The Use of Lightweight Aggregates in Geopolymeric Mortars: The Effect of Liquid Absorption on the Physical/Mechanical Properties of the Mortar.

Geopolymers have been proposed as a green alternative to Portland cement with lowered carbon footprints. In this work, a geopolymeric mortar obtained using waste materials is studied. Fly ash, a waste generated by coal combustion, is used as one of the precursors, and waste glass as lightweight aggregates (LWAs) to improve the thermal performance of the mortar.

Role of the Non-Canonical RNAi Pathway in the Antifungal Resistance and Virulence of Mucorales.

Mucorales are the causal agents for the lethal disease known as mucormycosis. Mortality rates of mucormycosis can reach up to 90%, due to the mucoralean antifungal drug resistance and the lack of effective therapies. A concerning urgency among the medical and scientific community claims to find targets for the development of new treatments.

The Evolutionary Significance of RNAi in the Fungal Kingdom.

RNA interference (RNAi) was discovered at the end of last millennium, changing the way scientists understood regulation of gene expression. Within the following two decades, a variety of different RNAi mechanisms were found in eukaryotes, reflecting the evolutive diversity that RNAi entails. The essential silencing mechanism consists of an RNase III enzyme called Dicer that cleaves double-stranded RNA (dsRNA) generating small interfering RNAs (siRNAs), a hallmark of RNAi.

Antimicrobial resistance profiles of microorganisms isolated from hospitalized patients in Dominican Republic.

Objective: To define the antimicrobial resistance profiles of the microorganisms most commonly isolated from hospitalized adult patients in Dominican Republic (DR).

Methods: A retrospective, cross-sectional study of phenotypic antimicrobial susceptibility patterns was conducted using data from 3 802 clinical microbiology reports specifying positive bacterial cultures in samples collected from patients admitted to the clinical, surgery, and intensive care units (ICU) at three tertiary-level care hospitals in the city of Santiago de los Caballeros from 1 January 2016 - 31 December 2017. Descriptive statistics and chi-square test ( ≤ 0.

A non-canonical RNA degradation pathway suppresses RNAi-dependent epimutations in the human fungal pathogen Mucor circinelloides.

Mucorales are a group of basal fungi that includes the casual agents of the human emerging disease mucormycosis. Recent studies revealed that these pathogens activate an RNAi-based pathway to rapidly generate drug-resistant epimutant strains when exposed to stressful compounds such as the antifungal drug FK506. To elucidate the molecular mechanism of this epimutation pathway, we performed a genetic analysis in Mucor circinelloides that revealed an inhibitory role for the non-canonical RdRP-dependent Dicer-independent silencing pathway, which is an RNAi-based mechanism involved in mRNA degradation that was recently identified.

Calcineurin orchestrates dimorphic transitions, antifungal drug responses and host-pathogen interactions of the pathogenic mucoralean fungus Mucor circinelloides.

Calcineurin plays essential roles in virulence and growth of pathogenic fungi and is a target of the natural products FK506 and Cyclosporine A. In the pathogenic mucoralean fungus Mucor circinelloides, calcineurin mutation or inhibition confers a yeast-locked phenotype indicating that calcineurin governs the dimorphic transition. Genetic analysis in this study reveals that two calcineurin A catalytic subunits (out of three) are functionally diverged.

A non-canonical RNA silencing pathway promotes mRNA degradation in basal Fungi.

The increasing knowledge on the functional relevance of endogenous small RNAs (esRNAs) as riboregulators has stimulated the identification and characterization of these molecules in numerous eukaryotes. In the basal fungus Mucor circinelloides, an emerging opportunistic human pathogen, esRNAs that regulate the expression of many protein coding genes have been described. These esRNAs share common machinery for their biogenesis consisting of an RNase III endonuclease Dicer, a single Argonaute protein and two RNA-dependent RNA polymerases.

Antifungal drug resistance evoked via RNAi-dependent epimutations.

Microorganisms evolve via a range of mechanisms that may include or involve sexual/parasexual reproduction, mutators, aneuploidy, Hsp90 and even prions. Mechanisms that may seem detrimental can be repurposed to generate diversity. Here we show that the human fungal pathogen Mucor circinelloides develops spontaneous resistance to the antifungal drug FK506 (tacrolimus) via two distinct mechanisms.

RNAi function, diversity, and loss in the fungal kingdom.

RNAi is conserved and has been studied in a broad cross-section of the fungal kingdom, including Neurospora crassa, Schizosaccharomyces pombe, Cryptococcus neoformans, and Mucor circinelloides. And yet well known species, including the model yeast Saccharomyces cerevisiae and the plant pathogen Ustilago maydis, have lost RNAi, providing insights and opportunities to illuminate benefits conferred both by the presence of RNAi and its loss. Some of the earliest studies of RNAi were conducted in Neurospora, contemporaneously with the elucidation of RNAi in Caenorhabditis elegans.

Calcineurin plays key roles in the dimorphic transition and virulence of the human pathogenic zygomycete Mucor circinelloides.

Many pathogenic fungi are dimorphic and switch between yeast and filamentous states. This switch alters host-microbe interactions and is critical for pathogenicity. However, in zygomycetes, whether dimorphism contributes to virulence is a central unanswered question.

Two distinct RNA-dependent RNA polymerases are required for initiation and amplification of RNA silencing in the basal fungus Mucor circinelloides.

RNA-dependent RNA polymerases (RdRPs) play key roles in the RNA silencing pathway in a number of organisms. They have been involved in the production of double-stranded RNA (dsRNA) molecules that initiate the silencing mechanism as well as in the amplification of the silencing signal. The roles of RdRPs from fungi in these processes are poorly described compared with other eukaryotes.

Endogenous short RNAs generated by Dicer 2 and RNA-dependent RNA polymerase 1 regulate mRNAs in the basal fungus Mucor circinelloides.

Endogenous short RNAs (esRNAs) play diverse roles in eukaryotes and usually are produced from double-stranded RNA (dsRNA) by Dicer. esRNAs are grouped into different classes based on biogenesis and function but not all classes are present in all three eukaryotic kingdoms. The esRNA register of fungi is poorly described compared to other eukaryotes and it is not clear what esRNA classes are present in this kingdom and whether they regulate the expression of protein coding genes.

A single dicer gene is required for efficient gene silencing associated with two classes of small antisense RNAs in Mucor circinelloides.

RNA silencing in the zygomycete Mucor circinelloides exhibits uncommon features, such as induction by self-replicative sense transgenes and the accumulation of two size classes of antisense small interfering RNAs (siRNAs). To investigate whether this silencing phenomenon follows the rules of a canonical RNA-silencing mechanism, we used hairpin RNA (hpRNA)-producing constructs as silencing triggers and analyzed the efficiency and stability of silencing in different genetic backgrounds. We show here that the dsRNA-induced silencing mechanism is also associated with the accumulation of two sizes of antisense siRNAs and that this mechanism is not mediated by the previously known dcl-1 (dicer-like) gene, which implies the existence of an additional dicer gene.

A RING-finger photocarotenogenic repressor involved in asexual sporulation in Mucor circinelloides.

Mucor circinelloides responds to blue light by activating the biosynthesis of carotenoids and bending its sporangiophores towards the light source. The CrgA protein product acts as a repressor of carotene biosynthesis, as its inactivation leads to the overaccumulation of carotenoids in both the dark and the light. We show here that asexual sporulation in Mucor is also stimulated by light and that the crgA gene is involved in sporulation, given that lack of crgA function affects both carotenogenesis and the normal production of spores.