451
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Davies LO, Schäfer H, Marshall S, Bramke I, Oliver RG, Bending GD. Light structures phototroph, bacterial and fungal communities at the soil surface. PLoS One 2013; 8:e69048. [PMID: 23894406 PMCID: PMC3716809 DOI: 10.1371/journal.pone.0069048] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Accepted: 06/04/2013] [Indexed: 02/01/2023] Open
Abstract
The upper few millimeters of soil harbour photosynthetic microbial communities that are structurally distinct from those of underlying bulk soil due to the presence of light. Previous studies in arid zones have demonstrated functional importance of these communities in reducing soil erosion, and enhancing carbon and nitrogen fixation. Despite being widely distributed, comparative understanding of the biodiversity of the soil surface and underlying soil is lacking, particularly in temperate zones. We investigated the establishment of soil surface communities on pasture soil in microcosms exposed to light or dark conditions, focusing on changes in phototroph, bacterial and fungal communities at the soil surface (0–3 mm) and bulk soil (3–12 mm) using ribosomal marker gene analyses. Microbial community structure changed with time and structurally similar phototrophic communities were found at the soil surface and in bulk soil in the light exposed microcosms suggesting that light can influence phototroph community structure even in the underlying bulk soil. 454 pyrosequencing showed a significant selection for diazotrophic cyanobacteria such as Nostoc punctiforme and Anabaena spp., in addition to the green alga Scenedesmus obliquus. The soil surface also harboured distinct heterotrophic bacterial and fungal communities in the presence of light, in particular, the selection for the phylum Firmicutes. However, these light driven changes in bacterial community structure did not extend to the underlying soil suggesting a discrete zone of influence, analogous to the rhizosphere.
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Affiliation(s)
- Lawrence O Davies
- School of Life Sciences, Gibbet Hill Campus, University of Warwick, Coventry, United Kingdom.
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452
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Zwack PJ, Robinson BR, Risley MG, Rashotte AM. Cytokinin response factor 6 negatively regulates leaf senescence and is induced in response to cytokinin and numerous abiotic stresses. PLANT & CELL PHYSIOLOGY 2013; 54:971-81. [PMID: 23539244 DOI: 10.1093/pcp/pct049] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Cytokinin response factor 6 (CRF6) is an Arabidopsis AP2/ERF transcription factor which is transcriptionally induced by cytokinin. Cytokinin is known to delay leaf senescence in wild-type (WT) plants, for example in dark-incubated detached leaves. This response is mediated by the cytokinin receptor Arabidopsis histidine kinase receptor 3 (AHK3). Similar to ahk3 mutants, crf6 leaves show decreased sensitivity to this cytokinin effect. Leaves overexpressing CRF6 retain more Chl than those of the WT under these conditions without exogenous cytokinin. It therefore appears that an increase in expression of CRF6 downstream of the perception of cytokinin by AHK3 is involved in the delay of leaf senescence. Intact crf6 plants also begin to undergo monocarpic senescence sooner than WT plants. Interestingly, plants overexpressing CRF6 display a more extreme acceleration of development than crf6 mutants, suggesting that a specific expression level or localization of CRF6 is necessary to prevent premature senescence. Expression analyses indicate that CRF6 is highly expressed in the veins of mature leaves and that this expression decreases with age. CRF6 expression is shown to be induced by abiotic stress, in addition to increased cytokinin. Together, these findings suggest that CRF6 functions to regulate developmental senescence negatively and may have a similar role in response to stress. CRF6 may therefore be involved in fine-tuning the timing of developmental and stress-induced senescence. CRF6 functioning in negative regulation of senescence is significant in that it is the first process known to be regulated by cytokinin, in which a CRF can be placed specifically downstream of the cytokinin signaling pathway.
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Affiliation(s)
- Paul J Zwack
- Department of Biological Sciences, 101 Rouse Life Sciences, Auburn University, Auburn, AL 36849, USA
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453
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Ezzat L, Merle PL, Furla P, Buttler A, Ferrier-Pagès C. The response of the Mediterranean gorgonian Eunicella singularis to thermal stress is independent of its nutritional regime. PLoS One 2013; 8:e64370. [PMID: 23667711 PMCID: PMC3648542 DOI: 10.1371/journal.pone.0064370] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Accepted: 04/13/2013] [Indexed: 11/19/2022] Open
Abstract
Over the last few decades, sessile benthic organisms from the Mediterranean Sea have suffered from the global warming of the world's oceans, and several mass mortality events were observed during warm summers. It has been hypothesized that mortality could have been due to a nutrient (food) shortage following the stratification of the water column. However, the symbiotic gorgonian Eunicella singularis has also presented a locally exceptional mortality, despite its autotrophic capacities through the photosynthesis of its dinoflagellate symbionts. Thus, this study has experimentally investigated the response of E. singularis to a thermal stress (temperature increase from 18 to 26°C), with colonies maintained more than 2 months under four nutritional diets: autotrophy only (AO), autotrophy and inorganic nitrogen addition (AN), autotrophy and heterotrophy (AH), heterotrophy only (HO). At 18°C, and contrary to many other anthozoans, supplementation of autotrophy with either inorganic nitrogen or food (heterotrophy) had no effect on the rates of respiration, photosynthesis, as well as in the chlorophyll, lipid and protein content. In the dark, heterotrophy maintained the gorgonian's metabolism, except a bleaching (loss of pigments), which did not affect the rates of photosynthesis. At 24°C, rates of respiration, and photosynthesis significantly decreased in all treatments. At 26°C, in addition to a decrease in the lipid content of all treatments, a bleaching was observed after 1 week in the AO treatment, while the AH and AN treatments resisted three weeks before bleaching. These last results suggest that, temperatures above 24°C impair the energetic reserves of this species and might explain the mortality events in the Mediterranean.
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Affiliation(s)
- Leïla Ezzat
- School of Architecture, Civil and Environmental Engineering-ENAC, Ecole Polytechnique Fédérale de Lausanne-EPFL, Lausanne, Switzerland.
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454
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A unique regulation of the expression of the psbA, psbD, and psbE genes, encoding the 01, 02 and cytochrome b559 subunits of the Photosystem II complex in the chlorophyll d containing cyanobacterium Acaryochloris marina. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2013; 1817:1083-94. [PMID: 23487854 DOI: 10.1016/j.bbabio.2012.04.010] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Photosynthetic electron transport, chromatic photoacclirnation and expression of the genes encoding the 01, 02, and cytochrome b559 subunits of the Photosystem II complex were studied in the chlorophyll d containing cyanobacterium Acaryochloris marina MBIC11017 under various environmental conditions. During oxygen deprivation and inhibition of photosynthetic electron transport by dibromothymoquinone the psbA1 gene encoding a 01' isoform was induced. All of the three psbA and one of the three psbD (psbD2) genes, encoding two different isoforms of the 01 and the abundant isoform of the 02 proteins, respectively were induced under exposure to UV-B radiation and high intensity visible light. Under far red light the amount of Photosystem II complexes increased, and expression of the psbE2 gene encoding the alpha-subunit of cytochrome b559 was enhanced. However, the psbF and psbE1 genes encoding the beta- and another isoform of alpha-cytochrome b559, respectively remained lowly expressed under all conditions. Far red light also induced the psbD3 gene encoding a 02' isoform whose primary structure is different from the abundant 02 isoform. psbD3 was also induced under low intensity visible light, when chromatic photoacclimation was indicated by a red-shifted absorption of chlorophyll d. Our results show that differential expression of multigene families encoding different isoforms of 01 and 02 plays an important role in the acclimation of A. marina to contrasting environmental conditions. Moreover, the disproportionate quantity of transcripts of the alpha and beta subunits of cytochrome b559 implies the existence of an alpha-alpha homodimer organization of cytochrome b559 in Photosystem II complexes.
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455
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Chen Y, Vaidyanathan S. Simultaneous assay of pigments, carbohydrates, proteins and lipids in microalgae. Anal Chim Acta 2013; 776:31-40. [PMID: 23601278 DOI: 10.1016/j.aca.2013.03.005] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2013] [Revised: 02/18/2013] [Accepted: 03/03/2013] [Indexed: 10/27/2022]
Abstract
Biochemical compositional analysis of microbial biomass is a useful tool that can provide insight into the behaviour of an organism and its adaptational response to changes in its environment. To some extent, it reflects the physiological and metabolic status of the organism. Conventional methods to estimate biochemical composition often employ different sample pretreatment strategies and analytical steps for analysing each major component, such as total proteins, carbohydrates, and lipids, making it labour-, time- and sample-intensive. Such analyses when carried out individually can also result in uncertainties of estimates as different pre-treatment or extraction conditions are employed for each of the component estimations and these are not necessarily standardised for the organism, resulting in observations that are not easy to compare within the experimental set-up or between laboratories. We recently reported a method to estimate total lipids in microalgae (Chen, Vaidyanathan, Anal. Chim. Acta, 724, 67-72). Here, we propose a unified method for the simultaneous estimation of the principal biological components, proteins, carbohydrates, lipids, chlorophyll and carotenoids, in a single microalgae culture sample that incorporates the earlier published lipid assay. The proposed methodology adopts an alternative strategy for pigment assay that has a high sensitivity. The unified assay is shown to conserve sample (by 79%), time (67%), chemicals (34%) and energy (58%) when compared to the corresponding assay for each component, carried out individually on different samples. The method can also be applied to other microorganisms, especially those with recalcitrant cell walls.
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Affiliation(s)
- Yimin Chen
- ChELSI Institute, Department of Chemical and Biological Engineering, The University of Sheffield, Sheffield, UK
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456
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Tanaka Y, Iguchi A, Inoue M, Mori C, Sakai K, Suzuki A, Kawahata H, Nakamura T. Microscopic observation of symbiotic and aposymbiotic juvenile corals in nutrient-enriched seawater. MARINE POLLUTION BULLETIN 2013; 68:93-98. [PMID: 23324544 DOI: 10.1016/j.marpolbul.2012.12.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2012] [Revised: 12/12/2012] [Accepted: 12/15/2012] [Indexed: 06/01/2023]
Abstract
Symbiotic and aposymbiotic juvenile corals, which were grown in the laboratory from the gametes of the scleractinian coral Acropora digitifera and had settled down onto plastic culture plates, were observed with a microscope under different nutrient conditions. The symbiotic corals successfully removed the surrounding benthic microalgae (BMA), whereas the aposymbiotic corals were in close physical contact with BMA. The areal growth rate of the symbiotic corals was significantly higher than that of the aposymbiotic corals. The addition of nutrients to the culture seawater increased the chlorophyll a content in the symbiotic coral polyps and enhanced the growth of some of the symbiotic corals, however the average growth rate was not significantly affected, most likely because of the competition with BMA. The comparison between the symbiotic and aposymbiotic juvenile corals showed that the establishment of a symbiotic association could be imperative for post-settlement juvenile corals to survive in high-nutrient seawater.
