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Saint-Sorny M, Dimitriades A, Delrue F, Johnson X. Proton Gradient Regulation 5 determines reserve partitioning between starch and lipids in C. reinhardtii. PHYSIOLOGIA PLANTARUM 2024; 176:e14539. [PMID: 39329246 DOI: 10.1111/ppl.14539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2024] [Revised: 08/17/2024] [Accepted: 08/20/2024] [Indexed: 09/28/2024]
Abstract
Nutrient deprivation induces reserve accumulation in unicellular algae. An absence of nitrogen in the growth media results in the reorganization of the photosynthetic apparatus and triggers an increase in starch and triacylglyceride (TAG) accumulation in different algal species. Here we study the integration of photosynthetic regulatory mechanisms with carbon partitioning under N stress in C. reinhardtii. The mutant, proton gradient regulation 5 (pgr5) is impaired in photosynthetic cyclic electron flow resulting in low chloroplastic ATP/NADPH ratios. Over a time course, under both mixotrophic and phototrophic conditions, the pgr5 mutant did not accumulate starch in the first three days, but rather degraded its meagre reserves. In contrast, there was a high TAG content in the pgr5 mutant which we show, is not linked to a selective increase in autophagy in pgr5. In all strains, proteins involved in alternative electron pathways are upregulated while Photosystem II and chlorophyll are strongly degraded; pgr5 only preferentially preserved some cyt b6f complex. Our results show that low ATP/NADPH ratios due to an absence of cyclic electron flow in pgr5 result in the mobilization of starch and strong TAG accumulation from the onset of N stress in Chlamydomonas.
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Affiliation(s)
- Maureen Saint-Sorny
- CEA, CNRS, Aix-Marseille Université, UMR 7265, BIAM, Photosynthesis and Environment Team, CEA Cadarache, Saint-Paul-lez-Durance, France
| | - Alexandra Dimitriades
- MicroAlgae Processes Platform-CEA, CEA Tech Région Sud, Saint Paul lez Durance, France
| | - Florian Delrue
- MicroAlgae Processes Platform-CEA, CEA Tech Région Sud, Saint Paul lez Durance, France
| | - Xenie Johnson
- CEA, CNRS, Aix-Marseille Université, UMR 7265, BIAM, Photosynthesis and Environment Team, CEA Cadarache, Saint-Paul-lez-Durance, France
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2
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Zhu H, Ye Z, Xu Z, Wei L. Transcriptomic Analysis Reveals the Effect of Urea on Metabolism of Nannochloropsis oceanica. Life (Basel) 2024; 14:797. [PMID: 39063552 PMCID: PMC11278182 DOI: 10.3390/life14070797] [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: 04/10/2024] [Revised: 06/20/2024] [Accepted: 06/21/2024] [Indexed: 07/28/2024] Open
Abstract
The eukaryotic microalga Nannochloropsis oceanica represents a promising bioresource for the production of biofuels and pharmaceuticals. Urea, a crucial nutrient for the photosynthetic N. oceanica, stimulates the accumulation of substances such as lipids, which influence growth and physiology. However, the specific mechanisms by which N. oceanica responds and adapts to urea addition remain unknown. High-throughput mRNA sequencing and differential gene expression analysis under control and urea-added conditions revealed significant metabolic changes. This involved the differential expression of 2104 genes, with 1354 being upregulated and 750 downregulated, resulting in the reprogramming of crucial pathways such as carbon and nitrogen metabolism, photosynthesis, and lipid metabolism. The results specifically showed that genes associated with photosynthesis in N. oceanica were significantly downregulated, particularly those related to light-harvesting proteins. Interestingly, urea absorption and transport may depend not only on specialized transport channels such as urease but also on alternative transport channels such as the ABC transporter family and the CLC protein family. In addition, urea caused specific changes in carbon and lipid metabolism. Genes associated with the Calvin cycle and carbon concentration mechanisms were significantly upregulated. In lipid metabolism, the expression of genes associated with lipases and polyunsaturated fatty acid synthesis was highly activated. Furthermore, the expression of several genes involved in the tricarboxylic acid cycle and folate metabolism was enhanced, making important contributions to energy supply and the synthesis and modification of genes and macromolecules. Our observations indicate that N. oceanica actively and dynamically regulates the redistribution of carbon and nitrogen after urea addition, providing references for further research on the effects of urea on N. oceanica.
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Affiliation(s)
- Han Zhu
- Ministry of Education Key Laboratory for Ecology of Tropical Islands, Key Laboratory of Tropical Animal and Plant Ecology of Hainan Province, College of Life Sciences, Hainan Normal University, Haikou 571158, China
- Hainan Observation and Research Station of Dongzhaigang Mangrove Wetland Ecosystem, Haikou 571129, China
- International Science and Technology Cooperation Laboratory for Marine Microalgae Ecological Carbon Sinks, Hainan Normal University, Haikou 571158, China
| | - Zhenli Ye
- Ministry of Education Key Laboratory for Ecology of Tropical Islands, Key Laboratory of Tropical Animal and Plant Ecology of Hainan Province, College of Life Sciences, Hainan Normal University, Haikou 571158, China
| | - Zhengru Xu
- College of Foreign Language, Hainan Normal University, Haikou 571157, China
| | - Li Wei
- Ministry of Education Key Laboratory for Ecology of Tropical Islands, Key Laboratory of Tropical Animal and Plant Ecology of Hainan Province, College of Life Sciences, Hainan Normal University, Haikou 571158, China
- Hainan Observation and Research Station of Dongzhaigang Mangrove Wetland Ecosystem, Haikou 571129, China
- International Science and Technology Cooperation Laboratory for Marine Microalgae Ecological Carbon Sinks, Hainan Normal University, Haikou 571158, China
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3
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Chauhan M, Arshi SA, Narayanan N, Arfin HU, Sharma A. A mechanistic insight on how Compromised Hydrolysis of Triacylglycerol 7 (CHT7) restrains the involvement of it's CXC domain from quiescence repression. Int J Biol Macromol 2024; 265:130844. [PMID: 38484809 DOI: 10.1016/j.ijbiomac.2024.130844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2024] [Revised: 03/03/2024] [Accepted: 03/11/2024] [Indexed: 03/18/2024]
Abstract
CHT7 is a regulator of quiescence repression in Chlamydomonas reinhardtii. Initially, CHT7's repression activity was thought to be managed by its DNA-binding CXC domain. Later, it was found that the CHT7-CXC domain is dispensable for CHT7's activities. Rather, CHT7's predicted protein domains were proposed to be involved in regulation activities by binding to other repressors in the cell. Yet, it remains unclear why and how CHT7 refrains its CXC domain from participating in any transcriptional activities. The question becomes more intriguing, since CXC binding regions are available in promoter regions of some of the misregulated genes in CHT7 mutant (cht7). Through biophysical experiments and molecular dynamics approaches, we studied the DNA recognition behavior of CHT7-CXC. The results indicate that this domain possesses sequence selectivity due to the differential binding abilities of its subdomains. Further, to understand if the case is that CXC loses its DNA binding capabilities in the vicinity of other repressors, we examined CHT7-CXC's DNA binding stability under the spatial constraint conditions created through fusing CHT7-CXC with AsLOV2. The results show limited ability of CHT7-CXC to withstand steric forces and provide insights to why and how algal cells may hold back CHT7-CXC's indulgence in quiescence repression. CLASSIFICATIONS: Biological Sciences, Biophysics and Computational Biology.
