Genomic and functional analyses unveil the response to hyphal wall stress in Candida albicans cells lacking β(1,3)-glucan remodeling

Class 2: Transcripts that are less abundant in the phr1Δ mutant than in the wild type. (XLSX 39 kb

A Bacterial Shortcut to Amyloidosis

21 p.-10 fig.The synthetic bacterial prionoid RepA-WH1 causes a vertically transmissible amyloid proteinopathy in Escherichia coli that inhibits growth and eventually kills the cells. Recent in vitro studies show that RepA-WH1 builds pores through model lipid membranes, suggesting a possible mechanism for bacterial cell death. By comparing acutely (A31V) and mildly (ΔN37) cytotoxic mutant variants of the protein, we report here that RepA-WH1(A31V) expression decreases the intracellular osmotic pressure and compromise bacterial viability under either aerobic or anaerobic conditions. Both are effects expected from threatening membrane integrity and are in agreement with findings on the impairment by RepA-WH1(A31V) of the proton motive force (PMF)-dependent transport of ions (Fe3+) and ATP1 synthesis. Systems approaches reveal that, in aerobiosis, the PMF-independent respiratory dehydrogenase NdhII is induced in response to the reduction in intracellular levels of iron. While NdhII is known to generate H2O2 as a by-product of the autoxidation of its FAD cofactor, key proteins in the defense against oxidative stress (OxyR, KatE), together with other stress-resistance factors, are sequestered by co-aggregation with the RepA-WH1(A31V) amyloid. Our findings suggest a route for RepA-WH1 toxicity in bacteria: a primary hit of damage to the membrane, compromising bionergetics, triggers a stroke of oxidative stress, which is exacerbated due to the aggregation-dependent inactivation of enzymes and transcription factors that enable the cellular response to such injury. The proteinopathy caused by the prion-like protein RepA-WH1 in bacteria recapitulates some of the core hallmarks of human amyloid diseases.This work has been supported by grants from Spanish AEI / EU-FEDER (BIO2012-30852, BIO2015- 68730-R and CSD2009-00088) and CSIC (i-LINK0889) to R.G. We acknowledge support of the publication fee by the CSIC Open Access Support Initiative through its Unit of Information Resources for Research (URICI).Peer reviewe

Evaluation of nanoremediation strategy in a Pb, Zn and Cd contaminated soil

We addressed the efficiency of a nanoremediation strategy using zero-valent iron nanoparticles (nZVI), in a case of co-mingled heavy metals (HM) pollution (Pb, Cd and Zn). We applied a combined set of physical-chemical, toxicological and molecular analyses to assess the effectiveness and ecosafety of nZVI (5% w/w) for environmental restoration. After 120 days, nZVI showed immobilization capacity for Pb (20%), it was scarcely effective for Zn (8%) and negligibly effective for Cd. The HMs immobilization in the nZVI treated soils (compared to control soil), reaches its maximum after 15 days (T3) as reflected in the decrease of HM toxicity towards V. fischeri. The overall abundance of the microbial community was similar in both sets of samples during all experiment, although an increase in the number of metabolically active bacteria was recorded 15 days post treatment. We studied the induced impact of nanoremediation on the soil microbial community structure by Next Generation Sequencing (NGS). Even when higher HM immobilization was recorded, no significant recovery of the microbial community structure was found in nZVI-treated soil. The most marked nZVI-induced structural shifts were observed at T3 (increase in the Firmicutes population with a decrease in Gram-negative bacteria). Predictive metagenomic analysis using PICRUSt showed differences among the predicted metagenomes of nZVI-treated and control soils. At T3 we found decrease in detoxification-related proteins or over-representation of germination-related proteins; after 120 days of nZVI exposure, higher abundance of proteins involved in regulation of cellular processes or sporulation-related proteins was detected. This study highlights the partial effectiveness of nanoremediation in multiple-metal contaminated soil in the short term. The apparent lack of recovery of biodiversity after application of nZVI and the decreased effectiveness of nanoremediation over time must be carefully considered to validate this technology when assurance of medium- to long-term immobilization of HMs is required.Ministerio de Economía y Competitividad (España)Comunidad de Madrid (España)Sección Deptal. de Farmacología y Toxicología (Veterinaria)Fac. de VeterinariaTRUEpu