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Domozych DS, LoRicco JG. The extracellular matrix of green algae. PLANT PHYSIOLOGY 2023; 194:15-32. [PMID: 37399237 PMCID: PMC10762512 DOI: 10.1093/plphys/kiad384] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 05/25/2023] [Accepted: 05/30/2023] [Indexed: 07/05/2023]
Abstract
Green algae display a wide range of extracellular matrix (ECM) components that include various types of cell walls (CW), scales, crystalline glycoprotein coverings, hydrophobic compounds, and complex gels or mucilage. Recently, new information derived from genomic/transcriptomic screening, advanced biochemical analyses, immunocytochemical studies, and ecophysiology has significantly enhanced and refined our understanding of the green algal ECM. In the later diverging charophyte group of green algae, the CW and other ECM components provide insight into the evolution of plants and the ways the ECM modulates during environmental stress. Chlorophytes produce diverse ECM components, many of which have been exploited for various uses in medicine, food, and biofuel production. This review highlights major advances in ECM studies of green algae.
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Affiliation(s)
- David S Domozych
- Department of Biology, Skidmore College, Saratoga Springs, NY 12866, USA
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2
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Domozych DS, Bagdan K. The cell biology of charophytes: Exploring the past and models for the future. PLANT PHYSIOLOGY 2022; 190:1588-1608. [PMID: 35993883 PMCID: PMC9614468 DOI: 10.1093/plphys/kiac390] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 07/26/2022] [Indexed: 06/15/2023]
Abstract
Charophytes (Streptophyta) represent a diverse assemblage of extant green algae that are the sister lineage to land plants. About 500-600+ million years ago, a charophyte progenitor successfully colonized land and subsequently gave rise to land plants. Charophytes have diverse but relatively simple body plans that make them highly attractive organisms for many areas of biological research. At the cellular level, many charophytes have been used for deciphering cytoskeletal networks and their dynamics, membrane trafficking, extracellular matrix secretion, and cell division mechanisms. Some charophytes live in challenging habitats and have become excellent models for elucidating the cellular and molecular effects of various abiotic stressors on plant cells. Recent sequencing of several charophyte genomes has also opened doors for the dissection of biosynthetic and signaling pathways. While we are only in an infancy stage of elucidating the cell biology of charophytes, the future application of novel analytical methodologies in charophyte studies that include a broader survey of inclusive taxa will enhance our understanding of plant evolution and cell dynamics.
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Affiliation(s)
| | - Kaylee Bagdan
- Department of Biology, Skidmore Microscopy Imaging Center, Skidmore College, Saratoga Springs, New York 12866, USA
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3
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Astafyeva Y, Gurschke M, Streit WR, Krohn I. Interplay between the microalgae Micrasterias radians and its symbiont Dyadobacter sp. HH091. Front Microbiol 2022; 13:1006609. [PMID: 36312980 PMCID: PMC9606717 DOI: 10.3389/fmicb.2022.1006609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 09/21/2022] [Indexed: 11/13/2022] Open
Abstract
Based on previous research, related to detailed insight into mutualistic collaboration of microalga and its microbiome, we established an artificial plant-bacteria system of the microalga Micrasterias radians MZCH 672 and the bacterial isolate Dyadobacter sp. HH091. The bacteria, affiliated with the phylum Bacteroidota, strongly stimulated growth of the microalga when it was added to axenic algal cultures. For further advances, we studied the isolate HH091 and its interaction with the microalga M. radians using transcriptome and extensive genome analyses. The genome of HH091 contains predicted polysaccharide utilizing gene clusters co-working with the type IX secretion system (T9SS) and conceivably involved in the algae-bacteria liaison. Here, we focus on characterizing the mechanism of T9SS, implementing the attachment and invasion of microalga by Dyadobacter sp. HH091. Omics analysis exposed T9SS genes: gldK, gldL, gldM, gldN, sprA, sprE, sprF, sprT, porU and porV. Besides, gld genes not considered as the T9SS components but required for gliding motility and protein secretion (gldA, gldB, gldD, gldF, gldG, gldH, gldI, gldJ), were also identified at this analysis. A first model of T9SS apparatus of Dyadobacter was proposed in a course of this research. Using the combination of fluorescence labeling of Dyadobacter sp. HH091, we examined the bacterial colonisation and penetration into the cell wall of the algal host M. radians MZCH 672.
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Felhofer M, Mayr K, Lütz-Meindl U, Gierlinger N. Raman imaging of Micrasterias: new insights into shape formation. PROTOPLASMA 2021; 258:1323-1334. [PMID: 34292402 PMCID: PMC8523415 DOI: 10.1007/s00709-021-01685-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Accepted: 06/24/2021] [Indexed: 06/13/2023]
Abstract
The algae Micrasterias with its star-shaped cell pattern is a perfect unicellular model system to study morphogenesis. How the indentations are formed in the primary cell wall at exactly defined areas puzzled scientists for decades, and they searched for chemical differences in the primary wall of the extending tips compared to the resting indents. We now tackled the question by Raman imaging and scanned in situ Micrasterias cells at different stages of development. Thousands of Raman spectra were acquired from the mother cell and the developing semicell to calculate chemical images based on an algorithm finding the most different Raman spectra. Each of those spectra had characteristic Raman bands, which were assigned to molecular vibrations of BaSO4, proteins, lipids, starch, and plant cell wall carbohydrates. Visualizing the cell wall carbohydrates revealed a cell wall thickening at the indentations of the primary cell wall of the growing semicell and uniplanar orientation of the cellulose microfibrils to the cell surface in the secondary cell wall. Crystalline cellulose dominated in the secondary cell wall spectra, while in the primary cell wall spectra, also xyloglucan and pectin were reflected. Spectral differences between the indent and tip region of the primary cell wall were scarce, but a spectral mixing approach pointed to more cellulose fibrils deposited in the indent region. Therefore, we suggest that cell wall thickening together with a denser network of cellulose microfibrils stiffens the cell wall at the indent and induces different cell wall extensibility to shape the lobes.
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Affiliation(s)
- Martin Felhofer
- Department of Nanobiotechnology, University of Natural Resources and Life Sciences Vienna (BOKU), 1190, Vienna, Austria
| | - Konrad Mayr
- Department of Nanobiotechnology, University of Natural Resources and Life Sciences Vienna (BOKU), 1190, Vienna, Austria
| | - Ursula Lütz-Meindl
- Department of Biosciences, University of Salzburg, 5020, Salzburg, Austria
| | - Notburga Gierlinger
- Department of Nanobiotechnology, University of Natural Resources and Life Sciences Vienna (BOKU), 1190, Vienna, Austria.