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457
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Mus F, Toussaint JP, Cooksey KE, Fields MW, Gerlach R, Peyton BM, Carlson RP. Physiological and molecular analysis of carbon source supplementation and pH stress-induced lipid accumulation in the marine diatom Phaeodactylum tricornutum. Appl Microbiol Biotechnol 2013; 97:3625-42. [DOI: 10.1007/s00253-013-4747-7] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2012] [Revised: 01/19/2013] [Accepted: 01/31/2013] [Indexed: 11/30/2022]
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458
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Ritchie RJ, Runcie JW. Photosynthetic Electron Transport in an Anoxygenic Photosynthetic BacteriumAfifella(Rhodopseudomonas)marinaMeasured Using PAM Fluorometry. Photochem Photobiol 2013; 89:370-83. [DOI: 10.1111/j.1751-1097.2012.01241.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2012] [Accepted: 09/07/2012] [Indexed: 12/01/2022]
Affiliation(s)
- Raymond J. Ritchie
- Tropical Environmental Plant Biology Unit; Faculty of Technology and Environment; Prince of Songkla University; Phuket; Thailand
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459
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Schliep M, Cavigliasso G, Quinnell RG, Stranger R, Larkum AWD. Formyl group modification of chlorophyll a: a major evolutionary mechanism in oxygenic photosynthesis. PLANT, CELL & ENVIRONMENT 2013; 36:521-7. [PMID: 22913508 DOI: 10.1111/pce.12000] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
We discuss recent advances in chlorophyll research in the context of chlorophyll evolution and conclude that some derivations of the formyl side chain arrangement of the porphyrin ring from that of the Chl a macrocycle can extend the photosynthetic active radiation (PAR) of these molecules, for example, Chl d and Chl f absorb light in the near-infrared region, up to ∼750 nm. Derivations such as this confer a selective advantage in particular niches and may, therefore, be beneficial for photosynthetic organisms thriving in light environments with particular light signatures, such as red- and near-far-red light-enriched niches. Modelling of formyl side chain substitutions of Chl a revealed yet unidentified but theoretically possible Chls with a distinct shift of light absorption properties when compared to Chl a.
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Affiliation(s)
- Martin Schliep
- School of Biological Sciences, The University of Sydney, Sydney, NSW 2006, Australia.
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460
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Behrendt L, Staal M, Cristescu SM, Harren FJ, Schliep M, Larkum AW, Kühl M. Reactive oxygen production induced by near-infrared radiation in three strains of the Chl d-containing cyanobacterium Acaryochloris marina. F1000Res 2013; 2:44. [PMID: 24555034 PMCID: PMC3894803 DOI: 10.12688/f1000research.2-44.v2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 03/10/2013] [Indexed: 11/20/2022] Open
Abstract
Cyanobacteria in the genus
Acaryochloris have largely exchanged Chl
a with Chl
d, enabling them to harvest near-infrared-radiation (NIR) for oxygenic photosynthesis, a biochemical pathway prone to generate reactive oxygen species (ROS). In this study, ROS production under different light conditions was quantified in three
Acaryochloris strains (MBIC11017, HICR111A and the novel strain CRS) using a real-time ethylene detector in conjunction with addition of 2-keto-4-thiomethylbutyric acid, a substrate that is converted to ethylene when reacting with certain types of ROS. In all strains, NIR was found to generate less ROS than visible light (VIS). More ROS was generated if strains MBIC11017 and HICR111A were adapted to NIR and then exposed to VIS, while strain CRS demonstrated the opposite behavior. This is the very first study of ROS generation and suggests that
Acaryochloris can avoid a considerable amount of light-induced stress by using NIR instead of VIS for its photosynthesis, adding further evolutionary arguments to their widespread appearance.
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Affiliation(s)
- Lars Behrendt
- Marine Biology Section, Department of Biology, University of Copenhagen, Helsingør, DK-3000, Denmark ; Section for Microbiology, Department of Biology, University of Copenhagen, Sølvgade, DK-1307, Denmark
| | - Marc Staal
- Marine Biology Section, Department of Biology, University of Copenhagen, Helsingør, DK-3000, Denmark
| | - Simona M Cristescu
- Life Science Trace Gas Facility, Radboud University Nijmegen, Heyendaalseweg, 6525 AJ, Netherlands
| | - Frans Jm Harren
- Life Science Trace Gas Facility, Radboud University Nijmegen, Heyendaalseweg, 6525 AJ, Netherlands
| | - Martin Schliep
- Plant Functional Biology and Climate Change Cluster, School of the Environment, University of Technology Sydney, Sydney, NSW 2007, Australia
| | - Anthony Wd Larkum
- Plant Functional Biology and Climate Change Cluster, School of the Environment, University of Technology Sydney, Sydney, NSW 2007, Australia
| | - Michael Kühl
- Marine Biology Section, Department of Biology, University of Copenhagen, Helsingør, DK-3000, Denmark ; Plant Functional Biology and Climate Change Cluster, School of the Environment, University of Technology Sydney, Sydney, NSW 2007, Australia ; Singapore Centre on Environmental Life Sciences Engineering, School of Biological Sciences, Nanyang Technological University, Nanyang, Singapore
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461
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He PJ, Mao B, Shen CM, Shao LM, Lee DJ, Chang JS. Cultivation of Chlorella vulgaris on wastewater containing high levels of ammonia for biodiesel production. BIORESOURCE TECHNOLOGY 2013; 129:177-81. [PMID: 23246758 DOI: 10.1016/j.biortech.2012.10.162] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2012] [Revised: 09/06/2012] [Accepted: 10/31/2012] [Indexed: 05/07/2023]
Abstract
The feasibility of cultivating Chlorella vulgaris with wastewater containing high ammonia nitrogen concentrations was examined. The average specific growth rate of C. vulgaris was 0.92 d(-1) at 17 mg L(-1) NH4+-N, but declined to 0.33 d(-1) at NH4+-N concentrations of 39-143 mg L(-1). At 39 mg L(-1) NH4+-N, lipid productivity reached a maximum value (23.3 mg L(-1)d(-1)) and dropped sharply at higher NH4+-N levels, which demonstrated NH4+-N should be controlled for biodiesel production. C16 and C18 fatty acids accounted for 80% of total fatty acids. Increasing NH4+-N from 17 to 207 mg L(-1) yielded additional short-chain and saturated fatty acids. Protein content was in positive correlation with NH4+-N content from 17 mg L(-1) (12%) to 207 mg L(-1) (42%). Carbohydrate in the dried algae cell was in the range of 14-45%, with a peak value occurring at 143 mg L(-1) NH4+-N. The results demonstrate that product quality can be manipulated by NH4+-N concentrations of the initial feeds.
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Affiliation(s)
- P J He
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China.
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462
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Li W, Gao K, Beardall J. Interactive effects of ocean acidification and nitrogen-limitation on the diatom Phaeodactylum tricornutum. PLoS One 2012; 7:e51590. [PMID: 23236517 PMCID: PMC3517544 DOI: 10.1371/journal.pone.0051590] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2012] [Accepted: 11/05/2012] [Indexed: 11/28/2022] Open
Abstract
Climate change is expected to bring about alterations in the marine physical and chemical environment that will induce changes in the concentration of dissolved CO(2) and in nutrient availability. These in turn are expected to affect the physiological performance of phytoplankton. In order to learn how phytoplankton respond to the predicted scenario of increased CO(2) and decreased nitrogen in the surface mixed layer, we investigated the diatom Phaeodactylum tricornutum as a model organism. The cells were cultured in both low CO(2) (390 μatm) and high CO(2) (1000 μatm) conditions at limiting (10 μmol L(-1)) or enriched (110 μmol L(-1)) nitrate concentrations. Our study shows that nitrogen limitation resulted in significant decreases in cell size, pigmentation, growth rate and effective quantum yield of Phaeodactylum tricornutum, but these parameters were not affected by enhanced dissolved CO(2) and lowered pH. However, increased CO(2) concentration induced higher rETR(max) and higher dark respiration rates and decreased the CO(2) or dissolved inorganic carbon (DIC) affinity for electron transfer (shown by higher values for K(1/2 DIC) or K(1/2 CO2)). Furthermore, the elemental stoichiometry (carbon to nitrogen ratio) was raised under high CO(2) conditions in both nitrogen limited and nitrogen replete conditions, with the ratio in the high CO(2) and low nitrate grown cells being higher by 45% compared to that in the low CO(2) and nitrate replete grown ones. Our results suggest that while nitrogen limitation had a greater effect than ocean acidification, the combined effects of both factors could act synergistically to affect marine diatoms and related biogeochemical cycles in future oceans.
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Affiliation(s)
- Wei Li
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, China
| | - Kunshan Gao
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, China
| | - John Beardall
- School of Biological Sciences, Monash University, Clayton, Victoria, Australia
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463
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Iredale RS, McDonald AT, Adams DG. A series of experiments aimed at clarifying the mode of action of barley straw in cyanobacterial growth control. WATER RESEARCH 2012; 46:6095-6103. [PMID: 22989994 DOI: 10.1016/j.watres.2012.08.040] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Revised: 08/22/2012] [Accepted: 08/24/2012] [Indexed: 06/01/2023]
Abstract
For over 25 years it has been known that rotting barley straw can be used to prevent the development of blooms of cyanobacteria and algae in freshwater bodies, although its effectiveness can be variable. The mode of action is still not understood, although a number of hypotheses have been suggested, many of which are supported by little or no experimental evidence. Here, we provide the first experimental confirmation that microbial activity is responsible for the release of either the growth inhibitory fraction, or its precursor, from whole straw, after three or more weeks of decomposition. However, a much more rapid release of inhibitory components was achieved by fine chopping of fresh straw. In bioassays of straw activity the choice of both the cyanobacterial test strain and the assay temperature affected the outcome. The inhibitory activity of straw was greater when decomposition was carried out in the presence of UV-supplemented visible light and this activity was reduced in the presence of catalase, implying that straw activity may in part involve hydrogen peroxide. A better understanding of straw decomposition is required to clarify the mode of action of straw and allow the optimisation of its use in the field.
