Stem cells as a therapeutic tool for the blind: biology and future prospects

Retinal degeneration due to genetic, diabetic and age-related disease is the most common cause of blindness in the developed world. Blindness occurs through the loss of the light-sensing photoreceptors; to restore vision, it would be necessary to introduce alternative photosensitive components into the eye. The recent development of an electronic prosthesis placed beneath the severely diseased retina has shown that subretinal stimulation may restore some visual function in blind patients. This proves that residual retinal circuits can be reawakened after photoreceptor loss and defines a goal for stem-cell-based therapy to replace photoreceptors. Advances in reprogramming adult cells have shown how it may be possible to generate autologous stem cells for transplantation without the need for an embryo donor. The recent success in culturing a whole optic cup in vitro has shown how large numbers of photoreceptors might be generated from embryonic stem cells. Taken together, these threads of discovery provide the basis for optimism for the development of a stem-cell-based strategy for the treatment of retinal blindness

Modelling and Analysis of Vibrations in a UAV Helicopter with a Vision System

The analysis of the nature and damping of unwanted vibrations on Unmanned Aerial Vehicle (UAV) helicopters are important tasks when images from on‐board vision systems are to be obtained. In this article, the authors model a UAV system, generate a range of vibrations originating in the main rotor and design a control methodology in order to damp these vibrations. The UAV is modelled using VehicleSim, the vibrations that appear on the fuselage are analysed to study their effects on the on‐board vision system by using Simmechanics software. Following this, the authors present a control method based on an Adaptive Neuro‐Fuzzy Inference System (ANFIS) to achieve satisfactory damping results over the vision system on board

Automated Synthesis of Tableau Calculi

This paper presents a method for synthesising sound and complete tableau calculi. Given a specification of the formal semantics of a logic, the method generates a set of tableau inference rules that can then be used to reason within the logic. The method guarantees that the generated rules form a calculus which is sound and constructively complete. If the logic can be shown to admit finite filtration with respect to a well-defined first-order semantics then adding a general blocking mechanism provides a terminating tableau calculus. The process of generating tableau rules can be completely automated and produces, together with the blocking mechanism, an automated procedure for generating tableau decision procedures. For illustration we show the workability of the approach for a description logic with transitive roles and propositional intuitionistic logic.Comment: 32 page

