DSpace Angular :: Browsing by Author "Díez, Beatriz"

Browsing by Author "Díez, Beatriz"

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Bacterial community structure in a sympagic habitat expanding with global warming: brackish ice brine at 85-90 degrees N
(2019) Fernández Gómez, Beatriz; Díez, Beatriz; Polz, Martin F.; Arroyo González, José Ignacio; Alfaro, Fernando D.; Marchandon, Germán; Sanhueza, Cynthia; Farías, Laura; Trefault Carrillo, Nicole Natalie; Marquet, P. A. (Pablo A.); Molina Montenegro, Marco A.; Sylvander, Peter; Snoeijs-Leijonmalm, Pauline
Compensatory Transcriptional Response of Fischerella thermalis to Thermal Damage of the Photosynthetic Electron Transfer Chain
(2022) Vergara-Barros, Pablo; Alcorta Loyola, Jaime Andrés; Casanova-Katny, Angélica; Nürnberg, Dennis J.; Díez, Beatriz
Key organisms in the environment, such as oxygenic photosynthetic primary producers (photosynthetic eukaryotes and cyanobacteria), are responsible for fixing most of the carbon globally. However, they are affected by environmental conditions, such as temperature, which in turn affect their distribution. Globally, the cyanobacterium Fischerella thermalis is one of the main primary producers in terrestrial hot springs with thermal gradients up to 60 °C, but the mechanisms by which F. thermalis maintains its photosynthetic activity at these high temperatures are not known. In this study, we used molecular approaches and bioinformatics, in addition to photophysiological analyses, to determine the genetic activity associated with the energy metabolism of F. thermalis both in situ and in high-temperature (40 °C to 65 °C) cultures. Our results show that photosynthesis of F. thermalis decays with temperature, while increased transcriptional activity of genes encoding photosystem II reaction center proteins, such as PsbA (D1), could help overcome thermal damage at up to 60 °C. We observed that F. thermalis tends to lose copies of the standard G4 D1 isoform while maintaining the recently described D1INT isoform, suggesting a preference for photoresistant isoforms in response to the thermal gradient. The transcriptional activity and metabolic characteristics of F. thermalis, as measured by metatranscriptomics, further suggest that carbon metabolism occurs in parallel with photosynthesis, thereby assisting in energy acquisition under high temperatures at which other photosynthetic organisms cannot survive. This study reveals that, to cope with the harsh conditions of hot springs, F. thermalis has several compensatory adaptations, and provides emerging evidence for mixotrophic metabolism as being potentially relevant to the thermotolerance of this species. Ultimately, this work increases our knowledge about thermal adaptation strategies of cyanobacteria.
Ecogenomics and Adaptation Strategies of Southern Ocean Viral Communities
(2021) Alarcón-Schumacher, Tomás ; Guajardo-Leiva, Sergio ; Martinez-Garcia, Manuel ; Díez, Beatriz; Bernstein, Hans C.
The Southern Ocean (SO) represents up to one-fifth of the total carbon drawdown worldwide. Intense selective pressures (low temperature, high UV radiation, and strong seasonality) and physical isolation characterize the SO, serving as a "natural" laboratory for the study of ecogenomics and unique adaptations of endemic viral populations. Here, we report 2,416 novel viral genomes from the SO, obtained from newly sequenced viral metagenomes in combination with mining of publicly available data sets, which represents a 25% increase in the SO viral genomes reported to date. They comprised 567 viral clusters (defined as approximately genus-level groups), with 186 genera endemic to the SO, demonstrating that the SO viral community is predominantly constituted by a large pool of genetically divergent viral species from widespread viral families. The predicted proteome from SO viruses revealed that several protein clusters related to cold-shock-event responses and quorum-sensing mechanisms involved in the lysogenic-lytic cycle shift decision were under positive selection, which is ultimately important for fine adaptation of viral populations in response to the strong selective pressures of the SO. Finally, changes in the hydrophobicity patterns and amino acid frequencies suggested marked temperature-driven genetic selection of the SO viral proteome. Our data provide valuable insights into how viruses adapt and remain successful in this extreme polar marine environment.
Fischerella thermalis: a model organism to study thermophilic diazotrophy, photosynthesis and multicellularity in cyanobacteria
(2019) Alcorta Loyola, Jaime Andrés; Vergara-Barros, Pablo; Antonaru, Laura A.; Alcamán-Arias, María E.; Nürnberg, Dennis J.; Díez, Beatriz