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Steiner P, Buchner O, Andosch A, Holzinger A, Lütz-Meindl U, Neuner G. Winter survival of the unicellular green alga Micrasterias denticulata: insights from field monitoring and simulation experiments. PROTOPLASMA 2021; 258:1335-1346. [PMID: 34304308 PMCID: PMC8523418 DOI: 10.1007/s00709-021-01682-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Accepted: 06/09/2021] [Indexed: 06/13/2023]
Abstract
Peat bog pools around Tamsweg (Lungau, Austria) are typical habitats of the unicellular green alga Micrasterias denticulata. By measurement of water temperature and irradiation throughout a 1-year period (2018/2019), it was intended to assess the natural environmental strain in winter. Freezing resistance of Micrasterias cells and their ability to frost harden and become tolerant to ice encasement were determined after natural hardening and exposure to a cold acclimation treatment that simulated the natural temperature decrease in autumn. Transmission electron microscopy (TEM) was performed in laboratory-cultivated cells, after artificial cold acclimation treatment and in cells collected from field. Throughout winter, the peat bog pools inhabited by Micrasterias remained unfrozen. Despite air temperature minima down to -17.3 °C, the water temperature was mostly close to +0.8 °C. The alga was unable to frost harden, and upon ice encasement, the cells showed successive frost damage. Despite an unchanged freezing stress tolerance, significant ultrastructural changes were observed in field-sampled cells and in response to the artificial cold acclimation treatment: organelles such as the endoplasmic reticulum and thylakoids of the chloroplast showed distinct membrane bloating. Still, in the field samples, the Golgi apparatus appeared in an impeccable condition, and multivesicular bodies were less frequently observed suggesting a lower overall stress strain. The observed ultrastructural changes in winter and after cold acclimation are interpreted as cytological adjustments to winter or a resting state but are not related to frost hardening as Micrasterias cells were unable to improve their freezing stress tolerance.
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Affiliation(s)
- Philip Steiner
- Department of Biosciences, University of Salzburg, Hellbrunnerstrasse 34, 5020, Salzburg, Austria
- Institute of Pharmacology, University of Linz, Huemerstrasse 3-5, 4020, Linz, Austria
| | - Othmar Buchner
- Department of Biosciences, University of Salzburg, Hellbrunnerstrasse 34, 5020, Salzburg, Austria.
| | - Ancuela Andosch
- Department of Biosciences, University of Salzburg, Hellbrunnerstrasse 34, 5020, Salzburg, Austria
| | - Andreas Holzinger
- Department of Botany, Functional Plant Biology, University of Innsbruck, Sternwartestrasse 15, 6020, Innsbruck, Austria
| | - Ursula Lütz-Meindl
- Department of Biosciences, University of Salzburg, Hellbrunnerstrasse 34, 5020, Salzburg, Austria
| | - Gilbert Neuner
- Department of Botany, Functional Plant Biology, University of Innsbruck, Sternwartestrasse 15, 6020, Innsbruck, Austria
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Xin A, Herburger K. Precursor biosynthesis regulation of lignin, suberin and cutin. PROTOPLASMA 2021; 258:1171-1178. [PMID: 34120228 DOI: 10.1007/s00709-021-01676-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2021] [Accepted: 06/01/2021] [Indexed: 06/12/2023]
Abstract
The extracellular matrix of plants can contain the hydrophobic biopolymers lignin, suberin and/or cutin, which provide mechanical strength and limit water loss and pathogen invasion. Due to their remarkable chemical resistance, these polymers have a high potential in various biotechnological applications and can replace petrol-based resources, for example, in the packing industry. However, despite the importance of these polymers, the regulation of their precursor biosynthesis is far from being fully understood. This is particularly true for suberin and cutin, which hinders efforts to engineer their formation in plants and produce customised biopolymers. This review brings attention to knowledge gaps in the current research and highlights some of the most recent findings on transcription factors that regulate lignin, suberin and cutin precursor biosynthesis. Finally, we also briefly discuss how some of the remaining knowledge gaps can be closed.
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Affiliation(s)
- Anzhou Xin
- Section for Plant Glycobiology, Department of Plant and Environmental Sciences, University of Copenhagen, 1871, Frederiksberg, Denmark
| | - Klaus Herburger
- Section for Plant Glycobiology, Department of Plant and Environmental Sciences, University of Copenhagen, 1871, Frederiksberg, Denmark.
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Domozych DS, Kozel L, Palacio-Lopez K. The effects of osmotic stress on the cell wall-plasma membrane domains of the unicellular streptophyte, Penium margaritaceum. PROTOPLASMA 2021; 258:1231-1249. [PMID: 33928433 DOI: 10.1007/s00709-021-01644-y] [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: 01/08/2021] [Accepted: 04/01/2021] [Indexed: 06/12/2023]
Abstract
Penium margaritaceum is a unicellular zygnematophyte (basal Streptophyteor Charophyte) that has been used as a model organism for the study of cell walls of Streptophytes and for elucidating organismal adaptations that were key in the evolution of land plants.. When Penium is incubated in sorbitol-enhance medium, i.e., hyperosmotic medium, 1000-1500 Hechtian strands form within minutes and connect the plasma membrane to the cell wall. As cells acclimate to this osmotic stress over time, further significant changes occur at the cell wall and plasma membrane domains. The homogalacturonan lattice of the outer cell wall layer is significantly reduced and is accompanied by the formation of a highly elongate, "filamentous" phenotype. Distinct peripheral thickenings appear between the CW and plasma membrane and contain membranous components and a branched granular matrix. Monoclonal antibody labeling of these thickenings indicates the presence of rhamnogalacturonan-I epitopes. Acclimatization also results in the proliferation of the cell's vacuolar networks and macroautophagy. Penium's ability to acclimatize to osmotic stress offers insight into the transition of ancient zygnematophytes from an aquatic to terrestrial existence.