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Affiliation(s)
- Robert S Iredale
- Institute of Integrative and Comparative Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
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464
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Hadj-Romdhane F, Jaouen P, Pruvost J, Grizeau D, Van Vooren G, Bourseau P. Development and validation of a minimal growth medium for recycling Chlorella vulgaris culture. BIORESOURCE TECHNOLOGY 2012; 123:366-74. [PMID: 22940343 DOI: 10.1016/j.biortech.2012.07.085] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2012] [Revised: 06/18/2012] [Accepted: 07/23/2012] [Indexed: 05/21/2023]
Abstract
When microalgae culture medium is recycled, ions (e.g. Na(+), K(+), Ca(2+)) that were not assimilated by the microalgae accumulate in the medium. Therefore, a growth medium (HAMGM) was developed that included ions that were more easily assimilated by Chlorella vulgaris, such as ammonium one (NH(4)(+)). Recycling performance was studied by carrying out 8-week continuous cultivation of C. vulgaris with recycled HAMGM medium. No loss of biomass productivity was observed compared to culture in a conventional medium, and accumulation of ions over time was negligible.
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Affiliation(s)
- F Hadj-Romdhane
- Université de Nantes, CNRS, GEPEA UMR-CNRS 6144, boulevard de l'Université, CRTT-BP 406, 44602 Saint-Nazaire Cedex, France
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465
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Van Vooren G, Le Grand F, Legrand J, Cuiné S, Peltier G, Pruvost J. Investigation of fatty acids accumulation in Nannochloropsis oculata for biodiesel application. BIORESOURCE TECHNOLOGY 2012; 124:421-32. [PMID: 23018107 DOI: 10.1016/j.biortech.2012.08.009] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2012] [Revised: 07/31/2012] [Accepted: 08/02/2012] [Indexed: 05/02/2023]
Abstract
Lipids production of the marine microalga species Nannochloropsis oculata was deeply investigated by studying under continuous light the effects of different nitrogen starvation strategies in photobioreactors of various thicknesses. Operating parameters like incident photons flux density (PFD), initial nitrogen (progressive starvation strategy) or biomass concentrations (sudden starvation strategy) were examined, with a detailed analysis of their effects on the quality and production kinetics of total (TL) and triglycerides (TG). In addition to the already known effect of nitrogen starvation to trigger reserve lipids accumulation (mainly TG), it was demonstrated the relevance of the light received per cell affecting TG content and productivities, as well as fatty acids (FA) profiles. With appropriate optimization, N. oculata was confirmed as an interesting candidate for biodiesel application, with high FA accumulation (up to around 50%DW with 43%DW in TG-FA), high productivity (maximum 3.6×10(-3)kg(TG-FA)m(-2)d(-1)) and a TG-FA profile close to palm oil.
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Affiliation(s)
- G Van Vooren
- Université de Nantes, CNRS, GEPEA, UMR-CNRS 6144, CRTT-BP 406, 44602 Saint-Nazaire Cedex, France
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466
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Jackson O, Taylor O, Adams DG, Knox JP. Arabinogalactan proteins occur in the free-living cyanobacterium genus Nostoc and in plant-Nostoc symbioses. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2012; 25:1338-49. [PMID: 22670754 DOI: 10.1094/mpmi-04-12-0095-r] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Arabinogalactan proteins (AGP) are a diverse family of proteoglycans associated with the cell surfaces of plants. AGP have been implicated in a wide variety of plant cell processes, including signaling in symbioses. This study investigates the existence of putative AGP in free-living cyanobacterial cultures of the nitrogen-fixing, filamentous cyanobacteria Nostoc punctiforme and Nostoc sp. strain LBG1 and at the symbiotic interface in the symbioses between Nostoc spp. and two host plants, the angiosperm Gunnera manicata (in which the cyanobacterium is intracellular) and the liverwort Blasia pusilla (in which the cyanobacterium is extracellular). Enzyme-linked immunosorbent assay, immunoblotting, and immunofluorescence analyses demonstrated that three AGP glycan epitopes (recognized by monoclonal antibodies LM14, MAC207, and LM2) are present in free-living Nostoc cyanobacterial species. The same three AGP glycan epitopes are present at the Gunnera-Nostoc symbiotic interface and the LM2 epitope is detected during the establishment of the Blasia-Nostoc symbiosis. Bioinformatic analysis of the N. punctiforme genome identified five putative AGP core proteins that are representative of AGP classes found in plants. These results suggest a possible involvement of AGP in cyanobacterial-plant symbioses and are also suggestive of a cyanobacterial origin of AGP.
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467
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Arabidopsis bHLH100 and bHLH101 control iron homeostasis via a FIT-independent pathway. PLoS One 2012; 7:e44843. [PMID: 22984573 PMCID: PMC3439455 DOI: 10.1371/journal.pone.0044843] [Citation(s) in RCA: 154] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2012] [Accepted: 08/07/2012] [Indexed: 12/03/2022] Open
Abstract
Iron deficiency induces a complex set of responses in plants, including developmental and physiological changes, to increase iron uptake from soil. In Arabidopsis, many transporters involved in the absorption and distribution of iron have been identified over the past decade. However, little is known about the signaling pathways and networks driving the various responses to low iron. Only the basic helix–loop–helix (bHLH) transcription factor FIT has been shown to control the expression of the root iron uptake machinery genes FRO2 and IRT1. Here, we characterize the biological role of two other iron-regulated transcription factors, bHLH100 and bHLH101, in iron homeostasis. First direct transcriptional targets of FIT were determined in vivo. We show that bHLH100 and bHLH101 do not regulate FIT target genes, suggesting that they play a non-redundant role with the two closely related bHLH factors bHLH038 and bHLH039 that have been suggested to act in concert with FIT. bHLH100 and bHLH101 play a crucial role in iron-deficiency responses, as attested by their severe growth defects and iron homeostasis related phenotypes on low-iron media. To gain further insight into the biological role of bHLH100 and bHLH101, we performed microarray analysis using the corresponding double mutant and showed that bHLH100 and bHLH101 likely regulate genes involved in the distribution of iron within the plant. Altogether, this work establishes bHLH100 and bHLH101 as key regulators of iron-deficiency responses independent of the master regulator FIT and sheds light on new regulatory networks important for proper growth and development under low iron conditions.
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468
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Johnson VR, Russell BD, Fabricius KE, Brownlee C, Hall-Spencer JM. Temperate and tropical brown macroalgae thrive, despite decalcification, along natural CO2 gradients. GLOBAL CHANGE BIOLOGY 2012; 18:2792-2803. [PMID: 24501057 DOI: 10.1111/j.1365-2486.2012.02716.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2012] [Revised: 03/29/2012] [Accepted: 03/31/2012] [Indexed: 06/03/2023]
Abstract
Predicting the impacts of ocean acidification on coastal ecosystems requires an understanding of the effects on macroalgae and their grazers, as these underpin the ecology of rocky shores. Whilst calcified coralline algae (Rhodophyta) appear to be especially vulnerable to ocean acidification, there is a lack of information concerning calcified brown algae (Phaeophyta), which are not obligate calcifiers but are still important producers of calcium carbonate and organic matter in shallow coastal waters. Here, we compare ecological shifts in subtidal rocky shore systems along CO2 gradients created by volcanic seeps in the Mediterranean and Papua New Guinea, focussing on abundant macroalgae and grazing sea urchins. In both the temperate and tropical systems the abundances of grazing sea urchins declined dramatically along CO2 gradients. Temperate and tropical species of the calcifying macroalgal genus Padina (Dictyoaceae, Phaeophyta) showed reductions in CaCO3 content with CO2 enrichment. In contrast to other studies of calcified macroalgae, however, we observed an increase in the abundance of Padina spp. in acidified conditions. Reduced sea urchin grazing pressure and significant increases in photosynthetic rates may explain the unexpected success of decalcified Padina spp. at elevated levels of CO2 . This is the first study to provide a comparison of ecological changes along CO2 gradients between temperate and tropical rocky shores. The similarities we found in the responses of Padina spp. and sea urchin abundance at several vent systems increases confidence in predictions of the ecological impacts of ocean acidification over a large geographical range.
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Affiliation(s)
- Vivienne R Johnson
- Marine Biology and Ecology Research Centre, University of Plymouth, Plymouth, PL4 8AA, UK; The Marine Biological Association of the United Kingdom (MBA), The Laboratory, Citadel Hill, Plymouth, PL1 2PB, UK
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469
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Yang G, Gao K. Physiological responses of the marine diatom Thalassiosira pseudonana to increased pCO2 and seawater acidity. MARINE ENVIRONMENTAL RESEARCH 2012; 79:142-151. [PMID: 22770534 DOI: 10.1016/j.marenvres.2012.06.002] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2011] [Revised: 05/25/2012] [Accepted: 06/02/2012] [Indexed: 06/01/2023]
Abstract
We studied the effects of elevated CO(2) concentration and seawater acidity on inorganic carbon acquisition, photoinhibition and photoprotection as well as growth and respiration in the marine diatom Thalassiosira pseudonana. After having grown under the elevated CO(2) level (1000 μatm, pH 7.83) at sub-saturating photosynthetically active radiation (PAR, 75 μmol photons m(-2) s(-1)) for 20 generations, photosynthesis and dark respiration of the alga increased by 25% (14.69 ± 2.55 fmol C cell(-1) h(-1)) and by 35% (4.42 ± 0.98 fmol O(2) cell(-1) h(-1)), respectively, compared to that grown under the ambient CO(2) level (390 μatm, pH 8.16), leading to insignificant effects on growth (1.09 ± 0.08 d(-1)v 1.04 ± 0.07 d(-1)). The photosynthetic affinity for CO(2) was lowered in the high-CO(2) grown cells, reflecting a down-regulation of the CO(2) concentrating mechanism (CCM). When exposed to an excessively high level of PAR, photochemical and non-photochemical quenching responded similarly in the low- and high-CO(2) grown cells, reflecting that photoinhibition was not influenced by the enriched level of CO(2). In T. pseudonana, it appeared that the energy saved due to the down-regulated CCM did not contribute to any additional light stress as previously found in another diatom Phaeodactylum tricornutum, indicating differential physiological responses to ocean acidification between these two diatom species.
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Affiliation(s)
- Guiyuan Yang
- State Key Laboratory of Marine Environmental Science, Xiamen University, Daxue Road 182 (HAIYANG-LOU), Xiamen, Fujian 361005, China.
