scholarly journals Marine and freshwater micropearls: biomineralization producing strontium-rich amorphous calcium carbonate inclusions is widespread in the genus <i>Tetraselmis</i> (Chlorophyta)

2018 ◽  
Vol 15 (21) ◽  
pp. 6591-6605 ◽  
Author(s):  
Agathe Martignier ◽  
Montserrat Filella ◽  
Kilian Pollok ◽  
Michael Melkonian ◽  
Michael Bensimon ◽  
...  
Keyword(s):  
Unicellular Alga ◽  
Amorphous Calcium Carbonate ◽  
Surrounding Water ◽  
Calcium Carbonates ◽  
Mineral Inclusions ◽  
Biomineralization Process ◽  
Unicellular Algae ◽  
Carbon Pump ◽  
Definite Pattern ◽  
Widespread Phenomenon

Abstract. Unicellular algae play important roles in the biogeochemical cycles of numerous elements, particularly through the biomineralization capacity of certain species (e.g., coccolithophores greatly contributing to the “organic carbon pump” of the oceans), and unidentified actors of these cycles are still being discovered. This is the case of the unicellular alga Tetraselmis cordiformis (Chlorophyta) that was recently discovered to form intracellular mineral inclusions, called micropearls, which had been previously overlooked. These intracellular inclusions of hydrated amorphous calcium carbonates (ACCs) were first described in Lake Geneva (Switzerland) and are the result of a novel biomineralization process. The genus Tetraselmis includes more than 30 species that have been widely studied since the description of the type species in 1878. The present study shows that many other Tetraselmis species share this biomineralization capacity: 10 species out of the 12 tested contained micropearls, including T. chui, T. convolutae, T. levis, T. subcordiformis, T. suecica and T. tetrathele. Our results indicate that micropearls are not randomly distributed inside the Tetraselmis cells but are located preferentially under the plasma membrane and seem to form a definite pattern, which differs among species. In Tetraselmis cells, the biomineralization process seems to systematically start with a rod-shaped nucleus and results in an enrichment of the micropearls in Sr over Ca (the Sr∕Ca ratio is more than 200 times higher in the micropearls than in the surrounding water or growth medium). This concentrating capacity varies among species and may be of interest for possible bioremediation techniques regarding radioactive 90Sr water pollution. The Tetraselmis species forming micropearls live in various habitats, indicating that this novel biomineralization process takes place in different environments (marine, brackish and freshwater) and is therefore a widespread phenomenon.

scholarly journals Marine and freshwater micropearls: Biomineralization producing strontium-rich amorphous calcium carbonate inclusions is widespread in the genus <i>Tetraselmis</i> (Chlorophyta)

2018 ◽  
Author(s):  
Agathe Martignier ◽  
Montserrat Filella ◽  
Kilian Pollok ◽  
Michael Melkonian ◽  
Michael Bensimon ◽  
...  
Keyword(s):  
Freshwater Species ◽  
Lake Geneva ◽  
Amorphous Calcium Carbonate ◽  
Surrounding Water ◽  
Calcium Carbonates ◽  
Mineral Inclusions ◽  
Biomineralization Process ◽  
Definite Pattern ◽  
Widespread Phenomenon ◽  
Tetraselmis Cordiformis

Abstract. The genus Tetraselmis (Chlorophyta) includes more than 30 species of unicellular micro-algae that have been widely studied since the description of the first species in 1878. Tetraselmis cordiformis (presumably the only freshwater species of the genus) was discovered recently to form intracellular mineral inclusions, called micropearls, which had been previously overlooked. These non-skeletal intracellular inclusions of hydrated amorphous calcium carbonates (ACC) were first described in Lake Geneva (Switzerland) and are the result of a novel biomineralization process. The present study shows that many Tetraselmis species share this biomineralization capacity: 10 species out of the 12 tested contained micropearls, including T. chui, T. convolutae, T. levis, T. subcordiformis, T. suecica and T. tetrathele. Our results indicate that micropearls are not randomly distributed inside the Tetraselmis cells, but are located preferentially under the plasma membrane and seem to form a definite pattern, which differs between species. In Tetraselmis cells, the biomineralization process seems to systematically start with a rod-shaped nucleus and results in an enrichment of the micropearls in strontium over calcium (the Sr / Ca ratio is up to 219 times higher in the micropearls than in the surrounding water or growth medium). This concentrating capacity varies from one species to the other, which might be of interest for possible bioremediation techniques regarding radioactive 90Sr water pollution. The Tetraselmis species forming micropearls live in various habitats, indicating that this novel biomineralization process can take place in different environments (marine, brackish and freshwater) and is therefore a widespread phenomenon.

