Metal-responsive RNA polymerase extracytoplasmic function (ECF) sigma factors

In order to survive, bacteria must adapt to multiple fluctuations in their environment, including coping with changes in metal concentrations. Many metals are essential for viability, since they act as cofactors of indispensable enzymes. But on the other hand, they are potentially toxic because they generate reactive oxygen species or displace other metals from proteins, turning them inactive. This dual effect of metals forces cells to maintain homeostasis using a variety of systems to import and export them. These systems are usually inducible, and their expression is regulated by metal sensors and signal-transduction mechanisms, one of which is mediated by extracytoplasmic function (ECF) sigma factors. In this review, we have focused on the metalresponsive ECF sigma factors, several of which are activated by iron depletion (FecI, FpvI and PvdS), while others are activated by excess of metals such as nickel and cobalt (CnrH), copper (CarQ and CorE) or cadmium and zinc (CorE2). We focus particularly on their physiological roles, mechanisms of action and signal transduction pathways.This work has been supported by the Spanish Government, grant BFU2016-75425-P to Aurelio Moraleda-Muñoz (70% funded by FEDER)

In depth analysis of the mechanism of action of metal-dependent sigma factors: characterization of CorE2 from Myxococcus xanthus

Extracytoplasmic function sigma factors represent the third pillar of signal-transduction mechanisms in bacteria. The variety of stimuli they recognize and mechanisms of action they use have allowed their classification into more than 50 groups. We have characterized CorE2 from Myxococcus xanthus, which belongs to group ECF44 and upregulates the expression of two genes when it is activated by cadmium and zinc. Sigma factors of this group contain a Cys-rich domain (CRD) at the C terminus which is essential for detecting metals. Point mutations at the six Cys residues of the CRD have revealed the contribution of each residue to CorE2 activity. Some of them are essential, while others are either dispensable or their mutations only slightly affect the activity of the protein. However, importantly, mutation of Cys174 completely shifts the specificity of CorE2 from cadmium to copper, indicating that the Cys arrangement of the CRD determines the metal specificity. Moreover, the conserved CxC motif located between the sigma2 domain and the sigma4.2 region has also been found to be essential for activity. The results presented here contribute to our understanding of the mechanism of action of metal-dependent sigma factors and help to define new common features of the members of this group of regulators.Spanish Government [CSD2009-00006, BFU2012-33248, 70% funded by FEDER]. Funding for open access charge: Grupo BIO318, Junta de Andalucía

Mechanisms of Action of Non-Canonical ECF Sigma Factors

Extracytoplasmic function (ECF) sigma factors are subunits of the RNA polymerase specialized in activating the transcription of a subset of genes responding to a specific environmental condition. The signal-transduction pathways where they participate can be activated by diverse mechanisms. The most common mechanism involves the action of a membrane-bound anti-sigma factor, which sequesters the ECF sigma factor, and releases it after the stimulus is sensed. However, despite most of these systems following this canonical regulation, there are many ECF sigma factors exhibiting a non-canonical regulatory mechanism. In this review, we aim to provide an updated and comprehensive view of the different activation mechanisms known for non-canonical ECF sigma factors, detailing their inclusion to the different phylogenetic groups and describing the mechanisms of regulation of some of their representative members such as EcfG from Rhodobacter sphaeroides, showing a partner-switch mechanism; EcfP from Vibrio parahaemolyticus, with a phosphorylation-dependent mechanism; or CorE from Myxococcus xanthus, regulated by a metal-sensing C-terminal extension.Spanish Government (PID2020-112634GB-I00)FEDER funds (grant A-BIO-126-UGR20

Development versus predation: Transcriptomic changes during the lifecycle of Myxococcus xanthus

Myxococcus xanthus is a multicellular bacterium with a complex lifecycle. It is a soil-dwelling predator that preys on a wide variety of microorganisms by using a group and collaborative epibiotic strategy. In the absence of nutrients this myxobacterium enters in a unique developmental program by using sophisticated and complex regulatory systems where more than 1,400 genes are transcriptional regulated to guide the community to aggregate into macroscopic fruiting bodies filled of environmentally resistant myxospores. Herein, we analyze the predatosome of M. xanthus, that is, the transcriptomic changes that the predator undergoes when encounters a prey. This study has been carried out using as a prey Sinorhizobium meliloti, a nitrogen fixing bacteria very important for the fertility of soils. The transcriptional changes include upregulation of genes that help the cells to detect, kill, lyse, and consume the prey, but also downregulation of genes not required for the predatory process. Our results have shown that, as expected, many genes encoding hydrolytic enzymes and enzymes involved in biosynthesis of secondary metabolites increase their expression levels. Moreover, it has been found that the predator modifies its lipid composition and overproduces siderophores to take up iron. Comparison with developmental transcriptome reveals that M. xanthus downregulates the expression of a significant number of genes coding for regulatory elements, many of which have been demonstrated to be key elements during development. This study shows for the first time a global view of the M. xanthus lifecycle from a transcriptome perspective.Grant PID2020-112634GB-I0 funded by MCIN/AEI/ 10.13039/501100011033FEDER funds (grant A-BIO-126-UGR20

