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PNAS Papers on Dietary Fiber Effects, Mushroom Toxin Genes, Retinal Degenerative Disease

A Washington University-led team looks at dietary fiber effects on gut microbial communities and blood plasma protein levels, particularly when it came to pea endosperm- or orange pulp-based snacks. Using targeted or shotgun sequencing and computational analyses, the team characterized microbial community components and microbial genes in fecal samples from individuals with specific snack supplements, focusing on carbohydrate-active enzymes such as glycoside hydrolases or polysaccharide lyases. Together with mass spec-based proteomic profiles on fecal and blood plasma samples, the results offer provide "a way to connect changes in consumer microbiomes produce by specific fiber types with host responses in the context of varying background diets," the authors explain. "This approach can be used to guide the design of fiber-containing snacks that more precisely manipulate microbiome features in ways that improve nutritional and health status."

A team from China, the US, and France considers the roots of alpha-amanitin toxin formation in unrelated poisonous mushrooms. Using more than a dozen genome sequences from Amanita, Lepiota, and Galerina mushroom species, together with phylogenetic and comparative analyses, the researchers saw signs of horizontal gene transfer for genes coding for oxygenase enzymes involved in amanitin biosynthesis. "Our analysis of multiple genomes showed that the evolution of alpha-amanitin biosynthetic pathways in the poisonous agarics in the Amanita, Lepiota, and Galerina clades entailed distinct evolutionary pathways include gene family expansion, biosynthetic genes, and genomic rearrangements," they write, noting that "[u]nrelated poisonous fungi produce the same deadly amanitin toxins using variations of the same pathway."

Researchers in the US and Italy rely on single-cell approaches to profile retinal pigment epithelium (RPE) cell subpopulations in an effort to understand retinal degenerative disease. The team tracked down five RPE subpopulations with artificial intelligence software and single-cell morphometric mapping — subpopulations that appeared to have variable vulnerability to monogenic or polygenic forms of retinal disease. "The results obtained here will allow study of molecular and functional [retinal pigment epithelium] differences responsible for regional retinal diseases," the authors write, "and will help develop precise cell and gene therapies for specific degenerative eye diseases.

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