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Geng X, Wu C, Yang Z, Zhu J, Tang K, Lin J, Liu Y, Zhang Y, An M, Zhao W, Yu Y. Spatiotemporal variations and impact factors of nutrients in the Sanya Bay, northern South China Sea. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023:10.1007/s11356-023-27527-8. [PMID: 37247146 DOI: 10.1007/s11356-023-27527-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Accepted: 05/05/2023] [Indexed: 05/30/2023]
Abstract
Nutrients play a fundamental role in maintaining coastal ecosystem stability. Based on two cruise observations in the winter of 2020 and the summer of 2021, the spatiotemporal variations of dissolved inorganic nitrogen (DIN) and orthophosphate (PO43-) and their influencing factors in Sanya Bay were analyzed. Results show that the mean DIN concentrations in the bay are 2.36 μmol/L in winter and 1.73 μmol/L in summer, and the mean PO43- concentrations are 0.08 μmol/L in winter and 0.04 μmol/L in summer. The nutrient concentrations and composition are significantly affected by the Sanya River. The surface DIN concentrations at the Sanya River estuary are 15.80 and 5.25 times than those inside the bay in winter and summer, respectively. Meanwhile, a high proportion of NO3- (74%) and a low proportion of NH4+ (20%) in DIN appear near the river estuary, while a low proportion of NO3- (37%) and a high proportion of NH4+ (53%) occur away from the estuary. In addition, the thermocline promotes the accumulation of NH4+ at the bottom layer in summer. The high proportion of NO3- is likely not favorable for the survival of coral reefs in eastern bay. Compared with the previous nutrient concentrations, the DIN concentration in the bay has a decrease after 2014, which might benefit from the implementation of the environmental protection policy by government.
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Affiliation(s)
- Xinxing Geng
- College of Marine Sciences, Hainan University, Haikou, 570228, China
| | - Chuanliang Wu
- Sanya Coral Reef Ecology Institute, Sanya, 572000, China
| | - Ziwei Yang
- College of Marine Sciences, Hainan University, Haikou, 570228, China
| | - Junying Zhu
- College of Marine Sciences, Hainan University, Haikou, 570228, China.
- State Key Laboratory of Marine Resources Utilization in South China Sea, Hainan University, Haikou, 570228, China.
- Guangxi Laboratory On the Study of Coral Reefs in the South China Sea, Guangxi University, Nanning, 530004, China.
| | - Kai Tang
- College of Marine Sciences, Hainan University, Haikou, 570228, China
| | - Jiamin Lin
- College of Marine Sciences, Hainan University, Haikou, 570228, China
| | - Yaxing Liu
- Sanya Coral Reef Ecology Institute, Sanya, 572000, China
| | - Yufang Zhang
- Sanya Coral Reef Ecology Institute, Sanya, 572000, China
| | - Mingxun An
- College of Marine Sciences, Hainan University, Haikou, 570228, China
| | - Weibin Zhao
- College of Marine Sciences, Hainan University, Haikou, 570228, China
| | - Yang Yu
- Key Laboratory of Ocean Circulation and Waves, Institute of Oceanology, and Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China
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Wang Y, Johnson GI, Postles A, Coyne KJ. Nitrate reductase enzymes in alga Chattonella subsalsa are regulated by environmental cues at the translational and post-translational levels. Front Microbiol 2023; 14:1059074. [PMID: 36937302 PMCID: PMC10018130 DOI: 10.3389/fmicb.2023.1059074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Accepted: 02/10/2023] [Indexed: 03/06/2023] Open
Abstract
Nitrate reductase (NR) catalyzes the rate-limiting step in nitrate assimilation. Plant and algal NRs have a highly conserved domain architecture but differ in regulation. In plants, NR activity is regulated by reversible phosphorylation and subsequent binding of 14-3-3 proteins at a conserved serine residue. Algal NRs typically lack 14-3-3 binding motifs, which have only recently been identified in a few algal species. Previous research indicates that the alga, Chattonella subsalsa, possesses a novel NR, NR2-2/2HbN (NR2), which incorporates a 2/2 hemoglobin domain. A second NR (NR3) in C. subsalsa lacks the cytochrome b5 (heme-Fe) domain but includes a putative binding motif for 14-3-3 proteins. The expression of NR2 and NR3 genes indicates that NR2 transcript abundance was regulated by light, nitrogen source, and temperature, while NR3 transcript levels were only regulated by light. Here, we measured total NR activity in C. subsalsa and the potential for regulation of NR activity by putative 14-3-3 binding proteins. Results indicate that NR activity in C. subsalsa was regulated by light, nitrogen source, and temperature at the translational level. NR activity was also regulated by endogenous rhythm and temperature at the post-translational level, supporting the hypothesis that NR3 is regulated by 14-3-3 binding proteins. Together with a previous report describing the regulation of NR gene expression in C. subsalsa, results suggest that C. subsalsa responds to environmental conditions by differential regulation of NRs at transcriptional, translational, and post-translational levels. This flexibility may provide a competitive advantage for this species in the environment. To date, this is the first report which provides evidence for the potential post-translational regulation of NR by 14-3-3 proteins in algal species and suggests that regulatory mechanisms for NR activity may be shared between plants and some algal species.
