Publications by authors named "Six C"

Cryptophytes are abundant and ubiquitous microalgae that constitute a major plastid source for kleptoplastidic ciliates and dinoflagellates. Despite their ecological significance, the understanding of their light preferences and photophysiology remains limited. Here, we provide a comprehensive study of the response of the haploid strain Teleaulax amphioxeia (Cr10EHU) to varying light irradiance.

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Dinophysis dinoflagellates are predators of Mesodinium ciliates, from which they retain only the plastids of cryptophyte origin. The absence of nuclear photosynthetic cryptophyte genes in Dinophysis raises intriguing physiological and evolutionary questions regarding the functional dynamics of these temporary kleptoplastids within a foreign cellular environment. In an experimental setup including two light conditions, the comparative analysis with Mesodinium rubrum and the cryptophyte Teleaulax amphioxeia revealed that Dinophysis acuminata possessed a smaller and less dynamic functional photosynthetic antenna for green light, a function performed by phycoerythrin.

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Marine comprise a numerically and ecologically prominent phytoplankton group, playing a major role in both carbon cycling and trophic networks in all oceanic regions except in the polar oceans. Despite their high abundance in coastal areas, our knowledge of communities in these environments is based on only a few local studies. Here, we use the global metagenome data set of the Ocean Sampling Day (June 21, 2014) to get a snapshot of the taxonomic composition of coastal communities worldwide, by recruitment on a reference database of 141 picocyanobacterial genomes, representative of the whole , , and diversity.

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This study evaluated the association between dietary patterns, Gas-Related Symptoms (GRS) and their impact on quality of life (QoL) in a representative sample (n=936) of the French adult population. During the 2018-2019 "Comportements et Consommations Alimentaires en France" (CCAF) survey (Behaviors and Food Consumption in France), online evaluation of GRS in adult participants was performed using the validated Intestinal Gas Questionnaire (IGQ), which captures the perception of GRS and their impact on QoL via 6 symptom dimensions scores (range 0-100; 100=worse) and a global score (mean of the sum of the 6 symptom dimensions scores). Socio-demographics, lifestyle parameters and dietary habits (7-day e-food diary) were also collected online.

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The most ubiquitous cyanobacteria, , have colonized different marine thermal niches through the evolutionary specialization of lineages adapted to different ranges of temperature seawater. We used the strains of temperature ecotypes to study how light utilization has evolved in the function of temperature. The tropical (clade II) was unable to grow under 16 °C but, at temperatures >25 °C, induced very high growth rates that relied on a strong synthesis of the components of the photosynthetic machinery, leading to a large increase in photosystem cross-section and electron flux.

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Article Synopsis
  • - Dinoflagellates, important parts of phytoplankton, often host parasites that can digest their nuclei, which impacts the dinoflagellates' metabolism and energy production.
  • - A study showed that despite the digestion of the dinoflagellate nucleus by the parasite, its chloroplasts remained functional throughout the infection, maintaining photosystem II activity.
  • - The research indicated that light increased parasite production and that organelles like mitochondria and chloroplasts continued to function better than nuclear genes during the infection, suggesting a mutual benefit for both the parasite and the host's bioenergetic systems.
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  • Free-living red coralline algae play a crucial role in coastal carbon and carbonate cycles, with the study focusing on maerl beds in the Bay of Brest, predominantly featuring Lithothamnion corallioides.
  • The research assessed how seasonal changes and local environmental factors influence the physiology of different maerl species, examining aspects like respiration, photosynthesis, and calcification rates.
  • Findings indicate that L. corallioides is best suited for local conditions, exhibiting resilience to dark dissolution in winter and high light calcification, while variations in the algae's morphology and environmental factors also significantly impact their metabolic performance.
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Marine picocyanobacteria of the genera and are the most abundant photosynthetic organisms on Earth, an ecological success thought to be linked to the differential partitioning of distinct ecotypes into specific ecological niches. However, the underlying processes that governed the diversification of these microorganisms and the appearance of niche-related phenotypic traits are just starting to be elucidated. Here, by comparing 81 genomes, including 34 new , we explored the evolutionary processes that shaped the genomic diversity of picocyanobacteria.