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470
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Gu N, Lin Q, Li G, Tan Y, Huang L, Lin J. Effect of salinity on growth, biochemical composition, and lipid productivity ofNannochloropsis oculataCS 179. Eng Life Sci 2012. [DOI: 10.1002/elsc.201100204] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Affiliation(s)
| | - Qiang Lin
- Key Laboratory of Marine Bio-resource Sustainable Utilization; South China Sea Institute of Oceanology; Chinese Academy of Sciences; Guangzhou; China
| | - Gang Li
- Key Laboratory of Marine Bio-resource Sustainable Utilization; South China Sea Institute of Oceanology; Chinese Academy of Sciences; Guangzhou; China
| | - Yehui Tan
- Key Laboratory of Marine Bio-resource Sustainable Utilization; South China Sea Institute of Oceanology; Chinese Academy of Sciences; Guangzhou; China
| | - Liangmin Huang
- Key Laboratory of Marine Bio-resource Sustainable Utilization; South China Sea Institute of Oceanology; Chinese Academy of Sciences; Guangzhou; China
| | - Junda Lin
- Vero Beach Marine Laboratory; Florida Institute of Technology; Vero Beach; FL; USA
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471
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Popovich CA, Damiani C, Constenla D, Martínez AM, Freije H, Giovanardi M, Pancaldi S, Leonardi PI. Neochloris oleoabundans grown in enriched natural seawater for biodiesel feedstock: evaluation of its growth and biochemical composition. BIORESOURCE TECHNOLOGY 2012; 114:287-93. [PMID: 22449985 DOI: 10.1016/j.biortech.2012.02.121] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2011] [Revised: 02/23/2012] [Accepted: 02/24/2012] [Indexed: 05/23/2023]
Abstract
The freshwater microalga Neochloris oleoabundans was used to study algal lipid production in enriched natural seawater, in order to assess its suitability as biodiesel feedstock. Optimal and nitrogen-stress (N-stress) conditions were analyzed. Under optimal conditions, the strain's growth rate was 0.73 div day(-1) and the biomass concentration was 1.5 g L(-1), while it had a maximum lipid yield under N-stress conditions (lipid content: 26% of dry weigh and lipid productivity: 56 mg L(-1) day(-1)). Lipid accumulation was mainly due to a significant increase of triacylglycerol content. Neutral lipids were characterized by a dominance of monounsaturated fatty acids and displayed a fatty acid profile that is suitable for biodiesel. This work offers an interesting alternative for sustainable microalgal oil synthesis for biodiesel production without using freshwater resources. However, further studies are necessary in order to optimize the lipid productivities required for commercial biodiesel production.
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Affiliation(s)
- Cecilia A Popovich
- Laboratorio de Estudios Básicos y Biotecnológicos en Algas y Hongos (LEBBAH), Centro de Recursos Naturales Renovables de la Zona Semiárida (CERZOS) -CONICET, Camino de La Carrindanga, Km 7, 8000 Bahía Blanca, Argentina.
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472
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Sinetova MA, Cervený J, Zavřel T, Nedbal L. On the dynamics and constraints of batch culture growth of the cyanobacterium Cyanothece sp. ATCC 51142. J Biotechnol 2012; 162:148-55. [PMID: 22575787 DOI: 10.1016/j.jbiotec.2012.04.009] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2011] [Revised: 04/18/2012] [Accepted: 04/23/2012] [Indexed: 10/28/2022]
Abstract
The unicellular, nitrogen fixing cyanobacterium Cyanothece sp. ATCC 51142 is of a remarkable potential for production of third-generation biofuels. As the biotechnological potential of Cyanothece 51142 varies with the time of the day, we argue that it will, similarly, depend on the phase of the culture growth. Here, we study the batch culture dynamics to discover the dominant constraints in the individual growth phases and identify potential for inducing or delaying transitions between culture growth phases in Cyanothece 51142. We found that specific growth rate in the exponential phase of the culture is much less dependent on incident irradiance than the photosynthetic activity. We propose that surplus electrons that are released by water splitting are used in futile processes providing photoprotection additional to non-photochemical quenching. We confirm that the transition from exponential to linear phase is caused by a light limitation and the transition from linear to stationary phase by nitrogen limitation. We observe spontaneous diurnal metabolic oscillations in stationary phase culture that are synchronized over the entire culture without an external clue. We tentatively propose that the self-synchronization of the metabolic oscillations is due to a cell-to-cell communication of the cyanobacteria that is necessary for nitrogenase activity in nitrate depleted medium.
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Affiliation(s)
- Maria A Sinetova
- Global Change Research Centre-CzechGlobe, Academy of Sciences of the Czech Republic, Zámek 136, CZ-37333 Nové Hrady, Czech Republic
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473
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Catherine A, Escoffier N, Belhocine A, Nasri AB, Hamlaoui S, Yéprémian C, Bernard C, Troussellier M. On the use of the FluoroProbe®, a phytoplankton quantification method based on fluorescence excitation spectra for large-scale surveys of lakes and reservoirs. WATER RESEARCH 2012; 46:1771-1784. [PMID: 22280952 DOI: 10.1016/j.watres.2011.12.056] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2011] [Revised: 12/20/2011] [Accepted: 12/26/2011] [Indexed: 05/31/2023]
Abstract
Although microscope analysis is very useful for studying phytoplankton community composition, it does not allow for high frequency (spatial and/or temporal) data acquisition. In an attempt to overcome this issue, fluorescence-based approaches that use selective excitation of pigment antennae have spread rapidly. However, the ability of spectral fluorescence to provide accurate estimates of phytoplankton biomass and composition is still debated, and only a few datasets have been tested to date. In this study, we sampled of a wide range of water bodies (n=50) in the Ile-de-France region (North Central France). We used the resulting extensive dataset to assess the ability of the bbe-Moldaenke FluoroProbe II (FP) to estimate phytoplankton community composition in lakes and reservoirs. We demonstrated that FP data yields better estimates of total phytoplankton biovolume than do spectrophotometric chlorophyll a measures and that FP data can be further corrected using the average chlorophyll a to biovolume ratio among phytoplankton groups. Overall, group-specific relationships between FP and biovolume data were consistent. However, we identified a number of cases where caution is required. We found that Euglenophytes are expected to depart from the global FP vs. biovolume relationship of the 'green' group due to varying Fv/Fm and pigment content in response to environmental conditions (photoautotrophic vs. photoheterotrophic growth). Then, it appears necessary to consider the composition of the Chromophytes community in order to obtain a good agreement between both biomass estimation methods. Finally, we confirmed the misattribution toward the 'red' group of phycoerythrin-containing cyanobacteria and the occurrence of a strong scattering in the relationship between the FP vs. biovolume of the 'blue' group that can be partly attributed to the occurrence of large colony-forming cyanobacteria (e.g., Microcystis spp, Aphanizomenon flos-aquae). We propose correcting procedures to improve the quality of data obtained from spectral fluorescence tools in the context of large-scale sampling of lakes and reservoirs.
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Affiliation(s)
- A Catherine
- UMR 7245 MCAM MNHN-CNRS, Equipe Cyanobactéries, Cyanotoxines et Environnement, Muséum National d'Histoire Naturelle, Case 39, 12 rue Buffon, F-75231 Paris Cedex 05, France
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474
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Biofilm growth and near-infrared radiation-driven photosynthesis of the chlorophyll d-containing cyanobacterium Acaryochloris marina. Appl Environ Microbiol 2012; 78:3896-904. [PMID: 22467501 DOI: 10.1128/aem.00397-12] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The cyanobacterium Acaryochloris marina is the only known phototroph harboring chlorophyll (Chl) d. It is easy to cultivate it in a planktonic growth mode, and A. marina cultures have been subject to detailed biochemical and biophysical characterization. In natural situations, A. marina is mainly found associated with surfaces, but this growth mode has not been studied yet. Here, we show that the A. marina type strain MBIC11017 inoculated into alginate beads forms dense biofilm-like cell clusters, as in natural A. marina biofilms, characterized by strong O(2) concentration gradients that change with irradiance. Biofilm growth under both visible radiation (VIS, 400 to 700 nm) and near-infrared radiation (NIR, ∼700 to 730 nm) yielded maximal cell-specific growth rates of 0.38 per day and 0.64 per day, respectively. The population doubling times were 1.09 and 1.82 days for NIR and visible light, respectively. The photosynthesis versus irradiance curves showed saturation at a photon irradiance of E(k) (saturating irradiance) >250 μmol photons m(-2) s(-1) for blue light but no clear saturation at 365 μmol photons m(-2) s(-1) for NIR. The maximal gross photosynthesis rates in the aggregates were ∼1,272 μmol O(2) mg Chl d(-1) h(-1) (NIR) and ∼1,128 μmol O(2) mg Chl d(-1) h(-1) (VIS). The photosynthetic efficiency (α) values were higher in NIR-irradiated cells [(268 ± 0.29) × 10(-6) m(2) mg Chl d(-1) (mean ± standard deviation)] than under blue light [(231 ± 0.22) × 10(-6) m(2) mg Chl d(-1)]. A. marina is well adapted to a biofilm growth mode under both visible and NIR irradiance and under O(2) conditions ranging from anoxia to hyperoxia, explaining its presence in natural niches with similar environmental conditions.
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475
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Li Y, Scales N, Blankenship RE, Willows RD, Chen M. Extinction coefficient for red-shifted chlorophylls: chlorophyll d and chlorophyll f. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2012; 1817:1292-8. [PMID: 22395150 DOI: 10.1016/j.bbabio.2012.02.026] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2012] [Revised: 02/23/2012] [Accepted: 02/23/2012] [Indexed: 11/30/2022]
Abstract
Both chlorophyll f and chlorophyll d are red-shifted chlorophylls in oxygenic photosynthetic organisms, which extend photon absorbance into the near infrared region. This expands the range of light that can be used to drive photosynthesis. Quantitative determination of chlorophylls is a crucial step in the investigation of chlorophyll-photosynthetic reactions in the field of photobiology and photochemistry. No methods have yet been worked out for the quantitative determination of chlorophyll f. There is also no method available for the precise quantitative determination of chlorophyll d although it was discovered in 1943. In order to obtain the extinction coefficients (ε) of chlorophyll f and chlorophyll d, the concentrations of chlorophylls were determined by Inductive Coupled Plasma Mass Spectrometry according to the fact that each chlorophyll molecule contains one magnesium (Mg) atom. Molar extinction coefficient ε(chl f) is 71.11×10(3)Lmol(-1)A(707nm)cm(-1) and ε(chl d) is 63.68×10(3)Lmol(-1)A(697nm)cm(-1) in 100% methanol. This article is part of a Special Issue entitled: Photosynthesis Research for Sustainability: from Natural to Artificial.