Is there an association between sleep disorders and diabetic foot? A scoping review

Diabetic foot is associated with a low quality of life since physical disabilities, mood disturbances and psychological disorders are frequent. One of the most important biological processes to ensure quality of life is sleep. Sleep disorders can impair glycemic control in patients with diabetes mellitus or even cause long-term type 2 diabetes mellitus. The aim of this study is to carry out a scoping review about the association between sleep cycle disorders and diabetic foot. PubMed, Scopus, CINAHL, PEDro, Cochrane Library, SCIELO and EMBASE databases were chosen for the search and the following terms were used: “diabetic foot”,“sleep*”,“rest-activity”,“mood” and“behavior”. All the studies should include outcome variables about sleep and diabetic foot. Finally, 12 articles were selected, all of whichwere observational. The most frequent variables were those regarding diabetic foot ulcer aspects and diabetic neuropathy on one side, and obstructive sleep apnea, sleep duration and sleep quality on the other side. The results suggest that there is a possible association between obstructive sleep apnea and the presence or history of diabetic foot ulcers. No direct associations between sleep quality or sleep duration and diabetic foot or diabetic foot ulcer variables have been found

Dimensiones culturales sobre el dengue en profesionales de la salud de méxico y colombia

Objetivo Comprender las dimensiones culturales del dengue en profesionales de la salud de México y Colombia. A fin de generar elementos para la formación y  actualización de los éstos en la prevención y atención de dicha enfermedad. Método Estudio antropológico cognitivo. Realizado en las ciudades de Morelia, México y Santiago de Cali, Colombia. Participaron un total de 197 profesionales de salud seleccionados por muestreo propositivo. Se utilizaron las técnicas de listados libres y el sorteo de montones. Se indagaron términos asociados al concepto dengue y grupos de dimensiones conceptuales. Resultados Las concepciones culturales del dengue en los participantes de México hicieron énfasis en la prevención. Los de Colombia mostraron un lenguaje biomédico y su interés se centró en la sintomatología. En general se mostró una visión integral del dengue que incluye la visión médica y aspectos sociales interrelacionados. Conclusiones Los profesionales de la salud requieren de mayor formación en torno al tema del dengue y su prevención

Primer registro de Litomosoides pardinasi (Nematoda: Onchocercidae) en roedores nativos y exóticos de Chile