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Affiliation(s)
- David S Domozych
- Department of Biology and Skidmore Microscopy Imaging Center, Skidmore College, Saratoga Springs, NY, 12866, USA.
| | - Li Kozel
- Department of Biology and Skidmore Microscopy Imaging Center, Skidmore College, Saratoga Springs, NY, 12866, USA
| | - Kattia Palacio-Lopez
- Department of Evolution, Ecology and Organismal Biology, The Ohio State University, Columbus, OH, USA
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8
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Ross IL, Shah S, Hankamer B, Amiralian N. Microalgal nanocellulose - opportunities for a circular bioeconomy. TRENDS IN PLANT SCIENCE 2021; 26:924-939. [PMID: 34144878 DOI: 10.1016/j.tplants.2021.05.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 04/16/2021] [Accepted: 05/17/2021] [Indexed: 06/12/2023]
Abstract
Over 3 billion years, photosynthetic algae have evolved complex uses for cellulose, the most abundant polymer worldwide. A major cell-wall component of lignocellulosic plants, seaweeds, microalgae, and bacteria, cellulose can be processed to nanocellulose, a promising nanomaterial with novel properties. The structural diversity of macro- and microalgal nanocelluloses opens opportunities to couple low-impact biomass production with novel, green-chemistry processing to yield valuable, sustainable nanomaterials for a multitude of applications ranging from novel wound dressings to organic solar cells. We review the origins of algal cellulose and the applications and uses of nanocellulose, and highlight the potential for microalgae as a nanocellulose source. Given the limited state of current knowledge, we identify research challenges and strategies to help to realise this potential.
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Affiliation(s)
- Ian L Ross
- Institute for Molecular Bioscience (IMB), The University of Queensland, Brisbane, QLD 4072, Australia.
| | - Sarah Shah
- Institute for Molecular Bioscience (IMB), The University of Queensland, Brisbane, QLD 4072, Australia
| | - Ben Hankamer
- Institute for Molecular Bioscience (IMB), The University of Queensland, Brisbane, QLD 4072, Australia
| | - Nasim Amiralian
- Australian Institute for Bioengineering and Nanotechnology (AIBN), The University of Queensland, Brisbane, QLD 4072, Australia.
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9
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Stamenković M, Steinwall E, Wulff A. Cultivation and Photophysiological Characteristics of Desmids in Moderately Saline Aquaculture Wastewater. JOURNAL OF PHYCOLOGY 2021; 57:726-741. [PMID: 33598949 DOI: 10.1111/jpy.13150] [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: 09/25/2020] [Revised: 01/22/2021] [Accepted: 01/28/2021] [Indexed: 06/12/2023]
Abstract
Although desmids typically inhabit freshwater environments characterized by low amounts of nutrients and low salinity, several desmid species have been recorded in eutrophic waters, indicating their adaptation to elevated pollution and conductivity. This study aimed to determine whether desmids could be used for remediation of moderately saline aquaculture wastewater (AWW) from a fish farm situated in the southeast of Sweden. Fourteen desmid strains isolated from different climates (tropical to polar) and trophic conditions (oligotrophic to eutrophic) were cultivated in diluted AWW and we estimated their growth rates, biomass, nutrient removal efficiency, chlorophyll fluorescence parameters and cellular C, N and P quotas. Despite being grown at moderate salinity, unfavourable N:P ratio, and relatively low light/temperature regime the eutrophic strains, Cosmarium humile, Cosmarium laeve and a meso-oligotrophic species Cosmarium impressulum, completely absorbed nitrate and phosphate from AWW media after 7 d, indicating their potential for remediation of fish effluents in colder climates. These species, along with the typical eutrophic species, Cosmarium meneghinii and Staurastrum chaetoceras, had biomass in the range 0.45-1.19 g · L-1 while maximum growth rates ranged from 0.36 to 0.51 · d-1 , similar to published rates for several fast-growing green microalgae cultivated in various AWW types. Tropical desmids had distinctly high values of saturating irradiance (Ik > 1,000 µmol photons · m-2 · s-1 ), and, along with eutrophic desmids, had high potential electron transport (rETRmax > 155 rel. units). Hence, the desmids studied demonstrated inherent photophysiological responses corresponding to their climate and trophic origin under the suboptimal growth conditions.
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Affiliation(s)
- Marija Stamenković
- Department of Ecology, Institute for Biological Research "Siniša Stanković", University of Belgrade, Bulevar despota Stefana 142, 11060, Belgrade, Serbia
- Department of Biological and Environmental Sciences, University of Gothenburg, Box 461, SE40530, Göteborg, Sweden
| | - Elin Steinwall
- Department of Biological and Environmental Sciences, University of Gothenburg, Box 461, SE40530, Göteborg, Sweden
| | - Angela Wulff
- Department of Biological and Environmental Sciences, University of Gothenburg, Box 461, SE40530, Göteborg, Sweden
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Bellini E, Betti C, Sanità di Toppi L. Responses to Cadmium in Early-Diverging Streptophytes (Charophytes and Bryophytes): Current Views and Potential Applications. PLANTS (BASEL, SWITZERLAND) 2021; 10:770. [PMID: 33919852 PMCID: PMC8070800 DOI: 10.3390/plants10040770] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 04/08/2021] [Accepted: 04/09/2021] [Indexed: 11/16/2022]
Abstract
Several transition metals are essential for plant growth and development, as they are involved in various fundamental metabolic functions. By contrast, cadmium (Cd) is a metal that can prove extremely toxic for plants and other organisms in a dose-dependent manner. Charophytes and bryophytes are early-diverging streptophytes widely employed for biomonitoring purposes, as they are able to cope with high concentrations of toxic metal(loid)s without showing any apparent heavy damage. In this review, we will deal with different mechanisms that charophytes and bryophytes have evolved to respond to Cd at a cellular level. Particular attention will be addressed to strategies involving Cd vacuolar sequestration and cell wall immobilization, focusing on specific mechanisms that help achieve detoxification. Understanding the effects of metal(loid) pollution and accumulation on the morpho-physiological traits of charophytes and bryophytes can be in fact fundamental for optimizing their use as phytomonitors and/or phytoremediators.
