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Demir-Yilmaz I, Novosel N, Levak Zorinc M, Mišić Radić T, Ftouhi MS, Guiraud P, Ivošević DeNardis N, Formosa-Dague C. Investigation of the role of cell hydrophobicity and EPS production in the aggregation of the marine diatom Cylindrotheca closterium under hypo-saline conditions. Mar Environ Res 2023; 188:106020. [PMID: 37187087 DOI: 10.1016/j.marenvres.2023.106020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 04/12/2023] [Accepted: 05/05/2023] [Indexed: 05/17/2023]
Abstract
Aggregation of diatoms is of global importance to understand settling of particulate organic carbon in aquatic systems. In this study, we investigate the aggregation of the marine diatom Cylindrotheca closterium during the exponential growth phase under hypo-saline conditions. The results of the flocculation/flotation experiments show that the aggregation of the diatom depends on the salinity. In favorable growth conditions for marine diatoms (salinity of 35), the highest aggregation is achieved. To explain these observations, we used a surface approach combining atomic force microscopy (AFM) and electrochemical methods to characterize both the cell surface properties and the structure of the extracellular polymeric substances (EPS) cell produce, and to quantify the amount of surface-active organic matter released. At a salinity of 35, the results showed that diatoms are soft, hydrophobic and release only small amounts of EPS organized into individual short fibrils. In contrast, diatoms adapt to a salinity of 5 by becoming much stiffer and more hydrophilic, producing larger amounts of EPS that structurally form an EPS network. Both adaptation responses of diatoms, the hydrophobic properties of diatoms and the release of EPS, appear to play an important role in diatom aggregation and explain the behavior observed at different salinities. This biophysical study provides important evidence allowing to get a deep insight into diatom interactions at the nanoscale, which may contribute to a better understanding of large-scale aggregation phenomena in aquatic systems.
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Affiliation(s)
- Irem Demir-Yilmaz
- TBI, Université de Toulouse, INSA, INRAE, CNRS, Toulouse, France; LAAS, Université de Toulouse, CNRS, Toulouse, France
| | - Nives Novosel
- Division for Marine and Environmental Research, Ruđer Bošković Institute, Zagreb, Croatia
| | - Maja Levak Zorinc
- Division for Marine and Environmental Research, Ruđer Bošković Institute, Zagreb, Croatia
| | - Tea Mišić Radić
- Division for Marine and Environmental Research, Ruđer Bošković Institute, Zagreb, Croatia
| | | | - Pascal Guiraud
- TBI, Université de Toulouse, INSA, INRAE, CNRS, Toulouse, France; Fédération de Recherche Fermat, CNRS, Toulouse, France
| | | | - Cécile Formosa-Dague
- TBI, Université de Toulouse, INSA, INRAE, CNRS, Toulouse, France; Fédération de Recherche Fermat, CNRS, Toulouse, France.
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Guermazi W, Masmoudi S, Trabelsi NA, Gammoudi S, Ayadi H, Morant-Manceau A, Hotos GN. Physiological and Biochemical Responses in Microalgae Dunaliella salina, Cylindrotheca closterium and Phormidium versicolor NCC466 Exposed to High Salinity and Irradiation. Life (Basel) 2023; 13:life13020313. [PMID: 36836671 PMCID: PMC9961930 DOI: 10.3390/life13020313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 01/16/2023] [Accepted: 01/19/2023] [Indexed: 01/24/2023] Open
Abstract
Dunaliella salina (Chlorophyceae), Phormidium versicolor (Cyanophyceae), and Cylindrotheca closterium (Bacillariophyceae) were isolated from three ponds in the solar saltern of Sfax (Tunisia). Growth, pigment contents, and photosynthetic and antioxidant enzyme activities were measured under controlled conditions of three light levels (300, 500, and 1000 µmol photons m-2 s-1) and three NaCl concentrations (40, 80, and 140 g L-1). The highest salinity reduced the growth of D. salina and P. versicolor NCC466 and strongly inhibited that of C. closterium. According to ΦPSII values, the photosynthetic apparatus of P. versicolor was stimulated by increasing salinity, whereas that of D. salina and C. closterium was decreased by irradiance rise. The production of carotenoids in D. salina and P. versicolor was stimulated when salinity and irradiance increased, whereas it decreased in the diatom. Catalase (CAT), Superoxide dismutase (SOD), and Ascorbate peroxidase (APX) activities were only detected when the three species were cultivated under E1000. The antioxidant activity of carotenoids could compensate for the low antioxidant enzyme activity measured in D. salina. Salinity and irradiation levels interact with the physiology of three species that have mechanisms of more or less effective stress resistance, hence different resistance to environmental stresses according to the species. Under these stress-controlled conditions, P. versicolor and C. closterium strains could provide promising sources of extremolyte for several purposes.