Practical applications using multi-UAV systems and aerial robotic swarms

[EN] Nowadays, there are a large number of unmanned aircraft on the market that can be commanded with high-level orders to perform complex tasks almost automatically, such as mapping crop fields. We can ask ourselves if it would be possible to coordinate a group of these robots to perform those same tasks more quickly, flexibly and robustly. In this work, we summarize the tasks that have been studied to be solved with systems composed by groups of unmanned aircraft and the algorithms used, as well as the methods and strategies on which they are based. Although the future of these systems is promising, there are certain legislative and technical obstacles that stop their implementation in a generalized way.[ES] A día de hoy, existen en el mercado una gran cantidad de aeronaves sin piloto que pueden ser comandadas con ordenes de alto nivel para realizar tareas complejas de forma casi automatica, como por ejemplo el mapeo de explotaciones agrícolas. De forma natural, nos podemos preguntar si sería posible coordinar a un grupo de estos robots para realizar esas mismas tareas de forma más rápida, flexible y robusta. En este trabajo se repasan las tareas que se han planteado resolver con sistemas compuestos por grupos de aeronaves no tripuladas y los algoritmos empleados, así como los metodos y estrategias en los que están basados. Aunque el futuro de estos sistemas es prometedor, existen ciertos obstaculos legislativos y técnicos que frenan su implantación de forma generalizada.Las investigaciones que han dado como resultado este trabajo han sido financiadas por RoboCity2030-DIH-CM, 426 Madrid Robotics Digital Innovation Hub, S2018/NMT-4331, financiadas por los Programas de Actividades I+D en la Comunidad Madrid, y por el proyecto TASAR (Team of Advanced Search And Rescue Robots), PID2019-105808RB-I00, financiado por el Ministerio de Ciencia e Innovacion (Gobierno de España).García-Aunon, P.; Roldán, J.; De León, J.; Del Cerro, J.; Barrientos, A. (2021). Aplicaciones practicas de los sistemas multi-UAV y enjambres aéreos. Revista Iberoamericana de Automática e Informática industrial. 18(3):230-241. https://doi.org/10.4995/riai.2020.13560OJS230241183Acevedo, J. J., Arrue, B. C., Maza, I., Ollero, A., 2013. Cooperative large area surveillance with a team of aerial mobile robots for long endurance missions. Journal of Intelligent & Robotic Systems 70 (1-4), 329-345. https://doi.org/10.1007/s10846-012-9716-3Albani, D., IJsselmuiden, J., Haken, R., Trianni, V., 2017. Monitoring and mapping with robot swarms for agricultural applications. In: 2017 14th IEEE International Conference on Advanced Video and Signal Based Surveillance (AVSS). IEEE, pp. 1-6. https://doi.org/10.1109/AVSS.2017.8078478Alvear, O., Zema, N. R., Natalizio, E., Calafate, C. T., 2017. Using uav-based systems to monitor air pollution in areas with poor accessibility. Journal of Advanced Transportation 2017. https://doi.org/10.1155/2017/8204353Augugliaro, F., Lupashin, S., Hamer, M., Male, C., Hehn, M., Mueller, M. W., Willmann, J. S., Gramazio, F., Kohler, M., D'Andrea, R., 2014. The flight assembled architecture installation: Cooperative construction with flying machines. IEEE Control Systems Magazine 34 (4), 46-64. https://doi.org/10.1109/MCS.2014.2320359Barrientos, A., Colorado, J., Cerro, J. d., Martinez, A., Rossi, C., Sanz, D., Valente, J., 2011. Aerial remote sensing in agriculture: A practical approach to area coverage and path planning for fleets of mini aerial robots. Journal of Field Robotics 28 (5), 667-689. https://doi.org/10.1002/rob.20403Beck, Z., Teacy, W. L., Rogers, A., Jennings, N. R., 2018. Collaborative online planning for automated victim search in disaster response. Robotics and Autonomous Systems 100, 251-266. https://doi.org/10.1016/j.robot.2017.09.014Bennet, D. J., MacInnes, C., Suzuki, M., Uchiyama, K., 2011. Autonomous three-dimensional formation flight for a swarm of unmanned aerial vehicles. Journal of guidance, control, and dynamics 34 (6), 1899-1908. https://doi.org/10.2514/1.53931Bernard, M., Kondak, K., Maza, I., Ollero, A., 2011. Autonomous transportation and deployment with aerial robots for search and rescue missions. Journal of Field Robotics 28 (6), 914-931. https://doi.org/10.1002/rob.20401Carrasco, Á. M., Novoa, S. C., Al-Kaff, A., Fernández, F. G., Gómez, D. M., de la Escalera Hueso, A., 2020. Vehículo aéreo no tripulado para vigilancia y monitorización de incendios. Revista Iberoamericana de Automática e Informática industrial.Chen, S., Li, C., Zhuo, S., 2017. A distributed coverage algorithm for multiuav with average voronoi partition. In: 2017 17th International Conference on Control, Automation and Systems (ICCAS). IEEE, pp. 1083-1086. https://doi.org/10.23919/ICCAS.2017.8204377Cieslewski, T., Choudhary, S., Scaramuzza, D., 2018. Data-efficient decentralized visual slam. In: 2018 IEEE International Conference on Robotics and Automation (ICRA). IEEE, pp. 2466-2473. https://doi.org/10.1109/ICRA.2018.8461155Cimino, M. G., Lazzeri, A., Vaglini, G., 2015. Combining stigmergic and flocking behaviors to coordinate swarms of drones performing target search. In: 2015 6th International Conference on Information, Intelligence, Systems and Applications (IISA). IEEE, pp. 1-6. https://doi.org/10.1109/IISA.2015.7387990Cledat, E., Cucci, D., 2017. Mapping gnss restricted environments with a drone tandem and indirect position control. ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences 4, 1. https://doi.org/10.5194/isprs-annals-IV-2-W3-1-2017Cole, D. T., Thompson, P., Göktogan, A. H., Sukkarieh, S., 2010. System development and demonstration of a cooperative uav team for mapping and tracking. The International Journal of Robotics Research 29 (11), 1371-1399. https://doi.org/10.1177/0278364910364685Darrah, M., Trujillo, M. M., Speransky, K., Wathen, M., 2017. Optimized 3d mapping of a large area with structures using multiple multirotors. In: 2017 International Conference on Unmanned Aircraft Systems (ICUAS). IEEE, pp. 716-722. https://doi.org/10.1109/ICUAS.2017.7991414Erignac, C., 2007. An exhaustive swarming search strategy based on distributed pheromone maps. In: AIAA Infotech@ Aerospace 2007 Conference and Exhibit. p. 2822. https://doi.org/10.2514/6.2007-2822Fu, Z., Chen, Y., Ding, Y., He, D., 2019. Pollution source localization based on multi-uav cooperative communication. IEEE Access 7, 29304-29312. https://doi.org/10.1109/ACCESS.2019.2900475Fujisawa, R., Imamura, H., Hashimoto, T., Matsuno, F., 2008. Communication using pheromone field for multiple robots. In: 2008 IEEE/RSJ International Conference on Intelligent Robots and Systems. IEEE, pp. 1391-1396. https://doi.org/10.1109/IROS.2008.4650971Garcia-Aunon, P., Barrientos, A., 2018a. Comparison of heuristic algorithms in discrete search and surveillance tasks using aerial swarms. Applied Sciences 8 (5), 711. https://doi.org/10.3390/app8050711Garcia-Aunon, P., Barrientos, A., 2018b. Control optimization of an aerial robotic swarm in a search task and its adaptation to different scenarios. Journal of computational science 29, 107-118. https://doi.org/10.1016/j.jocs.2018.10.004Garcia-Aunon, P., del Cerro, J., Barrientos, A., 2019a. Behavior-based control for an aerial robotic swarm in surveillance missions. Sensors 19 (20), 4584. https://doi.org/10.3390/s19204584Garcia-Aunon, P., Roldan, J. J., Barrientos, A., 2019b. Monitoring traffic in future cities with aerial swarms: Developing and optimizing a behavior-based surveillance algorithm. Cognitive Systems Research 54, 273-286. https://doi.org/10.1016/j.cogsys.2018.10.031Garnier, S., Tache, F., Combe, M., Grimal, A., Theraulaz, G., 2007. Alice in pheromone land: An experimental setup for the study of ant-like robots. In: 2007 IEEE Swarm Intelligence Symposium. IEEE, pp. 37-44. https://doi.org/10.1109/SIS.2007.368024George, J., Sujit, P., Sousa, J. B., 2011. Search strategies for multiple uav search and destroy missions. Journal of Intelligent & Robotic Systems 61 (1-4), 355-367. https://doi.org/10.1007/s10846-010-9486-8Hadaegh, F. Y., Chung, S.-J., Manohara, H. M., 2014. On development of 100- gram-class spacecraft for swarm applications. IEEE Systems Journal 10 (2), 673-684. https://doi.org/10.1109/JSYST.2014.2327972Han, J., Xu, Y., Di, L., Chen, Y., 2013. Low-cost multi-uav technologies for contour mapping of nuclear radiation field. Journal of Intelligent & Robotic Systems 70 (1-4), 401-410. https://doi.org/10.1007/s10846-012-9722-5Hauert, S., Winkler, L., Zufferey, J.-C., Floreano, D., 2008. Ant-based swarming with positionless micro air vehicles for communication relay. Swarm Intelligence 2 (2-4), 167-188. https://doi.org/10.1007/s11721-008-0013-5Hinzmann, T., Stastny, T., Conte, G., Doherty, P., Rudol, P., Wzorek, M., Galceran, E., Siegwart, R., Gilitschenski, I., 2016. Collaborative 3d reconstruction using heterogeneous uavs: System and experiments. In: International Symposium on Experimental Robotics. Springer, pp. 43-56. https://doi.org/10.1007/978-3-319-50115-4_5Ju, C., Son, H., 2018. Multiple uav systems for agricultural applications: control, implementation, and evaluation. Electronics 7 (9), 162. https://doi.org/10.3390/electronics7090162Kim, J. H., Kwon, J.-W., Seo, J., 2014. Multi-uav-based stereo vision system without gps for ground obstacle mapping to assist path planning of ugv. Electronics Letters 50 (20), 1431-1432. https://doi.org/10.1049/el.2014.2227Lanillos, P., Gan, S. K., Besada-Portas, E., Pajares, G., Sukkarieh, S., 2014. Multi-uav target search using decentralized gradient-based negotiation with expected observation. Information Sciences 282, 92-110. https://doi.org/10.1016/j.ins.2014.05.054Li, W., 2015. Persistent surveillance for a swarm of micro aerial vehicles by flocking algorithm. Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 229 (1), 185-194. https://doi.org/10.1177/0954410014529100Lyu, Y., Pan, Q., Zhang, Y., Zhao, C., Zhu, H., Tang, T., Liu, L., 2015. Simultaneously multi-uav mapping and control with visual servoing. In: 2015 International Conference on Unmanned Aircraft Systems (ICUAS). IEEE, pp. 125-131. https://doi.org/10.1109/ICUAS.2015.7152283Mahdoui, N., Frémont, V., Natalizio, E., 2017. Cooperative exploration strategy for micro-aerial vehicles fleet. In: 2017 IEEE International Conference on Multisensor Fusion and Integration for Intelligent Systems (MFI). IEEE, pp. 180-185. https://doi.org/10.1109/MFI.2017.8170426Maza, I., Ollero, A., 2007. Multiple uav cooperative searching operation using polygon area decomposition and efficient coverage algorithms. In: Distributed Autonomous Robotic Systems 6. Springer, pp. 221-230. https://doi.org/10.1007/978-4-431-35873-2_22Mirjan, A., Gramazio, F., Kohler, M., Augugliaro, F., D'Andrea, R., 2013. Architectural fabrication of tensile structures with flying machines. Green Design, Materials and Manufacturing Processes, 513-518. https://doi.org/10.1201/b15002-99Niedzielski, T., Jurecka, M., Mizinski, B., Remisz, J., Slopek, J., Spallek, W., Witek-Kasprzak, M., Kasprzak, Ł., Swierczynska-Chlasciak, M., 2018. A real-time field experiment on search and rescue operations assisted by unmanned aerial vehicles. Journal of Field Robotics 35 (6), 906-920. https://doi.org/10.1002/rob.21784Nigam, N., Bieniawski, S., Kroo, I., Vian, J., 2011. Control of multiple uavs for persistent surveillance: algorithm and flight test results. IEEE Transactions on Control Systems Technology 20 (5), 1236-1251. https://doi.org/10.1109/TCST.2011.2167331Odonkor, P., Ball, Z., Chowdhury, S., 2019. Distributed operation of collaborating unmanned aerial vehicles for time-sensitive oil spill mapping. Swarm and Evolutionary Computation 46, 52-68. https://doi.org/10.1016/j.swevo.2019.01.005Oh, S.