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Affiliation(s)
- Manisha Chauhan
- Multidisciplinary Centre for Advanced Research and Studies, Jamia Millia Islamia, New Delhi 110025, India
| | - Syeda Amna Arshi
- Multidisciplinary Centre for Advanced Research and Studies, Jamia Millia Islamia, New Delhi 110025, India
| | - Naveen Narayanan
- Regional Centre for Biotechnology, NCR-Cluster Faridabad, Haryana 121001, India
| | - Haseeb Ul Arfin
- Multidisciplinary Centre for Advanced Research and Studies, Jamia Millia Islamia, New Delhi 110025, India
| | - Amit Sharma
- Multidisciplinary Centre for Advanced Research and Studies, Jamia Millia Islamia, New Delhi 110025, India.
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4
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Vlasova V, Lapina T, Statinov V, Ermilova E. N-Acetyl-L-glutamate Kinase of Chlamydomonas reinhardtii: In Vivo Regulation by PII Protein and Beyond. Int J Mol Sci 2023; 24:12873. [PMID: 37629055 PMCID: PMC10454706 DOI: 10.3390/ijms241612873] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2023] [Revised: 08/10/2023] [Accepted: 08/13/2023] [Indexed: 08/27/2023] Open
Abstract
N-Acetyl-L-glutamate kinase (NAGK) catalyzes the rate-limiting step in the ornithine/arginine biosynthesis pathway in eukaryotic and bacterial oxygenic phototrophs. NAGK is the most highly conserved target of the PII signal transduction protein in Cyanobacteria and Archaeplastida (red algae and Chlorophyta). However, there is still much to be learned about how NAGK is regulated in vivo. The use of unicellular green alga Chlamydomonas reinhardtii as a model system has already been instrumental in identifying several key regulation mechanisms that control nitrogen (N) metabolism. With a combination of molecular-genetic and biochemical approaches, we show the existence of the complex CrNAGK control at the transcriptional level, which is dependent on N source and N availability. In growing cells, CrNAGK requires CrPII to properly sense the feedback inhibitor arginine. Moreover, we provide primary evidence that CrPII is only partly responsible for regulating CrNAGK activity to adapt to changing nutritional conditions. Collectively, our results suggest that in vivo CrNAGK is tuned at the transcriptional and post-translational levels, and CrPII and additional as yet unknown factor(s) are integral parts of this regulation.
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Affiliation(s)
| | | | | | - Elena Ermilova
- Biological Faculty, Saint-Petersburg State University, 199034 Saint-Petersburg, Russia; (V.V.); (T.L.); (V.S.)
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5
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Kurepa J, Smalle JA. Plant Hormone Modularity and the Survival-Reproduction Trade-Off. BIOLOGY 2023; 12:1143. [PMID: 37627027 PMCID: PMC10452219 DOI: 10.3390/biology12081143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 08/07/2023] [Accepted: 08/15/2023] [Indexed: 08/27/2023]
Abstract
Biological modularity refers to the organization of living systems into separate functional units that interact in different combinations to promote individual well-being and species survival. Modularity provides a framework for generating and selecting variations that can lead to adaptive evolution. While the exact mechanisms underlying the evolution of modularity are still being explored, it is believed that the pressure of conflicting demands on limited resources is a primary selection force. One prominent example of conflicting demands is the trade-off between survival and reproduction. In this review, we explore the available evidence regarding the modularity of plant hormones within the context of the survival-reproduction trade-off. Our findings reveal that the cytokinin module is dedicated to maximizing reproduction, while the remaining hormone modules function to ensure reproduction. The signaling mechanisms of these hormone modules reflect their roles in this survival-reproduction trade-off. While the cytokinin response pathway exhibits a sequence of activation events that aligns with the developmental robustness expected from a hormone focused on reproduction, the remaining hormone modules employ double-negative signaling mechanisms, which reflects the necessity to prevent the excessive allocation of resources to survival.
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Affiliation(s)
| | - Jan A. Smalle
- Plant Physiology, Biochemistry, Molecular Biology Program, Department of Plant and Soil Sciences, University of Kentucky, Lexington, KY 40546, USA;
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Kong F, Li M, Liu K, Ge Y, Yamasaki T, Beyly-Adriano A, Ohama T, Li-Beisson Y. Efficient approaches for nuclear transgene stacking in the unicellular green microalga Chlamydomonas reinhardtii. ALGAL RES 2023. [DOI: 10.1016/j.algal.2023.103048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/11/2023]
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7
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Lu H, Liu K, Zhang H, Xie X, Ge Y, Chi Z, Xue S, Kong F, Ohama T. Enhanced triacyclglycerols and starch synthesis in Chlamydomonas stimulated by the engineered biodegradable nanoparticles. Appl Microbiol Biotechnol 2023; 107:971-983. [PMID: 36622426 DOI: 10.1007/s00253-023-12366-x] [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: 05/07/2022] [Revised: 10/17/2022] [Accepted: 01/03/2023] [Indexed: 01/10/2023]
Abstract
Microalgae are promising feedstock for renewable fuels. The accumulation of oils in microalgae can be enhanced by nanoparticle exposure. However, the nanoparticles employed in previous studies are mostly non-biodegradable, which hinders nanoparticles developing as promising approach for biofuel production. We recently reported the engineered resin nanoparticles (iBCA-NPs), which were found to be biodegradable in this study. When the cells of green microalga Chlamydomonas reinhardtii were exposed to the iBCA-NPs for 1 h, the cellular triacyclglycerols (TAG) and starch contents increased by 520% and 60% than that in the control. The TAG production improved by 1.8-fold compared to the control without compromised starch production. Additionally, the content of total fatty acids increased by 1.3-fold than that in control. Furthermore, we found that the iBCA-NPs addition resulted in increased cellular reactive oxygen species (ROS) content and upregulated the activities of antioxidant enzymes. The relative expressions of the key genes involved in TAG and starch biosynthesis were also upregulated. Overall, our results showed that short exposure of the iBCA-NPs dramatically enhances TAG and starch accumulation in Chlamydomonas, which probably resulted from prompt upregulated expression of the key genes in lipid and starch metabolic pathways that were triggered by over-accumulated ROS. This study reported a useful approach to enhance energy-rich reserve accumulation in microalgae. KEY POINTS: 1. The first attempt to increase oil and starch in microalgae by biodegradable NPs. 2. The biodegradability of iBCA-NPs by the BOD test was more than 50% after 28 days. 3. The iBCA-NPs induce more energy reserves than that of previously reported NPs.
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Affiliation(s)
- Han Lu
- School of Bioengineering, Dalian University of Technology, Dalian, 116024, China
| | - Keqing Liu
- School of Bioengineering, Dalian University of Technology, Dalian, 116024, China
| | - Hao Zhang
- School of Bioengineering, Dalian University of Technology, Dalian, 116024, China
| | - Xi Xie
- Dalian Key Laboratory of Genetic Resources for Marine Shellfish, Liaoning Ocean and Fisheries Science Research Institute, Dalian, 116023, China
| | - Yunlong Ge
- School of Bioengineering, Dalian University of Technology, Dalian, 116024, China
| | - Zhanyou Chi
- School of Bioengineering, Dalian University of Technology, Dalian, 116024, China
| | - Song Xue
- School of Bioengineering, Dalian University of Technology, Dalian, 116024, China
| | - Fantao Kong
- School of Bioengineering, Dalian University of Technology, Dalian, 116024, China.