An unsuspected biomineralization process in the green algae class Chlorodendrophyceae 

2021 ◽  
Author(s):  
Inés Segovia Campos ◽  
Agathe Martignier ◽  
Montserrat Filella ◽  
Daniel Ariztegui
Keyword(s):  
Green Algae ◽  
Water Contamination ◽  
Culture Conditions ◽  
Cellular Mechanisms ◽  
Essential Information ◽  
Calcium Carbonates ◽  
Mineral Inclusions ◽  
Biomineralization Process ◽  
Laboratory Cultures ◽  
High Concentrations

&lt;p&gt;Chlorodendrophyceae are a class of unicellular green algae widespread in the aquatic environment (seawater, brackish water, and freshwater) that have recently been discovered to form intracellular carbonates. These mineral inclusions, called &lt;em&gt;micropearls&lt;/em&gt;, are mainly composed of hydrated amorphous calcium carbonates (ACC) in which strontium can also accumulate at high concentrations. Under natural and culture conditions, the Sr/Ca ratio of micropearls can be 200 times higher than in their environment, suggesting that Chlorodendrophyceae species may be considered as potential candidates for new bioremediation methods regarding radioactive &lt;sup&gt;90&lt;/sup&gt;Sr water contamination. Because very little is known about this phenomenon, ongoing experiments with laboratory cultures are providing essential information about the cellular mechanisms involved in this newly discovered biomineralization process and its impact on the geochemical cycles of Ca and Sr.&lt;/p&gt;

scholarly journals First Observation of Unicellular Organisms Concentrating Arsenic in ACC Intracellular Inclusions in Lake Waters

Geosciences ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 32
Author(s):  
Agathe Martignier ◽  
Montserrat Filella ◽  
Jean-Michel Jaquet ◽  
Mathieu Coster ◽  
Daniel Ariztegui
Keyword(s):  
Lake Geneva ◽  
Amorphous Calcium Carbonate ◽  
Lake Titicaca ◽  
Calcium Carbonates ◽  
Unicellular Eukaryotes ◽  
Biomineralization Process ◽  
Sr:Ca Ratios ◽  
Unicellular Organisms ◽  
Lake Waters ◽  
Chemical Groups

In unicellular organisms, intracellular inclusions of amorphous calcium carbonate (ACC) were initially described in cyanobacteria and, later, in unicellular eukaryotes from Lake Geneva (Switzerland/France). Inclusions in unicellular eukaryotes, named micropearls, consist of hydrated ACCs, frequently enriched in Sr or Ba, and displaying internal oscillatory zonations, due to variations in the Ba:Ca or Sr:Ca ratios. An analysis of our database, consisting of 1597 micropearl analyses from Lake Geneva and 34 from Lake Titicaca (Bolivia/Peru), showed that a certain number of Sr- and Ba-enriched micropearls from these lakes contain As in amounts measurable by EDXS. A Q-mode statistical analysis confirmed the existence of five chemically distinct morpho-chemical groups of As-bearing micropearls, among which was a new category identified in Lake Geneva, where As is often associated with Mg. This new type of micropearl is possibly produced in a small (7–12 μm size) bi-flagellated organism. Micropearls from Lake Titicaca, which contain Sr, were found in an organism very similar to Tetraselmis cordiformis, which was observed earlier in Lake Geneva. Lake Titicaca micropearls contain larger As amounts, which can be explained by the high As concentration in the water of this lake. The ubiquity of this observed biomineralization process points to the need for a better understanding of the role of amorphous or crystalline calcium carbonates in As cycling in surface waters.

scholarly journals First Observation of Unicellular Organisms Concentrating Arsenic in ACC Intracellular Inclusions

2021 ◽  
Author(s):  
Agathe Martignier ◽  
Montserrat Filella ◽  
Jean-Michel Jaquet ◽  
Mathieu Coster ◽  
Daniel Ariztegui
Keyword(s):  
Lake Geneva ◽  
Amorphous Calcium Carbonate ◽  
Lake Titicaca ◽  
Calcium Carbonates ◽  
Unicellular Eukaryotes ◽  
Biomineralization Process ◽  
Sr:Ca Ratios ◽  
New Type ◽  
Unicellular Organisms ◽  
Chemical Groups

