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 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 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.

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.

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 The molecular evolution of the vertebrate behavioural repertoire

2016 ◽  
Vol 371 (1685) ◽  
pp. 20150051 ◽  
Author(s):  
Seth G. N. Grant
Keyword(s):  
Molecular Mechanisms ◽  
Gene Mutations ◽  
Behavioural Disorders ◽  
Major Question ◽  
Unicellular Eukaryotes ◽  
General Importance ◽  
Duplication Events ◽  
Genomic Studies ◽  
Unicellular Organisms ◽  
Behavioural Repertoire

How the sophisticated vertebrate behavioural repertoire evolved remains a major question in biology. The behavioural repertoire encompasses the set of individual behavioural components that an organism uses when adapting and responding to changes in its external world. Although unicellular organisms, invertebrates and vertebrates share simple reflex responses, the fundamental mechanisms that resulted in the complexity and sophistication that is characteristic of vertebrate behaviours have only recently been examined. A series of behavioural genetic experiments in mice and humans support a theory that posited the importance of synapse proteome expansion in generating complexity in the behavioural repertoire. Genome duplication events, approximately 550 Ma, produced expansion in the synapse proteome that resulted in increased complexity in synapse signalling mechanisms that regulate components of the behavioural repertoire. The experiments demonstrate the importance to behaviour of the gene duplication events, the diversification of paralogues and sequence constraint. They also confirm the significance of comparative proteomic and genomic studies that identified the molecular origins of synapses in unicellular eukaryotes and the vertebrate expansion in proteome complexity. These molecular mechanisms have general importance for understanding the repertoire of behaviours in different species and for human behavioural disorders arising from synapse gene mutations.

scholarly journals Linking environmental observations and solid solution thermodynamic modeling: the case of Ba- and Sr-rich micropearls in Lake Geneva

2017 ◽  
Vol 89 (5) ◽  
pp. 645-652 ◽  
Author(s):  
Bruno Thien ◽  
Agathe Martignier ◽  
Jean-Michel Jaquet ◽  
Montserrat Filella
Keyword(s):  
Solid Solution ◽  
Trace Elements ◽  
Thermodynamic Modeling ◽  
Lake Geneva ◽  
Calcium Carbonates ◽  
Lake Waters ◽  
Non Equilibrium

AbstractIntracellular inclusions of amorphous Ba- and Sr-rich calcium carbonates – referred to as “micropearls”– have recently been detected in Lake Geneva. These micropearls are formed under conditions of pronounced Ba and Sr undersaturation in the lake waters. Their formation can be explained by the ability of certain microorganisms to preconcentrate these trace elements in tandem with a non-equilibrium solid-solution growing mechanism.

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 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.

scholarly journals Lipidomics ofThalassiosira pseudonanaunder Phosphorus Stress Reveal Underlying Phospholipid Substitution Dynamics and Novel Diglycosylceramide Substitutes

2018 ◽  
Vol 84 (6) ◽  
Author(s):  
Jonathan E. Hunter ◽  
Joost Brandsma ◽  
Marcus K. Dymond ◽  
Grielof Koster ◽  
C. Mark Moore ◽  
...  
Keyword(s):  
Membrane Lipids ◽  
Thalassiosira Pseudonana ◽  
Content Type ◽  
Biochemical Processes ◽  
Chemical Structures ◽  
P Limitation ◽  
New Type ◽  
Unicellular Organisms ◽  
The Individual ◽  
Successive Generations

ABSTRACTPhytoplankton replace phosphorus-containing lipids (P-lipids) with non-P analogues, boosting growth in P-limited oceans. In the model diatomThalassiosira pseudonana, the substitution dynamics of lipid headgroups are well described, but those of the individual lipids, differing in fatty acid composition, are unknown. Moreover, the behavior of lipids outside the common headgroup classes and the relationship between lipid substitution and cellular particulate organic P (POP) have yet to be reported. We investigated these through the mass spectrometric lipidomics of P-replete (P+) and P-depleted (P−)T. pseudonanacultures. Nonlipidic POP was depleted rapidly by the initiation of P stress, followed by the cessation of P-lipid biosynthesis and per-cell reductions in the P-lipid levels of successive generations. Minor P-lipid degradative breakdown was observed, releasing P for other processes, but most P-lipids remained intact. This may confer an advantage on efficient heterotrophic lipid consumers in P-limited oceans. Glycerophosphatidylcholine (PC), the predominant P-lipid, was similar in composition to its betaine substitute lipid. During substitution, PC was less abundant per cell and was more highly unsaturated in composition. This may reflect underlying biosynthetic processes or the regulation of membrane biophysical properties subject to lipid substitution. Finally, levels of several diglycosylceramide lipids increased as much as 10-fold under P stress. These represent novel substitute lipids and potential biomarkers for the study of P limitationin situ, contributing to growing evidence highlighting the importance of sphingolipids in phycology. These findings contribute much to our understanding of P-lipid substitution, a powerful and widespread adaptation to P limitation in the oligotrophic ocean.IMPORTANCEUnicellular organisms replace phosphorus (P)-containing membrane lipids with non-P substitutes when P is scarce, allowing greater growth of populations. Previous research with the model diatom speciesThalassiosira pseudonanagrouped lipids by polar headgroups in their chemical structures. The significance of the research reported here is threefold. (i) We described the individual lipids within the headgroups during P-lipid substitution, revealing the relationships between lipid headgroups and hinting at the underlying biochemical processes. (ii) We measured total cellular P, placing P-lipid substitution in the context of the broader response to P stress and yielding insight into the implications of substitution in the marine environment. (iii) We identified lipids previously unknown in this system, revealing a new type of non-P substitute lipid, which is potentially useful as a biomarker for the investigation of P limitation in the ocean.

scholarly journals Synchronized emergence under diatom sperm competition

2020 ◽  
Vol 287 (1936) ◽  
pp. 20201074
Author(s):  
Yuka Shirokawa ◽  
Masakazu Shimada
Keyword(s):  
Evolutionary Game ◽  
Cell Interaction ◽  
Mitotic Division ◽  
Substantial Part ◽  
Centric Diatom ◽  
Unicellular Eukaryotes ◽  
Cellular Decision Making ◽  
Dividing Cells ◽  
Unicellular Organisms ◽  
Mating Time

Appropriate timing of mating is crucial for the success of individuals. However, we know little about factors that explain variation in mating time in unicellular organisms. Unicellular eukaryotes often have facultative sexuality, that is, the less frequent sex is occasionally induced after long clonal reproduction. Thus, males originated from clonemates could be non-negligible mating rivals. Using a centric diatom whose clonal cells differentiate into either male or female, we analysed whether males (spermatogonium) compete or cooperate with each other. By analysing differentiation timing with hypotheses based on evolutionary game theory, we estimated that a substantial part of the variation in the mating timing of the diatom can be explained by results of optimization through interactions among selfish individuals rather than cooperation among clonemates. However, the competition is fiercer than expected owing to excessive synchronization, which was realized by adjustment of meiotic duration: cells completed mitotic division in the earlier mating phase took longer to enter into meiosis, whereas late-dividing cells entered into meiosis more quickly. Adjacent cells tended to synchronize, and model analyses suggest that cell–cell interaction can create a gap between the optimal and actual decisions. Our results provide insights into the evolution of cellular decision making and its restriction.

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