| | - Takeshi Ohama
- School of Environmental Science and Engineering, Kochi University of Technology, 185 Miyanokuchi, Tosayamada, Kami-City, 782-8502, Japan
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8
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Co-Expression of Lipid Transporters Simultaneously Enhances Oil and Starch Accumulation in the Green Microalga Chlamydomonas reinhardtii under Nitrogen Starvation. Metabolites 2023; 13:metabo13010115. [PMID: 36677040 PMCID: PMC9866645 DOI: 10.3390/metabo13010115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2022] [Revised: 12/31/2022] [Accepted: 01/09/2023] [Indexed: 01/13/2023] Open
Abstract
Lipid transporters synergistically contribute to oil accumulation under normal conditions in microalgae; however, their effects on lipid metabolism under stress conditions are unknown. Here, we examined the effect of the co-expression of lipid transporters, fatty acid transporters, (FAX1 and FAX2) and ABC transporter (ABCA2) on lipid metabolism and physiological changes in the green microalga Chlamydomonas under nitrogen (N) starvation. The results showed that the TAG content in FAX1-FAX2-ABCA2 over-expressor (OE) was 2.4-fold greater than in the parental line. Notably, in FAX1-FAX2-ABCA2-OE, the major membrane lipids and the starch and cellular biomass content also significantly increased compared with the control lines. Moreover, the expression levels of genes directly involved in TAG, fatty acid, and starch biosynthesis were upregulated. FAX1-FAX2-ABCA2-OE showed altered photosynthesis activity and increased ROS levels during nitrogen (N) deprivation. Our results indicated that FAX1-FAX2-ABCA2 overexpression not only enhanced cellular lipids but also improved starch and biomass contents under N starvation through modulation of lipid and starch metabolism and changes in photosynthesis activity. The strategy developed here could also be applied to other microalgae to produce FA-derived energy-rich and value-added compounds.
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9
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The Role of GmSnRK1-GmNodH Module in Regulating Soybean Nodulation Capacity. Int J Mol Sci 2023; 24:ijms24021225. [PMID: 36674741 PMCID: PMC9861110 DOI: 10.3390/ijms24021225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 11/25/2022] [Accepted: 11/29/2022] [Indexed: 01/11/2023] Open
Abstract
SnRK1 protein kinase plays hub roles in plant carbon and nitrogen metabolism. However, the function of SnRK1 in legume nodulation and symbiotic nitrogen fixation is still elusive. In this study, we identified GmNodH, a putative sulfotransferase, as an interacting protein of GmSnRK1 by yeast two-hybrid screen. The qRT-PCR assays indicate that GmNodH gene is highly expressed in soybean roots and could be induced by rhizobial infection and nitrate stress. Fluorescence microscopic analyses showed that GmNodH was colocalized with GsSnRK1 on plasma membrane. The physical interaction between GmNodH and GmSnRK1 was further verified by using split-luciferase complementary assay and pull-down approaches. In vitro phosphorylation assay showed that GmSnRK1 could phosphorylate GmNodH at Ser193. To dissect the function and genetic relationship of GmSnRK1 and GmNodH in soybean, we co-expressed the wild-type and mutated GmSnRK1 and GmNodH genes in soybean hairy roots and found that co-expression of GmSnRK1/GmNodH genes significantly promoted soybean nodulation rates and the expression levels of nodulation-related GmNF5α and GmNSP1 genes. Taken together, this study provides the first biological evidence that GmSnRK1 may interact with and phosphorylate GmNodH to synergistically regulate soybean nodulation.
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Transcriptome Analysis Reveals the Involvement of Alternative Splicing in the Nitrogen Starvation Response of Chlamydomonas reinhardtii. Processes (Basel) 2022. [DOI: 10.3390/pr10122719] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Alternative splicing (AS) is a regulatory mechanism of post-transcriptional regulation that plays an important role in plant response to abiotic stresses. However, corresponding research involving the mechanism of AS in the nitrogen starvation response of C. reinhardtii is rare. This study performed a comprehensive and systematic analysis of AS events in C. reinhardtii at nine time points (0 h, 10 m, 30 m, 1 h, 6 h, 8 h, 24 h, and 48 h) under nitrogen starvation. It used STAR and rMATS tools to identify and quantify the probability of the AS event happening through the transcriptome high-throughput sequencing data. A total of 5806 AS events in 3500 genes were identified, and the retained intron and skipped exon were considered the main AS types. The genes related to the AS event in nitrogen starvation were mainly involved in spliceosome and transporter and enriched in the citrate cycle and fatty acid degradation pathways. These results suggested that AS may play an important role in the nitrogen starvation response in C. reinhardtii, and provided insights into post-transcriptional regulation under nitrogen starvation.
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11
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Enhanced accumulation of oil through co-expression of fatty acid and ABC transporters in Chlamydomonas under standard growth conditions. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2022; 15:54. [PMID: 35596223 PMCID: PMC9123788 DOI: 10.1186/s13068-022-02154-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/08/2022] [Accepted: 05/07/2022] [Indexed: 11/10/2022]
Abstract
Abstract
Background
Chloroplast and endoplasmic reticulum (ER)-localized fatty acid (FA) transporters have been reported to play important roles in oil (mainly triacylglycerols, TAG) biosynthesis. However, whether these FA transporters synergistically contribute to lipid accumulation, and their effect on lipid metabolism in microalgae are unknown.
Results
Here, we co-overexpressed two chloroplast-localized FA exporters (FAX1 and FAX2) and one ER-localized FA transporter (ABCA2) in Chlamydomonas. Under standard growth conditions, FAX1/FAX2/ABCA2 over-expression lines (OE) accumulated up to twofold more TAG than the parental strain UVM4, and the total amounts of major polyunsaturated FAs (PUFA) in TAG increased by 4.7-fold. In parallel, the total FA contents and major membrane lipids in FAX1/FAX2/ABCA2-OE also significantly increased compared with those in the control lines. Additionally, the total accumulation contribution ratio of PUFA, to total FA and TAG synthesis in FAX1/FAX2/ABCA2-OE, was 54% and 40% higher than that in UVM4, respectively. Consistently, the expression levels of genes directly involved in TAG synthesis, such as type-II diacylglycerol acyltransferases (DGTT1, DGTT3 and DGTT5), and phospholipid:diacylglycerol acyltransferase 1 (PDAT1), significantly increased, and the expression of PGD1 (MGDG-specific lipase) was upregulated in FAX1/FAX2/ABCA2-OE compared to UVM4.
Conclusion
These results indicate that the increased expression of FAX1/FAX2/ABCA2 has an additive effect on enhancing TAG, total FA and membrane lipid accumulation and accelerates the PUFA remobilization from membrane lipids to TAG by fine-tuning the key genes involved in lipid metabolism under standard growth conditions. Overall, FAX1/FAX2/ABCA2-OE shows better traits for lipid accumulation than the parental line and previously reported individual FA transporter-OE. Our study provides a potential useful strategy to increase the production of FA-derived energy-rich and value-added compounds in microalgae.
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Caló G, De Marco MA, Salerno GL, Martínez-Noël GMA. TOR signaling in the green picoalga Ostreococcus tauri. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2022; 323:111390. [PMID: 35868347 DOI: 10.1016/j.plantsci.2022.111390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 06/29/2022] [Accepted: 07/15/2022] [Indexed: 06/15/2023]
Abstract
Target of rapamycin (TOR) is a master regulator that controls growth and metabolism by integrating external and internal signals. Although there was a great progress in the study of TOR in plants and in the model alga Chlamydomonas, scarce data are available in other green algae. Thus, in this work we studied TOR signaling in Ostreococcus tauri, the smallest free-living eukaryote described to date. This picoalga is particularly important because it has a key site at the base of the green lineage and is part of the marine phytoplankton, contributing to global photosynthesis. We investigated OtTOR complex in silico and experimentally, by using first- and second-generation TOR inhibitors, such as rapamycin and PP242. We analyzed the effect of TOR down-regulation on cell growth and on the accumulation of carbon reserves. The results showed that O. tauri responds to TOR inhibitors more similarly to plants than to Chlamydomonas, being PP242 a valuable tool to study this pathway. Besides, Ottor expression analysis revealed that the kinase is dynamically regulated under nutritional stress. Our data indicate that TOR signaling is conserved in O. tauri and we propose this alga as a good and simple model for studying TOR kinase and its regulation.