-H., Suk, J., 2010. Evolutionary design of the controller for the search of area with obstacles using multiple uavs. In: ICCAS 2010. IEEE, pp. 2541- 2546. https://doi.org/10.1109/ICCAS.2010.5670230Perez-Carabaza, S., Besada-Portas, E., Lopez-Orozco, J. A., Jesus, M., 2018. Ant colony optimization for multi-uav minimum time search in uncertain domains. Applied Soft Computing 62, 789-806. https://doi.org/10.1016/j.asoc.2017.09.009Qu, Y., Zhang, Y., Zhang, Y., 2015. A uav solution of regional surveillance based on pheromones and artificial potential field theory. In: 2015 International Conference on Unmanned Aircraft Systems (ICUAS). IEEE, pp. 380-385. https://doi.org/10.1109/ICUAS.2015.7152313Rastgoftar, H., Atkins, E. M., 2018. Cooperative aerial lift and manipulation (calm). Aerospace Science and Technology 82, 105-118. https://doi.org/10.1016/j.ast.2018.09.005Reina, D., Tawfik, H., Toral, S., 2018. Multi-subpopulation evolutionary algorithms for coverage deployment of uav-networks. Ad Hoc Networks 68, 16-32. https://doi.org/10.1016/j.adhoc.2017.09.005Reuder, J., Jonassen, M. O., Olafsson, H., 2012. The small unmanned meteorological observer sumo: Recent developments and applications of a micro-uas for atmospheric boundary layer research. Acta Geophysica 60 (5), 1454- 1473. https://doi.org/10.2478/s11600-012-0042-8Reynolds, C. W., 1987. Flocks, herds and schools: A distributed behavioral model. Vol. 21. ACM. https://doi.org/10.1145/37402.37406Roldan, J. J., Garcia-Aunon, P., Peña-Tapia, E., Barrientos, A., 2019. Swarm-city project: Can an aerial swarm monitor traffic in a smart city? In: 2019 IEEE International Conference on Pervasive Computing and Communications Workshops (PerCom Workshops). IEEE, pp. 862-867. https://doi.org/10.1109/PERCOMW.2019.8730677Santamaria, E., Segor, F., Tchouchenkov, I., 2013. Rapid aerial mapping with multiple heterogeneous unmanned vehicles. In: ISCRAM. Citeseer.Saska, M., Chudoba, J., Preucil, L., Thomas, J., Loianno, G., Tresnak, A., Vonasek, V., Kumar, V., 2014. Autonomous deployment of swarms of microaerial vehicles in cooperative surveillance. In: 2014 International Conference on Unmanned Aircraft Systems (ICUAS). IEEE, pp. 584-595. https://doi.org/10.1109/ICUAS.2014.6842301Savkin, A. V., Huang, H., 2019. Asymptotically optimal deployment of drones for surveillance and monitoring. Sensors 19 (9), 2068. https://doi.org/10.3390/s19092068Schilling, F., Lecoeur, J., Schiano, F., Floreano, D., 2018. Learning visionbased cohesive flight in drone swarms. arXiv preprint arXiv:1809.00543.Schmuck, P., Chli, M., 2017. Multi-uav collaborative monocular slam. In: 2017 IEEE International Conference on Robotics and Automation (ICRA). IEEE, pp. 3863-3870. https://doi.org/10.1109/ICRA.2017.7989445Silic, M. B., Song, Z., Mohseni, K., 2018. Anisotropic flocking control of distributed multi-agent systems using fluid abstraction. In: 2018 AIAA Information Systems-AIAA Infotech@ Aerospace. p. 2262. https://doi.org/10.2514/6.2018-2262Sreenath, K., Kumar, V., 2013. Dynamics, control and planning for cooperative manipulation of payloads suspended by cables from multiple quadrotor robots. rn 1 (r2), r3. https://doi.org/10.15607/RSS.2013.IX.011St-Onge, D., Kaufmann, M., Panerati, J., Ramtoula, B., Cao, Y., Coffey, E. B., Beltrame, G., 2019. Planetary exploration with robot teams. IEEE Robotics & Automation Magazine.Stavros, E. N., Agha, A., Sirota, A., Quadrelli, M., Ebadi, K., Yun, K., 2019. Smoke sky-exploring new frontiers of unmanned aerial systems for wildland fire science and applications. arXiv preprint arXiv:1911.08288.Techy, L., Schmale III, D. G., Woolsey, C. A., 2010. Coordinated aerobiological sampling of a plant pathogen in the lower atmosphere using two autonomous unmanned aerial vehicles. Journal of Field Robotics 27 (3), 335-343. https://doi.org/10.1002/rob.20335Tuna, G., Nefzi, B., Conte, G., 2014. Unmanned aerial vehicle-aided communications system for disaster recovery. Journal of Network and Computer Applications 41, 27-36. https://doi.org/10.1016/j.jnca.2013.10.002Twidwell, D., Allen, C. R., Detweiler, C., Higgins, J., Laney, C., Elbaum, S., 2016. Smokey comes of age: unmanned aerial systems for fire management. Frontiers in Ecology and the Environment 14 (6), 333-339. https://doi.org/10.1002/fee.1299Vasarhelyi, G., Viragh, C., Somorjai, G., Tarcai, N., Szorenyi, T., Nepusz, T., Vicsek, T., 2014. Outdoor flocking and formation flight with autonomous aerial robots. In: 2014 IEEE/RSJ International Conference on Intelligent Robots and Systems. IEEE, pp. 3866-3873. https://doi.org/10.1109/IROS.2014.6943105Verdu, T., Hattenberger, G., Lacroix, S., 2019. Flight patterns for clouds exploration with a fleet of uavs. https://doi.org/10.1109/ICUAS.2019.8797953Waharte, S., Trigoni, N., 2010. Supporting search and rescue operations with uavs. In: 2010 International Conference on Emerging Security Technologies. IEEE, pp. 142-147. https://doi.org/10.1109/EST.2010.31Wang, Z., Singh, S., Pavone, M., Schwager, M., 2018. Cooperative object transport in 3d with multiple quadrotors using no peer communication. In: 2018 IEEE International Conference on Robotics and Automation (ICRA). IEEE, pp. 1064-1071. https://doi.org/10.1109/ICRA.2018.8460742Zhao, N., Lu, W., Sheng, M., Chen, Y., Tang, J., Yu, F. R., Wong, K.-K., 2019. Uav-assisted emergency networks in disasters. IEEE Wireless Communications 26 (1), 45-51. https://doi.org/10.1109/MWC.2018.1800160Zheng, X., Wang, F., Li, Z., 2018. A multi-uav cooperative route planning methodology for 3d fine-resolution building model reconstruction. ISPRS journal of photogrammetry and remote sensing 146, 483-494. https://doi.org/10.1016/j.isprsjprs.2018.11.00

