Genetic Dissection of the Regulatory Network Associated with High c-di-GMP Levels in Pseudomonas putida KT2440

Most bacteria grow in nature forming multicellular structures named biofilms. The bacterial second messenger cyclic diguanosine monophosphate (c-di-GMP) is a key player in the regulation of the transition from planktonic to sessile lifestyles and this regulation is crucial in the development of biofilms. In Pseudomonas putida KT2440, Rup4959, a multidomain response regulator with diguanylate cyclase activity, when overexpressed causes an increment in the intracellular levels of c-di-GMP that gives rise to a pleiotropic phenotype consisting of increased biofilm formation and crinkly colony morphology. In a broad genomic screen we have isolated mutant derivatives that lose the crinkly morphology, designed as cfc (crinkle free colony). A total of 19 different genes have been identified as being related with the emergence of the cfc phenotype either because the expression or functionality of Rup4959 is compromised, or due to a lack of transduction of the c-di-GMP signal to downstream elements involved in the acquisition of the phenotype. Discernment between these possibilities was investigated by using a c-di-GMP biosensor and by HPLC-MS quantification of the second messenger. Interestingly five of the identified genes encode proteins with AAA+ ATPase domain. Among the bacterial determinants found in this screen are the global transcriptional regulators GacA, AlgU and FleQ and two enzymes involved in the arginine biosynthesis pathway. We present evidences that this pathway seems to be an important element to both the availability of the free pool of the second messenger c-di-GMP and to its further transduction as a signal for biosynthesis of biopolimers. In addition we have identified an uncharacterized hybrid sensor histidine kinase whose phosphoaceptor conserved histidine residue has been shown in this work to be required for in vivo activation of the orphan response regulator Rup4959, which suggests these two elements constitute a two-component phosphorelay system.This work was supported by grants BFU2010-17946 and BFU2013-43469-P from Plan Nacional de I+D+I (Spanish Government) and by EDFR funds. OH-R was supported by a FPI fellowship and LB-M by predoctoral fund from Junta de Andalucía. MAM was supported by the Postdoctoral Juan de la Cierva Spanish Research Program (JCI-2012-11815).Peer reviewedPeer Reviewe

Genes involved in ethylene and gibberellins metabolism are required for endosperm-limited germiantion of Sisymbrium officinales L. Seeds

The rupture of the seed coat and that of the endosperm were found to be two sequential events in the germination of Sisymbrium officinale L. seeds, and radicle protrusion did not occur exactly in the micropylar area but in the neighboring zone. The germination patterns were similar both in the presence of gibberellins (GA4+7) and in presence of ethrel. The analysis of genes involved in GAs synthesis and breakdown demonstrated that (1) SoGA2ox6 expression peaked just prior to radicle protrusion (20–22 h), while SoGA3ox2 and SoGA20ox2 expression was high at early imbibition (6 h) diminishing sharply thereafter; (2) the accumulation of SoGA20ox2 transcript was strongly inhibited by paclobutrazol (PB) as well as by inhibitors of ET synthesis and signaling (IESS) early after imbibition (6 h), while SoGA3ox2 and SoGA2ox6 expression was slowly depressed as germination progressed; (3) ethrel and GA4+7 positively or negatively affected expression of SoGA3ox2, SoGA20ox2, and SoGA2ox6, depending on the germination period studied. Regarding genes involved in ET synthesis, our results showed that SoACS7 was expressed, just prior to radicle emergence while SoACO2 expression slowly increased as germination progressed. Both genes were strongly inhibited by PB but were almost unaffected by externally added ethrel or GA4+7. These results suggest that GAs are more important than ET during the early stages of imbibition, while ET is more important at the late phases of germination of S. officinale L. seed

The interactive effects of arbuscular mycorrhiza and plant growth-promoting rhizobacteria synergistically enhance host plant defences against pathogens

Belowground interactions between plant roots, mycorrhizal fungi and plant growth-promoting rhizobacteria (PGPR) can improve plant health via enhanced nutrient acquisition and priming of the plant immune system. Two wheat cultivars differing in their ability to form mycorrhiza were (co)inoculated with the mycorrhizal fungus Rhizophagus irregularis and the rhizobacterial strain Pseudomonas putida KT2440. The cultivar with high mycorrhizal compatibility supported higher levels of rhizobacterial colonization than the low compatibility cultivar. Those levels were augmented by mycorrhizal infection. Conversely, rhizobacterial colonization of the low compatibility cultivar was reduced by mycorrhizal arbuscule formation. Single inoculations with R. irregularis or P. putida had differential growth effects on both cultivars. Furthermore, while both cultivars developed systemic priming of chitosan-induced callose after single inoculations with R. irregularis or P. putida, only the cultivar with high mycorrhizal compatibility showed a synergistic increase in callose responsiveness following co-inoculation with both microbes. Our results show that multilateral interactions between roots, mycorrhizal fungi and PGPR can have synergistic effects on growth and systemic priming of wheat