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Yang X, Bi Y, Ma X, Dong W, Wang X, Wang S. Transcriptomic analysis dissects the regulatory strategy of toxic cyanobacterium Microcystis aeruginosa under differential nitrogen forms. JOURNAL OF HAZARDOUS MATERIALS 2022; 428:128276. [PMID: 35051775 DOI: 10.1016/j.jhazmat.2022.128276] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2021] [Revised: 12/20/2021] [Accepted: 01/12/2022] [Indexed: 06/14/2023]
Abstract
The critical role of nitrogen in the global proliferation of cyanobacterial blooms is arousing increasing attention. However, the mechanism underlying the algal responses to differential nitrogen forms remains unclarified. The physiological and transcriptomic changes of Microcystis aeruginosa supplied with different nitrogen forms (nitrate and ammonium) were highlighted in this study. The results indicated that ammonium behaves better in stimulating the initial growth in N-limited cells than nitrate. However, a concomitant side effect is that cellular growth and photosynthesis decreased due to photosystem II damage induced by excess absorbed light energy under 10 mg L-1 ammonium. By contrast, adequate nitrate supply favored more efficient photosynthesis, higher biomass yield and microcystin quotas than ammonium. Depending on the supplied nitrogen form, different transcriptomic patterns were observed in M. aeruginosa. Under nitrate, the upregulation of genes involved in Arg biosynthesis, ornithine-urea cycle and photosynthesis increased nitrogen storage and cellular growth, while genes involved in cyclic electron flow around photosystem I and CO2-concentrating mechanism were heightened to dissipate excess energy under high ammonium. These insights provided important clues for understanding the physiological and molecular effects of available nitrogen forms on the frequent outbreaks of cyanobacteria.
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Affiliation(s)
- Xiaolong Yang
- School of Life Sciences, Nantong University, Nantong 226019, China; Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, China
| | - Yonghong Bi
- Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Xiaofei Ma
- School of Life Sciences, Nantong University, Nantong 226019, China
| | - Wei Dong
- School of Life Sciences, Nantong University, Nantong 226019, China
| | - Xun Wang
- School of Life Sciences, Nantong University, Nantong 226019, China
| | - Shoubing Wang
- Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, China.
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Huang S, Kong W, Yang Z, Yu H, Li F. Combination of Logistic and modified Monod functions to study Microcystis aeruginosa growth stimulated by fish feed. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2019; 167:146-160. [PMID: 30317119 DOI: 10.1016/j.ecoenv.2018.09.119] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Revised: 09/26/2018] [Accepted: 09/27/2018] [Indexed: 06/08/2023]
Abstract
The ecological health of aquaculture water is threatened by wasted fish feed and herbicides. In order to study the effect of prometryn and fish feed on Microcystis aeruginosa growth based on Monod and Logistic functions, four different concentrations of prometryn (0, 50, 100 and 200 μg L-1) and two different dosages of fish feed (0.075 g, 0.15 g; d < 0.85 mm) were added into the culture medium, and the fish feed was the source of nitrogen and phosphorus in the MII medium. Results showed that Microcystis aeruginosa growth can be fitted well by Logistic and modified Logistic functions with 0-200 μg L-1 prometryn (R2 = 0.981-0.998 and R2 = 0.989-0.999, respectively). With the same concentration of prometryn, the maximum algae density (Nmax) of Microcystis aeruginosa calculated by both Logistic and modified Logistic functions increased with increasing dosage of fish feed and with the same dosage of fish feed, Nmax declined with increasing concentrations of prometryn. Inhibition of prometryn on algae growth stimulated by fish feed is of double concentration-dependence, inhibition rates (I) are lower in 0.15 g fish feed medium than 0.75 g ones generally, implying that more nutrients can alleviate the stress caused by prometryn on algae. Derived formula for the specific growth rate, growth rate and inhibition rate using modified Logistic function agreed reasonably well with measured data. Jointly application of modified Monod and Logistic functions can better describe the relationship between specific growth rates and nutrients concentrations compared to combination of Monod and Logistic functions. In addition, equations for describing variations of nutrients concentrations (PO43--P and NH4+-N) with time were also derived based on both modified Monod and Logistic functions, which agree reasonably well with the measured data. In sum, the combination of modified Monod and Logistic functions provides a promising and robust method in studying algal growth stimulated by fish feed in incubator experiments.
