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J S Rivers - One of the best experts on this subject based on the ideXlab platform.
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physiological responses of the opportunistic macroalgae cladophora vagabunda l van den hoek and gracilaria tikvahiae mclachlan to environmental disturbances associated with eutrophication
Journal of Experimental Marine Biology and Ecology, 1995Co-Authors: P Peckol, J S RiversAbstract:Abstract Ability of macroalgae to tolerate environmental disturbances often contributes to their success in marine communities. We investigated the effects of episodic and chronic disturbances (hypoxia/anoxia, elevated Ammonium, reduced light) associated with eutrophication on physiological responses (respiration, photosynthesis, growth, nutrient Uptake) of the macroalgae, Cladophora vagabunda (L.) van den Hoek and Gracilaria tikvahiae (McLachlan). These opportunistic species accumulate into thick (0.3 to > 1 m) mats during summer in a eutrophic embayment (Waquoit Bay, Massachusetts), resulting in a highly reducing environment characterized by elevated Ammonium concentrations. Elevated (100 μM) Ammonium levels depressed growth and Ammonium Uptake rates of both species. In fact, C. vagabunda had high rates of Ammonium release under conditions similar to the in-mat environment (dark, elevated N). Ammonium Uptake rate was 2–3 times higher for G. tikvahiae under lighted vs. dark conditions. This light/dark effect was more dramatic for C. vagabunda ; presence of light, characteristic of the surface of the mat, substantially reduced the inhibitory effect of the elevated Ammonium treatment. In the field and laboratory, C. vagabunda and G. tikvahiae showed reduced respiration rates under stagnant conditions and hypoxia, respectively. As hypoxic, stagnant conditions occur frequently within the thick mats, a reduction in respiration may enable these species to survive these disturbances. We also investigated the potential for recovery of algal thalli buried within the anoxic region of the mat. C. vagabunda demonstrated remarkable resilience; following a 2-day acclimation period under lighted, aerated conditions, blackened fronds taken from anoxic regions of the mat showed nearly full physiological recovery, namely, photosynthetic performance and nutrient Uptake rates approached values measured for surface-collected fronds. Previous field measurements indicated that while C. vagabunda is capable of surviving long-term burial (> 3 months) within the mat, turnover of the mat is a frequent event during summer due to heavy motor-boat activity. The distinctive species' patterns may be critical acclimation responses to large swings in the oxygen and nutrient environments of the algal mat, contributing to the successful dominance of both Cladophora spp. and G. tikvahiae in this and other areas undergoing eutrophication.
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interactive effects of nitrogen and dissolved inorganic carbon on photosynthesis growth and Ammonium Uptake of the macroalgae cladophora vagabunda and gracilaria tikvahiae
Marine Biology, 1995Co-Authors: J S Rivers, Paulette PeckolAbstract:Dissolved inorganic carbon (DIC) is rarely considered limiting for macroalgae, but some research suggests that under conditions of N sufficiency, photosynthetic capacity is enhanced with DIC enrichment. During spring (April–May) and summer (July–August) 1993, we investigated the interactive effects of nitrogen (N) and DIC on photosynthetic capacity, growth, and nutrient Uptake rates of the macroalgae, Cladophora vagabunda (L.) van den Hoek and Gracilaria tikvahiae (McLachlan), dominant species in a temperate eutrophic estuary (Cape Cod, Massachusetts, USA). Water-column CO2 concentrations showed significant diurnal fluctuations, ranging from a morning CO2 peak (21 μM) to an afternoon low (13 μM) during summer, probably associated with metabolic activities in a thick algal mat. Results from instantaneous photosynthesis measurements and microcosm experiments indicate that DIC limits photosynthetic capacity and growth rates of C. vagabunda during summer, perhaps related to tissue N sufficiency and low water-column CO2 concentrations. For example, this species showed enhanced growth (F=8.69, P<0.02) under DIC but not N enrichment. G. tikvahiae showed marginal DIC enhancement of maximum photosynthetic rate, while growth was significantly stimulated by addition of N. Reduced thallus N of this species during the summer further identifies N as the primary factor limiting growth. In addition, G. tikvahiae has the ability to use DIC in its several forms, while C. vagabunda primarily uses dissolved CO2. DIC enrichment resulted in a depression of NH4+ Uptake rates for both species, particularly during summer at saturating (60 μM) Ammonium levels, suggesting competition between NH4+ Uptake and DIC acquisition under conditions of N sufficiency. Dominance of C. vagabunda and G. tikvahiae in areas undergoing eutrophication has been attributed to their successful procurement and storage of N as well as to high growth rates. The present study revealed that under conditions of N sufficiency during summer, DIC may control rates of production of these opportunistic macroalgae.