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Affiliation(s)
- Erika Bellini
- Department of Biology, University of Pisa, 56126 Pisa, Italy; (E.B.); (L.S.d.T.)
| | - Camilla Betti
- Department of Medicine, University of Perugia, 06132 Perugia, Italy
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11
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Fusion of Mitochondria to 3-D Networks, Autophagy and Increased Organelle Contacts are Important Subcellular Hallmarks during Cold Stress in Plants. Int J Mol Sci 2020; 21:ijms21228753. [PMID: 33228190 PMCID: PMC7699614 DOI: 10.3390/ijms21228753] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Revised: 11/12/2020] [Accepted: 11/14/2020] [Indexed: 12/25/2022] Open
Abstract
Low temperature stress has a severe impact on the distribution, physiology, and survival of plants in their natural habitats. While numerous studies have focused on the physiological and molecular adjustments to low temperatures, this study provides evidence that cold induced physiological responses coincide with distinct ultrastructural alterations. Three plants from different evolutionary levels and habitats were investigated: The freshwater alga Micrasterias denticulata, the aquatic plant Lemna sp., and the nival plant Ranunculus glacialis. Ultrastructural alterations during low temperature stress were determined by the employment of 2-D transmission electron microscopy and 3-D reconstructions from focused ion beam–scanning electron microscopic series. With decreasing temperatures, increasing numbers of organelle contacts and particularly the fusion of mitochondria to 3-dimensional networks were observed. We assume that the increase or at least maintenance of respiration during low temperature stress is likely to be based on these mitochondrial interconnections. Moreover, it is shown that autophagy and degeneration processes accompany freezing stress in Lemna and R. glacialis. This might be an essential mechanism to recycle damaged cytoplasmic constituents to maintain the cellular metabolism during freezing stress.
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12
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Zhou H, von Schwartzenberg K. Zygnematophyceae: from living algae collections to the establishment of future models. JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:3296-3304. [PMID: 32076703 DOI: 10.1093/jxb/eraa091] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Accepted: 02/17/2020] [Indexed: 06/10/2023]
Abstract
The class of conjugating green algae, Zygnematophyceae (Conjugatophyceae), is extremely rich in species and has attracted the interest of phycologists for a long time. It is now widely accepted that this class of charophyte algae holds a key position in the phylogenetic tree of streptophytes, where they represent the closest relatives to all land plants (embryophytes). It is increasingly evident that robust model plants that can be easily cultivated and genetically transformed are necessary to better understand the process of terrestrialization and the related molecular, cellular, and physiological adaptations. Living algae collections play an important role, not only for phylogenomic-based taxonomy but also for screening for suitable model organisms. For this review, we screened six major public algae collections for Zygnematophyceae strains and established a cumulative list comprising 738 different taxa (including species, subspecies, varieties, and forms). From the described biodiversity with 8883 registered taxa (AlgaeBase) the cultured Zygnematophyceae taxa worldwide cover only ~8.3%. We review the past research on this clade of algae and discuss it from the perspective of establishing a model organism. We present data on the life cycle of the genera Micrasterias and Spirogyra, representing the orders Desmidiales and Zygnematales, and outline the current status of genetic transformation of Zygnematophyceae algae and future research perspectives.
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Affiliation(s)
- Hong Zhou
- Microalgae and Zygnematophyceae Collection Hamburg, Institute for Plant Science and Microbiology, Universität Hamburg, Hamburg, Germany
| | - Klaus von Schwartzenberg
- Microalgae and Zygnematophyceae Collection Hamburg, Institute for Plant Science and Microbiology, Universität Hamburg, Hamburg, Germany
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13
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Domozych DS, Sun L, Palacio-Lopez K, Reed R, Jeon S, Li M, Jiao C, Sørensen I, Fei Z, Rose JKC. Endomembrane architecture and dynamics during secretion of the extracellular matrix of the unicellular charophyte, Penium margaritaceum. JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:3323-3339. [PMID: 31974570 PMCID: PMC7289721 DOI: 10.1093/jxb/eraa039] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Accepted: 01/21/2020] [Indexed: 05/02/2023]
Abstract
The extracellular matrix (ECM) of many charophytes, the assemblage of green algae that are the sister group to land plants, is complex, produced in large amounts, and has multiple essential functions. An extensive secretory apparatus and endomembrane system are presumably needed to synthesize and secrete the ECM, but structural details of such a system have not been fully characterized. Penium margaritaceum is a valuable unicellular model charophyte for studying secretion dynamics. We report that Penium has a highly organized endomembrane system, consisting of 150-200 non-mobile Golgi bodies that process and package ECM components into different sets of vesicles that traffic to the cortical cytoplasm, where they are transported around the cell by cytoplasmic streaming. At either fixed or transient areas, specific cytoplasmic vesicles fuse with the plasma membrane and secrete their constituents. Extracellular polysaccharide (EPS) production was observed to occur in one location of the Golgi body and sometimes in unique Golgi hybrids. Treatment of cells with brefeldin A caused disruption of the Golgi body, and inhibition of EPS secretion and cell wall expansion. The structure of the endomembrane system in Penium provides mechanistic insights into how extant charophytes generate large quantities of ECM, which in their ancestors facilitated the colonization of land.
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Affiliation(s)
- David S Domozych
- Department of Biology, Skidmore College, Saratoga Springs, NY, USA
- Correspondence:
| | - Li Sun
- Department of Biology, Skidmore College, Saratoga Springs, NY, USA
| | | | - Reagan Reed
- Department of Biology, Skidmore College, Saratoga Springs, NY, USA
| | - Susan Jeon
- Department of Biology, Skidmore College, Saratoga Springs, NY, USA
| | - Mingjia Li
- Department of Biology, Skidmore College, Saratoga Springs, NY, USA
| | - Chen Jiao
- Boyce Thompson Institute, Ithaca, NY, USA
| | - Iben Sørensen
- Plant Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY, USA
| | - Zhangjun Fei
- Boyce Thompson Institute, Ithaca, NY, USA
- U.S. Department of Agriculture-Agricultural Research Service, Robert W. Holley Center for Agriculture and Health, Ithaca, NY, USA
| | - Jocelyn K C Rose
- Plant Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY, USA
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14
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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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15
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Buchner O, Steiner P, Andosch A, Holzinger A, Stegner M, Neuner G, Lütz-Meindl U. A new technical approach for preparing frozen biological samples for electron microscopy. PLANT METHODS 2020; 16:48. [PMID: 32280364 PMCID: PMC7137184 DOI: 10.1186/s13007-020-00586-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Accepted: 03/23/2020] [Indexed: 05/08/2023]
Abstract
BACKGROUND Many methodological approaches have focused so far on physiological and molecular responses of plant tissues to freezing but only little knowledge is available on the consequences of extracellular ice-formation on cellular ultrastructure that underlies physiological reactions. In this context, the preservation of a defined frozen state during the entire fixation procedure is an essential prerequisite. However, current techniques are not able to fix frozen plant tissues for transmission electron microscopy (TEM) without interrupting the cold chain. Chemical fixation by glutaraldehyde and osmium tetroxide is not possible at sub-zero temperatures. Cryo-fixation methods, such as high pressure freeze fixation (HPF) representing the state-of-the-art technique for best structural preservation, are not equipped for freezing frozen samples. In order to overcome this obstacle, a novel technical approach for maintaining the cold chain of already frozen plant samples prior and during HPF is presented. RESULTS Different algae (Micrasterias denticulata, Klebsormidium crenulatum) and higher plant tissues (Lemna sp., Ranunculus glacialis, Pinus mugo) were successfully frozen and prepared for HPF at freezing temperatures (- 2 °C, - 5 °C, - 6 °C) within a newly developed automatic freezing unit (AFU), that we manufactured from a standard laboratory freezer. Preceding tests on photosynthetic electron transport and ability to plasmolyse show that the temperatures applied did not impair electron transport in PSII nor cell vitality. The transfer of the frozen specimen from the AFU into the HPF-device and subsequently cryo-fixation were performed without intermediate thawing. After cryo-substitution and further processing, the resulting TEM-micrographs showed excellent ultrastructure preservation of the different organisms when compared to specimens fixed at ambient temperature. CONCLUSIONS The method presented allows preserving the ultrastructure of plant cells in the frozen state during cryo-fixation. The resulting high quality TEM-images represent an important step towards a better understanding of the consequences of extracellular ice formation on cellular ultrastructure. It has the potential to provide new insights into changes of organelle structure, identification of intracellular injuries during ice formation and may help to understand freezing and thawing processes in plant tissues. It may be combined with analytical TEM such as electron energy loss spectroscopy (EELS), X-ray analyses (EDX) and various other electron microscopic techniques.
