Solving the minimum labelling spanning tree problem using hybrid local search

Given a connected, undirected graph whose edges are labelled (or coloured), the minimum labelling spanning tree (MLST) problem seeks a spanning tree whose edges have the smallest number of distinct labels (or colours). In recent work, the MLST problem has been shown to be NP-hard and some effective heuristics (Modified Genetic Algorithm (MGA) and Pilot Method (PILOT)) have been proposed and analyzed. A hybrid local search method, that we call Group-Swap Variable Neighbourhood Search (GS-VNS), is proposed in this paper. It is obtained by combining two classic metaheuristics: Variable Neighbourhood Search (VNS) and Simulated Annealing (SA). Computational experiments show that GS-VNS outperforms MGA and PILOT. Furthermore, a comparison with the results provided by an exact approach shows that we may quickly obtain optimal or near-optimal solutions with the proposed heuristic

Identification, characterization and antigenicity of the Plasmodium vivax rhoptry neck protein 1 (PvRON1)

<p>Abstract</p> <p>Background</p> <p><it>Plasmodium vivax </it>malaria remains a major health problem in tropical and sub-tropical regions worldwide. Several rhoptry proteins which are important for interaction with and/or invasion of red blood cells, such as <it>Pf</it>RONs, <it>Pf</it>92, <it>Pf</it>38, <it>Pf</it>12 and <it>Pf</it>34, have been described during the last few years and are being considered as potential anti-malarial vaccine candidates. This study describes the identification and characterization of the <it>P. vivax </it>rhoptry neck protein 1 (<it>Pv</it>RON1) and examine its antigenicity in natural <it>P. vivax </it>infections.</p> <p>Methods</p> <p>The <it>Pv</it>RON1 encoding gene, which is homologous to that encoding the <it>P. falciparum </it>apical sushi protein (ASP) according to the plasmoDB database, was selected as our study target. The <it>pvron1 </it>gene transcription was evaluated by RT-PCR using RNA obtained from the <it>P. vivax </it>VCG-1 strain. Two peptides derived from the deduced <it>P. vivax </it>Sal-I <it>Pv</it>RON1 sequence were synthesized and inoculated in rabbits for obtaining anti-<it>Pv</it>RON1 antibodies which were used to confirm the protein expression in VCG-1 strain schizonts along with its association with detergent-resistant microdomains (DRMs) by Western blot, and its localization by immunofluorescence assays. The antigenicity of the <it>Pv</it>RON1 protein was assessed using human sera from individuals previously exposed to <it>P. vivax </it>malaria by ELISA.</p> <p>Results</p> <p>In the <it>P. vivax </it>VCG-1 strain, RON1 is a 764 amino acid-long protein. <it>In silico </it>analysis has revealed that <it>Pv</it>RON1 shares essential characteristics with different antigens involved in invasion, such as the presence of a secretory signal, a GPI-anchor sequence and a putative sushi domain. The <it>Pv</it>RON1 protein is expressed in parasite's schizont stage, localized in rhoptry necks and it is associated with DRMs. Recombinant protein recognition by human sera indicates that this antigen can trigger an immune response during a natural infection with <it>P. vivax</it>.</p> <p>Conclusions</p> <p>This study shows the identification and characterization of the <it>P. vivax </it>rhoptry neck protein 1 in the VCG-1 strain. Taking into account that <it>Pv</it>RON1 shares several important characteristics with other <it>Plasmodium </it>antigens that play a functional role during RBC invasion and, as shown here, it is antigenic, it could be considered as a good vaccine candidate. Further studies aimed at assessing its immunogenicity and protection-inducing ability in the <it>Aotus </it>monkey model are thus recommended.</p

Briófitos del hayedo de peña Izaga (Navarra)

Se estudia la Flora Briofítica del hayedo de Peña de Izaga (Navarra). Se citan 64 especies (11 hepáticas y 53 musgos), comentando su autoecología. Se comparan áreas de hayedo típico (Helleboro/Fagetum 0. de Bolòs (1948) 1957) y comunidades limítrofes (comunidades importadoras), discutiéndose las posibles causas climáticas-ecológicas de las diferencias observadas. Résumé: On a étudié la Flore Muscinale des hêtraies de Peña Izaga (Navarra). La forêt climax (Helleboro-Fagetum 0. de Bolos (1948) 1957) et les communautés végétales limitrophes comprendent une bryoflore constituée par 64 espèces (11 hépatiques et 53 muscinées). On a fait une brève analyse de l'auto-écologie de chaque espèce et une discussion des facteurs du milieu qui causent leur distribution locale

Flora micológica de peña de Izaga (Navarra)

Se citan 103 especies de hongos, 12 Ascomycetes y 91 Basidiomycetes, recolectados en hayedo, pinar y quejigal de Peña Izaga (Navarra). Un total de 46 especies son nuevas citas para el catálogo micológico de la provincia. Summary: 103 species of Fungi, of them 12 Ascomycetes and 91 Basidiomycetes, are cited in the present work. They have been collected in woods of Fagus sylvatica L., Quercus faginea Lam. and Pinus nigra Arnold from Peña Izaga (Navarra). 16 of the species are new records for the micological catalogue of Navarra

Pteridófitos de la provincia de La Rioja

Se ha efectuado una puesta al día del catálogo de Pteridófitos presentes en la provincia de la Rioja. Se citan 38 especies y subespecies, 8 de las cuales son novedad para la provincia. Summary: We have made a revisión of the catalogue of Pteridophyta from Rioja. We have cited 38 species and subspecies, 8 of them are new records for our province