A new species of Lactifluus (Russulales, Agaricomycetes) from the Brazilian caatinga semiarid region

Lactifluus (Russulaceae) is a genus of ectomycorrhizal fungi, comprising mostly tropical milkcaps with more than 150 described species. In Brazil 24 milkcap species are known, but only three of these are described from the north-eastern region. The north east of Brazil is composed of different types of habitats, namely Atlantic Forest, part of the Cerrado ecoregions and the Caatinga Domain. From the semiarid Caatinga Domain, Lf. caatingae is described in this paper as a new species, using morphological and molecular data. The new species is characterised by the rusty brown to brownish orange basidiomes, subglobose to broadly ellipsoid, rarely globose basidiospores with verrucose ornamentation composed of warts up to 0.6 mu m, that are interconnected by fine lines forming a complete reticulum, and the lampropalisade structure of the pileipellis. Phylogenetic analysis shows that Lf. caatingae belongs to L. subg. Lactariopsis, more specifically to an unnamed clade containing exclusively Neotropical representatives

Pathogenic variants in glutamyl-tRNAGlnamidotransferase subunits cause a lethal mitochondrial cardiomyopathy disorder

Mitochondrial protein synthesis requires charging mt-tRNAs with their cognate amino acids by mitochondrial aminoacyl-tRNA synthetases, with the exception of glutaminyl mt-tRNA (mt-tRNAGln). mt-tRNAGlnis indirectly charged by a transamidation reaction involving the GatCAB aminoacyl-tRNA amidotransferase complex. Defects involving the mitochondrial protein synthesis machinery cause a broad spectrum of disorders, with often fatal outcome. Here, we describe nine patients from five families with genetic defects in a GatCAB complex subunit, including QRSL1, GATB, and GATC, each showing a lethal metabolic cardiomyopathy syndrome. Functional studies reveal combined respiratory chain enzyme deficiencies and mitochondrial dysfunction. Aminoacylation of mt-tRNAGlnand mitochondrial protein translation are deficient in patients’ fibroblasts cultured in the absence of glutamine but restore in high glutamine. Lentiviral rescue experiments and modeling in S. cerevisiae homologs confirm pathogenicity. Our study completes a decade of investigations on mitochondrial aminoacylation disorders, starting with DARS2 and ending with the GatCAB complex