Genomic analysis reveals the major driving forces of bacterial life in the rhizosphere

A global analysis of Pseudomonas putida gene expression performed during the interaction with maize roots revealed how a bacterial population adjusts its genetic program to the specific conditions of this lifestyle

Structural studies of T4S systems by electron microscopy

Abstract: Type IV secretion (T4S) systems are large dynamic nanomachines that transport DNA and/or proteins through the membranes of bacteria. Analysis of T4S system architecture is an extremely challenging task taking into account their multi protein organisation and lack of overall global symmetry. Nonetheless the last decade demonstrated an amazing progress achieved by X-ray crystallography and cryo-electron microscopy. In this review we present a structural analysis of this dynamic complex based on recent advances in biochemical, biophysical and structural studies

Tracking a moving sound source from a multi-rotor drone

We propose a method to track from a multirotor drone a moving source, such as a human speaker or an emergency whistle, whose sound is mixed with the strong ego-noise generated by rotating motors and propellers. The proposed method is independent of the specific drone and does not need pre-training nor reference signals. We first employ a time-frequency spatial filter to estimate, on short audio segments, the direction of arrival of the moving source and then we track these noisy estimations with a particle filter. We quantitatively evaluate the results using a ground-truth trajectory of the sound source obtained with an on-board camera and compare the performance of the proposed method with baseline solutions

Neutropenia febril por Metimazol

Las drogas antitiroideas son el principal tratamiento del Hipertiroidismo por Enfermedad de Graves, utilizándose como preparación para cirugía o tratamiento con Iodo 131 (I131). Estas drogas constituyen el grupo de las Tionamidas, siendo el más usado el Metimazol presentando efectos adversos mayormente leves y transitorios dependiendo de la dosis. Dentro de sus efectos adversos se describen artralgias, gastrointestinales, cutáneos y rara vez agranulocitosis como efecto adverso grave con una frecuencia de hasta el 0,6% y rondando el 50% de mortalidad. Este trabajo tiene por objetivo resaltar la importancia de aparición de fiebre en pacientes medicados con Metimazol, debido a su alta mortalidad.Facultad de Ciencias Médica

Radiological response to nivolumab in patients with hepatocellular carcinoma: A multicenter analysis of real-life practice

Background and aims: Immune-checkpoint inhibitors are effective in many advanced tumors. However, there is scarce information regarding the radiological response to these agents in hepatocellular carcinoma outside clinical trials. We aimed to describe the radiological response in a retrospective cohort of hepatocellular carcinoma patients treated with nivolumab and to analyze the radiological evolution according to tumor response at first post-treatment radiological assessment. Methods: We reviewed pre-treatment and post-treatment images (CT or MRI) obtained at different time-points in patients with hepatocellular carcinoma treated with nivolumab outside clinical trials at seven Spanish centers, assessing the response according to RECIST 1.1 and iRECIST and registering atypical responses. We also analyzed the imaging findings on subsequent assessments according to tumor status on the first posttreatment imaging assessment. Results: From the 118 patients with hepatocellular carcinoma treated with nivolumab, we finally analyzed data from 31 patients (71 % Child-Pugh A; 74 % BCLC-C). Median follow-up was 8.39 months [IQR 5.00-10.92]; median overall survival was 12.82 months (95 %CI 10.92-34.79). According to RECIST 1.1, the objective response rate was 16 % and according to iRECIST, the objective response rate was 22.6 %. Findings at the first post-treatment assessment varied, showing stable disease in 44.8 % of patients; findings during follow-up also varied widely, including 4 hyperprogressions and 3 pseudoprogressions. Conclusion: Imaging findings during nivolumab treatment are heterogeneous between and within patients. Progression of disease does not always signify treatment failure, and surrogate end-points may not reflect survival outcomes, making the management of hepatocellular carcinoma patients under immunotherapy challengin

Analysis of solvent tolerance in Pseudomonas putida DOT-T1E based on its genome sequence and a collection of mutants.

Work in our laboratory was supported by Fondo Social Europeo and Fondos FEDER from the European Union through project BIO2010-17227 and Junta de Andalucía Proyecto de Excelencia CVI-301