Litomosoides pardinasi es registrada por primera vez en roedores nativos y exóticos de Chile. La especie Litomosoides pardinasi, parásita de Phyllotis xanthopygus y Oligoryzomys longicaudatus en la Patagonia Argentina, fue encontrada en Chile parasitando la cavidad torácica y abdominal de O. longicaudatus (prevalencia (P)= 18.9%, intensidad media (MI)= 57.3) y de Phyllotis darwini (P= 4.2%, MI= 10), y la cavidad abdominal del roedor exótico Rattus rattus (P= 1.24%; MI= 22.5). La P total en roedores nativos de Chile fue significativamente menor que la P de Argentina, en tanto la MI total fue significativamente mayor. La P y MI de L. pardinasi en O. longicaudatus de Chile y Argentina no mostraron diferencias significativas; la P en P. darwini de Chile fue significativamente menor que la de P. xanthopygus de Argentina y que la de O. longicaudatus de Chile. Considerando la distribución de las especies de Litomosoides entre los sigmodontinos, estos resultados apoyan la hipótesis que L. pardinasi está bien establecida en O. longicaudatus y que posiblemente haya sido recientemente adquirida por P. darwini y R. rattus. Así, L. pardinasi colonizó primero a la Tribu Oryzomyini y posteriormente por un fenómeno de cambio de hospedero a la Tribu Phyllotini y a R. rattus.We report the first record of Litomosoides pardinasi in native and exotic rodents from Chile. Litomosoides pardinasi, described in the Argentine Patagonia parasitizing Phyllotis xanthopygus and Oligoryzomys longicaudatus, was found in Chile parasitizing the peritoneal and thoracic cavities of O. longicaudatus (prevalence (P)= 18.9%, mean intensity (MI)= 57.3) and Phyllotis darwini (P= 4.2%, MI= 10), and in the peritoneal cavity of Rattus rattus (P= 1.24%; MI= 22.5). Total P in native rodents from Chile was significantly lower than in Argentina, while the total MI was higher. Prevalence and MI of L. pardinasi in O. longicaudatus from Chile and Argentina showed non-significant differences; prevalence in P. darwini from Chile was significantly lower than in P. xanthopygus from Argentina and than in Chilean O. longicaudatus. Our results, together with those from Argentina, support the hypothesis that L. pardinasi is well established in O. longicaudatus, but seems to be recently acquired by P. darwini and the exotic R. rattus. Considering the known host distribution of Litomosoides species among the sigmodontines, our results also support the hypothesis that L. pardinasi first colonized the Oryzomyini tribe and later, by different phenomena of host-switching, colonized the Phyllotini tribe and the exotic R. rattus.Fil: Landaeta Aqueveque, Carlos. Universidad de Concepción; ChileFil: Notarnicola, Juliana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Estudios Parasitológicos y de Vectores. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios Parasitológicos y de Vectores; ArgentinaFil: Correa, Juana P.. Universidad de Chile; ChileFil: Yánez Mesa, Andrea. Universidad de Chile; ChileFil: Henriquez, AnaLía. Universidad Santo Tomás; ChileFil: Cattan, Pedro E.. Universidad de Chile; ChileFil: Botto Mahan, Carezza. Universidad de Chile; ChileFil: Torres Pérez, Fernando. Pontificia Universidad Catolica de Valparaiso; Chil

Identificación de las principales fases áridas del Pleistoceno superior en el registro sedimentario lacustre del maar de Fuentillejo (Campo de Calatrava)

Se han realizado análisis de facies sedimentarias, geoquímicos (análisis elemental, análisis moleculares de la fracción orgánica), propiedades físicas, palinológicos y mineralógicos para caracterizar el registro sedimentario de la laguna del maar de Fuentillejo, en la región volcánica central de España de Campo de Calatrava, con el objetivo de reconstruir los procesos paleoambientales y paleoclimáticos que controlaron los patrones de la vegetación y la sedimentación. Los primeros 29 m del sondeo FU-1 muestran acusadas variaciones en el aporte de terrígenos, la química de las aguas, la vegetación y en la fracción orgánica a lo largo del Pleistoceno superior y Holoceno. En las facies de dolomicritas (con magnesita y analcima), los datos polínicos muestran un incremento del componente herbáceo, fundamentalmente taxones estépicos –Chenopodiaceae, Artemisia y Ephedra-; junto con un índice Paq bajo, descenso en el porcentaje relativo de alcano n-C27 y un incremento de alcano n-C31. Esta facies, probablemente, es el resultado de un bajo nivel del lago y condiciones salinas-alcalinas, que se han interpretado como el periodo más árido en el techo de la unidad 19.2. Las facies siliciclásticas con valores altos de susceptibilidad magnética, alto contenido en polen de Juniperus, bajo índice Paq, descenso en el porcentaje relativo de alcanos n-C27 e incremento de n-C31 son indicativos de eventos climáticos áridos y fríos. Geochemical (elemental analysis, molecular analysis of organic compounds), physical, palynological, mineralogical and sedimentary facies analysis were performed to characterize the sedimentary record in Fuentillejo maar lake in the Central Spanish Volcanic Field of Calatrava, in order to reconstruct the paleoenvironmental and paleoclimatic processes which controlled vegetation patterns and deposition of different sedimentary facies. The upper 29 m of FU-1 core point out variations in clastic input, water chemistry, vegetation and organic fraction sources in the lake throughout the late Pleistocene and Holocene. In dolomite-mud facies (magnesite and analcime), the pollen data shows an increase of the herbs component, mainly –Chenopodiaceae, Artemisia and Ephedra- steppe taxa; low Paq index, decrease in the relative percentage of the n-C27 alkane and increase in the n-C31 alkane are also observed. This facies was probably the result of lower lake levels and more saline-alkaline conditions which can be interpreted as linked to the most arid periods, especially in the top of unit 19.2. Siliciclastic facies with high magnetic susceptibility values, high Juniperus pollen content, low Paq index, decrease in the relative percentage of the n-C27 alkane and increase in the n-C31 alkane are indicative of arid and colder climatic events

