Project description:We cultivated the flavobacterium Zobellia galactanivorans DsijT with fresh brown macroalgae with distinct chemical compositions. Its capacity to use macroalgae as the sole carbon source via the secretion of extracellular enzymes, leading to extensive tissue damages, highlights a sharing pioneer degrader behavior. RNA-seq transcriptome analysis revealed a metabolic shift toward the utilization of brown algal polysaccharides during tissue degradation. A subset of genes was specifically induced in cells grown with intact algae compared to purified polysaccharides. It notably includes genes involved in protection against oxidative burst, type IX secretion system proteins and novel uncharacterized Polysaccharides Utilization Loci (PULs). Comparative growth experiments and genomics between Zobellia members brought out putative genetic determinants of the pioneer behavior of Z. galactanivorans, whose in vitro role could be further characterized. This work constitutes the first investigation of the metabolic mechanisms of bacteria mediating fresh macroalgae breakdown, and will help unravel the role of marine microbes in the fate of macroalgal biomass.
Project description:Saccharibacteria (TM7) are obligate epibionts living on the surface of their host bacteria, and strongly correlated with dysbiotic microbiomes during periodontitis and other inflammatory diseases, suggesting they are putative pathogens. However, due to the recalcitrance of TM7 cultivation, no causal research has been conducted to investigate their role in inflammatory diseases. Here, we isolated multiple TM7 species on their host bacteria from periodontitis patients. These TM7 species reduced inflammation and consequential bone loss by modulating their host bacterial pathogenicity in mouse ligature-induced periodontitis model. Two host bacterial functions involved in collagen binding and utilization of eukaryotic sialic acid were identified as required for inducing bone loss and altered by TM7 association. This down-regulation of host bacterial pathogenicity by TM7 was shown for multiple TM7/host bacteria pairs, suggesting that, in contrast to their suspected pathogenic role, TM7 could protect mammalian hosts from inflammatory damage induced by their host bacteria.
Project description:Hypnea musciformis is a red macroalga that is widely distributed in tropical and subtropical regions. It is known to contain various bioactive compounds, including sulfated polysaccharides, flavonoids, and phlorotannins. Recent studies have investigated the potential anticancer effects of extracts from Hypnea musciformis demonstrating their have cytotoxic effects on various cancer cell lines. The anticancer effects of these extracts are thought to be due to the presence of bioactive compounds, which have been shown to have antitumor and immunomodulatory effects. However, further studies are needed to fully understand the molecular mechanisms that underlie these anticancer effects and to determine their potential as therapeutic agents for cancer treatment. We have performed transcriptome and proteome analysis in liver and colon cancer human cell lines following treatment with Hypnea musciformis macroalgae extracts to characterize its anti-tumor effect in detail at the molecular level and to link transcriptome and proteome responses to the observed phenotypes in vitro. We have identified that treatment with the macroalgae extract triggers p53-mediated response at the transcriptional and protein level in liver cancer cells, in contrast to colon cancer cells in which the effects are associated with metabolic changes. Overall, the available evidence suggests that extracts from Hypnea musciformis have the potential to serve as a source of anticancer agents in liver cancer cells through the activation of a p53-mediated anti-tumor response that is linked to inhibition of cellular proliferation and induction of apoptosis.
Project description:We combined new data with previously published data to characterize the population structure of Corsican population in the context of their geographic neighbors across Eurasia and North Africa.
Project description:Plant pathogens can cause serious diseases that impact global agriculture1. Understanding how the plant immune system naturally restricts pathogen infection holds a key to sustainable disease control in modern agricultural practices. However, despite extensive studies into the molecular and genetic basis of plant defense against pathogens since the 1950s2,3, one of the most fundamental questions in plant pathology remains unanswered: how resistant plants halt pathogen growth during immune activation. In the case of bacterial infections, a major bottleneck is an inability to determine the global bacterial transcriptome and metabolic responses in planta. Here, we developed an innovative pipeline that allows for in planta high-resolution bacterial transcriptome analysis with RNA-Seq, using the model plant Arabidopsis thaliana and the foliar bacterial pathogen Pseudomonas syringae. We examined a total of 27 combinations of plant immunity and bacterial virulence mutants to gain an unprecedented insight into the bacterial transcriptomic responses during plant immunity. We were able to identify specific bacterial transcriptomic signatures that are linked to bacterial inhibition during two major forms of plant immunity: pattern-triggered immunity and effector-triggered immunity. Among them, regulation of a P. syringae sigma factor gene, involved in iron regulation and an unknown process(es), was found to play a causative role in bacterial restriction during plant immunity. This study unlocked the enigmatic mechanisms of bacterial growth inhibition during plant immunity; results have broad basic and practical implications for future study of plant diseases.
Project description:Plant pathogens can cause serious diseases that impact global agriculture1. Understanding how the plant immune system naturally restricts pathogen infection holds a key to sustainable disease control in modern agricultural practices. However, despite extensive studies into the molecular and genetic basis of plant defense against pathogens since the 1950s2,3, one of the most fundamental questions in plant pathology remains unanswered: how resistant plants halt pathogen growth during immune activation. In the case of bacterial infections, a major bottleneck is an inability to determine the global bacterial transcriptome and metabolic responses in planta. Here, we developed an innovative pipeline that allows for in planta high-resolution bacterial transcriptome analysis with RNA-Seq, using the model plant Arabidopsis thaliana and the foliar bacterial pathogen Pseudomonas syringae. We examined a total of 27 combinations of plant immunity and bacterial virulence mutants to gain an unprecedented insight into the bacterial transcriptomic responses during plant immunity. We were able to identify specific bacterial transcriptomic signatures that are linked to bacterial inhibition during two major forms of plant immunity: pattern-triggered immunity and effector-triggered immunity. Among them, regulation of a P. syringae sigma factor gene, involved in iron regulation and an unknown process(es), was found to play a causative role in bacterial restriction during plant immunity. This study unlocked the enigmatic mechanisms of bacterial growth inhibition during plant immunity; results have broad basic and practical implications for future study of plant diseases.