Myroslav Sprynskyy - One of the best experts on this subject based on the ideXlab platform.
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Ammonium removal from aqueous solution by natural zeolite transcarpathian mordenite kinetics equilibrium and column tests
Separation and Purification Technology, 2005Co-Authors: Myroslav Sprynskyy, Mariya Lebedynets, Radoslaw Zbytniewski, Jacek Namiesnik, Boguslaw BuszewskiAbstract:Abstract The scope of this study was Ammonium ions removal from synthetic aqueous solutions by raw and pretreated natural zeolite, Transcarpathian mordenite under static and dynamic conditions. The cation exchange capacity of the Transcarpathian mordenite regarding Ammonium ions was evaluated as 1.64 meq/g at 1000 mg/l initial NH4–N concentration. The dynamic exchange capacity exceeded one estimated in equilibrium study at the same initial concentration that may be conditioned by the constant removal of ion exchange products. Ammonium Uptake rate was controlled by particle diffusion with diffusion coefficients determined in the range of 0.7–3.6 × 10−12 m2/s. Efficiency of Ammonium sorption may be improved by slowing down of initial solution rate in the column test and non-significantly by NaCl and HCl pretreatment of the mordenite. Ammonium sorption by the mordenite increased from the coarser to the finer fraction but this dependence became weaker to low flow rates. It was established that hydrogen ions displaced exchangeable cations on the mordenite in distilled water and hydrochloric acid with destroy of the zeolite framework structure in the last case. NH4+-ions removal from aqueous solutions occurs mainly by ion exchange with Na+- and Ca2+-ions at the practically equal parts of them because of the weakest affinity of the mordenite to these cations.
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Ammonium sorption from aqueous solutions by the natural zeolite transcarpathian clinoptilolite studied under dynamic conditions
Journal of Colloid and Interface Science, 2005Co-Authors: Myroslav Sprynskyy, Mariya Lebedynets, Pio Kowalczyk, Artur P. Terzyk, Jacek Namieśnik, Oguslaw UszewskiAbstract:The scope of this study is Ammonium-ion Uptake from synthetic aqueous solutions onto raw and pretreated forms of the natural zeolite Transcarpathian clinoptilolite under dynamic conditions. Hydrogen ions displaced exchangeable cations on the clinoptilolite in distilled water (sodium ions) and hydrochloric acid (sodium, potassium, and calcium ions) and destroyed the zeolite framework structure in the last case. Ammonium Uptake onto the zeolite occurs by exchange with Na(+), Ca(2+), and K(+) ions. Although Na(+) ions were observed to be more easily exchanged for both hydrogen and Ammonium ions, the role of Ca(2+) ions increased with zeolite saturation by NH(+)(4) ions. The maximum sorption capacity of the clinoptilolite toward NH(+)(4) ions, estimated under dynamic conditions, is significantly higher than that measured under static conditions; proximity of the values of a distribution coefficient and a retardation factor for different conditions (215-265 dm(3)/kg and 979-1107, respectively) allows us to use these parameters to model Ammonium Uptake onto the clinoptilolite. Slowing down or interruption in filtration resulted in the improvement of Ammonium sorption properties of the zeolite. The Ammonium removal improves with use of the finer fractions of the clinoptilolite up to 0.35 mm. A recycling study results confirmed the importance of external diffusion for Ammonium sorption by the clinoptilolite. Preliminary treatment of the sorbent confirmed the predominant importance of the ion-exchange mechanism. The advantage of prior NaCl treatment of the clinoptilolite in improvement of Ammonium removal over the other techniques was shown.
Stephen A Macko - One of the best experts on this subject based on the ideXlab platform.
