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

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)

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

Multilayer hazes over Saturn’s hexagon from Cassini ISS limb images

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Assessment of response of greenhouse foundations to traction, and their simulation ussing finite elements

La causa de colapso de las estructuras de invernaderos son las succiones provocadas por el viento. Actualmente no se calculan las cimentaciones sometidas a esluerzos de tracción yes la experiencia de los técnicos de las empresas constructoras, o el deseo de los agricultores. lo que determina las dimensiones y distancia entre el/as. En este trabajo. se han ensayado prototipos a escala real de los distintos tipos de pilotes usados en la construcción de invernaderos. determinando laluerza máxima de tracción y el desplazamiento asociado a la misma que pueden soportar. En este artículo. se desarrollan modelos no lineales mediante el método de elementos finitos. que permiten el cálculo de este tipo de cimentaciones con mayor aproximación a los resultados reales que el obtenido mediante el uso delórmulas empíricas.rhe cause 01the col/apse 01the structures 01greenhouses is the suction induced by wind. Currently, the design olthe loundations is not based on calculations oltraction. rhe experience 01the construction company or 01thelarmer determine the dimensions and separation 01greenhouse loundations. In this work. we tested prototypes 01diflerent types olpileloundations. used in the construction 01 greenhouse, to determine the maximumlorce 01 traction and the associated displacement which they can support. In this article. non-linear models using finite elements. are developed that enable more accurate calculation olthe actual results than obtained with empiricallormulas

Catalogue of Pavements with Recycled Aggregates from Construction and Demolition Waste

Construction and Demolition Waste come from debris generated during construction, renovation and demolition of buildings, roads, and bridges. Recycling and reuse are essential in terms of sustainability, mainly from an environmental point of view. Although the recommendation of the use of these recycled aggregates is currently included in some technical specifications, its use is still not widespread due mainly to the lack of knowledge on their technical application. This work is a compilation of the recommendations proposed in the “Catalogue of road pavements with recycled aggregates”, supported by the construction of experimental stretches. It proposes different structural sections for road pavements by using recycled aggregates

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

Plantas transgénicas con alto rendimiento en peso seco y almidón cuyos órganos de reserva presentan elevada textura, elevado contenido en almidón y elevado rendimiento en peso seco

Plantas transgénicas con alto rendimiento en peso seco y almidón cuyos órganos de reserva presentan elevada textura, elevado contenido en almidón y elevado rendimiento en peso seco. La presente invención proporciona plantas transgénicas con alto rendimiento en peso seco y almidón cuyos órganos de reserva presentan elevada textura, elevado contenido en almidón y elevado rendimiento en peso seco.Peer reviewedUniversidad Pública de Navarra OTRI, Consejo Superior de Investigaciones Científicas (España)B1 Patente sin examen previ

New design parameters for biparabolic beach profiles (SW Cadiz, Spain)

165 profiles of seventy-one beaches along the Gulf of Cadiz (SW, Spain) were studied to improve the formulation of the beach profile in tidal seas. Maritime climate, degree of energy exposure and size of the sand grains were taken into account to study the two sections of the biparabolic profile. The objective of the study was the determination of more accurate formulations of the design parameters for the equilibrium profile that involves tidal seas. These formulations were modelled and validated based on existing profiles to quantify the error existing between the real profile and the modelling. This comparative analysis was extended by considering the formulations proposed by other authors. The best results were obtained with the proposal presented herein