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Affiliation(s)
- Gonzalo Caló
- INBIOTEC, Vieytes, 3103, 7600 Mar del Plata, Argentina; FIBA, Vieytes 3103, 7600 Mar del Plata, Argentina
| | - María Agustina De Marco
- INBIOTEC, Vieytes, 3103, 7600 Mar del Plata, Argentina; FIBA, Vieytes 3103, 7600 Mar del Plata, Argentina
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Peter J, Huleux M, Spaniol B, Sommer F, Neunzig J, Schroda M, Li-Beisson Y, Philippar K. Fatty acid export (FAX) proteins contribute to oil production in the green microalga Chlamydomonas reinhardtii. Front Mol Biosci 2022; 9:939834. [PMID: 36120551 PMCID: PMC9470853 DOI: 10.3389/fmolb.2022.939834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 07/11/2022] [Indexed: 11/24/2022] Open
Abstract
In algae and land plants, transport of fatty acids (FAs) from their site of synthesis in the plastid stroma to the endoplasmic reticulum (ER) for assembly into acyl lipids is crucial for cellular lipid homeostasis, including the biosynthesis of triacylglycerol (TAG) for energy storage. In the unicellular green alga Chlamydomonas reinhardtii, understanding and engineering of these processes is of particular interest for microalga-based biofuel and biomaterial production. Whereas in the model plant Arabidopsis thaliana, FAX (fatty acid export) proteins have been associated with a function in plastid FA-export and hence TAG synthesis in the ER, the knowledge on the function and subcellular localization of this protein family in Chlamydomonas is still scarce. Among the four FAX proteins encoded in the Chlamydomonas genome, we found Cr-FAX1 and Cr-FAX5 to be involved in TAG production by functioning in chloroplast and ER membranes, respectively. By in situ immunolocalization, we show that Cr-FAX1 inserts into the chloroplast envelope, while Cr-FAX5 is located in ER membranes. Severe reduction of Cr-FAX1 or Cr-FAX5 proteins by an artificial microRNA approach results in a strong decrease of the TAG content in the mutant strains. Further, overexpression of chloroplast Cr-FAX1, but not of ER-intrinsic Cr-FAX5, doubled the content of TAG in Chlamydomonas cells. We therefore propose that Cr-FAX1 in chloroplast envelopes and Cr-FAX5 in ER membranes represent a basic set of FAX proteins to ensure shuttling of FAs from chloroplasts to the ER and are crucial for oil production in Chlamydomonas.
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Affiliation(s)
- Janick Peter
- Plant Biology, Center for Human- and Molecular Biology (ZHMB), Saarland University, Saarbrücken, Germany
| | - Marie Huleux
- Aix Marseille Univ, CEA, CNRS, Institute of Bioscience and Biotechnology of Aix Marseille, BIAM, Saint Paul-Lez-Durance, France
| | - Benjamin Spaniol
- Molecular Biotechnology and Systems Biology, TU Kaiserslautern, Kaiserslautern, Germany
| | - Frederik Sommer
- Molecular Biotechnology and Systems Biology, TU Kaiserslautern, Kaiserslautern, Germany
| | - Jens Neunzig
- Plant Biology, Center for Human- and Molecular Biology (ZHMB), Saarland University, Saarbrücken, Germany
| | - Michael Schroda
- Molecular Biotechnology and Systems Biology, TU Kaiserslautern, Kaiserslautern, Germany
| | - Yonghua Li-Beisson
- Aix Marseille Univ, CEA, CNRS, Institute of Bioscience and Biotechnology of Aix Marseille, BIAM, Saint Paul-Lez-Durance, France
| | - Katrin Philippar
- Plant Biology, Center for Human- and Molecular Biology (ZHMB), Saarland University, Saarbrücken, Germany
- *Correspondence: Katrin Philippar,
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Mechanisms of Sodium-Acetate-Induced DHA Accumulation in a DHA-Producing Microalga, Crypthecodinium sp. SUN. Mar Drugs 2022; 20:md20080508. [PMID: 36005511 PMCID: PMC9409966 DOI: 10.3390/md20080508] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Revised: 08/07/2022] [Accepted: 08/07/2022] [Indexed: 11/26/2022] Open
Abstract
Docosahexaenoic acid (DHA) is an omega-3 polyunsaturated fatty acid (PUFA) that is critical for the intelligence and visual development of infants. Crypthecodinium is the first microalga approved by the Food and Drug Administration for DHA production, but its relatively high intracellular starch content restricts fatty acid accumulation. In this study, different carbon sources, including glucose (G), sodium acetate (S) and mixed carbon (M), were used to investigate the regulatory mechanisms of intracellular organic carbon distribution in Crypthecodinium sp. SUN. Results show that glucose favored cell growth and starch accumulation. Sodium acetate limited glucose utilization and starch accumulation but caused a significant increase in total fatty acid (TFA) accumulation and the DHA percentage. Thus, the DHA content in the S group was highest among three groups and reached a maximum (10.65% of DW) at 96 h that was 2.92-fold and 2.24-fold of that in the G and M groups, respectively. Comparative transcriptome analysis showed that rather than the expression of key genes in fatty acids biosynthesis, increased intracellular acetyl-CoA content appeared to be the key regulatory factor for TFA accumulation. Additionally, metabolome analysis showed that the accumulated DHA-rich metabolites of lipid biosynthesis might be the reason for the higher TFA content and DHA percentage of the S group. The present study provides valuable insights to guide further research in DHA production.
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15
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Pokora W, Tułodziecki S, Dettlaff-Pokora A, Aksmann A. Cross Talk between Hydrogen Peroxide and Nitric Oxide in the Unicellular Green Algae Cell Cycle: How Does It Work? Cells 2022; 11:cells11152425. [PMID: 35954269 PMCID: PMC9368121 DOI: 10.3390/cells11152425] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 07/22/2022] [Accepted: 08/03/2022] [Indexed: 11/22/2022] Open
Abstract
The regulatory role of some reactive oxygen species (ROS) and reactive nitrogen species (RNS), such as hydrogen peroxide or nitric oxide, has been demonstrated in some higher plants and algae. Their involvement in regulation of the organism, tissue and single cell development can also be seen in many animals. In green cells, the redox potential is an important photosynthesis regulatory factor that may lead to an increase or decrease in growth rate. ROS and RNS are important signals involved in the regulation of photoautotrophic growth that, in turn, allow the cell to attain the commitment competence. Both hydrogen peroxide and nitric oxide are directly involved in algal cell development as the signals that regulate expression of proteins required for completing the cell cycle, such as cyclins and cyclin-dependent kinases, or histone proteins and E2F complex proteins. Such regulation seems to relate to the direct interaction of these signaling molecules with the redox-sensitive transcription factors, but also with regulation of signaling pathways including MAPK, G-protein and calmodulin-dependent pathways. In this paper, we aim to elucidate the involvement of hydrogen peroxide and nitric oxide in algal cell cycle regulation, considering the role of these molecules in higher plants. We also evaluate the commercial applicability of this knowledge. The creation of a simple tool, such as a precisely established modification of hydrogen peroxide and/or nitric oxide at the cellular level, leading to changes in the ROS-RNS cross-talk network, can be used for the optimization of the efficiency of algal cell growth and may be especially important in the context of increasing the role of algal biomass in science and industry. It could be a part of an important scientific challenge that biotechnology is currently focused on.