In unicellular organisms, intracellular inclusions of amorphous calcium carbonate (ACC) have been initially described in cyanobacteria and, later, in unicellular eukaryotes of Lake Geneva (Switzerland/France). Inclusions in unicellular eukaryotes ‒named micropearls‒ consist of hydrated ACCs, frequently enriched in Sr or Ba, displaying internal oscillatory zonations due to variations in the Ba:Ca or Sr:Ca ratios. The analysis of our database consisting of 1597 micropearl analyses from Lake Geneva and 34 from Lake Titicaca (Bolivia/Peru) has shown that a certain number of Sr and Ba-enriched micropearls from these lakes contain As in amounts measurable by EDXS. A Q-mode statistical analysis has confirmed the existence of five geochemically distinct morpho-chemical groups of As-bearing micropearls, among which a new category identified in Lake Geneva, where As is often associated with Mg. This new type of micropearl is possibly produced in a small (7-12 m size) bi-flagellated organism. Micropearls from Lake Titicaca, which contain Sr, are found in an organism very similar to Tetraselmis cordiformis, observed in Lake Geneva. Lake Titicaca micropearls contain higher As concentrations which can be explained by the high As concentration in the water of this lake. The ubiquity of the biomineralization process observed points to the need for better understanding of the role of amorphous or crystalline calcium carbonates in As cycling in surface waters.

scholarly journals Intermediates of tocopherol biosynthesis in the unicellular alga Scenedesmus obliquus. The presence of three isomeric methylphytylbenzoquinones

1987 ◽  
Vol 242 (2) ◽  
pp. 367-373 ◽  
Author(s):  
A Henry ◽  
R Powls ◽  
J F Pennock
Keyword(s):  
Carbon Atom ◽  
Hydroxy Group ◽  
Scenedesmus Obliquus ◽  
Alpha Tocopherol ◽  
Unicellular Alga ◽  
Unicellular Algae

Three isomers of methylphytylbenzoquinone have been isolated from lipids of the unicellular alga Scenedesmus obliquus, the most abundant being 2-methyl-6-phytylbenzoquinone (65% of the total). The 2-methyl-3-phytyl and 2-methyl-5-phytyl isomers amounted to 8 and 27% respectively. Previously problems have been encountered in the separation of the 3-phytyl and the 6-phytyl isomers, but in the present study it was found that they separated readily as quinols. Phytyl plastoquinone was also found and the relevance of these compounds to the biosynthesis of alpha-tocopherol is discussed. As well as phylloquinone, a hydroxyphylloquinone was detected, and studies indicated that it is the 5′ carbon atom to which the hydroxy group is attached. Such a compound has been found by workers using other unicellular algae.

scholarly journals Alien domains shaped the modular structure of plant NLR proteins

2019 ◽  
Author(s):  
Giuseppe Andolfo ◽  
Antimo Di Donato ◽  
Pasquale Chiaiese ◽  
Antonino De Natale ◽  
Antonino Pollio ◽  
...  
Keyword(s):  
Innate Immunity ◽  
Cell Surface ◽  
Surveillance System ◽  
Genomic Structure ◽  
Defense Responses ◽  
Leucine Rich Repeat ◽  
Unicellular Alga ◽  
Unicellular Algae ◽  
A Cell ◽  
Chromochloris Zofingiensis

Abstract Plant innate immunity mostly relies on nucleotide-binding (NB) and leucine-rich repeat (LRR) intracellular receptors to detect pathogen-derived molecules and to induce defense responses. A multi-taxa reconstruction of NB-domain associations allowed us to identify the first NB-LRR arrangement in the Chlorophyta division of the Viridiplantae. Our analysis points out that the basic NOD-like receptor (NLR) unit emerged in Chlorophytes by horizontal transfer and its diversification started from TIR-NB-LRR (TNL) members. The operon-based genomic structure of Chromochloris zofingiensis NLR copies suggests a functional origin of NLR clusters. Moreover, the transmembrane signatures of NLR proteins in the unicellular alga C. zofingiensis supports the hypothesis that the NLR-based immunity system of plants derives from a cell-surface surveillance system. Taken together, our findings suggest that NLRs originated in unicellular algae and may have a common origin with cell surface LRR receptors.