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Understanding how microorganisms adjust their metabolism to maintain their ability to cope with short-term environmental variations constitutes one of the major current challenges in microbial ecology. Here, the best physiologically characterized marine strain, WH7803, was exposed to modulated light/dark cycles or acclimated to continuous high-light (HL) or low-light (LL), then shifted to various stress conditions, including low (LT) or high temperature (HT), HL and ultraviolet (UV) radiations. Physiological responses were analyzed by measuring time courses of photosystem (PS) II quantum yield, PSII repair rate, pigment ratios and global changes in gene expression.

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Objectives And Method: We conducted a prospective study in 2013 to compare the whole-cell versus acellular pertussis vaccines effectiveness and duration of protection, following the occurrence of pertussis clusters.

Results: During seven school outbreaks, we identified 102 clinical pertussis cases, including 10 cases biologically confirmed by Bordetella pertussis specific PCR, among a cohort of 305 children in 2nd to 6th grade. The risk of pertussis when vaccinated with an acellular vaccine alone was 1.

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Background: Although cancer-related fatigue (CRF) has gained increased attention in the past decade, therapy remains a challenge. Treatment programs are more likely to be effective if the needs and interests of the persons involved are well represented. This can be achieved by stakeholder engagement.

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DNA vaccines expressing codon-optimized Venezuelan equine encephalitis virus (VEEV) and Ebola virus (EBOV) glycoprotein genes provide protective immunity to mice and nonhuman primates when delivered by intramuscular (IM) electroporation (EP). To achieve equivalent protective efficacy in the absence of EP, we evaluated VEEV and EBOV DNA vaccines constructed using minimalized Nanoplasmid expression vectors that are smaller than conventional plasmids used for DNA vaccination. These vectors may also be designed to co-express type I interferon inducing innate immune agonist genes that have an adjuvant effect.

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The wide latitudinal distribution of marine Synechococcus cyanobacteria partly relies on the differentiation of lineages adapted to distinct thermal environments. Membranes are highly thermosensitive cell components, and the ability to modulate their fluidity can be critical for the fitness of an ecotype in a particular thermal niche. We compared the thermophysiology of Synechococcus strains representative of major temperature ecotypes in the field.

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Venezuelan equine encephalitis virus (VEEV) is a known biological defense threat. A live-attenuated investigational vaccine, TC-83, is available, but it has a high non-response rate and can also cause severe reactogenicity. We generated two novel VEE vaccine candidates using self-amplifying mRNA (SAM).

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Pelagic cyanobacteria are key players in the functioning of aquatic ecosystems, and their viruses (cyanophages) potentially affect the abundance and composition of cyanobacterial communities. Yet, there are few well-described freshwater cyanophages relative to their marine counterparts, and in general, few cyanosiphoviruses (family ) have been characterized, limiting our understanding of the biology and the ecology of this prominent group of viruses. Here, we characterize S-LBS1, a freshwater siphovirus lytic to a phycoerythrin-rich isolate (Strain TCC793).

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We have previously shown that DNA vaccines expressing codon-optimized alphavirus envelope glycoprotein genes protect both mice and non-human primates from viral challenge when delivered by intramuscular electroporation (IM-EP). To determine if we could achieve equivalent immunogenicity and protective efficacy in the absence of electroporation, we co-delivered our Venezuelan equine encephalitis virus (VEEV) DNA vaccine with DNA plasmids expressing genetic adjuvants designed to augment immune responses. We tested the T1-inducing cytokine IL-12 as well as the granulocyte growth factor GM-CSF, both of which have demonstrated significant adjuvant effect when included in clinical DNA vaccine formulations.