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Affiliation(s)
- Wojciech Pokora
- Department of Plant Physiology and Biotechnology, Faculty of Biology, University of Gdańsk Wita, Stwosza 59, 83-308 Gdańsk, Poland
- Correspondence:
| | - Szymon Tułodziecki
- Department of Plant Physiology and Biotechnology, Faculty of Biology, University of Gdańsk Wita, Stwosza 59, 83-308 Gdańsk, Poland
| | | | - Anna Aksmann
- Department of Plant Physiology and Biotechnology, Faculty of Biology, University of Gdańsk Wita, Stwosza 59, 83-308 Gdańsk, Poland
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16
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Carro MDLM, Gonorazky G, Soto D, Mamone L, Bagnato C, Pagnussat LA, Beligni MV. Expression of Chlamydomonas reinhardtii chloroplast diacylglycerol acyltransferase 3 is induced by light in concert with triacylglycerol accumulation. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2022; 110:262-276. [PMID: 35043497 DOI: 10.1111/tpj.15671] [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: 01/19/2021] [Revised: 12/15/2021] [Accepted: 01/09/2022] [Indexed: 06/14/2023]
Abstract
Considerable progress has been made towards the understanding of triacylglycerol (TAG) accumulation in algae. One key aspect is finding conditions that trigger TAG production without reducing cell division. Previously, we identified a soluble diacylglycerol acyltransferase (DGAT), related to plant DGAT3, with heterologous DGAT activity. In this work, we demonstrate that Chlamydomonas reinhardtii DGAT3 localizes to the chloroplast and that its expression is induced by light, in correspondence with TAG accumulation. Dgat3 mRNAs and TAGs increase in both wild-type and starch-deficient cells grown with acetate upon transferring them from dark or low light to higher light levels, albeit affected by the particularities of each strain. The response of dgat3 mRNAs and TAGs to light depends on the pre-existing levels of TAGs, suggesting the existence of a negative regulatory loop in the synthesis pathway, although an effect of TAG turnover cannot be ruled out. Altogether, these results hint towards a possible role of DGAT3 in light-dependent TAG accumulation in C. reinhardtii.
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Affiliation(s)
- María de Las Mercedes Carro
- Instituto de Investigaciones Biológicas (IIB-CONICET-UNMdP), Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, B7608FBY, Mar del Plata, Argentina
| | - Gabriela Gonorazky
- Instituto de Investigaciones Biológicas (IIB-CONICET-UNMdP), Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, B7608FBY, Mar del Plata, Argentina
| | - Débora Soto
- Instituto de Investigaciones Biológicas (IIB-CONICET-UNMdP), Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, B7608FBY, Mar del Plata, Argentina
| | - Leandro Mamone
- Instituto de Investigaciones Biológicas (IIB-CONICET-UNMdP), Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, B7608FBY, Mar del Plata, Argentina
| | - Carolina Bagnato
- Instituto de Energía y Desarrollo Sustentable (IEDS), Comisión Nacional de Energía Atómica, Centro Atómico Bariloche, 8400, San Carlos de Bariloche, Argentina
| | - Luciana A Pagnussat
- Facultad de Ciencias Agrarias, Universidad Nacional de Mar del Plata, B7620EMA, Balcarce, Argentina
| | - María Verónica Beligni
- Instituto de Investigaciones Biológicas (IIB-CONICET-UNMdP), Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, B7608FBY, Mar del Plata, Argentina
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17
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Amino Acid Signaling for TOR in Eukaryotes: Sensors, Transducers, and a Sustainable Agricultural fuTORe. Biomolecules 2022; 12:biom12030387. [PMID: 35327579 PMCID: PMC8945916 DOI: 10.3390/biom12030387] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 02/26/2022] [Accepted: 02/28/2022] [Indexed: 02/06/2023] Open
Abstract
Eukaryotic cells monitor and regulate metabolism through the atypical protein kinase target of rapamycin (TOR) regulatory hub. TOR is activated by amino acids in animals and fungi through molecular signaling pathways that have been extensively defined in the past ten years. Very recently, several studies revealed that TOR is also acutely responsive to amino acid metabolism in plants, but the mechanisms of amino acid sensing are not yet established. In this review, we summarize these discoveries, emphasizing the diversity of amino acid sensors in human cells and highlighting pathways that are indirectly sensitive to amino acids, i.e., how TOR monitors changes in amino acid availability without a bona fide amino acid sensor. We then discuss the relevance of these model discoveries to plant biology. As plants can synthesize all proteinogenic amino acids from inorganic precursors, we focus on the possibility that TOR senses both organic metabolites and inorganic nutrients. We conclude that an evolutionary perspective on nutrient sensing by TOR benefits both agricultural and biomedical science, contributing to ongoing efforts to generate crops for a sustainable agricultural future.
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18
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Saggere RMS, Lee CWJ, Chan ICW, Durnford DG, Nedelcu AM. A life-history trade-off gene with antagonistic pleiotropic effects on reproduction and survival in limiting environments. Proc Biol Sci 2022; 289:20212669. [PMID: 35078364 PMCID: PMC8790358 DOI: 10.1098/rspb.2021.2669] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Although life-history trade-offs are central to life-history evolution, their mechanistic basis is often unclear. Traditionally, trade-offs are understood in terms of competition for limited resources among traits within an organism, which could be mediated by signal transduction pathways at the level of cellular metabolism. Nevertheless, trade-offs are also thought to be produced as a consequence of the performance of one activity generating negative consequences for other traits, or the result of genes or pathways that simultaneously regulate two life-history traits in opposite directions (antagonistic pleiotropy), independent of resource allocation. Yet examples of genes with antagonistic effects on life-history traits are limited. This study provides direct evidence for a gene-RLS1, that is involved in increasing survival in nutrient-limiting environments at a cost to immediate reproduction in the single-celled photosynthetic alga, Chlamydomonas reinhardtii. Specifically, we show that RLS1 mutants are unable to properly suppress their reproduction in phosphate-deprived conditions. Although these mutants have an immediate reproductive advantage relative to the parental strain, their long-term survival is negatively affected. Our data suggest that RLS1 is a bona fide life-history trade-off gene that suppresses immediate reproduction and ensures survival by downregulating photosynthesis in limiting environments, as part of the general acclimation response to nutrient deprivation in photosynthetic organisms.
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Affiliation(s)
- Rani M. S. Saggere
- Biology Department, University of New Brunswick, PO Box 4400, Fredericton, New Brunswick, Canada E3B 5A3
| | - Christopher W. J. Lee
- Biology Department, University of New Brunswick, PO Box 4400, Fredericton, New Brunswick, Canada E3B 5A3
| | - Irina C. W. Chan
- Biology Department, University of New Brunswick, PO Box 4400, Fredericton, New Brunswick, Canada E3B 5A3
| | - Dion G. Durnford
- Biology Department, University of New Brunswick, PO Box 4400, Fredericton, New Brunswick, Canada E3B 5A3
| | - Aurora M. Nedelcu
- Biology Department, University of New Brunswick, PO Box 4400, Fredericton, New Brunswick, Canada E3B 5A3
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19
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Daignan-Fornier B, Laporte D, Sagot I. Quiescence Through the Prism of Evolution. Front Cell Dev Biol 2021; 9:745069. [PMID: 34778256 PMCID: PMC8586652 DOI: 10.3389/fcell.2021.745069] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Accepted: 10/11/2021] [Indexed: 01/13/2023] Open
Abstract
Being able to reproduce and survive is fundamental to all forms of life. In primitive unicellular organisms, the emergence of quiescence as a reversible proliferation arrest has most likely improved cell survival under unfavorable environmental conditions. During evolution, with the repeated appearances of multicellularity, several aspects of unicellular quiescence were conserved while new quiescent cell intrinsic abilities arose. We propose that the formation of a microenvironment by neighboring cells has allowed disconnecting quiescence from nutritional cues. In this new context, non-proliferative cells can stay metabolically active, potentially authorizing the emergence of new quiescent cell properties, and thereby favoring cell specialization. Through its co-evolution with cell specialization, quiescence may have been a key motor of the fascinating diversity of multicellular complexity.