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Affiliation(s)
- Yaqiong Li
- School of Biological Sciences, University of Sydney, Sydney, Australia
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476
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Abundance and genetic diversity of aerobic anoxygenic phototrophic bacteria of coastal regions of the pacific ocean. Appl Environ Microbiol 2012; 78:2858-66. [PMID: 22307290 DOI: 10.1128/aem.06268-11] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Aerobic anoxygenic phototrophic (AAP) bacteria are photoheterotrophic microbes that are found in a broad range of aquatic environments. Although potentially significant to the microbial ecology and biogeochemistry of marine ecosystems, their abundance and genetic diversity and the environmental variables that regulate these properties are poorly understood. Using samples along nearshore/offshore transects from five disparate islands in the Pacific Ocean (Oahu, Molokai, Futuna, Aniwa, and Lord Howe) and off California, we show that AAP bacteria, as quantified by the pufM gene biomarker, are most abundant near shore and in areas with high chlorophyll or Synechococcus abundance. These AAP bacterial populations are genetically diverse, with most members belonging to the alpha- or gammaproteobacterial groups and with subclades that are associated with specific environmental variables. The genetic diversity of AAP bacteria is structured along the nearshore/offshore transects in relation to environmental variables, and uncultured pufM gene libraries suggest that nearshore communities are distinct from those offshore. AAP bacterial communities are also genetically distinct between islands, such that the stations that are most distantly separated are the most genetically distinct. Together, these results demonstrate that environmental variables regulate both the abundance and diversity of AAP bacteria but that endemism may also be a contributing factor in structuring these communities.
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477
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Dinitrogen fixation in a unicellular chlorophyll d-containing cyanobacterium. ISME JOURNAL 2012; 6:1367-77. [PMID: 22237545 DOI: 10.1038/ismej.2011.199] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Marine cyanobacteria of the genus Acaryochloris are the only known organisms that use chlorophyll d as a photosynthetic pigment. However, based on chemical sediment analyses, chlorophyll d has been recognized to be widespread in oceanic and lacustrine environments. Therefore it is highly relevant to understand the genetic basis for different physiologies and possible niche adaptation in this genus. Here we show that unlike all other known isolates of Acaryochloris, the strain HICR111A, isolated from waters around Heron Island, Great Barrier Reef, possesses a unique genomic region containing all the genes for the structural and enzymatically active proteins of nitrogen fixation and cofactor biosynthesis. Their phylogenetic analysis suggests a close relation to nitrogen fixation genes from certain other marine cyanobacteria. We show that nitrogen fixation in Acaryochloris sp. HICR111A is regulated in a light-dark-dependent fashion. We conclude that nitrogen fixation, one of the most complex physiological traits known in bacteria, might be transferred among oceanic microbes by horizontal gene transfer more often than anticipated so far. Our data show that the two powerful processes of oxygenic photosynthesis and nitrogen fixation co-occur in one and the same cell also in this branch of marine microbes and characterize Acaryochloris as a physiologically versatile inhabitant of an ecological niche, which is primarily driven by the absorption of far-red light.
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478
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Davis PA, Caylor S, Whippo CW, Hangarter RP. Changes in leaf optical properties associated with light-dependent chloroplast movements. PLANT, CELL & ENVIRONMENT 2011; 34:2047-2059. [PMID: 21819411 DOI: 10.1111/j.1365-3040.2011.02402.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We surveyed 24 plant species to examine how leaf anatomy influenced chloroplast movement and how the optical properties of leaves change with chloroplast position. All species examined exhibited light-dependent chloroplast movements but the associated changes in leaf absorptance varied considerably in magnitude. Chloroplast movement-dependent changes in leaf absorptance were greatest in shade species, in which absorptance changes of >10% were observed between high- and low-light treatments. Using the Kubelka-Munk theory, we found that changes in the absorption (k) and chlorophyll a absorption efficiency (k*) associated with chloroplast movement correlated with cell diameter, such that the narrower, more columnar cells found in sun leaves restricted the ability of chloroplasts to move. The broader, more spherical cells of shade leaves allowed greater chloroplast rearrangements and in low-light conditions allowed efficient light capture. Across the species tested, light-dependent chloroplast movements modulated leaf optical properties and light absorption efficiency by manipulating the package (sieve or flattening) effect but not the detour (path lengthening) effect.
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Affiliation(s)
- Phillip A Davis
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
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479
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Norici A, Bazzoni AM, Pugnetti A, Raven JA, Giordano M. Impact of irradiance on the C allocation in the coastal marine diatom Skeletonema marinoi Sarno and Zingone. PLANT, CELL & ENVIRONMENT 2011; 34:1666-77. [PMID: 21707652 DOI: 10.1111/j.1365-3040.2011.02362.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Elemental stoichiometry and organic composition were investigated in an Adriatic strain of Skeletonema marinoi, cultured at 25 [low light (LL)] and 250 [high light (HL)]µmol photon m⁻² s⁻¹. Inorganic carbon acquisition, fixation and allocation, and silicic acid and orthophosphate uptake were also studied. The C:P ratio was below the Redfield ratio, especially at LL. In HL cells, N quota was halved, C quota was similar, silica quota was lower, growth rate and long-term net primary productivity were almost doubled, relative to LL cells. The HL:LL cell quota ratios were 6 for lipid, 0.5 for protein and 0.4 for carbohydrate. Phosphoenolpyruvate carboxylase (PEPc) and glutamine synthetase (GS) activities were unaffected by the growth irradiance; phosphoenolpyruvate carboxykinase (PEPck) was 2.5-fold more active in LL cells. This suggests that in S. marinoi, C₄ photosynthesis is unlikely, PEPc is anaplerotic and PEPck may be involved in the conversion of lipid C to carbohydrates, especially in LL cells. Because about 50% of the cost for the production of an HL cell is caused by lipid biosynthesis, we propose that the preferential allocation of C to lipid at HL takes advantage of the relatively high volume-based energy content of lipids, in an organism that reduces its size at each vegetative cell division.
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Affiliation(s)
- Alessandra Norici
- Laboratorio di Fisiologia delle Alghe, Dipartimento di Scienze del Mare, Università Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona, Italy
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480
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Steinke M, Brading P, Kerrison P, Warner ME, Suggett DJ. CONCENTRATIONS OF DIMETHYLSULFONIOPROPIONATE AND DIMETHYL SULFIDE ARE STRAIN-SPECIFIC IN SYMBIOTIC DINOFLAGELLATES (SYMBIODINIUM SP., DINOPHYCEAE)(1). JOURNAL OF PHYCOLOGY 2011; 47:775-83. [PMID: 27020013 DOI: 10.1111/j.1529-8817.2011.01011.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Dimethyl sulfide (DMS) and dimethylsulfoniopropionate (DMSP) are sulfur compounds that may function as antioxidants in algae. Symbiotic dinoflagellates of the genus Symbiodinium show strain-specific differences in their susceptibility to temperature-induced oxidative stress and have been shown to contain high concentrations of DMSP. We investigated continuous cultures of four strains from distinct phylotypes (A1, A13, A2, and B1) that can be characterized by differential thermal tolerances. We hypothesized that strains with high thermal tolerance have higher concentrations of DMSP and DMS in comparison to strains with low thermal tolerance. DMSP concentrations were strain-specific with highest concentrations occurring in A1 (225 ± 3.5 mmol · L(-1 ) cell volume [CV]) and lowest in A2 (158 ± 3.8 mmol · L(-1 ) CV). Both strains have high thermal tolerance. Strains with low thermal tolerance (A13 and B1) showed DMSP concentrations in between these extremes (194 ± 19.0 and 160 ± 6.1 mmol · L(-1 ) CV, respectively). DMS data further confirmed this general pattern with high DMS concentrations in A1 and A13 (4.1 ± 1.22 and 2.1 ± 0.37 mmol · L(-1 ) CV, respectively) and low DMS concentrations in A2 and B1 (0.3 ± 0.06 and 0.5 ± 0.22 mmol · L(-1) CV, respectively). Hence, the strain-specific differences in DMSP and DMS concentrations did not match the different abilities of the four phylotypes to withstand thermal stress. Future work should quantify the possible dynamics in DMSP and DMS concentrations during periods of high oxidative stress in Symbiodinium sp. and address the role of these antioxidants in zooxanthellate cnidarians.
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Affiliation(s)
- Michael Steinke
- University of Essex, Department of Biological Sciences, Coral Reef Research Unit, Wivenhoe Park, Colchester CO4 3SQ, UKCollege of Earth, Ocean, and Environment, University of Delaware, 700 Pilottown Road, Lewes, Delaware 19958, USAUniversity of Essex, Department of Biological Sciences, Coral Reef Research Unit, Wivenhoe Park, Colchester CO4 3SQ, UK
| | - Patrick Brading
- University of Essex, Department of Biological Sciences, Coral Reef Research Unit, Wivenhoe Park, Colchester CO4 3SQ, UKCollege of Earth, Ocean, and Environment, University of Delaware, 700 Pilottown Road, Lewes, Delaware 19958, USAUniversity of Essex, Department of Biological Sciences, Coral Reef Research Unit, Wivenhoe Park, Colchester CO4 3SQ, UK
| | - Philip Kerrison
- University of Essex, Department of Biological Sciences, Coral Reef Research Unit, Wivenhoe Park, Colchester CO4 3SQ, UKCollege of Earth, Ocean, and Environment, University of Delaware, 700 Pilottown Road, Lewes, Delaware 19958, USAUniversity of Essex, Department of Biological Sciences, Coral Reef Research Unit, Wivenhoe Park, Colchester CO4 3SQ, UK
| | - Mark E Warner
- University of Essex, Department of Biological Sciences, Coral Reef Research Unit, Wivenhoe Park, Colchester CO4 3SQ, UKCollege of Earth, Ocean, and Environment, University of Delaware, 700 Pilottown Road, Lewes, Delaware 19958, USAUniversity of Essex, Department of Biological Sciences, Coral Reef Research Unit, Wivenhoe Park, Colchester CO4 3SQ, UK
| | - David J Suggett
- University of Essex, Department of Biological Sciences, Coral Reef Research Unit, Wivenhoe Park, Colchester CO4 3SQ, UKCollege of Earth, Ocean, and Environment, University of Delaware, 700 Pilottown Road, Lewes, Delaware 19958, USAUniversity of Essex, Department of Biological Sciences, Coral Reef Research Unit, Wivenhoe Park, Colchester CO4 3SQ, UK
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481
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Chiang CL, Lee CM, Chen PC. Utilization of the cyanobacteria Anabaena sp. CH1 in biological carbon dioxide mitigation processes. BIORESOURCE TECHNOLOGY 2011; 102:5400-5405. [PMID: 21232935 DOI: 10.1016/j.biortech.2010.10.089] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2010] [Revised: 10/18/2010] [Accepted: 10/20/2010] [Indexed: 05/30/2023]
Abstract
Before switching totally to alternative fuel stage, CO(2) mitigation process has considered a transitional strategy for combustion of fossil fuels inevitably. In comparison to other CO(2) mitigation options, such as oceanic or geologic injection, the biological photosynthetic process would present a far superior and sustainable solution under both environmental and social considerations. The utilization of the cyanobacteria Anabaena sp. CH1 in carbon dioxide mitigation processes is analyzed in our research. It was found that an original developed photobioreactor with internal light source exhibits high light utilization. Anabaena sp. CH1 demonstrates excellent CO(2) tolerance even at 15% CO(2) level. This enables flue gas from power plant to be directly introduced to Anabaena sp. CH1 culture. Double light intensity and increased 47% CO(2) bubble retention time could enhance CO(2) removal efficiencies by 79% and 67%, respectively. A maximum CO(2) fixation rate of 1.01 g CO(2)L(-1)day(-1) was measured experimentally.