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Uptake of urea and amino acids by the macroalgae ulva lactuca chlorophyta and gracilaria vermiculophylla rhodophyta
Marine Ecology Progress Series, 2005Co-Authors: Anna Christina Tyler, Karen J Mcglathery, Stephen A MackoAbstract:Dissolved organic nitrogen (DON) makes up a large fraction of the total dissolved nitro- gen pool in coastal waters, but is often ignored as a potential nitrogen source for primary producers. In laboratory experiments, we measured the Uptake of small, labile DON compounds, urea and a variety of different amino acids, by the common estuarine macroalgae Ulva lactuca and Gracilaria vermiculophylla. Urea Uptake was measured based on its disappearance from solution; amino acid Uptake was measured using this method as well as by assimilation of 15 N- and 13 C-labeled amino acids. The Michaelis-Menten Uptake parameters (Km, Vmax, Vmax/Km) were calculated for all com- pounds. Whereas both species were capable of assimilating urea and amino acids, U. lactuca consis- tently exhibited significantly higher Uptake rates than G. vermiculophylla. There were 2 distinct phases of Uptake for urea, an initially rapid 'surge' Uptake phase and a slower, 'sustained' phase. This suggests that both species can take advantage of pulsed urea availability. Vmax rates for urea for U. lactuca were lower than published values for Ammonium Uptake, but were still high enough to be a significant factor at natural urea concentrations. We did not observe surge Uptake of amino acids by either species and the Uptake rates varied substantially among the 6 amino acids studied. The differ- ential Uptake of 15 N and 13 C by U. lactuca suggested that both alanine and glycine are decarboxy- lated prior to Uptake. However, following decarboxylation, the residual of the glycine molecule is assimilated, while the amine group on alanine is likely removed prior to assimilation. Glycine Uptake rates by N-starved or NH4 + -fertilized macroalgae were higher than Uptake rates by NO3 - -fertilized macroalgae, which suggests that the induction of glycine and Ammonium Uptake may be similar. The low half-saturation constant (Km) and the high affinity at low concentrations (Vmax/Km) that we measured for amino acids suggests that macroalgae can take advantage of the low concentration of amino acids found in estuarine waters. This study shows that macroalgae are capable of utilizing DON and that under conditions of low inorganic nitrogen availability, organic nitrogen may provide a significant portion of the total N demand.
Paulette Peckol - One of the best experts on this subject based on the ideXlab platform.
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interactive effects of nitrogen and dissolved inorganic carbon on photosynthesis growth and Ammonium Uptake of the macroalgae cladophora vagabunda and gracilaria tikvahiae
Marine Biology, 1995Co-Authors: J S Rivers, Paulette PeckolAbstract:Dissolved inorganic carbon (DIC) is rarely considered limiting for macroalgae, but some research suggests that under conditions of N sufficiency, photosynthetic capacity is enhanced with DIC enrichment. During spring (April–May) and summer (July–August) 1993, we investigated the interactive effects of nitrogen (N) and DIC on photosynthetic capacity, growth, and nutrient Uptake rates of the macroalgae, Cladophora vagabunda (L.) van den Hoek and Gracilaria tikvahiae (McLachlan), dominant species in a temperate eutrophic estuary (Cape Cod, Massachusetts, USA). Water-column CO2 concentrations showed significant diurnal fluctuations, ranging from a morning CO2 peak (21 μM) to an afternoon low (13 μM) during summer, probably associated with metabolic activities in a thick algal mat. Results from instantaneous photosynthesis measurements and microcosm experiments indicate that DIC limits photosynthetic capacity and growth rates of C. vagabunda during summer, perhaps related to tissue N sufficiency and low water-column CO2 concentrations. For example, this species showed enhanced growth (F=8.69, P<0.02) under DIC but not N enrichment. G. tikvahiae showed marginal DIC enhancement of maximum photosynthetic rate, while growth was significantly stimulated by addition of N. Reduced thallus N of this species during the summer further identifies N as the primary factor limiting growth. In addition, G. tikvahiae has the ability to use DIC in its several forms, while C. vagabunda primarily uses dissolved CO2. DIC enrichment resulted in a depression of NH4+ Uptake rates for both species, particularly during summer at saturating (60 μM) Ammonium levels, suggesting competition between NH4+ Uptake and DIC acquisition under conditions of N sufficiency. Dominance of C. vagabunda and G. tikvahiae in areas undergoing eutrophication has been attributed to their successful procurement and storage of N as well as to high growth rates. The present study revealed that under conditions of N sufficiency during summer, DIC may control rates of production of these opportunistic macroalgae.