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Photosynthetic picoeukaryotesx in the genus Micromonas show among the widest latitudinal distributions on Earth, experiencing large thermal gradients from poles to tropics. Micromonas comprises at least four different species often found in sympatry. While such ubiquity might suggest a wide thermal niche, the temperature response of the different strains is still unexplored, leaving many questions as for their ecological success over such diverse ecosystems.

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In previous studies, we showed that deoxyribonucleic acid (DNA) vaccines expressing codon-optimized filovirus envelope glycoprotein genes protect mice and nonhuman primates from viral challenge when delivered by intramuscular (IM) electroporation (EP). To determine whether we could achieve equivalent immunogenicity and protective efficacy by a simplified delivery method, we generated DNA vaccine plasmids expressing genetic adjuvants to potentiate immune responses. We tested the Th1-inducing cytokine interleukin-12 and the granulocyte growth factor granulocyte-macrophage colony stimulating factor, both of which have demonstrated significant adjuvant effect when included in clinical DNA vaccine formulations.

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Article Synopsis
  • The PsbU and PsbV proteins are crucial for stabilizing the oxygen-evolving complex in photosystem II, but many marine cyanobacteria, like Prochlorococcus, do not have these proteins yet still retain PsbO.
  • A study comparing different Prochlorococcus strains revealed that while some strains lacking PsbU and PsbV had lower oxygen evolution rates, others adapted well under high light conditions, indicating PsbO may be enough for efficient oxygen production.
  • The research also found that Prochlorococcus can have negative net oxygen evolution rates in low light, which could explain the low oxygen levels in environments where they thrive, suggesting their role as key oxyphototrophs.
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All characterized members of the ubiquitous genus Acaryochloris share the unique property of containing large amounts of chlorophyll (Chl) d, a pigment exhibiting a red absorption maximum strongly shifted towards infrared compared to Chl a. Chl d is the major pigment in these organisms and is notably bound to antenna proteins structurally similar to those of Prochloron, Prochlorothrix and Prochlorococcus, the only three cyanobacteria known so far to contain mono- or divinyl-Chl a and b as major pigments and to lack phycobilisomes. Here, we describe RCC1774, a strain isolated from the foreshore near Roscoff (France).

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Background: Although cancer-related fatigue (CRF) has gained increased attention in the past decade, it remains difficult to treat. An integrative approach combining conventional and complementary medicine interventions seems highly promising. Treatment programs are more likely to be effective if the needs and interests of the people involved are well represented.

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The marine cyanobacteria of the genus Synechococcus are important primary producers, displaying a wide latitudinal distribution that is underpinned by diversification into temperature ecotypes. The physiological basis underlying these ecotypes is poorly known. In many organisms, regulation of membrane fluidity is crucial for acclimating to variations in temperature.

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The green picoalgal genus Micromonas is broadly distributed in estuaries, coastal marine habitats and open oceans, from the equator to the poles. Phylogenetic, ecological and genomic analyses of culture strains and natural populations have suggested that this cosmopolitan genus is composed of several cryptic species corresponding to genetic lineages. We performed a detailed analysis of variations in morphology, pigment content, and sequences of the nuclear-encoded small-subunit rRNA gene and the second internal transcribed spacer (ITS2) from strains isolated worldwide.

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Crimean-Congo hemorrhagic fever virus (CCHFV) is a tick-borne virus capable of causing a severe hemorrhagic fever disease in humans. There are currently no licensed vaccines to prevent CCHFV-associated disease. We developed a DNA vaccine expressing the M-segment glycoprotein precursor gene of CCHFV and assessed its immunogenicity and protective efficacy in two lethal mouse models of disease: type I interferon receptor knockout (IFNAR-/-) mice; and a novel transiently immune suppressed (IS) mouse model.

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Iron is an essential micronutrient involved in many biological processes and is often limiting for primary production in large regions of the World Ocean. Metagenomic and physiological studies have identified clades or ecotypes of marine phytoplankton that are specialized in iron depleted ecological niches. Although less studied, eukaryotic picophytoplankton does contribute significantly to primary production and carbon transfer to higher trophic levels.

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