Detoxification of azo dyes by a novel pH-versatile, salt-resistant laccase from Streptomyces ipomoea

A newly identified extracellular laccase produced by Streptomyces ipomoea CECT 3341 (SilA) was cloned and overexpressed, and its physicochemical characteristics assessed together with its capability to decolorize and detoxify an azotype dye. Molecular analysis of the deduced sequence revealed that SilA contains a TAT-type signal peptide at the N-terminus and only two cupredoxine domains; this is consistent with reports describing two other Streptomyces laccases but contrasts with most laccases, which contain three cupredoxine domains. The heterologous expression and purification of SilA revealed that the homodimer is the only active form of the enzyme. Its stability at high pH and temperature, together with its resistance to high concentrations of NaCl and to typical laccase inhibitors such as sodium azide confirmed the unique properties of this novel laccase. The range of substrates that SilA is able to oxidize was found to be pH-dependent; at alkaline pH, SilA oxidized a wide range of phenolic compounds, including the syringyl and guayacil moieties derived from lignin. The oxidative potential of this enzyme to use phenolic compounds as natural redox mediators was shown through the coordinated action of SilA and acetosyringone (as mediator), which resulted in the complete detoxification of the azo-type dye Orange II.This work was financially supported by the Spanish Ministry of Science (CICYT Project CTQ2004-0344/PPQ to MEA and BFU 2006-00972/BMC to JMD). We thank the Autonomous Government of Madrid and the University of Alcalá for the fellowship awarded to R.M

Primer registro de Litomosoides pardinasi (Nematoda: Onchocercidae) en roedores nativos y exóticos de Chile

We report the first record of Litomosoides pardinasi in native and exotic rodents from Chile. Litomosoides pardinasi, described in the Argentine Patagonia parasitizing Phyllotis xanthopygus and Oligoryzomys longicaudatus, was found in Chile parasitizing the peritoneal and thoracic cavities of O. longicaudatus (prevalence (P)= 18.9%, mean intensity (MI)= 57.3) and Phyllotis darwini (P= 4.2%, MI= 10), and in the peritoneal cavity of Rattus rattus (P= 1.24%; MI= 22.5). Total P in native rodents from Chile was significantly lower than in Argentina, while the total MI was higher. Prevalence and MI of L. pardinasi in O. longicaudatus from Chile and Argentina showed non-significant differences; prevalence in P. darwini from Chile was significantly lower than in P. xanthopygus from Argentina and than in Chilean O. longicaudatus. Our results, together with those from Argentina, support the hypothesis that L. pardinasi is well established in O. longicaudatus, but seems to be recently acquired by P. darwini and the exotic R. rattus. Considering the known host distribution of Litomosoides species among the sigmodontines, our results also support the hypothesis that L. pardinasi first colonized the Oryzomyini tribe and later, by different phenomena of host-switching, colonized the Phyllotini tribe and the exotic R. rattus.Litomosoides pardinasi es registrada por primera vez en roedores nativos y exóticos de Chile. La especie Litomosoides pardinasi, parásita de Phyllotis xanthopygus y Oligoryzomys longicaudatus en la Patagonia Argentina, fue encontrada en Chile parasitando la cavidad torácica y abdominal de O. longicaudatus (prevalencia (P)= 18.9%, intensidad media (MI)= 57.3) y de Phyllotis darwini (P= 4.2%, MI= 10), y la cavidad abdominal del roedor exótico Rattus rattus (P= 1.24%; MI= 22.5). La P total en roedores nativos de Chile fue significativamente menor que la P de Argentina, en tanto la MI total fue significativamente mayor. La P y MI de L. pardinasi en O. longicaudatus de Chile y Argentina no mostraron diferencias significativas; la P en P. darwini de Chile fue significativamente menor que la de P. xanthopygus de Argentina y que la de O. longicaudatus de Chile. Considerando la distribución de las especies de Litomosoides entre los sigmodontinos, estos resultados apoyan la hipótesis que L. pardinasi está bien establecida en O. longicaudatus y que posiblemente haya sido recientemente adquirida por P. darwini y R. rattus. Así, L. pardinasi colonizó primero a la Tribu Oryzomyini y posteriormente por un fenómeno de cambio de hospedero a la Tribu Phyllotini y a R. rattus.Facultad de Ciencias Naturales y Muse