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20
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Yazdani M, Croen MG, Fish TL, Thannhauser TW, Ahner BA. Overexpression of native ORANGE (OR) and OR mutant protein in Chlamydomonas reinhardtii enhances carotenoid and ABA accumulation and increases resistance to abiotic stress. Metab Eng 2021; 68:94-105. [PMID: 34571147 DOI: 10.1016/j.ymben.2021.09.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2020] [Revised: 09/01/2021] [Accepted: 09/18/2021] [Indexed: 01/13/2023]
Abstract
The carotenoid content of plants can be increased by overexpression of the regulatory protein ORANGE (OR) or a mutant variant known as the 'golden SNP'. In the present study, a strong light-inducible promoter was used to overexpress either wild type CrOR (CrORWT) or a mutated CrOR (CrORHis) containing a single histidine substitution for a conserved arginine in the microalgae Chlamydomonas reinhardtii. Overexpression of CrORWT and CrORHis roughly doubled and tripled, respectively, the accumulation of several different carotenoids, including β-carotene, α-carotene, lutein and violaxanthin in C. reinhardtii and upregulated the transcript abundance of nearly all relevant carotenoid biosynthetic genes. In addition, microscopic analysis revealed that the OR transgenic cells were larger than control cells and exhibited larger chloroplasts with a disrupted morphology. Moreover, both CrORWT and CrORHis cell lines showed increased tolerance to salt and paraquat stress. The levels of endogenous phytohormone abscisic acid (ABA) were also increased in CrORWT and CrORHis lines, not only in normal growth conditions but also in growth medium supplemented with salt and paraquat. Together these results offer new insights regarding the role of the native OR protein in regulating carotenoid biosynthesis and the accumulation of several carotenoids in microalgae, and establish a new functional role for OR to modulate oxidative stress tolerance potentially mediated by ABA.
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Affiliation(s)
- Mohammad Yazdani
- Department of Biological and Environmental Engineering, Cornell University, Ithaca, NY, USA
| | - Michelle G Croen
- Department of Biological and Environmental Engineering, Cornell University, Ithaca, NY, USA
| | - Tara L Fish
- Robert W. Holley Center for Agriculture and Health, USDA-ARS, Cornell University, Ithaca, NY, USA
| | - Theodore W Thannhauser
- Robert W. Holley Center for Agriculture and Health, USDA-ARS, Cornell University, Ithaca, NY, USA
| | - Beth A Ahner
- Department of Biological and Environmental Engineering, Cornell University, Ithaca, NY, USA.
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21
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Smythers AL, Iannetta AA, Hicks LM. Crosslinking mass spectrometry unveils novel interactions and structural distinctions in the model green alga Chlamydomonas reinhardtii. Mol Omics 2021; 17:917-928. [PMID: 34499065 DOI: 10.1039/d1mo00197c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Interactomics is an emerging field that seeks to identify both transient and complex-bound protein interactions that are essential for metabolic functions. Crosslinking mass spectrometry (XL-MS) has enabled untargeted global analysis of these protein networks, permitting largescale simultaneous analysis of protein structure and interactions. Increased commercial availability of highly specific, cell permeable crosslinkers has propelled the study of these critical interactions forward, with the development of MS-cleavable crosslinkers further increasing confidence in identifications. Herein, the global interactome of the unicellular alga Chlamydomonas reinhardtii was analyzed via XL-MS by implementing the MS-cleavable disuccinimidyl sulfoxide (DSSO) crosslinker and enriching for crosslinks using strong cation exchange chromatography. Gentle lysis via repeated freeze-thaw cycles facilitated in vitro analysis of 157 protein-protein crosslinks (interlinks) and 612 peptides linked to peptides of the same protein (intralinks) at 1% FDR throughout the C. reinhardtii proteome. The interlinks confirmed known protein relationships across the cytosol and chloroplast, including coverage on 42% and 38% of the small and large ribosomal subunits, respectively. Of the 157 identified interlinks, 92% represent the first empirical evidence of interaction observed in C. reinhardtii. Several of these crosslinks point to novel associations between proteins, including the identification of a previously uncharacterized Mg-chelatase associated protein (Cre11.g477733.t1.2) bound to seven distinct lysines on Mg-chelatase (Cre06.g306300.t1.2). Additionally, the observed intralinks facilitated characterization of novel protein structures across the C. reinhardtii proteome. Together, these data establish a framework of protein-protein interactions that can be further explored to facilitate understanding of the dynamic protein landscape in C. reinhardtii.
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Affiliation(s)
- Amanda L Smythers
- Department of Chemistry, University of North Carolina at Chapel Hill, Kenan Laboratories, 125 South Road, CB#3290, Chapel Hill, NC 27599-3290, USA.
| | - Anthony A Iannetta
- Department of Chemistry, University of North Carolina at Chapel Hill, Kenan Laboratories, 125 South Road, CB#3290, Chapel Hill, NC 27599-3290, USA.
| | - Leslie M Hicks
- Department of Chemistry, University of North Carolina at Chapel Hill, Kenan Laboratories, 125 South Road, CB#3290, Chapel Hill, NC 27599-3290, USA.
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22
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Di Caprio F. A fattening factor to quantify the accumulation ability of microorganisms under N-starvation. N Biotechnol 2021; 66:70-78. [PMID: 33862285 DOI: 10.1016/j.nbt.2021.04.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2020] [Revised: 04/06/2021] [Accepted: 04/10/2021] [Indexed: 01/04/2023]
Abstract
Many microorganisms can accumulate biomass in the form of lipids and polysaccharides, which can be used for biofuels, bioplastics, food and feed. Some innovative bioprocesses exploit the competitive advantage provided by such accumulation ability, mainly under N-starvation, to select high-accumulating strains against biological contaminants, by using uncoupled nutrient feeding. However, there is no general and easily comparable parameter available to compare biomass accumulation ability among different microbial strains, which could measure the competitive advantage. Here, a parameter termed "fattening factor" (ηx) is described to quantify such strain-specific biomass accumulation ability in bacteria, yeasts and microalgae. This parameter measures how many fold a microbial population can increase its biomass just as the result of accumulation. It is derived from considerations about the main metabolic aspects of cells' response to N-starvation, which induces variations in cell cycle, biomass production and biochemical composition. The fattening factor described here should be easily estimatable in N-starvation for every culturable microbial strain, by measuring the amount of accumulated biomass.
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Affiliation(s)
- Fabrizio Di Caprio
- Department of Chemistry, University Sapienza of Rome, Piazzale Aldo Moro 5, 00185, Rome, Italy.