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Affiliation(s)
- Suiliang Huang
- Key Laboratory of Pollution Processes and Environmental Criteria of the Ministry of Education, Key Laboratory of Urban Ecological Environment Rehabilitation and Pollution Control of Tianjin, Numerical Simulation Group for Water Environment, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China.
| | - Wenwen Kong
- Key Laboratory of Pollution Processes and Environmental Criteria of the Ministry of Education, Key Laboratory of Urban Ecological Environment Rehabilitation and Pollution Control of Tianjin, Numerical Simulation Group for Water Environment, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China
| | - Zhenjiang Yang
- Key Laboratory of Pollution Processes and Environmental Criteria of the Ministry of Education, Key Laboratory of Urban Ecological Environment Rehabilitation and Pollution Control of Tianjin, Numerical Simulation Group for Water Environment, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China
| | - Hui Yu
- Key Laboratory of Pollution Processes and Environmental Criteria of the Ministry of Education, Key Laboratory of Urban Ecological Environment Rehabilitation and Pollution Control of Tianjin, Numerical Simulation Group for Water Environment, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China
| | - Fengyuan Li
- Key Laboratory of Pollution Processes and Environmental Criteria of the Ministry of Education, Key Laboratory of Urban Ecological Environment Rehabilitation and Pollution Control of Tianjin, Numerical Simulation Group for Water Environment, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China
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Expression of novel nitrate reductase genes in the harmful alga, Chattonella subsalsa. Sci Rep 2018; 8:13417. [PMID: 30194416 PMCID: PMC6128913 DOI: 10.1038/s41598-018-31735-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Accepted: 08/23/2018] [Indexed: 12/20/2022] Open
Abstract
Eukaryotic nitrate reductase (NR) catalyzes the first step in nitrate assimilation and is regulated transcriptionally in response to external cues and intracellular metabolic status. NRs are also regulated post-translationally in plants by phosphorylation and binding of 14-3-3 proteins at conserved serine residues. 14-3-3 binding motifs have not previously been identified in algal NRs. A novel NR (NR2-2/2HbN) with a 2/2 hemoglobin domain was recently described in the alga Chattonella subsalsa. Here, a second NR (NR3) in C. subsalsa is described with a 14-3-3 binding motif but lacking the Heme-Fe domain found in other NRs. Transcriptional regulation of both NRs was examined in C. subsalsa, revealing differential gene expression over a diel light cycle, but not under constant light. NR2 transcripts increased with a decrease in temperature, while NR3 remained unchanged. NR2 and NR3 transcript levels were not inhibited by growth on ammonium, suggesting constitutive expression of these genes. Results indicate that Chattonella responds to environmental conditions and intracellular metabolic status by differentially regulating NR transcription, with potential for post-translational regulation of NR3. A survey of algal NRs also revealed the presence of 14-3-3 binding motifs in other algal species, indicating the need for future research on regulation of algal NRs.
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Lu X, Song S, Lu Y, Wang T, Liu Z, Li Q, Zhang M, Suriyanarayanan S, Jenkins A. Response of the phytoplankton community to water quality in a local alpine glacial lake of Xinjiang Tianchi, China: potential drivers and management implications. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2017; 19:1300-1311. [PMID: 28858346 DOI: 10.1039/c7em00180k] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Eutrophication has become one of the most serious threats to aquatic ecosystems in the world. With the combined drivers of climate change and human activities, eutrophication has expanded from warm shallow lakes to cold-water lakes in relatively high latitude regions and has raised greater concerns over lake aquatic ecosystem health. A two-year field study was carried out to investigate water quality, phytoplankton characteristics and eutrophication status in a typical alpine glacial lake of Tianchi, a scenic area and an important drinking water source in the Xinjiang Autonomous Region of China, in 2014 and 2015. Clear seasonal and annual variations of nutrients and organic pollutants were found especially during rainy seasons. For the phytoplankton community, Bacillariophyta held the dominant position in terms of both species and biomass throughout the year, suggesting the dominant characteristics of diatoms in the phytoplankton structure in such a high-altitude cold-water lake. This was quite different from plain and warm lakes troubled with cyanobacterial blooming. Moreover, the dominant abundance of Cyclotella sp. in Tianchi might suggest regional warming caused by climate change, which might have profound effects on the local ecosystems and hydrological cycle. Based on water quality parameters, a comprehensive trophic level index TLI (Σ) was calculated to estimate the current status of eutrophication, and the results inferred emerging eutrophication in Tianchi. Results from Canonical Correspondence Analysis (CCA) and correlation analysis of phytoplankton genera and physico-chemical variables of water indicated that abiotic factors significantly influenced the phytoplankton community and its succession in Tianchi Lake. These abiotic factors could explain 77.82% of the total variance, and ammonium was identified as the most discriminant variable, which could explain 41% of the total variance followed by TP (29%). An estimation of annual nutrient loadings to Tianchi was made, and the results indicated that about 212.97 t of total nitrogen and 32.14 t of total phosphorus were transported into Tianchi Lake annually. Human socio-economic activities (runoff caused by historical overgrazing and increasing tourism) were identified as the most important contributors to Tianchi nutrient loadings.
