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Candida glabrata and Candida albicans, the most frequently isolated candidiasis species in the world, have developed mechanisms of resistance to treatment with azoles. Among the clinically used antifungal drugs are statins and other compounds that inhibit 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR), resulting in decreased growth and ergosterol levels in yeasts. Ergosterol is a key element for the formation of the yeast cell membrane. However, statins often cause DNA damage to yeast cells, facilitating mutation and drug resistance. The aim of the current contribution was to synthesize seven series of compounds as inhibitors of the HMGR enzyme of Candida ssp., and to evaluate their effect on cellular growth, ergosterol synthesis and generation of petite mutants of C. glabrata and C. albicans. Compared to the reference drugs (fluconazole and simvastatin), some HMGR inhibitors caused lower growth and ergosterol synthesis in the yeast species and generated fewer petite mutants. Moreover, heterologous expression was achieved in Pichia pastoris, and compounds 1a, 1b, 6g and 7a inhibited the activity of recombinant CgHMGR and showed better binding energy values than for α-asarone and simvastatin. Thus, we believe these are good candidates for future antifungal drug development.

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RESUMEN El estudio del funcionamiento de los ecosistemas altoandinos es de gran importancia pues cualquier modificación influirá en toda la cuenca; sin embargo, el conocimiento de estos ambientes aún es limitado. Por ello, se buscó determinar el efecto de la estacionalidad sobre el ensamble del macrobentos de un río altoandino y determinar las variables limnológicas, geomorfológicas e hidrológico-hidráulicas que más lo influencian. En el río El Salto, ubicado por encima de los 4500 msnm, en ambientes altoandinos al sur del Perú, se colectó macrobentos en el año 2020 en 11 unidades hidromorfológicas, registrándose variables limnológicas (oxígeno disuelto, porcentaje de saturación, conductividad, TSD, temperatura, pH, turbidez y SS), geomorfológicas (granulometría) e hidrológico-hidráulicas (caudal, velocidad, profundidad, ancho de cauce) en temporadas seca y húmeda. El análisis de componentes principales (ACP) de las variables fisicoquímicas evidenció que el caudal, la conductividad, el pH y los sólidos totales disueltos explicaron la mayor variabilidad de los datos (70 %). En cuanto a la granulometría, se encontró la predominancia de canto rodado y limo. El número de especies y la densidad fueron mayores en temporada seca que en la húmeda. Sin embargo, la diversidad, riqueza y equidad fueron mayores en temporada húmeda. El análisis de ordenación (nMDS, stress=0,09) mostró estructura diferente del ensamble macrobentónico entre ambas temporadas. Se concluye que la estacionalidad, dada por diversos factores, principalmente el caudal y la velocidad de flujo determinan variaciones en el ensamble del macrobentos, confirmando los cambios drásticos a los que están sometidos estos ecosistemas altoandinos con climas extremos.

ABSTRACT The study of the functioning of the high Andean ecosystems is of great importance since any change will influence the entire basin. However, knowledge of these environments is still limited. Therefore, we sought to determine the effect of seasonality on the macrobenthos assemblage of a high Andean River and to determine the limnological, geomorphological, and hydrological-hydraulic variables that most influence it. In the El Salto River, located 4,500 meters above sea level, in high Andean environments in southern Peru, macrobenthos was collected in 2020 in 11 hydro morphological units, recording limnological variables (dissolved oxygen, saturation percentage, conductivity, TSD, temperature, pH, turbidity and SS), geomorphological (granulometry) and hydrological-hydraulic (flow, velocity, depth, channel width) in dry and wet seasons. The principal component analysis (PCA) of the physicochemical variables showed that the flow rate, conductivity, pH, and total dissolved solids explained the greatest variability of the data (70 %). The predominance of boulders and silt was found. The number of species and density were higher in the dry season than in the wet season. However, the diversity, richness, and equity were higher in the wet season. The ordination analysis (nMDS, stress=0.09) showed a different structure of the macrobenthic assemblage between both seasons. It is concluded that seasonality, given by various factors, mainly flow rate and flow velocity, determine variations in the macrobenthos assemblage, confirming the drastic changes to which these high Andean ecosystems with extreme climates are subjected.

