University of Seville

About: University of Seville is a education organization based out in Seville, Andalucía, Spain. It is known for research contribution in the topics: Population & Model predictive control. The organization has 20098 authors who have published 47317 publications receiving 947007 citations. The organization is also known as: Universidad de Sevilla.

Halophilic bacteria as a source of novel hydrolytic enzymes.

Abstract: Hydrolases constitute a class of enzymes widely distributed in nature from bacteria to higher eukaryotes. The halotolerance of many enzymes derived from halophilic bacteria can be exploited wherever enzymatic transformations are required to function under physical and chemical conditions, such as in the presence of organic solvents and extremes in temperature and salt content. In recent years, different screening programs have been performed in saline habitats in order to isolate and characterize novel enzymatic activities with different properties to those of conventional enzymes. Several halophilic hydrolases have been described, including amylases, lipases and proteases, and then used for biotechnological applications. Moreover, the discovery of biopolymer-degrading enzymes offers a new solution for the treatment of oilfield waste, where high temperature and salinity are typically found, while providing valuable information about heterotrophic processes in saline environments. In this work, we describe the results obtained in different screening programs specially focused on the diversity of halophiles showing hydrolytic activities in saline and hypersaline habitats, including the description of enzymes with special biochemical properties. The intracellular lipolytic enzyme LipBL, produced by the moderately halophilic bacterium Marinobacter lipolyticus, showed advantages over other lipases, being an enzyme active over a wide range of pH values and temperatures. The immobilized LipBL derivatives obtained and tested in regio- and enantioselective reactions, showed an excellent behavior in the production of free polyunsaturated fatty acids (PUFAs). On the other hand, the extremely halophilic bacterium, Salicola marasensis sp. IC10 showing lipase and protease activities, was studied for its ability to produce promising enzymes in terms of its resistance to temperature and salinity.

Role of breakup processes in fusion enhancement of drip-line nuclei at energies below the Coulomb barrier

Abstract: We carry out realistic coupled-channel calculations for the ${}^{11}\mathrm{Be}{+}^{208}\mathrm{Pb}$ reaction in order to discuss the effects of breakup of the projectile nucleus on subbarrier fusion. We discretize in energy the particle continuum states, which are associated with the breakup process, and construct the coupling form factors to these states on a microscopic basis. The incoming boundary condition is employed in solving coupled-channel equations, which enables us to define the flux for complete fusion inside the Coulomb barrier. It is shown that complete fusion cross sections are significantly enhanced due to the couplings to the continuum states compared with the no-coupling case at energies below the Coulomb barrier, while they are hindered at above barrier energies.

Human lymphocyte-synthesized melatonin is involved in the regulation of the interleukin-2/interleukin-2 receptor system.

Abstract: Since melatonin was first isolated in 1958 up to the last few years, this substance was considered a hormone exclusive to the pineal gland. Although melatonin has lately been identified in a large number of extrapineal sites, its potential biological actions have not yet been studied. This paper shows that human lymphocyte-synthesized melatonin plays a crucial role modulating IL-2/IL-2 receptor system because when blocking melatonin biosynthesis by the tryptophan hydroxylase inhibitor, parachlorophenylalanine, both IL-2 and IL-2 receptor levels fell, restoring them by adding exogenous melatonin. Moreover, we demonstrated that this endogenous melatonin interfered with the exogenous melatonin effect on IL-2 production. Melatonin exerted these effects by a receptor-mediated action mechanism because both IL-2 and IL-2 receptor expressions significantly decreased when lymphocytes were incubated in the presence of the specific membrane and/or nuclear melatonin receptor antagonists, luzindole, and/or CGP 55644, respectively. Finally, we made the real significance of the membrane melatonin receptors in this process clear, so prostaglandin E(2)-induced inhibition on IL-2 production increased when we blocked the membrane receptors using luzindole. In conclusion, these data show that endogenous melatonin is an essential part for an accurate response of human lymphocytes through the modulation of IL-2/IL-2 receptor system.