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Affiliation(s)
- Othmar Buchner
- Department of Biosciences, University of Salzburg, Hellbrunnerstrasse 34, 5020 Salzburg, Austria
| | - Philip Steiner
- Department of Biosciences, University of Salzburg, Hellbrunnerstrasse 34, 5020 Salzburg, Austria
| | - Ancuela Andosch
- Department of Biosciences, University of Salzburg, Hellbrunnerstrasse 34, 5020 Salzburg, Austria
| | - Andreas Holzinger
- Department of Botany, University of Innsbruck, Sternwartestrasse 15, 6020 Innsbruck, Austria
| | - Matthias Stegner
- Department of Botany, University of Innsbruck, Sternwartestrasse 15, 6020 Innsbruck, Austria
| | - Gilbert Neuner
- Department of Botany, University of Innsbruck, Sternwartestrasse 15, 6020 Innsbruck, Austria
| | - Ursula Lütz-Meindl
- Department of Biosciences, University of Salzburg, Hellbrunnerstrasse 34, 5020 Salzburg, Austria
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16
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Fields C, Bischof J, Levin M. Morphological Coordination: A Common Ancestral Function Unifying Neural and Non-Neural Signaling. Physiology (Bethesda) 2020; 35:16-30. [DOI: 10.1152/physiol.00027.2019] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Nervous systems are traditionally thought of as providing sensing and behavioral coordination functions at the level of the whole organism. What is the evolutionary origin of the mechanisms enabling the nervous systems’ information processing ability? Here, we review evidence from evolutionary, developmental, and regenerative biology suggesting a deeper, ancestral function of both pre-neural and neural cell-cell communication systems: the long-distance coordination of cell division and differentiation required to create and maintain body-axis symmetries. This conceptualization of the function of nervous system activity sheds new light on the evolutionary transition from the morphologically rudimentary, non-neural Porifera and Placazoa to the complex morphologies of Ctenophores, Cnidarians, and Bilaterians. It further allows a sharp formulation of the distinction between long-distance axis-symmetry coordination based on external coordinates, e.g., by whole-organism scale trophisms as employed by plants and sessile animals, and coordination based on body-centered coordinates as employed by motile animals. Thus we suggest that the systems that control animal behavior evolved from ancient mechanisms adapting preexisting ionic and neurotransmitter mechanisms to regulate individual cell behaviors during morphogenesis. An appreciation of the ancient, non-neural origins of bioelectrically mediated computation suggests new approaches to the study of embryological development, including embryological dysregulation, cancer, regenerative medicine, and synthetic bioengineering.
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Affiliation(s)
- Chris Fields
- 23 Rue des Lavandières, Caunes Minervois, France
| | - Johanna Bischof
- Allen Discovery Center at Tufts University, Medford, Massachusetts
| | - Michael Levin
- Allen Discovery Center at Tufts University, Medford, Massachusetts
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17
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Palacio-López K, Tinaz B, Holzinger A, Domozych DS. Arabinogalactan Proteins and the Extracellular Matrix of Charophytes: A Sticky Business. FRONTIERS IN PLANT SCIENCE 2019; 10:447. [PMID: 31031785 PMCID: PMC6474363 DOI: 10.3389/fpls.2019.00447] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Accepted: 03/25/2019] [Indexed: 05/20/2023]
Abstract
Charophytes represent the group of green algae whose ancestors invaded land and ultimately gave rise to land plants 450 million years ago. While Zygnematophyceae are believed to be the direct sister lineage to embryophytes, different members of this group (Penium, Spirogyra, Zygnema) and the advanced thallus forming Coleochaete as well as the sarcinoid basal streptophyte Chlorokybus were investigated concerning their vegetative extracellular matrix (ECM) properties. Many taxa exhibit adhesion phenomena that are critical for affixing to a substrate or keeping cells together in a thallus, however, there is a great variety in possible reactions to e.g., wounding. In this study an analysis of adhesion mechanisms revealed that arabinogalactan proteins (AGPs) are most likely key adhesion molecules. Through use of monoclonal antibodies (JIM13) or the Yariv reagent, AGPs were located in cell surface sheaths and cell walls that were parts of the adhesion focal zones on substrates including wound induced rhizoid formation. JIM5, detecting highly methyl-esterfied homoglacturonan and JIM8, an antibody detecting AGP glycan and LM6 detecting arabinans were also tested and a colocalization was found in several examples (e.g., Zygnema) suggesting an interplay between these components. AGPs have been described in this study to perform both, cell to cell adhesion in algae forming thalli and cell to surface adhesion in the filamentous forms. These findings enable a broader evolutionary understanding of the function of AGPs in charophyte green algae.