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Affiliation(s)
- Xiaotian Lu
- State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
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Malerba ME, Heimann K, Connolly SR. Improving dynamic phytoplankton reserve-utilization models with an indirect proxy for internal nitrogen. J Theor Biol 2016; 404:1-9. [PMID: 27216639 DOI: 10.1016/j.jtbi.2016.05.023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2016] [Revised: 05/10/2016] [Accepted: 05/16/2016] [Indexed: 12/01/2022]
Abstract
Ecologists have often used indirect proxies to represent variables that are difficult or impossible to measure directly. In phytoplankton, the internal concentration of the most limiting nutrient in a cell determines its growth rate. However, directly measuring the concentration of nutrients within cells is inaccurate, expensive, destructive, and time-consuming, substantially impairing our ability to model growth rates in nutrient-limited phytoplankton populations. The red chlorophyll autofluorescence (hereafter "red fluorescence") signal emitted by a cell is highly correlated with nitrogen quota in nitrogen-limited phytoplankton species. The aim of this study was to evaluate the reliability of including flow cytometric red fluorescence as a proxy for internal nitrogen status to model phytoplankton growth rates. To this end, we used the classic Quota model and designed three approaches to calibrate its model parameters to data: where empirical observations on cell internal nitrogen quota were used to fit the model ("Nitrogen-Quota approach"), where quota dynamics were inferred only from changes in medium nutrient depletion and population density ("Virtual-Quota approach"), or where red fluorescence emission of a cell was used as an indirect proxy for its internal nitrogen quota ("Fluorescence-Quota approach"). Two separate analyses were carried out. In the first analysis, stochastic model simulations were parameterized from published empirical relationships and used to generate dynamics of phytoplankton communities reared under nitrogen-limited conditions. Quota models were fitted to the dynamics of each simulated species with the three different approaches and the performance of each model was compared. In the second analysis, we fit Quota models to laboratory time-series and we calculate the ability of each calibration approach to describe the observed trajectories of internal nitrogen quota in the culture. Results from both analyses concluded that the Fluorescence-Quota approach including per-cell red fluorescence as a proxy of internal nitrogen substantially improved the ability of Quota models to describe phytoplankton dynamics, while still accounting for the biologically important process of cell nitrogen storage. More broadly, many population models in ecology implicitly recognize the importance of accounting for storage mechanisms to describe the dynamics of individual organisms. Hence, the approach documented here with phytoplankton dynamics may also be useful for evaluating the potential of indirect proxies in other ecological systems.
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Affiliation(s)
- Martino E Malerba
- AIMS@JCU, James Cook University, Townsville, Queensland 4811, Australia; Australian Institute of Marine Science, Townsville, Queensland 4811, Australia; College of Marine and Environmental Sciences, James Cook University, Townsville, Queensland 4811, Australia.
| | - Kirsten Heimann
- College of Marine and Environmental Sciences, James Cook University, Townsville, Queensland 4811, Australia; Centre for Sustainable Tropical Fisheries and Aquaculture, Townsville, Queensland 4811, Australia
| | - Sean R Connolly
- College of Marine and Environmental Sciences, James Cook University, Townsville, Queensland 4811, Australia; Australian Research Council Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Queensland 4811, Australia
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Malerba ME, Heimann K, Connolly SR. Nutrient utilization traits vary systematically with intraspecific cell size plasticity. Funct Ecol 2016. [DOI: 10.1111/1365-2435.12662] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- Martino E. Malerba
- AIMS@JCU James Cook University Townsville QLD 4811 Australia
- Australian Institute of Marine Science Townsville QLD 4811 Australia
- College of Marine and Environmental Sciences James Cook University Townsville QLD 4811 Australia
| | - Kirsten Heimann
- College of Marine and Environmental Sciences James Cook University Townsville QLD 4811 Australia
- Centre for Sustainable Tropical Fisheries and Aquaculture Townsville QLD 4811 Australia
| | - Sean R. Connolly
- College of Marine and Environmental Sciences James Cook University Townsville QLD 4811 Australia
- Australian Research Council Centre of Excellence for Coral Reef Studies James Cook University Townsville QLD 4811 Australia
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