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Affiliation(s)
- Wassim Guermazi
- Laboratory of Marine Biodiversity and Environment (LR18ES/30), University of Sfax, Sfax CP 3000, Tunisia
| | - Salma Masmoudi
- Laboratory of Marine Biodiversity and Environment (LR18ES/30), University of Sfax, Sfax CP 3000, Tunisia
- LUNAM, Laboratoire Mer, Molécules, Santé (EA 2160), Université du Maine, Avenue Olivier Messiaen, CEDEX 9, 72085 Le Mans, France
| | - Neila Annabi Trabelsi
- Laboratory of Marine Biodiversity and Environment (LR18ES/30), University of Sfax, Sfax CP 3000, Tunisia
| | - Sana Gammoudi
- Laboratory of Marine Biodiversity and Environment (LR18ES/30), University of Sfax, Sfax CP 3000, Tunisia
| | - Habib Ayadi
- Laboratory of Marine Biodiversity and Environment (LR18ES/30), University of Sfax, Sfax CP 3000, Tunisia
| | - Annick Morant-Manceau
- LUNAM, Laboratoire Mer, Molécules, Santé (EA 2160), Université du Maine, Avenue Olivier Messiaen, CEDEX 9, 72085 Le Mans, France
| | - George N. Hotos
- Plankton Culture Laboratory, Department of Fisheries and Aquaculture, University of Patras, 30200 Messolonghi, Greece
- Correspondence:
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Klapper F, Audoor S, Vyverman W, Pohnert G. Pheromone Mediated Sexual Reproduction of Pennate Diatom Cylindrotheca closterium. J Chem Ecol 2021; 47:504-512. [PMID: 33914225 PMCID: PMC8217010 DOI: 10.1007/s10886-021-01277-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 04/06/2021] [Accepted: 04/13/2021] [Indexed: 12/01/2022]
Abstract
Benthic diatoms dominate primary production in marine subtidal and intertidal environments. Their extraordinary species diversity and ecological success is thought to be linked with their predominantly heterothallic sexual reproduction. Little is known about pheromone involvement during mating of pennate diatoms. Here we describe pheromone guided mating in the coastal raphid diatom Cylindrotheca closterium. We show that the two mating types (mt+ and mt−) have distinct functions. Similar to other benthic diatoms, mt+ cells are searching for the mt− cells to pair. To enhance mating efficiency mt− exudes an attraction pheromone which we proved by establishing a novel capillary assay. Further, two more pheromones produced by mt− promote the sexual events. One arrests the cell cycle progression of mt+ while the other induces gametogenesis of mt+. We suggest that C. closterium shares a functionally similar pheromone system with other pennate diatoms like Seminavis robusta and Pseudostaurosira trainorii which synchronize sexual events and mate attraction. Remarkably, we found no evidence of mt+ producing pheromones, which differentiates C. closterium from other pennates and suggests a less complex pheromone system in C. closterium.
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Affiliation(s)
- Franziska Klapper
- Bioorganic Analytics, Institute for Inorganic and Analytical Chemistry, Friedrich Schiller University Jena, Lessingstrasse 8, 07743, Jena, Germany
| | - Sien Audoor
- Laboratory of Protistology and Aquatic Ecology, Department of Biology, University Gent, Krijgslaan 281 S8, 9000, Gent, Belgium
| | - Wim Vyverman
- Laboratory of Protistology and Aquatic Ecology, Department of Biology, University Gent, Krijgslaan 281 S8, 9000, Gent, Belgium
| | - Georg Pohnert
- Bioorganic Analytics, Institute for Inorganic and Analytical Chemistry, Friedrich Schiller University Jena, Lessingstrasse 8, 07743, Jena, Germany. .,Max Planck Institute for Chemical Ecology, Hans-Knöll-Straße 8, 07745, Jena, Germany.
