos/metabolismo , RNA Longo não Codificante/genética , Tuberculose/metabolismo , Adulto , Feminino , Perfilação da Expressão Gênica , Regulação da Expressão Gênica , Humanos , Masculino , Pessoa de Meia-Idade , Tuberculose/genética , Adulto Jovem
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