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Extracts of Hibiscus sabdariffa L. (commonly called Rosselle or "Jamaica flower" in Mexico) have been shown to have antibiotic and antivirulence properties in several bacteria. Here, an organic extract of H. sabdariffa L. is shown to inhibit motility in Salmonella enterica serovars Typhi and Typhimurium. The compound responsible for this effect was purified and found to be the hibiscus acid. When tested, this compound also inhibited motility and reduced the secretion of both flagellin and type III secretion effectors. Purified hibiscus acid was not toxic in tissue-cultured eukaryotic cells, and it was able to reduce the invasion of Salmonella Typhimurium in epithelial cells. Initial steps to understand its mode of action showed it might affect membrane proton balance.

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BACKGROUND: Urinary tract infections (UTIs) are a public health problem in Mexico, and uropathogenic Escherichia coli (UPEC) is one of the main etiological agents. Flagella, type I fimbriae, and curli promote the ability of these bacteria to successfully colonize its host. AIM: This study aimed to determine whether flagella-, type I fimbriae-, and curli-expressing UPEC induces the release of proinflammatory cytokines in an established coculture system. METHODS: The fliC, fimH, and csgA genes by UPEC strain were disrupted by allelic replacement. Flagella, type I fimbriae, and curli were visualized by transmission electron microscopy (TEM). HTB-5 (upper chamber) and HMC-1 (lower chamber) cells cocultured in Transwell® plates were infected with these UPEC strains and purified proteins. There was adherence to HTB-5 cells treated with different UPEC strains and they were quantified as colony-forming units (CFU)/mL. RESULTS: High concentrations of IL-6 and IL-8 were induced by the FimH and FliC proteins; however, these cytokines were detected in low concentrations in presence of CsgA. Compared with UPEC CFT073, CFT073ΔfimH, CFT073ΔfimHΔfliC, and CFT073ΔcsgAΔfimH strains significantly reduced the adherence to HTB-5 cells. CONCLUSION: The FimH and FliC proteins are involved in IL-6 and IL-8 release in a coculture model of HTB-5 and HMC-1 cells.

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The pathogen Vibrio cholerae has multiple iron acquisition systems which allow bacteria to exploit a variety of iron sources across the different environments on which it thrives. The expression of such iron uptake systems is highly regulated, mainly by the master iron homeostasis regulator Fur but also by other mechanisms. Recently, we documented that the expression of many of the iron-responsive genes is also modulated by riboflavin. Among them, the open reading frame VCA0231, repressed both by riboflavin and iron, encodes a putative transcriptional regulator of the AraC/XylS family. Nonetheless, the genes or functions affected by this factor are unknown. In the present study, a series of in silico analyses was performed in order to identify the putative functions associated with the product of VCA0231. The STRING database predicted many iron uptake genes as functional partners for the product of VCA0231. In addition, a genomic neighborhood analysis with the Enzyme Function Initiative tools detected many Pfam families involved in iron homeostasis genetically associated with VCA0231. Moreover, a phylogenetic tree showed that other AraC/XylS members known to regulate siderophore utilization in bacteria clustered together and the product of VCA0231 localized in this cluster. This suggested that the product of VCA0231, here named IurV, is involved in the regulation of iron uptake processes. RNAseq was performed to determine the transcriptional effects of a deletion in VCA0231. A total of 52 genes were overexpressed and 21 genes were downregulated in response to the iurV deletion. Among these, several iron uptake genes and other iron homeostasis-related genes were found. Six gene ontology (GO) functional terms were enriched in the upregulated genes, of which five were related to iron metabolism. The regulatory pattern observed in the transcriptomics of a subset of genes was independently confirmed by quantitative real time PCR analysis. The results indicate that IurV is a novel regulator of the AraC/XylS family involved in the repression of iron uptake genes. Whether this effect is direct or indirect remains to be determined.

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Salmonella enterica serotype Typhimurium is a bacterium that causes gastroenteritis and diarrhea in humans. The genome of S. Typhimurium codes for diverse virulence factors, among which are the toxin-antitoxin (TA) systems. SehAB is a type II TA, where SehA is the toxin and SehB is the antitoxin. It was previously reported that the absence of the SehB antitoxin affects the growth of S. Typhimurium. In addition, the SehB antitoxin can interact directly with the SehA toxin neutralizing its toxic effect as well as repressing its own expression. We identified conserved residues on SehB homologous proteins. Point mutations were introduced at both N- and C-terminal of SehB antitoxin to analyze the effect of these changes on its transcription repressor function, on its ability to form homodimers and on the virulence of S. Typhimurium. All changes in amino acid residues at both the N- and C-terminal affected the repressor function of SehB antitoxin and they were required for DNA-binding activity. Mutations in the amino acid residues at the N-terminal showed a lower capacity for homodimer formation of the SehB protein. However, none of the SehB point mutants were affected in the interaction with the SehA toxin. In terms of virulence, the eight single-amino acid mutations were attenuated for virulence in the mouse model. In agreement with our results, the eight amino acid residues of SehB antitoxin were required for its repressor activity, affecting both homodimerization and DNA-binding activity, supporting the notion that both activities of SehB antitoxin are required to confer virulence to Salmonella enterica.

