Mitochondrial Redox Metabolism in Trypanosomatids Is Independent of Tryparedoxin Activity

Tryparedoxins (TXNs) are oxidoreductases unique to trypanosomatids (including Leishmania and Trypanosoma parasites) that transfer reducing equivalents from trypanothione, the major thiol in these organisms, to sulfur-dependent peroxidases and other dithiol proteins. The existence of a TXN within the mitochondrion of trypanosomatids, capable of driving crucial redox pathways, is considered a requisite for normal parasite metabolism. Here this concept is shown not to apply to Leishmania. First, removal of the Leishmania infantum mitochondrial TXN (LiTXN2) by gene-targeting, had no significant effect on parasite survival, even in the context of an animal infection. Second, evidence is presented that no other TXN is capable of replacing LiTXN2. In fact, although a candidate substitute for LiTXN2 (LiTXN3) was found in the genome of L. infantum, this was shown in biochemical assays to be poorly reduced by trypanothione and to be unable to reduce sulfur-containing peroxidases. Definitive conclusion that LiTXN3 cannot directly reduce proteins located within inner mitochondrial compartments was provided by analysis of its subcellular localization and membrane topology, which revealed that LiTXN3 is a tail-anchored (TA) mitochondrial outer membrane protein presenting, as characteristic of TA proteins, its N-terminal end (containing the redox-active domain) exposed to the cytosol. This manuscript further proposes the separation of trypanosomatid TXN sequences into two classes and this is supported by phylogenetic analysis: i) class I, encoding active TXNs, and ii) class II, coding for TA proteins unlikely to function as TXNs. Trypanosoma possess only two TXNs, one belonging to class I (which is cytosolic) and the other to class II. Thus, as demonstrated for Leishmania, the mitochondrial redox metabolism in Trypanosoma may also be independent of TXN activity. The major implication of these findings is that mitochondrial functions previously thought to depend on the provision of electrons by a TXN enzyme must proceed differently

The Beaker phenomenon and the genomic transformation of northwest Europe

From around 2750 to 2500 bc, Bell Beaker pottery became widespread across western and central Europe, before it disappeared between 2200 and 1800 bc. The forces that propelled its expansion are a matter of long-standing debate, and there is support for both cultural diffusion and migration having a role in this process. Here we present genome-wide data from 400 Neolithic, Copper Age and Bronze Age Europeans, including 226 individuals associated with Beaker-complex artefacts. We detected limited genetic affinity between Beaker-complex-associated individuals from Iberia and central Europe, and thus exclude migration as an important mechanism of spread between these two regions. However, migration had a key role in the further dissemination of the Beaker complex. We document this phenomenon most clearly in Britain, where the spread of the Beaker complex introduced high levels of steppe-related ancestry and was associated with the replacement of approximately 90% of Britain’s gene pool within a few hundred years, continuing the east-to-west expansion that had brought steppe-related ancestry into central and northern Europe over the previous centuries

Processi di bio-essiccazione dei rifiuti urbani indifferenziati ai fini energetici

Due to the limited possibilities of FOS (Stabilized Organic Fraction) usage both for environmental restorations and landfill coverings, the selection of the bio-drying single flow process as a pretreatment for an high quality CDR (RDF-Refuse Derived Fuel) is currently the only alternative to dual flow Mechanical and Biological Treatment (TMB). The purpose of this study is the analysis of a real scale operating bio-drying process case by performance recording/analysis and consequent limits & strengths /Weaknesses identification in various usual/unusual conditions. Continuous monitoring system of biological process has been developed and optimized and a bio-chemical process model has been developed using experimental tests data. The strengths have been identified in the minimization of the FOS (Stabilized Organic Fraction) quantities and in the higher yield of CDR (RDF-Refuse Derived Fuel) on the total amount of incoming waste. Primary strength consist in better quality CDR (RDF-Refuse Derived Fuel) obtained by eliminating most of the problems related to the waste refining process subsequent phase, with the possibility of adopting bio-dried material refining techniques and technologies, not usable for wet waste, with the same yields

Functional characterization of mitochondria isolated from the ancient gymnosperm Araucaria angustifolia

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Mitochondria were isolated from embryogenic cell cultures of Araucaria angustifolia, an ancient gymnosperm. The mitochondria obtained oxidized NADH and succinate as respiratory substrates and were able to sustain a high transmembrane electrical potential. They were able to take up Ca2+ supported by substrate oxidation, sensitive to ruthenium red and dependent on membrane potential. The influx of the ion was Pi dependent and at least one efflux pathway was demonstrated by ruthenium red addition. The mitochondria also oxidized externally added NADH, and presented oxygen consumption insensitive to cyanide and sensitive to salicyl hydroxamic acid (SHAM) suggesting the presence of external NADH dehydrogenase and alternative oxidase (AOX), respectively. Besides, mitochondria were uncoupled, in the absence of BSA, by the addition of oleic acid suggesting the presence of the plant uncoupling mitochondrial protein. (C) 2008 Elsevier Ireland Ltd. All rights reserved.1755701705Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Uma proposta de solução para o problema da construção de escalas de motoristas e cobradores de ônibus por meio do algoritmo do matching de peso máximo A proposed solution for bus driver and fare collector scheduling problems using the maximum weight matching algorithm