Shenkui Liu - One of the best experts on this subject based on the ideXlab platform.
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Identification and characterization of a PutAMT1;1 gene from Piccinellia tenuiflora. PLoS One. 2013; 8: e83111. doi: 10.1371/journal.pone.0083111 PMID
2016Co-Authors: Bo Sun, Aimin Zhou, Xinxin Zhang, Imshik Lee, Shenkui LiuAbstract:Nitrogen is one of the most important limiting factors for plant growth. However, as Ammonium is readily converted into ammonia (NH3) when soil pH rises above 8.0, this activity depletes the availability of Ammonium (NH4+) in alkaline soils, consequently preventing the growth of most plant species. The perennial wild grass Puccinellia tenuiflora is one of a few plants able to grow in soils with extremely high salt and alkaline pH (>9.0) levels. Here, we assessed how this species responds to Ammonium under such conditions by isolating and analyzing the functions of a putative Ammonium transporter (PutAMT1;1). PutAMT1;1 is the first member of the AMT1 (Ammonium transporter) family that has been identified in P. tenuiflora. This gene (1) functionally complemented a yeast mutant deficient in Ammonium Uptake (2), is preferentially expressed in the anther of P. tenuiflora, and (3) is significantly upregulated by Ammonium ions in both the shoot and roots. The PutAMT1;1 protein is localized in the plasma membrane and around the nuclear periphery in yeast cells and P. tenuiflora suspension cells. Immunoelectron microscopy analysis also indicated that PutAMT1;1 is localized in the endomembrane. The overexpression of PutAMT1;1 in A. thaliana enhanced plant growth, and increased plant susceptibility to toxic methylAmmonium (MeA). Here, we confirmed that PutAMT1;1 is an Ammonium-inducible Ammonium transporter in P. tenuiflora. On the basis of the results of PutAMT1;1 overexpression in A. thaliana, this gene might be useful for improving the root to shoot mobilization o
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identification and characterization of a putamt1 1 gene from puccinellia tenuiflora
PLOS ONE, 2013Co-Authors: Bo Sun, Aimin Zhou, Xinxin Zhang, Imshik Lee, Shenkui LiuAbstract:Nitrogen is one of the most important limiting factors for plant growth. However, as Ammonium is readily converted into ammonia (NH3) when soil pH rises above 8.0, this activity depletes the availability of Ammonium (NH4(+)) in alkaline soils, consequently preventing the growth of most plant species. The perennial wild grass Puccinellia tenuiflora is one of a few plants able to grow in soils with extremely high salt and alkaline pH (>9.0) levels. Here, we assessed how this species responds to Ammonium under such conditions by isolating and analyzing the functions of a putative Ammonium transporter (PutAMT1;1). PutAMT1;1 is the first member of the AMT1 (Ammonium transporter) family that has been identified in P. tenuiflora. This gene (1) functionally complemented a yeast mutant deficient in Ammonium Uptake (2), is preferentially expressed in the anther of P. tenuiflora, and (3) is significantly upregulated by Ammonium ions in both the shoot and roots. The PutAMT1;1 protein is localized in the plasma membrane and around the nuclear periphery in yeast cells and P. tenuiflora suspension cells. Immunoelectron microscopy analysis also indicated that PutAMT1;1 is localized in the endomembrane. The overexpression of PutAMT1;1 in A. thaliana enhanced plant growth, and increased plant susceptibility to toxic methylAmmonium (MeA). Here, we confirmed that PutAMT1;1 is an Ammonium-inducible Ammonium transporter in P. tenuiflora. On the basis of the results of PutAMT1;1 overexpression in A. thaliana, this gene might be useful for improving the root to shoot mobilization of MeA (or NH4(+)).