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Affiliation(s)
- Chang-Ling Chiang
- Department of Environmental Engineering, National Chung Hsing University, 250, Kuo-Kuang Road, Taichung 402, Taiwan.
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482
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Holland AD, Dragavon JM, Sigee DC. Intrinsic autotrophic biomass yield and productivity in algae: Experimental methods for strain selection. Biotechnol J 2011; 6:572-83. [DOI: 10.1002/biot.201000260] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2010] [Revised: 11/05/2010] [Accepted: 12/20/2010] [Indexed: 11/10/2022]
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483
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Tal O, Haim A, Harel O, Gerchman Y. Melatonin as an antioxidant and its semi-lunar rhythm in green macroalga Ulva sp. JOURNAL OF EXPERIMENTAL BOTANY 2011; 62:1903-10. [PMID: 21220782 PMCID: PMC3060675 DOI: 10.1093/jxb/erq378] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2010] [Revised: 10/03/2010] [Accepted: 11/02/2010] [Indexed: 05/17/2023]
Abstract
The presence and role of melatonin in plants are still under debate owing to difficulties of identification and quantification. Accordingly, although it has been frequently proposed that melatonin acts as an antioxidant in phototrophic organisms, experimental data on its physiological role are scarce. This study describes the use of a rapid and simple new method for quantification of melatonin in the marine macroalga Ulva sp., organisms routinely exposed to tide-related environmental stresses and known for their high tolerance to abiotic conditions. The method was used here to show that exposure to oxidative stress-inducing environmental conditions (elevated temperature and heavy metals) induced a rise in melatonin level in the algae. Addition of exogenous melatonin alleviated the algae from cadmium-induced stress. Interestingly, although the algae were taken from a culture growing free floating and kept under constant photoperiod and water level, they exhibited a semi-lunar rhythm of melatonin levels that correlated with predicted spring tides. The correlation can probably be interpreted as reflecting preparation for predicted low tides, when the algae are exposed to increasing temperature, desiccation, and salinity, all known to induce oxidative stress. Given the simplicity of the described method it can easily be adapted for the study of melatonin in many other phototrophic organisms. These results provide, for the first time, experimental data that support both an antioxidant role for melatonin and its semi-lunar rhythm in macroalgae.
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Affiliation(s)
- Ofir Tal
- The Israeli Center for Interdisciplinary Research in Chronobiology, Department of Evolutionary and Environmental Biology, Faculty of Natural Sciences, University of Haifa, Mount Carmel, 31905 Haifa, Israel
| | - Abraham Haim
- The Israeli Center for Interdisciplinary Research in Chronobiology, Department of Evolutionary and Environmental Biology, Faculty of Natural Sciences, University of Haifa, Mount Carmel, 31905 Haifa, Israel
| | - Orna Harel
- The Israeli Center for Interdisciplinary Research in Chronobiology, Department of Evolutionary and Environmental Biology, Faculty of Natural Sciences, University of Haifa, Mount Carmel, 31905 Haifa, Israel
| | - Yoram Gerchman
- Department of Biology, Faculty of Natural Sciences, University of Haifa at Oranim, 36006 Tivon, Israel
- To whom correspondence should be addressed: E-mail:
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484
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Srichaikul B, Bunsang R, Samappito S, Butkhup L, Bakker G. Comparative Study of Chlorophyll Content in Leaves of Thai Morus alba Linn. Species. ACTA ACUST UNITED AC 2011. [DOI: 10.3923/psres.2011.17.20] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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485
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Pruvost J, Van Vooren G, Le Gouic B, Couzinet-Mossion A, Legrand J. Systematic investigation of biomass and lipid productivity by microalgae in photobioreactors for biodiesel application. BIORESOURCE TECHNOLOGY 2011; 102:150-8. [PMID: 20675127 DOI: 10.1016/j.biortech.2010.06.153] [Citation(s) in RCA: 150] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2010] [Revised: 06/23/2010] [Accepted: 06/25/2010] [Indexed: 05/04/2023]
Abstract
We describe a methodology to investigate the potential of given microalgae species for biodiesel production by characterizing their productivity in terms of both biomass and lipids. A multi-step approach was used: determination of biological needs for macronutrients (nitrate, phosphate and sulphate), determination of maximum biomass productivity (the "light-limited" regime), scaling-up of biomass production in photobioreactors, including a theoretical framework to predict corresponding productivities, and investigation of how nitrate starvation protocol affects cell biochemical composition and triggers triacylglycerol (TAG) accumulation. The methodology was applied to two freshwater strains, Chlorella vulgaris and Neochloris oleoabundans, and one seawater diatom strain, Cylindrotheca closterium. The highest total lipid content was achieved with N. oleoabundans (25-37% of DW), while the highest TAG content was found in C. vulgaris (11-14% of DW). These two species showed similar TAG productivities.
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Affiliation(s)
- J Pruvost
- Université de Nantes, CNRS, GEPEA UMR-CNRS 6144, bd de l'Université, CRTT-BP 406, 44602 Saint-Nazaire Cedex, France.
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486
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Di Valentin M, Ceola S, Agostini G, Telfer A, Barber J, Böhles F, Santabarbara S, Carbonera D. The photo-excited triplet state of chlorophylldin methyl-tetrahydrofuran studied by optically detected magnetic resonance and time-resolved EPR. Mol Phys 2010. [DOI: 10.1080/00268970701627797] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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487
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Du H, Wang N, Cui F, Li X, Xiao J, Xiong L. Characterization of the beta-carotene hydroxylase gene DSM2 conferring drought and oxidative stress resistance by increasing xanthophylls and abscisic acid synthesis in rice. PLANT PHYSIOLOGY 2010; 154:1304-18. [PMID: 20852032 PMCID: PMC2971608 DOI: 10.1104/pp.110.163741] [Citation(s) in RCA: 167] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2010] [Accepted: 09/16/2010] [Indexed: 05/18/2023]
Abstract
Drought is a major limiting factor for crop production. To identify critical genes for drought resistance in rice (Oryza sativa), we screened T-DNA mutants and identified a drought-hypersensitive mutant, dsm2. The mutant phenotype was caused by a T-DNA insertion in a gene encoding a putative β-carotene hydroxylase (BCH). BCH is predicted for the biosynthesis of zeaxanthin, a carotenoid precursor of abscisic acid (ABA). The amounts of zeaxanthin and ABA were significantly reduced in two allelic dsm2 mutants after drought stress compared with the wild type. Under drought stress conditions, the mutant leaves lost water faster than the wild type and the photosynthesis rate, biomass, and grain yield were significantly reduced, whereas malondialdehyde level and stomata aperture were increased in the mutant. The mutant is also hypersensitive to oxidative stresses. The mutant had significantly lower maximal efficiency of photosystem II photochemistry and nonphotochemical quenching capacity than the wild type, indicating photoinhibition in photosystem II and decreased capacity for eliminating excess energy by thermal dissipation. Overexpression of DSM2 in rice resulted in significantly increased resistance to drought and oxidative stresses and increases of the xanthophylls and nonphotochemical quenching. Some stress-related ABA-responsive genes were up-regulated in the overexpression line. DSM2 is a chloroplast protein, and the response of DSM2 to environmental stimuli is distinctive from the other two BCH members in rice. We conclude that the DSM2 gene significantly contributes to control of the xanthophyll cycle and ABA synthesis, both of which play critical roles in the establishment of drought resistance in rice.
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Affiliation(s)
| | | | | | | | | | - Lizhong Xiong
- National Key Laboratory of Crop Genetic Improvement, National Center of Plant Gene Research (Wuhan), Huazhong Agricultural University, Wuhan 430070, China
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488
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Schliep M, Crossett B, Willows RD, Chen M. 18O labeling of chlorophyll d in Acaryochloris marina reveals that chlorophyll a and molecular oxygen are precursors. J Biol Chem 2010; 285:28450-6. [PMID: 20610399 DOI: 10.1074/jbc.m110.146753] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The cyanobacterium Acaryochloris marina was cultured in the presence of either H(2)(18)O or (18)O(2), and the newly synthesized chlorophylls (Chl a and Chl d) were isolated using high performance liquid chromatography and analyzed by mass spectroscopy. In the presence of H(2)(18)O, newly synthesized Chl a and d, both incorporated up to four isotopic (18)O atoms. Time course H(2)(18)O labeling experiments showed incorporation of isotopic (18)O atoms originating from H(2)(18)O into Chl a, with over 90% of Chl a (18)O-labeled at 48 h. The incorporation of isotopic (18)O atoms into Chl d upon incubation in H(2)(18)O was slower compared with Chl a with approximately 50% (18)O-labeled Chl d at 115 h. The rapid turnover of newly synthesized Chl a suggested that Chl a is the direct biosynthetic precursor of Chl d. In the presence of (18)O(2) gas, one isotopic (18)O atom was incorporated into Chl a with approximately the same kinetic incorporation rate observed in the H(2)(18)O labeling experiment, reaching over 90% labeling intensity at 48 h. The incorporation of two isotopic (18)O atoms derived from molecular oxygen ((18)O(2)) was observed in the extracted Chl d, and the percentage of double isotopic (18)O-labeled Chl d increased in parallel with the decrease of non-isotopic-labeled Chl d. This clearly indicated that the oxygen atom in the C3(1)-formyl group of Chl d is derived from dioxygen via an oxygenase-type reaction mechanism.
