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Chlorodendrophyceae are a class of green microalgae that have recently been discovered to form intracellular inclusions of stable amorphous calcium carbonate (ACC) that can be highly enriched in strontium. These mineral inclusions are called micropearls and are the result of a traditionally overlooked biomineralization process that is not yet fully understood. By adopting a multidisciplinary approach, the present work provides new insights into the micropearl formation process and its physiological role. Experiments performed with laboratory cultures of Tetraselmis chui suggest that micropearls must play an essential role in the species forming them and show that their formation requires high calcium and strontium uptake by the cells. Analysis of T. chui complete genome and transcriptome has allowed to identify for the first time a series of proteins that could be potentially involved in the micropearl formation process, including several calcium and bicarbonate transport proteins as well as carbonic anhydrases. Finally, this work evidences the high potential of micropearl-forming species to be used as bioremediation agents targeting strontium-90 contamination in aquatic environments.

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 micropearls, 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 90Sr 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.

Temperature and light play a crucial role in regulating phytoplankton blooms in the Ocean. To assess the importance of these two parameters experimentally, microcosms were conducted on seven picoplankton communities (

The adaptive strategy of Tetraselmis indica to survive darkness was evaluated over a period of 182 days. Resting cells formation and reduction in catabolic activity facilitated dark survival and th...

We report here the first mitogenome sequences for the chlorophyte class Chlorodendrophyceae. The mitogenomes of Tetraselmis sp. CCMP 881 and Scherffelia dubia (SAG 17.86) are 46,904 bp and ...

Tetraselmis desikacharyi is a marine alga, known as an important plankton for aquaculture as a feed organism. However, the genomic study on this class is rare. Here, we present a complete Chlorodendrophyceae chloroplast genome of T. desikacharyi, belonging to Chlorodendrophyceae with a full length of 149,934bp, characterized by a very small single-copy (SSC) region without any genes and a large inverted repeat (IR) region. A maximum-likelihood (ML) phylogenetic analysis was performed using three kinds of data comprising 50 protein-coding genes, which placed the Chlorodendrophyceae as a deep-diverging lineage of the core Chlorophyta.nnT. desikacharyi, characterized by their intense green colored chloroplast, is important for aquaculture as a feed organism, and for studying plankton growth cycles due to their fast growth rate (Arora et al., 2013; Norris et al., 1980). However, only two chloroplast genomes have been published in ...

The present work uncovers a potentially ancient but yet undescribed biomineralization process, in which unicellular planktonic eukaryotes produce multiple intracellular inclusions of near-amorphous calcium carbonate (ACC), called micropearls. This process is not linked to a specific habitat and occurs in multiple areas around the world in marine, brackish and freshwater environments. This unsuspected biomineralization capacity was discovered to be common in the Tetraselmis genus (Chlorodendrophyceae, Chlorophyta). In these organisms, the micropearls may be slightly enriched in strontium and their arrangement forms a pattern (alignements linked to the chloroplast shape), which is characteristic for a given species. Another organism forming micropearls highly enriched in barium was detected in Lake Geneva (Switzerland). It is still unidentified, but might belong to the zooplankton. All the micropearls seem to result of a biologically controlled process. They represent a new physiological feature for eukaryotes.

Especies del genero Tetraselmis (Chlorodendrophyceae, Chlorophyta) han sido tradicionalmente usadas en centros acuicolas como alimento para larvas de una variedad de organismos marinos. Adicionalmente, algunas cepas con alto contenido de lipidos han sido recientemente consideradas como fuente potencial para la produccion de biodiesel. Aunque muchas especies de Tetraselmis se encuentran morfologica y ultraestructuralmente bien caracterizadas, todavia hay ambiguedades taxonomicas al interior del genero. El analisis de secuencias de ADN, una herramienta complementaria y conveniente para delimitar especies, ha sido pobremente utilizado en Tetraselmis. En este estudio, se caracterizaron tres cepas de Tetraselmis, aisladas de aguas costeras chilenas, utilizando un enfoque integrativo (morfologia, ultraestructura y filogenia molecular). Basado en la ultraestructura del pirenoide de las cepas estudiadas, dos de ellas (Dichato y Coliumo) pertenecen al subgenero Parviselmis, mientras que la cepa de Caldera corresponde al subgenero Tetrathele. Aunque no fue posible identificar las cepas a nivel especifico, el analisis filogenetico de las secuencias ITS-1 e ITS-2 y la estructura secundaria del ITS-2 demostraron claramente que las cepas de Dichato y Coliumo son la misma especie, y podrian pertenecer a T. suecica o a T. chui, mientras que la cepa de Caldera podria corresponder a una especie no descrita aun para la ciencia. Los resultados obtenidos demuestran la necesidad de llevar a cabo una revision taxonomica del genero Tetraselmis, utilizando un enfoque integrativo, el cual incluya las cepas autenticas de las especies.