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Zhang F, Chi J. Influences of nutritional conditions on degradation of dibutyl phthalate in coastal sediments with Cylindrotheca closterium. Mar Pollut Bull 2020; 153:111021. [PMID: 32275567 DOI: 10.1016/j.marpolbul.2020.111021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Revised: 02/22/2020] [Accepted: 02/22/2020] [Indexed: 06/11/2023]
Abstract
In this work, microphytobenthos Cylindrotheca closterium was planted on the surface of coastal sediments to investigate its influence on dibutyl phthalate (DBP) degradation in sediments under different nutritional conditions. The results indicated that C. closterium largely utilized nutrients from the overlying water. Addition of nitrogen, phosphorus or silicon increased algal biomass (as chlorophyll a) by 0.97-3.16, 1.75-2.36 and 1.61-3.09 times, respectively, meanwhile it changed bacterial community structure in sediments with C. closterium. Growth of C. closterium was more sensitive to nitrogen content in the overlying water. Inoculation of C. closterium increased the relative abundances of dominant aerobic bacteria by 10-67%. Compared with treatments without C. closterium, inoculation of C. closterium increased DBP degradation percentage in sediments (8.5-18.9% increment), which was positively correlated with chlorophyll a content. Thus, microphytobenthos showed the potential for improving the cleansing of polluted coastal sediments, which was obviously related to nutritional conditions in the overlying water.
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Affiliation(s)
- Fan Zhang
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300350, PR China
| | - Jie Chi
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300350, PR China.
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Lauritano C, Helland K, Riccio G, Andersen JH, Ianora A, Hansen EH. Lysophosphatidylcholines and Chlorophyll-Derived Molecules from the Diatom Cylindrotheca closterium with Anti-Inflammatory Activity. Mar Drugs 2020; 18:md18030166. [PMID: 32192075 PMCID: PMC7143213 DOI: 10.3390/md18030166] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 03/13/2020] [Accepted: 03/13/2020] [Indexed: 12/20/2022] Open
Abstract
Microalgae have been shown to be excellent producers of lipids, pigments, carbohydrates, and a plethora of secondary metabolites with possible applications in the pharmacological, nutraceutical, and cosmeceutical sectors. Recently, various microalgal raw extracts have been found to have anti-inflammatory properties. In this study, we performed the fractionation of raw extracts of the diatom Cylindrotheca closterium, previously shown to have anti-inflammatory properties, obtaining five fractions. Fractions C and D were found to significantly inhibit tumor necrosis factor alpha (TNF-⍺) release in LPS-stimulated human monocyte THP-1 cells. A dereplication analysis of these two fractions allowed the identification of their main components. Our data suggest that lysophosphatidylcholines and a breakdown product of chlorophyll, pheophorbide a, were probably responsible for the observed anti-inflammatory activity. Pheophorbide a is known to have anti-inflammatory properties. We tested and confirmed the anti-inflammatory activity of 1-palmitoyl-sn-glycero-3-phosphocholine, the most abundant lysophosphatidylcholine found in fraction C. This study demonstrated the importance of proper dereplication of bioactive extracts and fractions before isolation of compounds is commenced.
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Affiliation(s)
- Chiara Lauritano
- Department of Marine Biotechnology, Stazione Zoologica Anton Dohrn, CAP80121 Naples, Italy; (G.R.); (A.I.)
- Correspondence: ; Tel.: +39-081-5833-221
| | - Kirsti Helland
- Marbio, UiT—The Arctic University of Norway, Breivika N-9037 Tromsø, Norway; (K.H.); (J.H.A.); (E.H.H.)
| | - Gennaro Riccio
- Department of Marine Biotechnology, Stazione Zoologica Anton Dohrn, CAP80121 Naples, Italy; (G.R.); (A.I.)
| | - Jeanette H. Andersen
- Marbio, UiT—The Arctic University of Norway, Breivika N-9037 Tromsø, Norway; (K.H.); (J.H.A.); (E.H.H.)
| | - Adrianna Ianora
- Department of Marine Biotechnology, Stazione Zoologica Anton Dohrn, CAP80121 Naples, Italy; (G.R.); (A.I.)
| | - Espen H. Hansen
- Marbio, UiT—The Arctic University of Norway, Breivika N-9037 Tromsø, Norway; (K.H.); (J.H.A.); (E.H.H.)