RNA-seq analysis of the Rhizobium tropici CIAT 899 Transcripitome shows similarites in the activation patterns of symbiotic genes in the presence of apigenin and salt.

Rhizobium tropici strain CIAT 899 establishes effective symbioses with several legume species, including Phaseolus vulgaris and Leucaena leucocephala. This bacterium synthesizes a large variety of nodulation factors in response to nod-gene inducing flavonoids and, surprisingly, also under salt stress conditions. The aim of this study was to identify differentially expressed genes in the presence of both inducer molecules, and analyze the promoter regions located upstream of these genes. Results obtained by RNA-seq analyses of CIAT 899 induced with apigenin, a nod gene-inducing flavonoid for this strain, or salt allowed the identification of 19 and 790 differentially expressed genes, respectively. Fifteen of these genes were up-regulated in both conditions and were involved in the synthesis of both Nod factors and indole-3-acetic acid. Transcription of these genes was presumably activated through binding of at least one of the five NodD proteins present in this strain to specific nod box promoter sequences when the bacterium was induced by both apigenin and salt. Finally, under saline conditions, many other transcriptional responses were detected, including an increase in the transcription of genes involved in trehalose catabolism, chemotaxis and protein secretion, as well as ribosomal genes, and a decrease in the transcription of genes involved in transmembrane transport. To our knowledge this is the first time that a transcriptomic study shows that salt stress induces the expression of nodulation genes in the absence of flavonoids. Thus, in the presence of both nodulation inducer molecules, apigenin and salt, R. tropici CIAT 899 up-regulated the same set of symbiotic genes. It could be possible that the increases in the transcription levels of several genes related to nodulation under saline conditions could represent a strategy to establish symbiosis under abiotic stressing conditions