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Affiliation(s)
- Martin Schliep
- Schools of Biological Sciences, The University of Sydney, Sydney, New South Wales 2006, Australia
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489
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Hodaifa G, Martínez ME, Sánchez S. Influence of temperature on growth of Scenedesmus obliquus in diluted olive mill wastewater as culture medium. Eng Life Sci 2010. [DOI: 10.1002/elsc.201000005] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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490
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Lilley RM, Ralph PJ, Larkum AWD. The determination of activity of the enzyme Rubisco in cell extracts of the dinoflagellate alga Symbiodinium sp. by manganese chemiluminescence and its response to short-term thermal stress of the alga. PLANT, CELL & ENVIRONMENT 2010; 33:995-1004. [PMID: 20102538 DOI: 10.1111/j.1365-3040.2010.02121.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The dinoflagellate alga Symbiodinium sp., living in symbiosis with corals, clams and other invertebrates, is a primary producer in coral reefs and other marine ecosystems. The function of the carbon-fixing enzyme ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) in dinoflagellates is difficult to study because its activity is rapidly lost after extraction from the cell. We report procedures for the extraction of Rubisco from Symbiodinium cells and for stable storage. We describe a continuous assay for Rubisco activity in these crude cell extracts using the Mn(2+) chemiluminescence of Rubisco oxygenase. Chemiluminescence time courses exhibited initial transients resembling bacterial Form II Rubisco, followed by several minutes of linearly decreasing activity. The initial activity was determined from extrapolation of this linear section of the time course. The activity of fast-frozen cell extracts was stable at -80 degrees C and, after thawing and storage on ice, remained stable for up to 1 h before declining non-linearly. Crude cell extracts bound [(14)C] 2-carboxy-D-arabitinol 1,5-bisphosphate to a high molecular mass fraction separable by gel filtration chromatography. After pre-treatment of Symbiodinium cell cultures in darkness at temperatures above 30 degrees C, the extracted Rubisco activities decreased, with almost complete loss of activity above 36 degrees C. The implications for the sensitivity to elevated temperature of Symbiodinium photosynthesis are assessed.
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Affiliation(s)
- Ross McC Lilley
- School of Biological Sciences, University of Sydney, NSW 2008, Australia.
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491
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Martínez-Lüscher J, Holmer M. Potential effects of the invasive species Gracilaria vermiculophylla on Zostera marina metabolism and survival. MARINE ENVIRONMENTAL RESEARCH 2010; 69:345-349. [PMID: 20096926 DOI: 10.1016/j.marenvres.2009.12.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2009] [Revised: 12/23/2009] [Accepted: 12/30/2009] [Indexed: 05/28/2023]
Abstract
The potential threat to seagrasses of the invasive algae, Gracilaria vermiculophylla was assessed through metabolic indicators under experimental conditions. Net leaf photosynthesis (LNP) and dark respiration (LDR) were measured from leaf segments of Zostera marina shoots under different loads of G. vermiculophylla (control, low 2.2kg FW m(-2) and high 4kg FW m(-2)) in mesocosm experiments separated in tanks at four temperatures (19, 23.5, 26 and 30 degrees C). LNP decreased in the presence of the high density G. vermiculophylla mat (25% on average), being the most severe reductions at 30 degrees C (35% less in high). LDR did not respond significantly to differences in algal biomass, whereas a progressive increase was found with increasing temperatures (3.4 times higher at 30 degrees C than at 19 degrees C). Sulphide in porewater was measured weekly in order clarify the role of sediment conditions on seagrass metabolism, and increased both with algal biomass (29% in high) and temperature (from 0.5mM at 26 degrees C to 2.6mM at 30 degrees C), but changes in LNP and LDR were not correlated with sulphide concentrations. Seagrass survival rates showed decreasing trend with algal biomass at all the temperatures (from 74% to 21% survival). G. vermiculophylla showed harmful effects on Z. marina metabolism and survival with synergistic effects of temperature suggesting greater impact of invasive species under future higher water temperatures.
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492
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Mohr R, Voss B, Schliep M, Kurz T, Maldener I, Adams DG, Larkum ADW, Chen M, Hess WR. A new chlorophyll d-containing cyanobacterium: evidence for niche adaptation in the genus Acaryochloris. ISME JOURNAL 2010; 4:1456-69. [PMID: 20505751 DOI: 10.1038/ismej.2010.67] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Chlorophyll d is a photosynthetic pigment that, based on chemical analyses, has only recently been recognized to be widespread in oceanic and lacustrine environments. However, the diversity of organisms harbouring this pigment is not known. Until now, the unicellular cyanobacterium Acaryochloris marina is the only characterized organism that uses chlorophyll d as a major photopigment. In this study we describe a new cyanobacterium possessing a high amount of chlorophyll d, which was isolated from waters around Heron Island, Great Barrier Reef (23° 26' 31.2″ S, 151° 54' 50.4″ E). The 16S ribosomal RNA is 2% divergent from the two previously described isolates of A. marina, which were isolated from waters around the Palau islands (Pacific Ocean) and the Salton Sea lake (California), suggesting that it belongs to a different clade within the genus Acaryochloris. An overview sequence analysis of its genome based on Illumina technology yielded 871 contigs with an accumulated length of 8 371 965 nt. Their analysis revealed typical features associated with Acaryochloris, such as an extended gene family for chlorophyll-binding proteins. However, compared with A. marina MBIC11017, distinct genetic, morphological and physiological differences were observed. Light saturation is reached at lower light intensities, Chl d/a ratios are less variable with light intensity and the phycobiliprotein phycocyanin is lacking, suggesting that cyanobacteria of the genus Acaryochloris occur in distinct ecotypes. These data characterize Acaryochloris as a niche-adapted cyanobacterium and show that more rigorous attempts are worthwhile to isolate, cultivate and analyse chlorophyll d-containing cyanobacteria for understanding the ecophysiology of these organisms.
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Affiliation(s)
- Remus Mohr
- Faculty of Biology, University of Freiburg, Schaenzlestrasse 1, Freiburg, Germany
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493
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Nikolić DB, Samardzić JT, Bratić AM, Radin IP, Gavrilović SP, Rausch T, Maksimović VR. Buckwheat (Fagopyrum esculentum Moench) FeMT3 gene in heavy metal stress: protective role of the protein and inducibility of the promoter region under Cu(2+) and Cd(2+) treatments. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2010; 58:3488-94. [PMID: 20187605 DOI: 10.1021/jf904483a] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The protective role in vivo of buckwheat metallothionein type 3 (FeMT3) during metal stress and the responsiveness of its promoter to metal ions were examined. Increased tolerance to heavy metals of FeMT3 producing Escherichia coli and cup1(Delta) yeast cells was detected. The defensive ability of buckwheat MT3 during Cd and Cu stresses was also demonstrated in Nicotiana debneyii leaves transiently expressing FeMT3. In contrast to phytochelatins, the cytoplasmatic localization of FeMT3 was not altered under heavy metal stress. Functional analysis of the corresponding promoter region revealed extremely high inducibility upon Cu(2+) and Cd(2+) treatments. The confirmed defense ability of FeMT3 protein in vivo and the great responsiveness of its promoter during heavy metal exposure make this gene a suitable candidate for biotechnological applications.
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Affiliation(s)
- Dragana B Nikolić
- Laboratory for Plant Molecular Biology, Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Vojvode Stepe 444a, Belgrade, Serbia.
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494
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Pruvost J, Van Vooren G, Cogne G, Legrand J. Investigation of biomass and lipids production with Neochloris oleoabundans in photobioreactor. BIORESOURCE TECHNOLOGY 2009; 100:5988-95. [PMID: 19560349 DOI: 10.1016/j.biortech.2009.06.004] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2009] [Revised: 05/29/2009] [Accepted: 06/02/2009] [Indexed: 05/09/2023]
Abstract
The fresh water microalga Neochloris oleoabundans was investigated for its ability to accumulate lipids and especially triacylglycerols (TAG). A systematic study was conducted, from the determination of the growth medium to its characterization in an airlift photobioreactor. Without nutrient limitation, a maximal biomass areal productivity of 16.5 g m(-2) day(-1) was found. Effects of nitrogen starvation to induce lipids accumulation was next investigated. Due to initial N. oleoabundans total lipids high content (23% of dry weight), highest productivity was obtained without mineral limitation with a maximal total lipids productivity of 3.8 g m(-2) day(-1). Regarding TAG, an almost similar productivity was found whatever the protocol was: continuous production without mineral limitation (0.5 g m(-2) day(-1)) or batch production with either sudden or progressive nitrogen deprivation (0.7 g m(-2) day(-1)). The decrease in growth rate reduces the benefit of the important lipids and TAG accumulation as obtained in nitrogen starvation (37% and 18% of dry weight, respectively).
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Affiliation(s)
- J Pruvost
- GEPEA, Université de Nantes, CNRS, UMR6144, Bd de l'Université, CRTT-BP 406, 44602 Saint-Nazaire Cedex, France.
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495
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Duxbury Z, Schliep M, Ritchie RJ, Larkum AWD, Chen M. Chromatic photoacclimation extends utilisable photosynthetically active radiation in the chlorophyll d-containing cyanobacterium, Acaryochloris marina. PHOTOSYNTHESIS RESEARCH 2009; 101:69-75. [PMID: 19582591 DOI: 10.1007/s11120-009-9466-7] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2009] [Accepted: 06/23/2009] [Indexed: 05/28/2023]
Abstract
Chromatic photoacclimation and photosynthesis were examined in two strains of Acaryochloris marina (MBIC11017 and CCMEE5410) and in Synechococcus PCC7942. Acaryochloris contains Chl d, which has an absorption peak at ca 710 nm in vivo. Cultures were grown in one of the three wavelengths (525 nm, 625 nm and 720 nm) of light from narrow-band photodiodes to determine the effects on pigment composition, growth rate and photosynthesis: no growth occurred in 525 nm light. Synechococcus did not grow in 720 nm light because Chl a does not absorb effectively at this long wavelength. Acaryochloris did grow in 720 nm light, although strain MBIC11017 showed a decrease in phycobilins over time. Both Synechococcus and Acaryochloris MBIC11017 showed a dramatic increase in phycobilin content when grown in 625 nm light. Acaryochloris CCMEE5410, which lacks phycobilins, would not grow satisfactorily under 625 nm light. The cells adjusted their pigment composition in response to the light spectral conditions under which they were grown. Photoacclimation and the Q (y) peak of Chl d could be understood in terms of the ecological niche of Acaryochloris, i.e. habitats enriched in near infrared radiation.