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Stock W, Vanelslander B, Rüdiger F, Sabbe K, Vyverman W, Karsten U. Thermal Niche Differentiation in the Benthic Diatom Cylindrotheca closterium (Bacillariophyceae) Complex. Front Microbiol 2019; 10:1395. [PMID: 31293543 PMCID: PMC6598499 DOI: 10.3389/fmicb.2019.01395] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Accepted: 06/04/2019] [Indexed: 01/01/2023] Open
Abstract
Coastal waters are expected to undergo severe warming in the coming decades. Very little is known about how diatoms, the dominant primary producers in these habitats, will cope with these changes. We investigated the thermal niche of Cylindrotheca closterium, a widespread benthic marine diatom, using 24 strains collected over a wide latitudinal gradient. A multi-marker phylogeny in combination with a species delimitation approach shows that C. closterium represents a (pseudo)cryptic species complex, and this is reflected in distinct growth response patterns in terms of optimum growth temperature, maximum growth rate, and thermal niche width. Strains from the same clade displayed a similar thermal response, suggesting niche conservation between closely related strains. Due to their lower maximum growth rate and smaller thermal niche width, we expect the polar species to be particularly sensitive to warming, and, in the absence of adaptation, to be replaced with species from lower latitudes.
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Affiliation(s)
- Willem Stock
- Laboratory of Protistology and Aquatic Ecology, Department of Biology, Ghent University, Ghent, Belgium
| | - Bart Vanelslander
- Laboratory of Protistology and Aquatic Ecology, Department of Biology, Ghent University, Ghent, Belgium
| | - Franziska Rüdiger
- Institute of Biological Sciences, Applied Ecology and Phycology, University of Rostock, Rostock, Germany
| | - Koen Sabbe
- Laboratory of Protistology and Aquatic Ecology, Department of Biology, Ghent University, Ghent, Belgium
| | - Wim Vyverman
- Laboratory of Protistology and Aquatic Ecology, Department of Biology, Ghent University, Ghent, Belgium
| | - Ulf Karsten
- Institute of Biological Sciences, Applied Ecology and Phycology, University of Rostock, Rostock, Germany
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Xu W, Wang J, Tan L, Guo X, Xue Q. Variation in allelopathy of extracellular compounds produced by Cylindrotheca closterium against the harmful-algal-bloom dinoflagellate Prorocentrum donghaiense. Mar Environ Res 2019; 148:19-25. [PMID: 31077964 DOI: 10.1016/j.marenvres.2019.05.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Revised: 04/26/2019] [Accepted: 05/02/2019] [Indexed: 06/09/2023]
Abstract
Allelopathy between algae is an ecological strategy that can facilitate or inhibit the occurrence of algal blooms. The role of allelopathic effects of marine microalgae Cylindrotheca closterium in other phytoplankton population dynamics are still limited. In the current study, the effects of cell-free filtrates of diatom Cylindrotheca closterium on two common dinoflagellates (Prorocentrum donghaiense and Prorocentrum cordatum), a chrysophyceae (Isochrysis galbana) and a diatom (Chaetoceros curvisetus) were investigated within controlled laboratory experiments. It was observed that the growth of P. donghaiense was significantly suppressed and approximately 80% cells disappeared after 8-d exposure, while the other three algae was less sensitive. P. donghaiense was very sensitive to the exudates of C. closterium from the stationary phase by comparing various percentage (10, 30, 50, 70 and 100%) of filtrates. In addition, the allelopathic effects of extracellular compounds of C. closterium extracted by three different organic solvents (ethyl acetate, chloroform and petroleum ether) on P. donghaiense were explored by determining cell density, chlorophyll content and maximum photosystem II (PSII) quantum yield (Fv/Fm). It was found that the compounds extracted by ethyl acetate and chloroform appeared to exhibit less toxicity on P. donghaiense than that of petroleum ether. The present results indicated that the allelochemicals released by C. closterium might be concentrated effectively in the petroleum ether extraction phase, which provided a new perspective for controlling the red tides of P. donghaiense in the East China Sea by means of the ecological inhibitors extracted.