NrcR, a new transcriptional regulator of Rhizobium tropici CIAT 899 involved in the Legume root-nodule symbiosis.

The establishment of nitrogen-fixing rhizobium-legume symbioses requires a highly complex cascade of events. In this molecular dialogue the bacterial NodD transcriptional regulators in conjunction with plant inducers, mostly flavonoids, are responsible for the biosynthesis and secretion of Nod factors which are key molecules for successful nodulation. Other transcriptional regulators related to the symbiotic process have been identified in rhizobial genomes, including negative regulators such as NolR. Rhizobium tropici CIAT 899 is an important symbiont of common bean (Phaseolus vulgaris L.), and its genome encompasses intriguing features such as five copies of nodD genes, as well as other possible transcriptional regulators including the NolR protein. Here we describe and characterize a new regulatory gene located in the non-symbiotic plasmid pRtrCIAT899c, that shows homology (46% identity) with the nolR gene located in the chromosome of CIAT 899. The mutation of this gene, named nrcR (nolR-like plasmid c Regulator), enhanced motility and exopolysaccharide production in comparison to the wild-type strain. Interestingly, the number and decoration of Nod Factors produced by this mutant were higher than those detected in the wildtype strain, especially under salinity stress. The nrcR mutant showed delayed nodulation and reduced competitiveness with P. vulgaris, and reduction in nodule number and shoot dry weight in both P. vulgaris and Leucaena leucocephala. Moreover, the mutant exhibited reduced capacity to induce the nodC gene in comparison to the wild-type CIAT 899. The finding of a new nod-gene regulator located in a non-symbiotic plasmid may reveal the existence of even more complex mechanisms of regulation of nodulation genes in R. tropici CIAT 899 that may be applicable to other rhizobial species

Regulatory nodD1 and nodD2 genes of Rhizobium tropici strain CIAT 899 and their roles in the early stages of molecular signaling and host-legume nodulation.