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The ability of bacteria and archaea to modulate metabolic process, defensive response, and pathogenic capabilities depend on their repertoire of genes and capacity to regulate the expression of them. Transcription factors (TFs) have fundamental roles in controlling these processes. TFs are proteins dedicated to favor and/or impede the activity of the RNA polymerase. In prokaryotes these proteins have been grouped into families that can be found in most of the different taxonomic divisions. In this work, the association between the expansion patterns of 111 protein regulatory families was systematically evaluated in 1351 non-redundant prokaryotic genomes. This analysis provides insights into the functional and evolutionary constraints imposed on different classes of regulatory factors in bacterial and archaeal organisms. Based on their distribution, we found a relationship between the contents of some TF families and genome size. For example, nine TF families that represent 43.7% of the complete collection of TFs are closely associated with genome size; i.e., in large genomes, members of these families are also abundant, but when a genome is small, such TF family sizes are decreased. In contrast, almost 102 families (56.3% of the collection) do not exhibit or show only a low correlation with the genome size, suggesting that a large proportion of duplication or gene loss events occur independently of the genome size and that various yet-unexplored questions about the evolution of these TF families remain. In addition, we identified a group of families that have a similar distribution pattern across Bacteria and Archaea, suggesting common functional and probable coevolution processes, and a group of families universally distributed among all the genomes. Finally, a specific association between the TF families and their additional domains was identified, suggesting that the families sense specific signals or make specific protein-protein contacts to achieve the regulatory roles.

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O estudo foi realizado em diferentes ambientes da várzea do rio Ivinhema com o intuito de analisar a variação espacial e temporal da assembléia de invertebrados bentônicos, bem como sua relação com as variáveis físicas e químicas e o nível hidrométrico. Foram estudados quatro ambientes, o canal principal do rio, o canal Ipoitã, a lagoa Ventura (sem comunicação) e a lagoa dos Patos (com comunicação). As coletas foram realizadas trimestralmente de fevereiro a novembro de 2002. O sistema rio Ivinhema foi caracterizado por um regime de potamofase bimodal com intensidades moderadas e grandes amplitudes, permanecendo em potamofase 184 dias em 2001 e 67 dias em 2002. Foram observadas as variações espacial e temporal, quanto às variáveis físicas e químicas, sumarizadas em uma PCA. Dos 37 táxons registrados, Nematoda, Corbiculidae, Oligochaeta, Acari, Ostracoda e Chironomidae foram os mais abundantes, sendo as larvas de Chironomidae o táxon predominante no canal Ipoitã e na lagoa Ventura. Entretanto, a análise da estrutura da assembléia (CA) demonstrou que a assembléia bentônica do rio Ivinhema é dissimilar a das lagoas. A relação entre PCA e CA não foi significativa, indicando que no sistema Ivinhema há uma estrutura complexa e que a uniformidade espacial da densidade e temporal da assembléia bentônica deve-se à maior conectividade entre os ambientes.

This study was developed in different environments of the Ivinhema river floodplain in order to analyze the spatial and temporal variation of benthic assemblages and their relationship with physical and chemical variables and water level. Samples were taken quarterly between February and November 2002 in four environments: Ivinhema main channel, Ipoitã channel, Patos lake (with direct connectivity) and Ventura lake (without connectivity). The system was characterized by a bimodal potamophase cycle with moderate intensities and large amplitudes, remaining in potamophase for 184 days in 2001 and 67 days in 2002. Physical and chemical parameters, summarized in a PCA, showed spatial and temporal variation. Moderate intensity and great width pulses were recorded. Physicochemical variables changed spatially and temporally. Nematoda, Corbiculidae, Oligochaeta, Acari, Ostracoda and Chironomidae were the most abundant taxa registered and the larvae of Chironomidae were the most predominant in the Ivinhema main channel, Ipoitã channel and Ventura lake. Total density changed between months, but the analysis of the structure of the assembly (CA) showed that the benthic assembly of the Ivinhema main channel is dissimilar to the ponds. The relationship between PCA and CA was not significant, indicating that the Ivinhema system had a complex structure and that the spatial uniformity of density and temporal uniformity of benthic assemblage is due to the greater connectivity between the sites.

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