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Affiliation(s)
| | - Berke Tinaz
- Department of Biology, Skidmore College, Saratoga Springs, NY, United States
| | | | - David S. Domozych
- Department of Biology, Skidmore College, Saratoga Springs, NY, United States
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18
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Yoshitake Y, Ohta H, Shimojima M. Autophagy-Mediated Regulation of Lipid Metabolism and Its Impact on the Growth in Algae and Seed Plants. FRONTIERS IN PLANT SCIENCE 2019; 10:709. [PMID: 31214225 PMCID: PMC6558177 DOI: 10.3389/fpls.2019.00709] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Accepted: 05/13/2019] [Indexed: 05/08/2023]
Abstract
Under nutrient starvation conditions, algae and seed-plant cells accumulate carbon metabolites such as storage lipids, triacylglycerols (TAGs), and starches. Recent research has suggested the involvement of autophagy in the regulation of carbon metabolites under nutrient starvation. When algae are grown under carbon starvation conditions, such as growth in darkness or in the presence of a photosynthesis inhibitor, lipid droplets are surrounded by phagophores. Indeed, the amount of TAGs in an autophagy-deficient mutant has been found to be greater than that in wild type under nitrogen starvation, and cerulenin, which is one of the inhibitors of fatty acid synthesis, induces autophagy. In land plants, TAGs accumulate predominantly in seeds and etiolated seedlings. These TAGs are degraded in peroxisomes via β-oxidation during germination as a source of carbon for growth without photosynthesis. A global analysis of the role of autophagy in Arabidopsis seedlings under carbon starvation revealed that a lack of autophagy enhances the accumulation of TAGs and fatty acids. In Oryza sativa, autophagy-mediated degradation of TAGs and diacylglycerols has been suggested to be important for pollen development. In this review, we introduce and summarize research findings demonstrating that autophagy affects lipid metabolism and discuss the role of autophagy in membrane and storage-lipid homeostasis, each of which affects the growth and development of seed plants and algae.
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Affiliation(s)
- Yushi Yoshitake
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Japan
| | - Hiroyuki Ohta
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Japan
- Open Innovation Platform with Enterprises, Research Institute and Academia (OPERA), Japan Science and Technology Agency, Chiyoda, Japan
| | - Mie Shimojima
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Japan
- *Correspondence: Mie Shimojima,
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19
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Neustupa J, Stastny J. Symmetry breaking of the cellular lobes closely relates to phylogenetic structure within green microalgae of the Micrasterias lineage (Zygnematophyceae). PeerJ 2018; 6:e6098. [PMID: 30568863 PMCID: PMC6287601 DOI: 10.7717/peerj.6098] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Accepted: 11/11/2018] [Indexed: 11/20/2022] Open
Abstract
Green microalgae of the Micrasterias lineage are unicellular microorganisms with modular morphology consisting of successively differentiated lobes. Due to their morphological diversity and peculiar morphogenesis, these species are important model systems for studies of cytomorphogenesis and cellular plasticity. Interestingly, the phylogenetic structure of the Micrasterias lineage and most other Desmidiales is poorly related to the traditional morphological characters used for delimitation of taxa. In this study, we focused on symmetry breaking between adjacent cellular lobes in relation to phylogeny of the studied species. While pronounced morphological asymmetry between the adjacent lobes is typical for some species, others have been characterized by the almost identical morphologies of these structures. We asked whether there is any detectable average shape asymmetry between the pairs of lobes and terminal lobules in 19 Micrasterias species representing all major clades of this desmidiacean lineage. Then, we evaluated whether the asymmetric patterns among species are phylogenetically structured. The analyses showed that the phylogeny was in fact strongly related to the patterns of morphological asymmetry between the adjacent cellular lobes. Thus, evolution of the asymmetric development between the adjacent lobes proved to be the key event differentiating cellular shape patterns of Micrasterias. Conversely, the phylogeny was only weakly related to asymmetry between the pairs of terminal lobules. The subsequent analyses of the phylogenetic morphological integration showed that individual hierarchical levels of cellular morphology were only weakly coordinated with regard to asymmetric variation among species. This finding indicates that evolutionary differentiation of morphogenetic processes leading to symmetry breaking may be relatively independent at different branching levels. Such modularity is probably the key to the evolvability of cellular shapes, leading to the extraordinary morphological diversity of these intriguing microalgae.
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Affiliation(s)
- Jiri Neustupa
- Department of Botany, Faculty of Science, Charles University Prague, Prague, Czech Republic
| | - Jan Stastny
- Department of Botany, Faculty of Science, Charles University Prague, Prague, Czech Republic
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20
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Niedermeier M, Gierlinger N, Lütz-Meindl U. Biomineralization of strontium and barium contributes to detoxification in the freshwater alga Micrasterias. JOURNAL OF PLANT PHYSIOLOGY 2018; 230:80-91. [PMID: 30195163 DOI: 10.1016/j.jplph.2018.08.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Revised: 07/27/2018] [Accepted: 08/22/2018] [Indexed: 06/08/2023]
Abstract
The unicellular model alga Micrasterias denticulata inhabits acid peat bogs that are highly endangered by pollutants due to their high humidity. As it was known from earlier studies that algae like Micrasterias are capable of storing barium naturally in form of BaSO4 crystals, it was interesting to experimentally investigate distribution and sequestration of barium and the chemically similar alkaline earth metal strontium. Additionally, we intended to analyze whether biomineralization by crystal formation contributes to diminution of the generally toxic effects of these minerals to physiology and structure of this alga which is closely related to higher plants. The results show that depending on the treatment differently shaped crystals are formed in BaCl2 and Cl2Sr exposed Micrasterias cells. Modern microscopic techniques such as analytical TEM by electron energy loss spectroscopy and Raman microscopy provide evidence for the chemical composition of these crystals. It is shown that barium treatment results in the formation of insoluble BaSO4 crystals that develop within distinct compartments. During strontium exposure long rod-like crystals are formed and are surrounded by membranes. Based on the Raman signature of these crystals their composition is attributed to strontium citrate. These crystals are instable and are dissolved during cell death. During strontium as well as barium treatment cell division rates and photosynthetic oxygen production decreased in dependence of the concentration, whereas cell vitality was reduced only slightly. Together with the fact that TEM analyses revealed only minor ultrastructural alterations as consequence of relatively high concentrated BaCl2 and Cl2Sr exposure, this indicates that biomineralization of Sr and Ba protects the cells from severe damage or cell death at least within a particular concentration range and time period. In the case of Sr treatment where ROS levels were found to be elevated, hallmarks for autophagy of single organelles were observed by TEM, indicating beginning degradation processes.