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Affiliation(s)
- Wenjing Xu
- Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao, 266100, China
| | - Jiangtao Wang
- Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao, 266100, China.
| | - Liju Tan
- Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao, 266100, China
| | - Xin Guo
- Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao, 266100, China
| | - Qiaona Xue
- Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao, 266100, China
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Zhang F, Ding Z, Gong H, Chi J. Effects of microphytobenthos Cylindrotheca closterium on the fate of di-n-butyl phthalate in an aquatic microcosm. Mar Pollut Bull 2019; 140:101-106. [PMID: 30803623 DOI: 10.1016/j.marpolbul.2019.01.033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Revised: 01/16/2019] [Accepted: 01/16/2019] [Indexed: 06/09/2023]
Abstract
Effects of Cylindrotheca closterium, a marine benthic diatom, on the fate of di-n-butyl phthalate (DBP) in a water-sediment system were investigated. Model calculation results showed that DBP residue was 38.5% lower in the system with C. closterium than in the system without C. closterium. The net flux from water to sediment increased by 7.3 times in the presence of C. closterium. As a result, the total biodegradation flux of DBP in the system with C. closterium was increased by 25.6%. According to the 16 s rDNA sequencing, the presence of C. closterium decreased the bacterial population as well as bacterial community diversity in sediments. Moreover, the population of C. closterium, capable of efficiently degrading DBP, was much higher than that of the dominant DBP-degrading bacteria, demonstrating that degradation of DBP by C. closterium should be the main reason for the degradation enhancement in sediments.
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Affiliation(s)
- Fan Zhang
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300350, PR China
| | - Zheng Ding
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300350, PR China
| | - Haofei Gong
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300350, PR China
| | - Jie Chi
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300350, PR China.
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Li Y, Gao J, Meng F, Chi J. Enhanced biodegradation of phthalate acid esters in marine sediments by benthic diatom Cylindrotheca closterium. Sci Total Environ 2015; 508:251-257. [PMID: 25481253 DOI: 10.1016/j.scitotenv.2014.12.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Revised: 11/30/2014] [Accepted: 12/01/2014] [Indexed: 06/04/2023]
Abstract
Cylindrotheca closterium, a marine benthic diatom, was inoculated on the surface of marine sediments spiked with diethyl phthalate (DEP) and dibutyl phthalate (DBP) to investigate the effects of benthic microalgae on the degradation of the contaminants. The elimination of DEP and DBP from unsterilized sediments with C. closterium (treatment BA) was compared with that from unsterilized sediments without C. closterium (treatment B), sterilized sediments with C. closterium (treatment A) and sterilized sediments without C. closterium (treatment N). The results showed that during the 8-day experiment, inoculation with C. closterium increased the removal rates of the contaminants from the sediments, and more significantly from the surface layer (top 0.5 cm) of sediments than from the bottom layer of sediments. In the surface sediments, the first-order elimination rate constants (k) of DEP and DBP were in the order of treatment BA (2.098 and 0.309 d(-1))>treatment B (0.460 and 0.256 d(-1))>treatment A (0.216 and 0.039 d(-1))>treatment N (nil (no data)), indicating that microbial degradation played a major role in the removal of the contaminants from the sediments. A similar trend was also observed in bottom sediments (0.444 and 0.165 d(-1) in treatment BA, 0.329 and 0.194 d(-1) in treatment B, 0.129 d(-1) and nil in treatment A), but the difference of k values between treatments BA and B was relatively small. The positive effect of C. closterium on total phospholipid fatty acid (PLFA) content in sediments was observed, which was mainly related to the increase of biomass of aerobic bacteria as a result of improved sediment oxygenation and release of exudates (e.g. exopolysaccharides) by C. closterium. Moreover, Pearson correlation analysis showed a significant positive correlation between the elimination ratios of the contaminants and abundance of total aerobic bacterial PLFAs, suggesting that aerobic bacteria played a key role in C. closterium-promoted degradation of the contaminants in sediments.
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Affiliation(s)
- Ying Li
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, PR China; College of Marine Science and Engineering, Tianjin Key Laboratory of Marine Resources and Chemistry, Tianjin University of Science and Technology, Tianjin 300457, PR China
| | - Jing Gao
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, PR China
| | - Fanbo Meng
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, PR China
| | - Jie Chi
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, PR China.