Nodulation and symbiotic nitrogen fixation are mediated by several genes, both of the host legume and of the bacterium. The rhizobial regulatory nodD gene plays a critical role, orchestrating the transcription of the other nodulation genes. Rhizobium tropici strain CIAT 899 is an effective symbiont of several legumes?with an emphasis on common bean (Phaseolus vulgaris)?and is unusual in carrying multiple copies of nodD, the roles of which remain to be elucidated. Results: Phenotypes, Nod factors and gene expression of nodD1 and nodD2 mutants of CIAT 899 were compared with those of the wild type strain, both in the presence and in the absence of the nod-gene-inducing molecules apigenin and salt (NaCl). Differences between the wild type and mutants were observed in swimming motility and IAA (indole acetic acid) synthesis. In the presence of both apigenin and salt, large numbers of Nod factors were detected in CIAT 899, with fewer detected in the mutants. nodC expression was lower in both mutants; differences in nodD1 and nodD2 expression were observed between the wild type and the mutants, with variation according to the inducing molecule, and with a major role of apigenin with nodD1 and of salt with nodD2. In the nodD1 mutant, nodulation was markedly reduced in common bean and abolished in leucaena (Leucaena leucocephala) and siratro (Macroptilium atropurpureum), whereas a mutation in nodD2 reduced nodulation in common bean, but not in the other two legumes. Conclusion: Our proposed model considers that full nodulation of common bean by R. tropici requires both nodD1 and nodD2, whereas, in other legume species that might represent the original host, nodD1 plays the major role. In general, nodD2 is an activator of nod-gene transcription, but, in specific conditions, it can slightly repress nodD1. nodD1 and nodD2 play other roles beyond nodulation, such as swimming motility and IAA synthesis

ENTRAP and its potential interaction with European networks

AbstractENTRAP comprises a pan-European cooperation of leading scientific institutions and regulatory bodies in the field of nuclear-waste characterization and its quality assurance for the safe disposal of radioactive waste. Here, the scope of this cooperation is presented and explained and links or interfaces for a potential collaboration with partners fulfilling tasks of IDG-TP are pursued

Coassembly and coupling of SK2 channels and mGlu5 receptors

Group I metabotropic glutamate (mGlu) receptors regulate hippocampal CA1 pyramidal neuron excitability via Ca(2+) wave-dependent activation of small-conductance Ca(2+)-activated K(+) (SK) channels. Here, we show that mGlu5 receptors and SK2 channels coassemble in heterologous coexpression systems and in rat brain. Further, in cotransfected cells or rat primary hippocampal neurons, mGlu5 receptor stimulation activated apamin-sensitive SK2-mediated K(+) currents. In addition, coexpression of mGlu5 receptors and SK2 channels promoted plasma membrane targeting of both proteins and correlated with increased mGlu5 receptor function that was unexpectedly blocked by apamin. These results demonstrate a reciprocal functional interaction between mGlu5 receptors and SK2 channels that reflects their molecular coassembly

The order parameter-entropy relation in some universal classes: experimental evidence

The asymptotic behaviour near phase transitions can be suitably characterized by the scaling of $\Delta s/Q^2$ with $\epsilon=1-T/T_c$, where $\Delta s$ is the excess entropy and $Q$ is the order parameter. As $\Delta s$ is obtained by integration of the experimental excess specific heat of the transition $\Delta c$, it displays little experimental noise so that the curve $\log(\Delta s/Q^2)$ versus $\log\epsilon$ is better constrained than, say, $\log\Delta c$ versus $\log\epsilon$. The behaviour of $\Delta s/Q^2$ for different universality classes is presented and compared. In all cases, it clearly deviates from being a constant. The determination of this function can then be an effective method to distinguish asymptotic critical behaviour. For comparison, experimental data for three very different systems, Rb2CoF4, Rb2ZnCl4 and SrTiO3, are analysed under this approach. In SrTiO3, the function $\Delta s/Q^2$ does not deviate within experimental resolution from a straight line so that, although Q can be fitted with a non mean-field exponent, the data can be explained by a classical Landau mean-field behaviour. In contrast, the behaviour of $\Delta s/Q^2$ for the antiferromagnetic transition in Rb2CoF4 and the normal-incommensurate phase transition in Rb2ZCl4 is fully consistent with the asymptotic critical behaviour of the universality class corresponding to each case. This analysis supports, therefore, the claim that incommensurate phase transitions in general, and the A$_2$BX$_4$ compounds in particular, in contrast with most structural phase transitions, have critical regions large enough to be observable.Comment: 13 pp. 9 ff. 2 tab. RevTeX. Submitted to J. Phys.: Cond. Matte