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Biology subjects

Millet, Y.

Publications and source records attributed to Millet, Y..

2 recordsLinked to original sources

Synthetic glycans that control gut microbiome structure mitigate colitis in mice

Relative abundances of bacterial species in the gut microbiome have been linked to many diseases. Species of gut bacteria are ecologically differentiated by their abilities to metabolize different glycans, making glycan delivery a powerful way to alter the microbiome to promote health. We describe the properties and therapeutic potential of chemically diverse synthetic glycans (SGs). Fermentation of SGs by gut microbiome cultures resulted in compound-specific shifts in taxonomic and metabolite profiles not observed with reference glycans, including prebiotics. Model enteric pathogens grow poorly on most SGs, potentially increasing their safety for at-risk populations. SGs increased survival, reduced weight loss, and improved clinical scores in mouse models of colitis. Synthetic glycans are thus a promising modality to improve health through selective changes to the gut microbiome.

microbiology↗

A screen for mutants deficient in coronatine-mediated suppression of root immunity identifies Arabidopsis SDA1 as a novel integrator of immunity and phytohormone signaling

Despite the importance of the root immune system in the interaction with rhizosphere microbes, the majority of genetic screens for immunity regulators have been performed in leaves. A previous screen identified 27 hsm (hormone-mediated suppression of MAMP-triggered immunity) mutants that are impaired in jasmonic acid (JA)-mediated suppression of pattern-triggered immunity (PTI) in roots. Here we characterized 16 of the hsm mutants that retain JA sensitivity and are potential negative regulators of root immunity. We found that the majority of hsm mutants show enhanced resistance to Fusarium, a root fungal pathogen; however, only a subset are more resistant to a foliar pathogen. Surprisingly, 12 of 16 hsm mutants are also impaired in abscisic acid (ABA)-mediated suppression of PTI, suggesting a largely shared pathway between JA- and ABA-mediated immune suppression in roots. Although all hsm mutants are insensitive to JA-mediated suppression of root immunity, hsm4 shows hypersensitivity to JA-mediated root growth inhibition and JA-induced gene expression. Consistently, hsm4 is more resistant to leaf pathogens, suggesting that HSM4 is a negative regulator of both root and leaf immunity. Hsm4 was mapped to a mutation in a conserved ARM-repeat protein homologous to yeast SDA1, which has been reported to regulate 60S ribosome biogenesis. As translational reprogramming is a critical layer of immune regulation, this work suggests that AtSDA1 is a novel negative translational regulator of immunity. Additionally, a comprehensive characterization of all 16 hsm mutants provides a genetic toolkit to identify novel mechanisms that regulate root immunity.

plant biology↗