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23
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Di Caprio F. Cultivation processes to select microorganisms with high accumulation ability. Biotechnol Adv 2021; 49:107740. [PMID: 33838283 DOI: 10.1016/j.biotechadv.2021.107740] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2020] [Revised: 02/26/2021] [Accepted: 03/26/2021] [Indexed: 10/21/2022]
Abstract
The microbial ability to accumulate biomolecules is fundamental for different biotechnological applications aiming at the production of biofuels, food and bioplastics. However, high accumulation is a selective advantage only under certain stressful conditions, such as nutrient depletion, characterized by lower growth rate. Conventional bioprocesses maintain an optimal and stable environment for large part of the cultivation, that doesn't reward cells for their accumulation ability, raising the risk of selection of contaminant strains with higher growth rate, but lower accumulation of products. Here in this work the physiological responses of different microorganisms (microalgae, bacteria, yeasts) under N-starvation and energy starvation are reviewed, with the aim to furnish relevant insights exploitable to develop tailored bioprocesses to select specific strains for their higher accumulation ability. Microorganism responses to starvation are reviewed focusing on cell cycle, biomass production and variations in biochemical composition. Then, the work describes different innovative bioprocess configurations exploiting uncoupled nutrient feeding strategies (feast-famine), tailored to maintain a selective pressure to reward the strains with higher accumulation ability in mixed microbial populations. Finally, the main models developed in recent studies to describe and predict microbial growth and intracellular accumulation upon N-starvation and feast-famine conditions have been reviewed.
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Affiliation(s)
- Fabrizio Di Caprio
- Department of Chemistry, University Sapienza of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy.
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24
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Soós V, Shetty P, Maróti G, Incze N, Badics E, Bálint P, Ördög V, Balázs E. Biomolecule composition and draft genome of a novel, high-lipid producing Scenedesmaceae microalga. ALGAL RES 2021. [DOI: 10.1016/j.algal.2020.102181] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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25
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Di Caprio F, Pipitone LM, Altimari P, Pagnanelli F. Extracellular and intracellular phenol production by microalgae during photoautotrophic batch cultivation. N Biotechnol 2020; 62:1-9. [PMID: 33358937 DOI: 10.1016/j.nbt.2020.12.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Revised: 12/12/2020] [Accepted: 12/13/2020] [Indexed: 12/20/2022]
Abstract
Understanding the mechanisms of phenol production by microalgae can contribute to the development of microalgal biorefinery processes with higher economic and environmental sustainability. However, little is known about how phenols are produced and accumulate during microalgal cultivation. In this study, both extracellular and intracellular phenol production by two microalgal strains (Tetradesmus obliquus and Chlorella sp.) were investigated throughout a conventional photoautotrophic batch cultivation. The highest intracellular phenol content (10-25 mg g-1) and productivity (12-18 mg L-1 d-1) were attained for both strains in the first part of the batch, indicating a positive relation with nutrient availability and biomass productivity. Extracellular phenol production was 2-20 fold lower than intracellular phenols, but reached up to 27 mg L-1 for T. obliquus and 13 mg L-1 for Chlorella sp. The latter finding highlights relevant issues about the management of the exhausted culture medium, due to likely antimicrobial effects.
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Affiliation(s)
- Fabrizio Di Caprio
- University Sapienza of Rome, Department of Chemistry, Piazzale Aldo Moro 5, 00185, Rome, Italy.
| | - Luca Maria Pipitone
- University Sapienza of Rome, Department of Chemistry, Piazzale Aldo Moro 5, 00185, Rome, Italy
| | - Pietro Altimari
- University Sapienza of Rome, Department of Chemistry, Piazzale Aldo Moro 5, 00185, Rome, Italy
| | - Francesca Pagnanelli
- University Sapienza of Rome, Department of Chemistry, Piazzale Aldo Moro 5, 00185, Rome, Italy
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26
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Polle JE, Roth R, Ben-Amotz A, Goodenough U. Ultrastructure of the green alga Dunaliella salina strain CCAP19/18 (Chlorophyta) as investigated by quick-freeze deep-etch electron microscopy. ALGAL RES 2020. [DOI: 10.1016/j.algal.2020.101953] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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27
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Smythers AL, McConnell EW, Lewis HC, Mubarek SN, Hicks LM. Photosynthetic Metabolism and Nitrogen Reshuffling Are Regulated by Reversible Cysteine Thiol Oxidation Following Nitrogen Deprivation in Chlamydomonas. PLANTS 2020; 9:plants9060784. [PMID: 32585825 PMCID: PMC7355495 DOI: 10.3390/plants9060784] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 06/01/2020] [Accepted: 06/19/2020] [Indexed: 12/13/2022]
Abstract
As global temperatures climb to historic highs, the far-reaching effects of climate change have impacted agricultural nutrient availability. This has extended to low latitude oceans, where a deficit in both nitrogen and phosphorus stores has led to dramatic decreases in carbon sequestration in oceanic phytoplankton. Although Chlamydomonas reinhardtii, a freshwater model green alga, has shown drastic systems-level alterations following nitrogen deprivation, the mechanisms through which these alterations are triggered and regulated are not fully understood. This study examined the role of reversible oxidative signaling in the nitrogen stress response of C. reinhardtii. Using oxidized cysteine resin-assisted capture enrichment coupled with label-free quantitative proteomics, 7889 unique oxidized cysteine thiol identifiers were quantified, with 231 significantly changing peptides from 184 proteins following 2 h of nitrogen deprivation. These results demonstrate that the cellular response to nitrogen assimilation, photosynthesis, pigment biosynthesis, and lipid metabolism are regulated by reversible oxidation. An enhanced role of non-damaging oxidative pathways is observed throughout the photosynthetic apparatus that provides a framework for further analysis in phototrophs.
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28
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Bunbury F, Helliwell KE, Mehrshahi P, Davey MP, Salmon DL, Holzer A, Smirnoff N, Smith AG. Responses of a Newly Evolved Auxotroph of Chlamydomonas to B 12 Deprivation. PLANT PHYSIOLOGY 2020; 183:167-178. [PMID: 32079734 PMCID: PMC7210614 DOI: 10.1104/pp.19.01375] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Accepted: 02/04/2020] [Indexed: 05/10/2023]
Abstract
The corrinoid B12 is synthesized only by prokaryotes yet is widely required by eukaryotes as an enzyme cofactor. Microalgae have evolved B12 dependence on multiple occasions, and we previously demonstrated that experimental evolution of the non-B12-requiring alga Chlamydomonas reinhardtii in media supplemented with B12 generated a B12-dependent mutant (hereafter metE7). This clone provides a unique opportunity to study the physiology of a nascent B12 auxotroph. Our analyses demonstrate that B12 deprivation of metE7 disrupts C1 metabolism, causes an accumulation of starch and triacylglycerides, and leads to a decrease in photosynthetic pigments, proteins, and free amino acids. B12 deprivation also caused a substantial increase in reactive oxygen species, which preceded rapid cell death. Survival could be improved without compromising growth by simultaneously depriving the cells of nitrogen, suggesting a type of cross protection. Significantly, we found further improvements in survival under B12 limitation and an increase in B12 use efficiency after metE7 underwent a further period of experimental evolution, this time in coculture with a B12-producing bacterium. Therefore, although an early B12-dependent alga would likely be poorly adapted to coping with B12 deprivation, association with B12-producers can ensure long-term survival whilst also providing a suitable environment for evolving mechanisms to tolerate B12 limitation better.