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Affiliation(s)
- Zane Duxbury
- School of Biological Sciences (A08), University of Sydney, Sydney, NSW, 2006, Australia
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496
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Brain RA, Cedergreen N. Biomarkers in aquatic plants: selection and utility. REVIEWS OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2009; 198:49-109. [PMID: 19253039 DOI: 10.1007/978-0-387-09647-6_2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
This review emphasizes the predictive ability, sensitivity and specificity of aquatic plant biomarkers as biomonitoring agents of exposure and effect. Biomarkers of exposure are those that provide functional measures of exposure that are characterized at a sub-organism level. Biomarkers of effect require causal linkages between the biomarker and effects, measured at higher levels of biological organization. With the exception of pathway specific metabolites, the biomarkers assessed in this review show variable sensitivity and predictive ability that is often confounded by variations in growth conditions, rendering them unsuitable as stand alone indicators of environmental stress. The use of gene expression for detecting pollution has been, and remains immature; this immaturity derives from inadequate knowledge on predictive ability, sensitivity and specificity. Moreover, the ability to the detect mode of action of unknown toxicants using gene expression is not as clear-cut as initially hypothesized. The principal patterns in gene expression is not as clear-cut as initially hypothesized. The principal patterns in gene expression are generally derived from stress induced genes, rather than on ones that respond to substances with known modes of action (Baerson et al. 2005). Future developments in multivariate statistics and chemometric methods that enhance pattern analyses in ways that could produce a "fingerprint", may improve methods for discovering modes of action of unknown toxicants. Pathway specific metabolites are unambiguous, sensitive, correlate well to growth effects, and are relatively unaffected by growth conditions. These traits make them excellent biomarkers under both field and laboratory conditions. Changes in metabolites precede visible growth effects; therefore, measuring changes in metabolite concentrations (Harring et al. 1998; Shaner et al. 2005). The metabolic phase I enzymes (primarily associated with P-450 activity) are non-specific biomarkers, and few studies relate them to growth parameters. P-450 activity both increases and decreases in response to chemical stress, often confounding interpretation of experimental results. Alternatively, phase II metabolic enzymes (e.g., glutathione S-transferases; GST's) appear to be sensitive biomarkers of exposure, and potentially effect. Some GST's are affected by growth factors, but others may only be induced by xenobiotics. Measuring xenobiotic-induced GST's, or their gene expression patterns, are good candidates for future biomarkers of the cumulative load of chemical stress, both in the laboratory and under field conditions. Phytochelatins respond to some but not all metal ions, and may therefore be used as biomarkers of exposure to identify the presence and bioavailability of ions to which they respond. However, more data on their specificity to, and interactions with growth factors, in more species are needed. The flavenoids are only represented by one heavy metal exposure study; therefore their use as biomarkers is currently difficult to judge. Stress proteins tend to be specific for toxicants that affect protein function. Growth factors are known to affect the level of stress proteins; hence, the use of stress proteins as biomarkers will be confined to experiments performed under controlled growth conditions, where they can be excellent indicators of proteotoxicity. Reactive oxygen species (ROS), ROS scavenging enzymes, changes in pigment content, photosynthesis and chlorophyll fluorescence are all affected by growth factors, particularly light and nutrient availability. Therefore, these biomarkers are best suited to investigate the mode of action of toxicants under controlled growth conditions. These biomarkers are sensitive to xenobiotic stressors that affect various processes in the photosynthetic apparatus, and can be used to diagnose which photosynthetic process or processes are primarily affected. Chlorophyll fluorescence is a non-destructive measure, and is thereby well suited for repeated measures of effect and recovery (Abbaspoor and Streibig 2005; Abbaspoor et al. 2006; Cedergreen et al. 2004). Bi-phasic responses (over time and with dose) are probably major sources of variation in sensitivity for many biomarkers. Metabolic enzymes, stress proteins, ROS and their corresponding scavenging enzymes increase in a time-frame and at doses in which plant cell damage is still repairable. However, when toxicity progresses to the point of cell damage, the concentration/activity of the biomarker either stabilizes or decreases. Examples of this response pattern are given in Lei et al. (2006); Pflugmacher et al. (2000b); Teisseire et al. (1998); and Teisseire and Guy (2000). Gene expression is also a time-dependent phenomenon varying several fold within a few hour. Therefore, bi-phasic response patterns make timing and dose-range, within which the biomarkers can be used as measures of both exposure and effect, extremely important. As a result, most biomarkers are best suited for situations in which the time and dose dependence of the biomarker, in the investigated species, are established. Notwithstanding the previously mentioned limitations, all assessed biomarkers provide valuable information on the physiological effects of specific stressors, and are valuable tools in the search for understanding xenobiotic modes of action. However, the future use of aquatic plant biomarkers will probably be confined to laboratory studies designed to assess toxicant modes of action, until further knowledge is gained regarding the time, dose and growth-factor dependence of biomarkers, in different species. No single biomarker is viable in gaining a comprehensive understanding of xenobiotic stress. Only through the concomitant measurement of a suite of appropriate biomarkers will our diagnostic capacity be enhanced and the field of ecotoxicology, as it relates to aquatic plants, advanced.
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Affiliation(s)
- Richard A Brain
- Center for Reservoir and Aquatic Systems Research, Department of Environmental Science, Baylor University, Waco, Texas 76798, USA
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497
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Higgins MB, Robinson RS, Casciotti KL, McIlvin MR, Pearson A. A Method for Determining the Nitrogen Isotopic Composition of Porphyrins. Anal Chem 2008; 81:184-92. [DOI: 10.1021/ac8017185] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Meytal B. Higgins
- Department of Earth and Planetary Sciences, Harvard University, Cambridge, Massachusetts 02138, Graduate School of Oceanography, University of Rhode Island, Narragansett, Rhode Island 02882, and Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543
| | - Rebecca S. Robinson
- Department of Earth and Planetary Sciences, Harvard University, Cambridge, Massachusetts 02138, Graduate School of Oceanography, University of Rhode Island, Narragansett, Rhode Island 02882, and Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543
| | - Karen L. Casciotti
- Department of Earth and Planetary Sciences, Harvard University, Cambridge, Massachusetts 02138, Graduate School of Oceanography, University of Rhode Island, Narragansett, Rhode Island 02882, and Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543
| | - Matthew R. McIlvin
- Department of Earth and Planetary Sciences, Harvard University, Cambridge, Massachusetts 02138, Graduate School of Oceanography, University of Rhode Island, Narragansett, Rhode Island 02882, and Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543
| | - Ann Pearson
- Department of Earth and Planetary Sciences, Harvard University, Cambridge, Massachusetts 02138, Graduate School of Oceanography, University of Rhode Island, Narragansett, Rhode Island 02882, and Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543
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498
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Schenderlein M, Çetin M, Barber J, Telfer A, Schlodder E. Spectroscopic studies of the chlorophyll d containing photosystem I from the cyanobacterium, Acaryochloris marina. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2008; 1777:1400-8. [DOI: 10.1016/j.bbabio.2008.08.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2008] [Revised: 07/16/2008] [Accepted: 08/14/2008] [Indexed: 11/28/2022]
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499
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Veley KM, Michaels SD. Functional redundancy and new roles for genes of the autonomous floral-promotion pathway. PLANT PHYSIOLOGY 2008; 147:682-95. [PMID: 18408043 PMCID: PMC2409018 DOI: 10.1104/pp.108.118927] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2008] [Accepted: 04/04/2008] [Indexed: 05/19/2023]
Abstract
The early-flowering habit of rapid-cycling accessions of Arabidopsis (Arabidopsis thaliana) is, in part, due to the genes of the autonomous floral-promotion pathway (AP). The AP promotes flowering by repressing expression of the floral inhibitor FLOWERING LOCUS C (FLC). AP mutants are therefore late flowering due to elevated levels of FLC, and this late-flowering phenotype is eliminated by loss-of-function mutations in FLC. To further investigate the role of the AP, we created a series of double mutants. In contrast to the phenotypes of single mutants, which are largely limited to delayed flowering, a subset of AP double mutants show a range of defects in growth and development. These phenotypes include reduced size, chlorophyll content, growth rate, and fertility. Unlike the effects of the AP on flowering time, these phenotypes are FLC independent. Recent work has also shown that two AP genes, FCA and FPA, are required for the repression and, in some cases, proper DNA methylation of two transposons. We show that similar effects are seen for all AP genes tested. Microarray analysis of gene expression in AP single and double mutants, however, suggests that the AP is not likely to play a broad role in the repression of gene expression through DNA methylation: very few of the genes that have been reported to be up-regulated in DNA methylation mutants are misexpressed in AP mutants. Together, these data indicate that the genes of the AP play important and sometimes functionally redundant roles in aspects of development in addition to flowering time.
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Affiliation(s)
- Kira M Veley
- Department of Biology, Indiana University, Bloomington, Indiana 47405, USA
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500
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Ritchie RJ. Fitting light saturation curves measured using modulated fluorometry. PHOTOSYNTHESIS RESEARCH 2008; 96:201-15. [PMID: 18415696 DOI: 10.1007/s11120-008-9300-7] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2007] [Accepted: 03/28/2008] [Indexed: 05/08/2023]
Abstract
A blue diode PAM (Pulse Amplitude Modulation) fluorometer was used to measure rapid Photosynthesis (P) versus Irradiance (E) curves (P vs. E curves) in Synechococcus (classical cyanobacteria), Prochlorothrix (prochlorophyta), Chlorella (chlorophyta), Rhodomonas (cryptophyta), Phaeodactylum (bacillariophyta) Acaryochloris (Chl d/a cyanobacteria) and Subterranean Clover (Trifolium subterraneum, Papilionaceae, Angiospermae). Effective quantum yield (Phi(PSII)) versus irradiance curves could be described by a simple exponential decay function (Phi(PSII) = Phi(PSII, maxe(-kE)) although Log/Log transformation was sometimes found to be necessary to obtain the best fits. Photosynthesis was measured as relative Electron Transport Rate (rETR) standardised on a chlorophyll basis. P versus E curves were fitted to the waiting-in-line function (an equation of the form P = P(max) x k x E x e(-kE)) allowing half-saturating and optimal irradiances (E(optimum)) to be estimated. The second differential of the equation shows that at twice optimal light intensities, there is a point of inflection in the P versus E curve. Photosynthesis is inhibited 26.4% at this point of inflection. The waiting-in-line model was found to be a very good descriptor of photosynthetic light saturation curves and superior to hyperbolic functions with an asymptotic saturation point (Michaelis-Menten, exponential saturation and hyperbolic tangent). The exponential constants (k) of the Phi(PSII) versus E and P versus E curves should be equal because rETR is directly proportional to Phi(PSII) x E. The conventionally calculated Non-Photochemical Quenching (NPQ) in Synechococcus was not significantly different to zero but NPQ versus E curves for the other algae could be fitted to an exponential saturation model. The kinetics of NPQ does not appear to be related to the kinetics of Phi(PSII) or rETR.
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Affiliation(s)
- Raymond J Ritchie
- School of Biological Sciences A-08, The University of Sydney, Sydney, NSW 2006, Australia.
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