The crystal structure of the Sgt1-Skp1 complex: the link between Hsp90 and both SCF E3 ubiquitin ligases and kinetochores

The essential cochaperone Sgt1 recruits Hsp90 chaperone activity to a range of cellular factors including SCF E3 ubiquitin ligases and the kinetochore in eukaryotes. In these pathways Sgt1 interacts with Skp1, a small protein that heterodimerizes with proteins containing the F-box motif. We have determined the crystal structure of the interacting domains of Saccharomyces cerevisiae Sgt1 and Skp1 at 2.8 Å resolution and validated the interface in the context of the full-length proteins in solution. The BTB/POZ domain of Skp1 associates with Sgt1 via the concave surface of its TPR domain using residues that are conserved in humans. Dimerization of yeast Sgt1 occurs via an insertion that is absent from monomeric human Sgt1. We identify point mutations that disrupt dimerization and Skp1 binding in vitro and find that the interaction with Skp1 is an essential function of Sgt1 in yeast. Our data provide a structural rationale for understanding the phenotypes of temperature-sensitive Sgt1 mutants and for linking Skp1-associated proteins to Hsp90-dependent pathways

Different roles for CD4+ and CD8+ T lymphocytes and macrophage subsets in the control of a generalized virus infection

The importance of T-lymphocyte subsets in the control of poxvirus infections is controversial. To determine the relative contribution of lymphocyte subsets important for recovery from infection with ectromelia virus (EV), a natural murine poxvirus pathogen, C57BL/6 (B6) mice lacking functional CD8+ T cells because of disruption of the beta2-microglobulin gene or lacking functional CD4+ T cells because of disruption of the I-(A)beta gene, acutely depleted of CD8+ or CD4+ T cells with monoclonal antibody, or depleted of macrophage subsets by the macrophage suicide technique were used. Recovery from infection was strictly dependent on the effector functions of CD8+ T cells, in the absence of which 100% mortality resulted. This lymphocyte population had demonstrable antiviral activity early in the infection process even before class I major histocompatibility complex (MHC)-restricted CD8+ cytotoxic T-lymphocyte (CTL) activity was detectable. CD4+ T cells were found to be necessary for the generation of an optimal virus-specific, class I MHC-restricted CD8+ CTL response and contributed to virus clearance not involving cytolytic mechanisms. In both models of CD4+ T-cell deficiency, virus clearance was incomplete and persisted at low levels in most organs and at very high levels in the skin, but the animals did not die. The elimination of macrophage subpopulations impeded virus clearance, impaired the generation of class I MHC-restricted antiviral CTL response, and resulted in 100% mortality. These findings establish an absolute requirement for CD8+ and CD4+ T lymphocytes and macrophage subsets in the elimination of a natural murine poxvirus infection and support the idea that macrophages may be essential accessory cells for the generation of class I MHC-restricted antiviral CTL responses

Produtividade da pimenta-do-reino em função de doses de esterco bovino Yield of black pepper submitted to different levels of cattle manure

Embora o estado da Paraíba tenha mostrado certa aptidão para o cultivo da pimenta-do-reino, sendo possível recomendá-la como alternativa de diversificação agrícola, não existe qualquer recomendação de adubação para a espécie. Este trabalho foi realizado na UFPB, em Areia, PB, e teve como objetivo avaliar genótipos de pimenta-do-reino adubados com doses crescentes de esterco bovino, em delineamento experimental de blocos casualizados, com os tratamentos dispostos no esquema fatorial 5 x 3, sendo o primeiro fator representado pelas doses de esterco (0; 4; 8; 12 e 16 kg planta-1) e o segundo pelos genótipos (Bragantina, Iaçará e Cingapura), com quatro repetições. A pimenta-do-reino respondeu positivamente ao emprego de esterco bovino, nas condições edafoclimáticas de Areia. As máximas produções de pimenta verde por planta, dos genótipos Bragantina (1012 g), Iaçará (1269 g) e Cingapura (627 g), foram obtidas com as doses estimadas de 7,3; 8,6 e 7,0 kg planta-1 de esterco bovino, respectivamente. Para produção da pimenta seca, as doses estimadas em 6,5; 8,9 e 7,8 kg planta-1 de esterco bovino foram responsáveis pelas máximas produções correspondendo a 358, 793 e 204 g planta-1 para os genótipos Bragantina, Iaçará e Cingapura, respectivamente.<br>Although Paraíba State, has shown aptitude for black pepper cultivation, being possible to recommend it as an alternative for agricultural diversification in that area, no recommendation for black pepper crop fertilization exists. This research was conducted at the Universidade Federal da Paraíba, in Areia, Paraíba State, Brazil, to evaluate black pepper genotypes submitted to increasing levels of cattle manure. The experimental design was of randomized blocks, with treatments in the factorial 5 x 3 scheme. The first factor was represented by cattle manure levels (0; 4; 8; 12; and 16 kg plant-1) and the second factor, by the black pepper genotypes (Iaçará, Cingapura and Bragantina), with four replications. Black pepper production increased with the use of cattle manure in environmental conditions. The highest pepper yield per plant of Bragantina (1012 g), Iaçará (1269 g), and Cingapura (627 g) were obtained with 7.3; 8.6; and 7.0 kg of cattle manure/plant, respectively. The estimated yields of dry pepper were of 6.5; 8.9; and 7.8 kg plant-1, responding to maximum yields of 358, 793 and 204 g plant-1 for Bragantina, Iaçará and Cingapure genotypes, respectively

Analysis of football player’s motion in view of fractional calculus

Accurately retrieving the position of football players over time may lay the foundations for a whole series of possible new performance metrics for coaches and assistants. Despite the recent developments of automatic tracking systems, the misclassification problem (i.e., misleading a given player by another) still exists and requires human operators as final evaluators. This paper proposes an adaptive fractional calculus (FC) approach to improve the accuracy of tracking methods by estimating the position of players based on their trajectory so far. One half-time of an official football match was used to evaluate the accuracy of the proposed approach under different sampling periods of 250, 500 and 1000 ms. Moreover, the performance of the FC approach was compared with position-based and velocity-based methods. The experimental evaluation shows that the FC method presents a high classification accuracy for small sampling periods. Such results suggest that fractional dynamics may fit the trajectory of football players, thus being useful to increase the autonomy of tracking systems.info:eu-repo/semantics/publishedVersio