Arsenolipid biosynthesis by the unicellular alga Dunaliella tertiolecta is influenced by As/P ratio in culture experiments

Metallomics ◽  
2018 ◽  
Vol 10 (1) ◽  
pp. 145-153 ◽  
Author(s):  
Ronald A. Glabonjat ◽  
Josef Ehgartner ◽  
Elliott G. Duncan ◽  
Georg Raber ◽  
Kenneth B. Jensen ◽  
...  
Keyword(s):  
Dunaliella Tertiolecta ◽  
Water Soluble ◽  
Unicellular Alga ◽  
Unicellular Algae

Culture experiments exposing unicellular algae to varying arsenate/phosphate regimes and determining their arsenometallomes by HPLC–MS shows the interconnection of arsenolipids and water-soluble arsenicals.

Biogeohemical significance of Intracellular calcification by Cyanobacteria

2020 ◽  
Author(s):  
Neha Mehta ◽  
Feriel-Skouri Panet ◽  
Karim Benzerara
Keyword(s):  
Carbon Capture ◽  
Alkaline Earth ◽  
Physiological Role ◽  
Vital Role ◽  
Amorphous Calcium Carbonate ◽  
High Concentration ◽  
In Vitro Synthesis ◽  
Calcium Carbonates ◽  
Alkaline Earth Elements

&lt;p&gt;Cyanobacteria are an abundant and diverse group of photosynthetic bacteria that have shaped Earth&amp;#8217;s environment for billions of years and play a vital role in the cycling of numerous elements such as carbon, calcium, and phosphorus. In particular, their impact on the global carbon cycle is of significant interest in the context of carbon capture and climate change, as they sequester atmospheric CO&lt;sub&gt;2&lt;/sub&gt; into organic carbon and biogenic calcium carbonates (CaCO&lt;sub&gt;3&lt;/sub&gt;) through a process called calcification.&amp;#160; The process of calcification has long been considered as extracellular and non-biologically controlled. However, recently, several cyanobacterial species have been reported to form intracellular amorphous calcium carbonate (ACC) inclusions. These cyanobacteria were found in diverse&amp;#160;environments and accumulate high concentrations of AEE (Ca, Ba and Sr) from solutions&amp;#160;undersaturated with respect to AEE-carbonate phases.&amp;#160;Moreover, one of these cyanobacteria species, &lt;em&gt;G. lithophora&lt;/em&gt; was shown to selectively accumulate stable and radioactive alkaline earth elements (AEE) within the intracellular amorphous carbonates and/or polyp inclusions (Mehta et al., 2019). Recently, it was confirmed that cyanobacteria forming intracellular ACC contained a much higher content of alkaline earth elements (AEE) than all other cyanobacteria (DeWever et al., 2019). The high concentration of Ba and Sr within these intracellular inclusions was surprising because Ba and Sr have usually been considered as having no physiological role at all. The high concentration of Ca within these intracellular inclusions was directly in contrast with the traditional paradigm of cells maintaining a state of homeostasis with respect to Ca. Furthermore, Sr/Ca and Ba/Ca ratios in these ACC inclusions were very different from those expected from abiotic precipitation in the solution surrounding the cells (Cam et al. 2015). To understand the biological driver behind these observations, first, I will present a review of the above mentioned &amp;#8220;vital effects&amp;#8221; in the context of intracellular calcification in cyanobacteria. Second, using batch incubation experiments, I will show that high Ca concentrations are vital not only for the growth of &lt;em&gt;G. lithophora&lt;/em&gt;, but also for the uptake of Ba by &lt;em&gt;G. lithophora&lt;/em&gt;. Lastly, I will examine Ca homeostasis in ACC forming cyanobacterial strains by using an antagonist/inhibitor of a known channel/transporter involved in Ca transport. &amp;#160;Overall, these insights will shed some light on the role of cyanobacteria forming intracellular ACC on carbonate (bio)mineralization, in both modern and ancient Earth&amp;#8217;s environment.&amp;#160;&lt;/p&gt;&lt;p&gt;Reference:&lt;/p&gt;&lt;p&gt;N Mehta, K Benzerara, B Kocar, V Chapon, Sequestration of radionuclidesRadium-226 and Strontium-90 by cyanobacteria forming intracellular calcium carbonates, ES&amp;T 2019&lt;/p&gt;&lt;p&gt;De Wever, A.; Benzerara, K. et al. Evidence of High Ca Uptake by Cyanobacteria Forming Intracellular CaCO 3 and Impact on Their Growth. Geobiology 2019&lt;/p&gt;&lt;p&gt;Cam, N., Georgelin, T., Jaber, M., Lambert, J.-F., and Benzerara, K, In vitro synthesis of amorphous Mg-, Ca-, Sr- and Ba-carbonates: what do we learn about intracellular calcification by cyanobacteria? Geochim. Cosmochim. Acta 2015&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;

scholarly journals Nano-Hydroxyapatite Derived from Biogenic and Bioinspired Calcium Carbonates: Synthesis and In Vitro Bioactivity