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Affiliation(s)
- Martin Niedermeier
- University of Salzburg, Department of Biosciences, Hellbrunner Straße 34, 5020 Salzburg, Austria.
| | - Notburga Gierlinger
- BOKU-University of Natural Resources and Life Sciences, Department of Nanobiotechnology, Muthgasse 11/II, 1190 Vienna, Austria.
| | - Ursula Lütz-Meindl
- University of Salzburg, Department of Biosciences, Hellbrunner Straße 34, 5020 Salzburg, Austria.
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21
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Steiner P, Luckner M, Kerschbaum H, Wanner G, Lütz-Meindl U. Ionic stress induces fusion of mitochondria to 3-D networks: An electron tomography study. J Struct Biol 2018; 204:52-63. [PMID: 29981486 DOI: 10.1016/j.jsb.2018.06.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Revised: 06/27/2018] [Accepted: 06/30/2018] [Indexed: 01/05/2023]
Abstract
Mitochondria are central organelles for energy supply of cells and play an important role in maintenance of ionic balance. Consequently mitochondria are highly sensitive to any kind of stress to which they mainly response by disturbance of respiration, ROS production and release of cytochrome c into the cytoplasm. Many of the physiological and molecular stress reactions of mitochondria are well known, yet there is a lack of information on corresponding stress induced structural changes. 3-D visualization of high-pressure frozen cells by FIB-SEM tomography and TEM tomography as used for the present investigation provide an excellent tool for studying structure related mitochondrial stress reactions. In the present study it is shown that mitochondria in the unicellular fresh-water algal model system Micrasterias as well as in the closely related aquatic higher plant Lemna fuse to local networks as a consequence of exposure to ionic stress induced by addition of KCl, NaCl and CoCl2. In dependence on concentration and duration of the treatment, fusion of mitochondria occurs either by formation of protuberances arising from the outer mitochondrial membrane, or by direct contact of the surface of elongated mitochondria. As our results show that respiration is maintained in both model systems during ionic stress and mitochondrial fusion, as well as formation of protuberances are reversible, we assume that mitochondrial fusion is a ubiquitous process that may help the cells to cope with stress. This may occur by interconnecting the respiratory chains of the individual mitochondria and by enhancing the buffer capacity against stress induced ionic imbalance.
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Affiliation(s)
- Philip Steiner
- Department of Biosciences, University of Salzburg, Hellbrunnerstraße 34, A-5020 Salzburg, Austria
| | - Manja Luckner
- Ultrastructural Research, Faculty of Biology, Ludwig-Maximilians-University, Munich, Großhadernerstr. 2-4, D-82152 Planegg-Martinsried, Germany
| | - Hubert Kerschbaum
- Department of Biosciences, University of Salzburg, Hellbrunnerstraße 34, A-5020 Salzburg, Austria
| | - Gerhard Wanner
- Ultrastructural Research, Faculty of Biology, Ludwig-Maximilians-University, Munich, Großhadernerstr. 2-4, D-82152 Planegg-Martinsried, Germany
| | - Ursula Lütz-Meindl
- Department of Biosciences, University of Salzburg, Hellbrunnerstraße 34, A-5020 Salzburg, Austria.
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22
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Fontanini D, Andreucci A, Ruffini Castiglione M, Basile A, Sorbo S, Petraglia A, Degola F, Bellini E, Bruno L, Varotto C, Sanità di Toppi L. The phytochelatin synthase from Nitella mucronata (Charophyta) plays a role in the homeostatic control of iron(II)/(III). PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2018; 127:88-96. [PMID: 29554573 DOI: 10.1016/j.plaphy.2018.03.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Revised: 03/10/2018] [Accepted: 03/12/2018] [Indexed: 06/08/2023]
Abstract
Although some charophytes (sister group to land plants) have been shown to synthesize phytochelatins (PCs) in response to cadmium (Cd), the functional characterization of their phytochelatin synthase (PCS) is still completely lacking. To investigate the metal response and the presence of PCS in charophytes, we focused on the species Nitella mucronata. A 40 kDa immunoreactive PCS band was revealed in mono-dimensional western blot by using a polyclonal antibody against Arabidopsis thaliana PCS1. In two-dimensional western blot, the putative PCS showed various spots with acidic isoelectric points, presumably originated by post-translational modifications. Given the PCS constitutive expression in N. mucronata, we tested its possible involvement in the homeostasis of metallic micronutrients, using physiological concentrations of iron (Fe) and zinc (Zn), and verified its role in the detoxification of a non-essential metal, such as Cd. Neither in vivo nor in vitro exposure to Zn resulted in PCS activation and PC significant biosynthesis, while Fe(II)/(III) and Cd were able to activate the PCS in vitro, as well as to induce PC accumulation in vivo. While Cd toxicity was evident from electron microscopy observations, the normal morphology of cells and organelles following Fe treatments was preserved. The overall results support a function of PCS and PCs in managing Fe homeostasis in the carophyte N. mucronata.