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Affiliation(s)
- Freddy Bunbury
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EA, United Kingdom
| | - Katherine E Helliwell
- Marine Biological Association of the United Kingdom, Citadel Hill, Plymouth EX4 4PY, United Kingdom
- School of Biosciences, University of Exeter, Exeter, PL1 2PB, United Kingdom
| | - Payam Mehrshahi
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EA, United Kingdom
| | - Matthew P Davey
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EA, United Kingdom
| | - Deborah L Salmon
- School of Biosciences, University of Exeter, Exeter, PL1 2PB, United Kingdom
| | - Andre Holzer
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EA, United Kingdom
| | - Nicholas Smirnoff
- School of Biosciences, University of Exeter, Exeter, PL1 2PB, United Kingdom
| | - Alison G Smith
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EA, United Kingdom
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Lundquist PK, Shivaiah KK, Espinoza-Corral R. Lipid droplets throughout the evolutionary tree. Prog Lipid Res 2020; 78:101029. [PMID: 32348789 DOI: 10.1016/j.plipres.2020.101029] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2020] [Revised: 04/11/2020] [Accepted: 04/18/2020] [Indexed: 12/11/2022]
Abstract
Intracellular lipid droplets are utilized for lipid storage and metabolism in organisms as evolutionarily diverse as animals, fungi, plants, bacteria, and archaea. These lipid droplets demonstrate great diversity in biological functions and protein and lipid compositions, yet fundamentally share common molecular and ultrastructural characteristics. Lipid droplet research has been largely fragmented across the diversity of lipid droplet classes and sub-classes. However, we suggest that there is great potential benefit to the lipid community in better integrating the lipid droplet research fields. To facilitate such integration, we survey the protein and lipid compositions, functional roles, and mechanisms of biogenesis across the breadth of lipid droplets studied throughout the natural world. We depict the big picture of lipid droplet biology, emphasizing shared characteristics and unique differences seen between different classes. In presenting the known diversity of lipid droplets side-by-side it becomes necessary to offer for the first time a consistent system of categorization and nomenclature. We propose a division into three primary classes that reflect their sub-cellular location: i) cytoplasmic lipid droplets (CYTO-LDs), that are present in the eukaryotic cytoplasm, ii) prokaryotic lipid droplets (PRO-LDs), that exist in the prokaryotic cytoplasm, and iii) plastid lipid droplets (PL-LDs), that are found in plant plastids, organelles of photosynthetic eukaryotes. Within each class there is a remarkable array of sub-classes displaying various sizes, shapes and compositions. A more integrated lipid droplet research field will provide opportunities to better build on discoveries and accelerate the pace of research in ways that have not been possible.
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Affiliation(s)
- Peter K Lundquist
- Department of Biochemistry & Molecular Biology, Michigan State University, East Lansing, MI 48824, USA; Plant Resilience Institute, Michigan State University, East Lansing, MI, 48824, USA.
| | - Kiran-Kumar Shivaiah
- Department of Biochemistry & Molecular Biology, Michigan State University, East Lansing, MI 48824, USA; Plant Resilience Institute, Michigan State University, East Lansing, MI, 48824, USA
| | - Roberto Espinoza-Corral
- Department of Biochemistry & Molecular Biology, Michigan State University, East Lansing, MI 48824, USA; Plant Resilience Institute, Michigan State University, East Lansing, MI, 48824, USA
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Kokabi K, Gorelova O, Zorin B, Didi-Cohen S, Itkin M, Malitsky S, Solovchenko A, Boussiba S, Khozin-Goldberg I. Lipidome Remodeling and Autophagic Respose in the Arachidonic-Acid-Rich Microalga Lobosphaera incisa Under Nitrogen and Phosphorous Deprivation. FRONTIERS IN PLANT SCIENCE 2020; 11:614846. [PMID: 33329680 PMCID: PMC7728692 DOI: 10.3389/fpls.2020.614846] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Accepted: 11/02/2020] [Indexed: 05/09/2023]
Abstract
The green microalga Lobosphaera incisa accumulates triacylglycerols (TAGs) with exceptionally high levels of long-chain polyunsaturated fatty acid (LC-PUFA) arachidonic acid (ARA) under nitrogen (N) deprivation. Phosphorous (P) deprivation induces milder changes in fatty acid composition, cell ultrastructure, and growth performance. We hypothesized that the resource-demanding biosynthesis and sequestration of ARA-rich TAG in lipid droplets (LDs) are associated with the enhancement of catabolic processes, including membrane lipid turnover and autophagic activity. Although this work focuses mainly on N deprivation, a comparative analysis of N and P deprivation responses is included. The results of lipidomic profiling showed a differential impact of N and P deprivation on the reorganization of glycerolipids. The formation of TAG under N deprivation was associated with the enhanced breakdown of chloroplast glycerolipids and the formation of lyso-lipids. N-deprived cells displayed a profound reorganization of cell ultrastructure, including internalization of cellular material into autophagic vacuoles, concomitant with the formation of LDs, while P-deprived cells showed better cellular ultrastructural integrity. The expression of the hallmark autophagy protein ATG8 and the major lipid droplet protein (MLDP) genes were coordinately upregulated, but to different extents under either N or P deprivation. The expression of the Δ5-desaturase gene, involved in the final step of ARA biosynthesis, was coordinated with ATG8 and MLDP, exclusively under N deprivation. Concanamycin A, the inhibitor of vacuolar proteolysis and autophagic flux, suppressed growth and enhanced levels of ATG8 and TAG in N-replete cells. The proportions of ARA in TAG decreased with a concomitant increase in oleic acid under both N-replete and N-deprived conditions. The photosynthetic apparatus's recovery from N deprivation was impaired in the presence of the inhibitor, along with the delayed LD degradation. The GFP-ATG8 processing assay showed the release of free GFP in N-replete and N-deprived cells, supporting the existence of autophagic flux. This study provides the first insight into the homeostatic role of autophagy in L. incisa and points to a possible metabolic link between autophagy and ARA-rich TAG biosynthesis.
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Affiliation(s)
- Kamilya Kokabi
- The Albert Katz International School for Desert Studies, The Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, Israel
- Microalgal Biotechnology Laboratory, The French Associates Institute for Agriculture and Biotechnology of Drylands, The J. Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede Boqer Campus, Midreshet Ben-Gurion, Israel
| | - Olga Gorelova
- Department of Bioengineering, Faculty of Biology, Moscow State University, GSP-1, Moscow, Russia
| | - Boris Zorin
- Microalgal Biotechnology Laboratory, The French Associates Institute for Agriculture and Biotechnology of Drylands, The J. Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede Boqer Campus, Midreshet Ben-Gurion, Israel
| | - Shoshana Didi-Cohen
- Microalgal Biotechnology Laboratory, The French Associates Institute for Agriculture and Biotechnology of Drylands, The J. Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede Boqer Campus, Midreshet Ben-Gurion, Israel
| | - Maxim Itkin
- Metabolic Profiling Unit, Life Science Core Facilities, Weizmann Institute of Science, Rehovot, Israel
| | - Sergey Malitsky
- Metabolic Profiling Unit, Life Science Core Facilities, Weizmann Institute of Science, Rehovot, Israel
| | - Alexei Solovchenko
- Department of Bioengineering, Faculty of Biology, Moscow State University, GSP-1, Moscow, Russia
- Institute of Natural Sciences, Derzhavin Tambov State University, Tambov, Russia
- Peoples Friendship University of Russia (RUDN University), Moscow, Russia
| | - Sammy Boussiba
- Microalgal Biotechnology Laboratory, The French Associates Institute for Agriculture and Biotechnology of Drylands, The J. Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede Boqer Campus, Midreshet Ben-Gurion, Israel
| | - Inna Khozin-Goldberg
- Microalgal Biotechnology Laboratory, The French Associates Institute for Agriculture and Biotechnology of Drylands, The J. Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede Boqer Campus, Midreshet Ben-Gurion, Israel
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