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 264
Author(s):  
Francesca Cestari ◽  
Francesca Agostinacchio ◽  
Anna Galotta ◽  
Giovanni Chemello ◽  
Antonella Motta ◽  
...  
Keyword(s):  
Cell Adhesion ◽  
Calcium Carbonate ◽  
Inductively Coupled Plasma ◽  
Calcium Phosphates ◽  
Optical Emission ◽  
Molar Ratio ◽  
In Vitro Tests ◽  
Amorphous Calcium Carbonate ◽  
Calcium Carbonates

Biogenic calcium carbonates naturally contain ions that can be beneficial for bone regeneration and therefore are attractive resources for the production of bioactive calcium phosphates. In the present work, cuttlefish bones, mussel shells, chicken eggshells and bioinspired amorphous calcium carbonate were used to synthesize hydroxyapatite nano-powders which were consolidated into cylindrical pellets by uniaxial pressing and sintering 800–1100 °C. Mineralogical, structural and chemical composition were studied by SEM, XRD, inductively coupled plasma/optical emission spectroscopy (ICP/OES). The results show that the phase composition of the sintered materials depends on the Ca/P molar ratio and on the specific CaCO3 source, very likely associated with the presence of some doping elements like Mg2+ in eggshell and Sr2+ in cuttlebone. Different CaCO3 sources also resulted in variable densification and sintering temperature. Preliminary in vitro tests were carried out (by the LDH assay) and they did not reveal any cytotoxic effects, while good cell adhesion and proliferation was observed at day 1, 3 and 5 after seeding through confocal microscopy. Among the different tested materials, those derived from eggshells and sintered at 900 °C promoted the best cell adhesion pattern, while those from cuttlebone and amorphous calcium carbonate showed round-shaped cells and poorer cell-to-cell interconnection.

Temperature differentially affects the persistence of polyunsaturated aldehydes in seawater

2013 ◽  
Vol 10 (5) ◽  
pp. 403 ◽  
Author(s):  
Ana Bartual ◽  
María J. Ortega
Keyword(s):  
Organic Compounds ◽  
Rapid Growth ◽  
Algal Blooms ◽  
Seawater Temperature ◽  
Phytoplankton Species ◽  
Surrounding Water ◽  
Unicellular Algae ◽  
The Stability ◽  
Polyunsaturated Aldehydes ◽  
Water Depths

Environmental context Diatoms, unicellular algae that live suspended in the water column, can undergo periods of rapid growth, called blooms. When these algal blooms die, organic compounds including polyunsaturated aldehydes are released to the surrounding water with currently unknown ecological effects. Here we demonstrate that temperature differentially affects the persistence of three major polyunsaturated aldehydes produced by diatoms, and we quantify the removal rates from seawater of these compounds. Abstract Polyunsaturated aldehydes (PUAs) are volatile compounds commonly released into the environment by different fresh and seawater phytoplankton species. Diatoms are among the main producers of these metabolites in seawater. The release of these metabolites in seawater is known to be wound-activated as a consequence of predation or cell lysis. Hence, the interaction of phytoplankton species that produce PUAs with other marine organisms is being thoroughly investigated. However, the stability of these compounds in seaweater once they are released and their persistence under different environmental conditions have never been quantified. In this work, we reveal an important effect of seawater temperature on the persistence of dissolved 2E,4E/Z-decadienal (DECA), 2E,4E/Z-octadienal (OCTA) and 2E,4E/Z-heptadienal (HEPTA) in seawater at the nanomolar scale. These three aldehydes were more persistent at 10°C than at either 15 or 20°C. Half lives of OCTA and HEPTA were reduced from 200h at 10°C to 80h at 15°C and 60h at 20°C. In addition, DECA was consistently more persistent than OCTA and HEPTA at the three temperatures assayed. This dependence of the persistence of dissolved PUAs on seawater temperature could determine a differential effect of equivalent PUA concentrations on the diversity and plankton community’s structure at different water depths, seasons or latitudes.

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