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Affiliation(s)
| | | | | | - Adriana Basile
- Department of Biology, University of Naples "Federico II", Naples, Italy
| | - Sergio Sorbo
- CeSMA, Microscopy Section, University of Naples "Federico II", Naples, Italy
| | - Alessandro Petraglia
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parma, Italy
| | - Francesca Degola
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parma, Italy
| | - Erika Bellini
- Department of Biology, University of Pisa, Pisa, Italy; Department of Biology, University of Rome "Tor Vergata", Rome, Italy
| | - Laura Bruno
- Department of Biology, University of Rome "Tor Vergata", Rome, Italy
| | - Claudio Varotto
- Department of Biodiversity and Molecular Ecology, "Edmund Mach" Foundation, S. Michele all'Adige (TN), Italy
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23
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Fields C, Levin M. Multiscale memory and bioelectric error correction in the cytoplasm-cytoskeleton-membrane system. WILEY INTERDISCIPLINARY REVIEWS-SYSTEMS BIOLOGY AND MEDICINE 2017; 10. [DOI: 10.1002/wsbm.1410] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Revised: 08/19/2017] [Accepted: 10/04/2017] [Indexed: 12/12/2022]
Affiliation(s)
- Chris Fields
- 21 Rue des Lavandiéres, 11160 Caunes Minervois; France
| | - Michael Levin
- Allen Discovery Center at Tufts University; Medford MA USA
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24
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Neustupa J. Asymmetry and integration of cellular morphology in Micrasterias compereana. BMC Evol Biol 2017; 17:1. [PMID: 28049419 PMCID: PMC5209845 DOI: 10.1186/s12862-016-0855-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2016] [Accepted: 12/17/2016] [Indexed: 01/07/2023] Open
Abstract
Background Unicellular green algae of the genus Micrasterias (Desmidiales) have complex cells with multiple lobes and indentations, and therefore, they are considered model organisms for research on plant cell morphogenesis and variation. Micrasterias cells have a typical biradial symmetric arrangement and multiple terminal lobules. They are composed of two semicells that can be further differentiated into three structural components: the polar lobe and two lateral lobes. Experimental studies suggested that these cellular parts have specific evolutionary patterns and develop independently. In this study, different geometric morphometric methods were used to address whether the semicells of Micrasterias compereana are truly not integrated with regard to the covariation of their shape data. In addition, morphological integration within the semicells was studied to ascertain whether individual lobes constitute distinct units that may be considered as separate modules. In parallel, I sought to determine whether the main components of morphological asymmetry could highlight underlying cytomorphogenetic processes that could indicate preferred directions of variation, canalizing evolutionary changes in cellular morphology. Results Differentiation between opposite semicells constituted the most prominent subset of cellular asymmetry. The second important asymmetric pattern, recovered by the Procrustes ANOVA models, described differentiation between the adjacent lobules within the quadrants. Other asymmetric components proved to be relatively unimportant. Opposite semicells were shown to be completely independent of each other on the basis of the partial least squares analysis analyses. In addition, polar lobes were weakly integrated with adjacent lateral lobes. Conversely, higher covariance levels between the two lateral lobes of the same semicell indicated mutual interconnection and significant integration between these parts. Conclusions Micrasterias cells are composed of several successively disintegrated parts. These integration patterns concurred with presumed scenarios of morphological evolution within the lineage. In addition, asymmetric differentiation in the shape of the lobules involves two major patterns: asymmetry across the isthmus axis and among the adjacent lobules. Notably, asymmetry among the adjacent lobules may be related to evolutionary differentiation among species, but it may also point out developmental instability related to environmental factors. Electronic supplementary material The online version of this article (doi:10.1186/s12862-016-0855-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jiří Neustupa
- Department of Botany, Faculty of Science, Charles University, Prague, Czech Republic.
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25
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Schwarz V, Andosch A, Geretschläger A, Affenzeller M, Lütz-Meindl U. Carbon starvation induces lipid degradation via autophagy in the model alga Micrasterias. JOURNAL OF PLANT PHYSIOLOGY 2017; 208:115-127. [PMID: 27936433 DOI: 10.1016/j.jplph.2016.11.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Revised: 11/17/2016] [Accepted: 11/18/2016] [Indexed: 05/08/2023]
Abstract
Autophagy is regarded as crucial intracellular process in plant development but also in intracellular stress response. It is known to be controlled by the energy level of the cell and consequently can be triggered by energy deprivation. In this study carbon starvation evoked in different ways was investigated in the freshwater algae model system Micrasterias denticulata (Streptophyta) which is closely related to higher plants. Cells exposed to the photosynthesis inhibiting herbicide DCMU, to the glycolysis inhibitor 2-Deoxy-d-glucose and to complete darkness over up to 9 weeks for preventing metabolism downstream of glucose supply, were investigated by means of Nile red staining and analyses in CLSM, and TEM after cryo-preparation. Our results show that lipid bodies containing both neutral and polar lipids are evenly distributed inside the chloroplast in control cells. During carbon starvation they are displaced into the cytoplasm and are either degraded via autophagy and/or excreted from the cell. Upon discharge from the chloroplast lipid bodies become engulfed by double membranes probably deriving from the ER, thus forming autophagosomes which later fuse with vacuoles. Coincidently indications for autophagy of other organelles and cytoplasmic portions were found during starvation and particularly in DCMU treated cells the number of starch grains decreased and pyrenoids disintegrated. Additionally our molecular data provide first evidence for the existence of a single ATG8 isoform in Micrasterias. ATG8 is known as main regulator of both bulk and selective autophagy in eucaryotes. Our study indicates that lipid degradation during carbon starvation is achieved via "classical" autophagy in the alga Micrasterias. This process has so far only been very rarely observed in plant cells and seems to allow recruitment of lipids for energy supply on the one hand and elimination of unusable or toxicated lipids on the other hand.
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Affiliation(s)
- Viola Schwarz
- Plant Physiology Division, Cell Biology and Physiology Department, University of Salzburg, A-5020 Salzburg, Austria
| | - Ancuela Andosch
- Plant Physiology Division, Cell Biology and Physiology Department, University of Salzburg, A-5020 Salzburg, Austria
| | - Anja Geretschläger
- Plant Physiology Division, Cell Biology and Physiology Department, University of Salzburg, A-5020 Salzburg, Austria
| | - Matthias Affenzeller
- AG Ecology, Biodiversity and Evolution of Plants, Department of Ecology and Evolution, University of Salzburg, A-5020 Salzburg, Austria
| | - Ursula Lütz-Meindl
- Plant Physiology Division, Cell Biology and Physiology Department, University of Salzburg, A-5020 Salzburg, Austria.
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Domozych DS, Popper ZA, Sørensen I. Charophytes: Evolutionary Giants and Emerging Model Organisms. FRONTIERS IN PLANT SCIENCE 2016; 7:1470. [PMID: 27777578 PMCID: PMC5056234 DOI: 10.3389/fpls.2016.01470] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Accepted: 09/15/2016] [Indexed: 05/20/2023]
Abstract
Charophytes are the group of green algae whose ancestral lineage gave rise to land plants in what resulted in a profoundly transformative event in the natural history of the planet. Extant charophytes exhibit many features that are similar to those found in land plants and their relatively simple phenotypes make them efficacious organisms for the study of many fundamental biological phenomena. Several taxa including Micrasterias, Penium, Chara, and Coleochaete are valuable model organisms for the study of cell biology, development, physiology and ecology of plants. New and rapidly expanding molecular studies are increasing the use of charophytes that in turn, will dramatically enhance our understanding of the evolution of plants and the adaptations that allowed for survival on land. The Frontiers in Plant Science series on "Charophytes" provides an assortment of new research reports and reviews on charophytes and their emerging significance as model plants.
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Affiliation(s)
- David S. Domozych
- Department of Biology, Skidmore College, Saratoga SpringsNY, USA
- *Correspondence: David S. Domozych,
| | - Zoë A. Popper
- Botany and Plant Science, School of Natural Science, National University of IrelandGalway, Ireland
| | - Iben Sørensen
- Plant Biology Section, School of Integrative Plant Science, Cornell University, IthacaNY, USA
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