O objetivo deste trabalho é mostrar a aplicação do Algoritmo do Matching de peso máximo, na elaboração de jornadas de trabalho para motoristas e cobradores de ônibus. Este problema deve ser resolvido levando-se em consideração o maior aproveitamento possível das tabelas de horários, com o objetivo de minimizar o número de funcionários, de horas extras e de horas ociosas. Desta forma, os custos das companhias de transporte público são minimizados. Na primeira fase do trabalho, supondo-se que as tabelas de horários já estejam divididas em escalas de curta e de longa duração, as escalas de curta duração são combinadas para a formação da jornada diária de trabalho de um funcionário. Esta combinação é feita com o Algoritmo do Matching de peso máximo, no qual as escalas são representadas por vértices de um grafo, e o peso máximo é atribuído às combinações de escalas que não formam horas extras e horas ociosas. Na segunda fase, uma jornada de final de semana é designada para cada jornada semanal de dias úteis. Por meio destas duas fases, as jornadas semanais de trabalho para motoristas e cobradores de ônibus podem ser construídas com custo mínimo. A terceira e última fase deste trabalho consiste na designação das jornadas semanais de trabalho para cada motorista e cobrador de ônibus, considerando-se suas preferências. O Algoritmo do Matching de peso máximo é utilizado para esta fase também. Este trabalho foi aplicado em três empresas de transporte público da cidade de Curitiba - PR, nas quais os algoritmos utilizados anteriormente eram heurísticos, baseados apenas na experiência do encarregado por esta tarefa.<br>The purpose of this paper is to discuss how the maximum weight Matching Algorithm can be applied to schedule the workdays of bus drivers and bus fare collectors. This scheduling should be based on the best possible use of timetables in order to minimize the number of employees, overtime and idle hours, thereby minimizing the operational costs of public transportation companies. In the first phase of this study, assuming that the timetables are already divided into long and short duration schedules, the short schedules can be combined to make up an employee's workday. This combination is done by the maximum weight Matching Algorithm, in which the scales are represented by vertices on a graph and the maximum weight is attributed to combinations of scales that do not lead to overtime or idle hours. In the second phase, a weekend schedule is assigned for every weekly work schedule. Based on these two phases, the weekly work schedules of bus drivers and bus fare collectors can be arranged at a minimal cost. The third and final phase of this study consisted of assigning a weekly work schedule to each bus driver and collector, considering his/her preferences. The maximum weight Matching Algorithm was also used in this phase. This method was applied in three public transportation companies in Curitiba, state of Paraná, which had until then used old heuristic algorithms based solely on managerial experience

Técnicas da pesquisa operacional aplicadas na otimização dos serviços postais Operations research techniques applied in the post services

O presente trabalho apresenta uma metodologia para a otimização do serviço de entrega de correspondências realizado pela Empresa de Correios e Telégrafos (ECT) a partir da aplicação de algumas técnicas da Pesquisa Operacional. Como o serviço de entrega e as etapas que o antecedem (separação e ordenação dos objetos) são realizadas manualmente, existe a necessidade de otimizá-las e isto é possível redefindo-se as regiões de atendimento para cada carteiro. Para tanto, o problema foi tratado como um problema de roteamento de veículos. Vários algoritmos clássicos foram utilizados; inicialmente para definir as áreas de atendimento dos carteiros, chamados de distritos postais e, a seguir, para estabelecer o roteiro de entrega das correspondências, considerando, nesta fase, as distâncias reais entre os pontos de entrega. Vários testes computacionais foram realizados, variando-se os algoritmos e parâmetros iniciais e suas respostas comparadas através das distâncias totais e de tempos computacionais, determinando-se, assim, os algoritmos com melhores desempenhos.A solution is proposed for the problem of correspondence delivery done by the post service system, using some Operation Research techniques. Having in mind that the delivery and its preceding phases (selection and sorting) are manually made, there is a necessity to optimise these procedures and that is possible reorganising the postmen's delivery areas. To do that, this problem was treated as a Vehicle Routing Problem. Many classic algorithms were used, at first to determine the postmen's delivery area, called postal districts, and then to establish the mail delivery route, using in this phase the real distance among the delivery points. Many tests were done changing the algorithms and initial parameters, and the results were compared using the total distances and the computational time spent, in order to determine the algorithms with the best performance