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Pletikapić G, Berquand A, Radić TM, Svetličić V. QUANTITATIVE NANOMECHANICAL MAPPING OF MARINE DIATOM IN SEAWATER USING PEAK FORCE TAPPING ATOMIC FORCE MICROSCOPY(1). J Phycol 2012; 48:174-85. [PMID: 27009662 DOI: 10.1111/j.1529-8817.2011.01093.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
It is generally accepted that a diatom cell wall is characterized by a siliceous skeleton covered by an organic envelope essentially composed of polysaccharides and proteins. Understanding of how the organic component is associated with the silica structure provides an important insight into the biomineralization process and patterning on the cellular level. Using a novel atomic force microscopy (AFM) imaging technique (Peak Force Tapping), we characterized nanomechanical properties (elasticity and deformation) of a weakly silicified marine diatom Cylindrotheca closterium (Ehrenb.) Reimann et J. C. Lewin (strain CCNA1). The nanomechanical properties were measured over the entire cell surface in seawater at a resolution that was not achieved previously. The fibulae were the stiffest (200 MPa) and the least deformable (only 1 nm). Girdle band region appeared as a series of parallel stripes characterized by two sets of values of Young's modulus and deformation: one for silica stripes (43.7 Mpa, 3.7 nm) and the other between the stripes (21.3 MPa, 13.4 nm). The valve region was complex with average values of Young's modulus (29.8 MPa) and deformation (10.2 nm) with high standard deviations. After acid treatment, we identified 15 nm sized silica spheres in the valve region connecting raphe with the girdle bands. The silica spheres were neither fused together nor forming a nanopattern. A cell wall model is proposed with individual silica nanoparticles incorporated in an organic matrix. Such organization of girdle band and valve regions enables the high flexibility needed for movement and adaptation to different environments while maintaining the integrity of the cell.
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Affiliation(s)
- Galja Pletikapić
- Division for Marine and Environmental Research, Ruđer Bošković Institute, Zagreb 10000, CroatiaBruker Nano GmbH, Mannheim 68165, GermanyDivision for Marine and Environmental Research, Ruđer Bošković Institute, Zagreb 10000, Croatia
| | - Alexandre Berquand
- Division for Marine and Environmental Research, Ruđer Bošković Institute, Zagreb 10000, CroatiaBruker Nano GmbH, Mannheim 68165, GermanyDivision for Marine and Environmental Research, Ruđer Bošković Institute, Zagreb 10000, Croatia
| | - Tea Mišić Radić
- Division for Marine and Environmental Research, Ruđer Bošković Institute, Zagreb 10000, CroatiaBruker Nano GmbH, Mannheim 68165, GermanyDivision for Marine and Environmental Research, Ruđer Bošković Institute, Zagreb 10000, Croatia
| | - Vesna Svetličić
- Division for Marine and Environmental Research, Ruđer Bošković Institute, Zagreb 10000, CroatiaBruker Nano GmbH, Mannheim 68165, GermanyDivision for Marine and Environmental Research, Ruđer Bošković Institute, Zagreb 10000, Croatia
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Svetličić V, Zutić V, Radić TM, Pletikapić G, Zimmermann AH, Urbani R. Polymer networks produced by marine diatoms in the northern Adriatic sea. Mar Drugs 2011; 9:666-79. [PMID: 21731556 DOI: 10.3390/md9040666] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2011] [Revised: 04/05/2011] [Accepted: 04/07/2011] [Indexed: 11/17/2022] Open
Abstract
Using high resolution molecular technique of atomic force microscopy, we address the extracellular polymer production of Adriatic diatom Cylindrotheca closterium analyzed at the single cell level and the supramolecular organization of gel phase isolated from the Northern Adriatic macroaggregates. Our results revealed that extracellular polysaccharides freshly produced by marine diatoms can self-assemble directly to form gel network characteristics of the macroscopic gel phase in the natural aquatorium. Based on the experiments performed with isolated polysaccharide fractions of C. closterium and of macroaggregates gel phase, we demonstrated that the polysaccharide self-assembly into gel network can proceed independent of any bacterial mediation or interaction with inorganic particles.
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