https://hdl.handle.net/10259/4862 2026-05-11T20:19:20Z https://hdl.handle.net/10259/11586 An Efficient, Organic Solvent-Free Method for Extraction and Concentration of Hepatitis E Virus from Pig Liver Santamaría Palacios, Jorge; García, Nerea; Rodríguez Lázaro, David The presence of the hepatitis E virus (HEV) in pork products, particularly in pig liver has been frequently described. However, a standardized method is not still available for the detection of HEV in foods, particularly in those difficult food matrixes such as pig meat and pork products. The aim of this study was to design, optimize and evaluate a new method of food-separation and virus concentration for HEV in pig liver samples. This method is based on organic flocculation and avoids the use of organic solvents. The virus recovery rates and analytical sensitivity of the method using murine norovirus MNV-1 as a surrogate were 73.6–82.2% and at least 1 × 103 TCID50 per g of liver in 100% of the replicates, respectively. Furthermore, this new methodology was validated by testing the presence of HEV RNA in naturally infected pig liver samples, comparing it with two other commonly used concentration methods. The new extraction method run satisfactory in comparison with the two reference methods; statistically equivalent (p < 0.05) to one of the methods used while presented statistically significant better results (p < 0.05) compared to the second method. Consequently, our results indicate that the new extraction method can be an adequate cost-effective and ecologically friendly alternative for the food separation and concentration of HEV RNA in pig liver samples. 2025-01-01T00:00:00Z https://hdl.handle.net/10259/11321 Identification of PimR as a Positive Regulator of Pimaricin Biosynthesis in Streptomyces natalensis Antón Fidalgo, Nuria; Mendes, Marta V.; Martín, Juan F.; Aparicio, Jesús F. Sequencing of the DNA region on the left fringe of the pimaricin gene cluster revealed the presence of a 3.6-kb gene, pimR, whose deduced product (1,198 amino acid residues) was found to have amino acid sequence homology with bacterial regulatory proteins. Database comparisons revealed that PimR represents the archetype of a new class of regulators, combining a Streptomyces antibiotic regulatory protein (SARP)-like N-terminal section with a C-terminal half homologous to guanylate cyclases and large ATP-binding regulators of the LuxR family. Gene replacement of pimR from Streptomyces natalensis chromosome results in a complete loss of pimaricin production, suggesting that PimR is a positive regulator of pimaricin biosynthesis. Gene expression analysis by reverse transcriptase PCR (RT-PCR) of the pimaricin gene cluster revealed that S. natalensis ΔPimR shows no expression at all of the cholesterol oxidase-encoding gene pimE, and very low level transcription of the remaining genes of the cluster except for the mutant pimR gene, thus demonstrating that this regulator activates the transcription of all the genes belonging to the pimaricin gene cluster but not its own transcription. 2004-05-01T00:00:00Z https://hdl.handle.net/10259/11297 Biosynthetic rules for marcrolide construction Aparicio Fernández, Jesús Manuel; Mendes, Marta V.; Antón Fidalgo, Nuria; Martín Martín, Juan Francisco Macrolides constitute a large class of natural metabolites produced by giant multifunctional enzymes in a process resembling fatty acid biosynthesis. Like f atty acids, macrolides and other polyketides are assernbled by decarboxylative condensations of simple carboxylic acids. But while fatty acid intermediates are fully reduced, macrolide and other polyketide intermediates suffer the suppression of reduction or dehydration reactions at given biosynthetic steps. In the last years much progress has 'been made in our understanding of the linear and modular organisation of the gene clusters, and the enzymes encoded by them, responsiblefor... 2002-01-01T00:00:00Z https://hdl.handle.net/10259/11295 Red blood cells derived from peripheral blood and bone marrow CD34+ human haematopoietic stem cells are permissive to Plasmodium parasites infection Fernandez Becerra, Carmen; Lelievre, Joel; Ferrer, Mireia; Antón Fidalgo, Nuria; Thomson, Richard; Peligero, Cristina; Almela, Maria Jesus; Lacerda, Marcus VG; Herreros, Esperanza; del Portillo, Hernando A The production of fully functional human red cells in vitro from haematopoietic stem cells (hHSCs) has been successfully achieved. Recently, the use of hHSCs from cord blood represented a major improvement to develop the continuous culture system for Plasmodium vivax. Here, we demonstrated that CD34+ hHSCs from peripheral blood and bone marrow can be expanded and differentiated to reticulocytes using a novel stromal cell. Moreover, these reticulocytes and mature red blood cells express surface markers for entrance of malaria parasites contain adult haemoglobin and are also permissive to invasion by P. vivax and Plasmodium falciparum parasites. 2013-09-01T00:00:00Z