The true-branching cyanobacterium Fischerella thermalis (also known as Mastigocladus laminosus) is widely distributed in hot springs around the world. Morphologically, it has been described as early as 1837. However, its taxonomic placement remains controversial. F. thermalis belongs to the same genus as mesophilic Fischerella species but forms a monophyletic clade of thermophilic Fischerella strains and sequences from hot springs. Their recent divergence from freshwater or soil true-branching species and the ongoing process of specialization inside the thermal gradient make them an interesting evolutionary model to study. F. thermalis is one of the most complex prokaryotes. It forms a cellular network in which the main trichome and branches exchange metabolites and regulators via septal junctions. This species can adapt to a variety of environmental conditions, with its photosynthetic apparatus remaining active in a temperature range from 15 to 58 °C. Together with its nitrogen-fixing ability, this allows it to dominate in hot spring microbial mats and contribute significantly to the de novo carbon and nitrogen input. Here, we review the current knowledge on the taxonomy and distribution of F. thermalis, its morphological complexity, and its physiological adaptations to an extreme environment.
Genomic Features for Desiccation Tolerance and Sugar Biosynthesis in the Extremophile Gloeocapsopsis sp. UTEX B3054
(2019) Urrejola, Catalina; Alcorta Loyola, Jaime Andrés; Salas, Loreto; Vásquez, Mónica; Polz, Martin; Vicuña, Rafael; Díez, Beatriz
For tolerating extreme desiccation, cyanobacteria are known to produce both compatible solutes at intracellular level and a copious amount of exopolysaccharides as a protective coat. However, these molecules make cyanobacterial cells refractory to a broad spectrum of cell disruption methods, hindering genome sequencing, and molecular studies. In fact, few genomes are already available from cyanobacteria from extremely desiccated environments such as deserts. In this work, we report the 5.4 Mbp draft genome (with 100% of completeness in 105 contigs) of Gloeocapsopsis sp. UTEX B3054 (subsection I; Order Chroococcales), a cultivable sugar-rich and hardly breakable hypolithic cyanobacterium from the Atacama Desert. Our in silico analyses focused on genomic features related to sugar-biosynthesis and adaptation to dryness. Among other findings, screening of Gloeocapsopsis genome revealed a unique genetic potential related to the biosynthesis and regulation of compatible solutes and polysaccharides. For instance, our findings showed for the first time a novel genomic arrangement exclusive of Chroococcaceae cyanobacteria associated with the recycling of trehalose, a compatible solute involved in desiccation tolerance. Additionally, we performed a comparative genome survey and analyses to entirely predict the highly diverse pool of glycosyltransferases enzymes, key players in polysaccharide biosynthesis and the formation of a protective coat to dryness. We expect that this work will set the fundamental genomic framework for further research on microbial tolerance to desiccation and to a wide range of other extreme environmental conditions. The study of microorganisms like Gloeocapsopsis sp. UTEX B3054 will contribute to expand our limited understanding regarding water optimization and molecular mechanisms allowing extremophiles to thrive in xeric environments such as the Atacama Desert.
Global phylogenomic novelty of the Cas1 gene from hot spring microbial communities
(2022) Salgado Salgado, Oscar; Guajardo-Leiva, Sergio; Moya-Beltrán, Ana; Barbosa, Carla; Ridley, Christina; Tamayo-Leiva, Javier; Quatrini, Raquel; Mojica, Francisco; Díez, Beatriz
The Cas1 protein is essential for the functioning of CRISPR-Cas adaptive systems. However, despite the high prevalence of CRISPR-Cas systems in thermophilic microorganisms, few studies have investigated the occurrence and diversity of Cas1 across hot spring microbial communities. Phylogenomic analysis of 2,150 Cas1 sequences recovered from 48 metagenomes representing hot springs (42–80°C, pH 6–9) from three continents, revealed similar ecological diversity of Cas1 and 16S rRNA associated with geographic location. Furthermore, phylogenetic analysis of the Cas1 sequences exposed a broad taxonomic distribution in thermophilic bacteria, with new clades of Cas1 homologs branching at the root of the tree or at the root of known clades harboring reference Cas1 types. Additionally, a new family of casposases was identified from hot springs, which further completes the evolutionary landscape of the Cas1 superfamily. This ecological study contributes new Cas1 sequences from known and novel locations worldwide, mainly focusing on under-sampled hot spring microbial mat taxa. Results herein show that circumneutral hot springs are environments harboring high diversity and novelty related to adaptive immunity systems.
Temperature modulates Fischerella thermalis ecotypes in Porcelana Hot Spring
(2018) Alcorta Loyola, Jaime Andrés; Espinoza Lara, Sebastián Andrés; Tomeu, Viver; Alcaman Arias, María E.; Trefault Carrillo, Nicole Natalie; Rosselló-Móra, Ramon; Díez, Beatriz

Browsing by Author "Díez, Beatriz"

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