Experimental tests of host-virus coevolution in natural killer yeast strains

Fungi may carry cytoplasmic viruses that encode anticompetitor toxins. These so-called killer viruses may provide competitive benefits to their host, but also incur metabolic costs associated with viral replication, toxin production and immunity. Mechanisms responsible for the stable maintenance of these endosymbionts are insufficiently understood. Here, we test whether co-adaptation of host and killer virus underlies their stable maintenance in seven natural and one laboratory strain of the genus Saccharomyces. We employ cross-transfection of killer viruses, all encoding the K1-type toxin, to test predictions from host-virus co-adaptation. These tests support local adaptation of hosts and/or their killer viruses. First, new host-virus combinations have strongly reduced killing ability against a standard sensitive strain when compared with re-constructed native combinations. Second, viruses are more likely to be lost from new than from original hosts upon repeated bottlenecking or the application of stressful conditions. Third, host fitness is increased after the re-introduction of native viruses, but decreased after the introduction of new viruses. Finally, rather than a trade-off, original combinations show a positive correlation between killing ability and fitness. Together, these results suggest that natural yeast killer strains and their viruses have co-adapted, allowing the transition from a parasitic to a mutualistic symbiosis.</p

Grounding and extracting modal responses in cognitive agents: 'AND' query and states of incomplete knowledge

In this study an original way of modeling language grounding and generation for a simple set of language responses is presented. It is assumed that the language is used by a cognitive agent and consists of a few modal belief and possibility formulas that are used by this agent to communicate its opinions on the current state of an object. The cognitive agent is asked a simple AND query and the language is tailored to this situation. The agent's knowledge bases are characterized by certain incompleteness of information on the current state of objects. The language of the available responses is originally grounded in the agent's previous empirical experience. According to the assumptions of the cognitive linguistics and the phenomenology of knowledge, this experience is the basic source of meaning represented by the available formulas (responses). In the study the idea of an epistemic satisfaction relation is introduced that describes states of the agent's knowledge in which particular formulas are satisfied in the epistemic sense. Additionally, a formal description of the semantic power of formulas is presented. The concepts of the empirical satisfaction relation and the semantic power of formulas are used to define a model of particular language behavior that preserves the assumption of language grounding. Two examples of possible implementations are given. These implementations are basic ones and refer to statistical characteristics of the stored empirical experience of the cognitive agent

Physical activity, physical fitness and quality of life of the University of the Third Age students

Background: Physical activity (PA) has a positive effect on human health at all ages and it is especially important in older people. When insufficient, it may lead to the deterioration of a person’s health status. Aim of the study: The aim of the study was to assess the declared PA of the Universities of the Third Age (U3A) students and to examine the relationship between the level of PA, physical performance, and quality of life in this population. Material and methods: The study included 99 subjects, aged ≥60 years, with a Mini Mental State Examination score ≥24. Participants were examined using the International Physical Activity Questionnaire (IPAQ), the Short Form Health Survey (SF-36) questionnaire, the Short Physical Performance Battery (SPPB), the Activities of Daily Living scale (ADL), the Lawton Instrumental Activities of Daily Living scale (IADL), and the short form of the geriatric depression scale (GDS). Handgrip strength (HS) was measured using the baseline hydraulic dynamometer. Results: Statistically significant differences in the results of women and men were demonstrated in 5 variables: the level of PA measured with the IPAQ, physical component summary of the SF-36 questionnaire, the total SPPB score, HS of the dominant hand and the non-dominant hand. In all examinations, men obtained higher scores than women. Positive correlations between PA and the result of the ADL, IADL, SPPB, HS and physical component summary of the SF-36 questionnaire were shown. Conclusions: The study confirmed that the participants of the U3A classes mostly meet the recommendations regarding minimum PA and they willingly undertake regular PA. It translates into high functional and physical fitness, stronger muscles and a good QoL

Overexpression of Endogenous Anti-Oxidants with Selenium Supplementation Protects Trophoblast Cells from Reactive Oxygen Species-Induced Apoptosis in a Bcl-2-Dependent Manner

The human placenta provides life support for the developing foetus, and a healthy placenta is a prerequisite to a healthy start to life. Placental tissue is subject to oxidative stress which can lead to pathological conditions of pregnancy such as preeclampsia, preterm labour and intrauterine growth restriction. Up-regulation of endogenous anti-oxidants may alleviate placental oxidative stress and provide a therapy for these complications of pregnancy. In this study, selenium supplementation, as inorganic sodium selenite (NaSel) or organic selenomethionine (SeMet), was used to increase the protein production and cellular activity of the important redox active proteins glutathione peroxidase (GPx) and thioredoxin reductase (Thx-Red). Placental trophoblast cell lines, BeWo, JEG-3 and Swan-71, were cultured in various concentrations of NaSel or SeMet for 24 h and cell extracts prepared for western blots and enzyme assays. Rotenone and antimycin were used to stimulate mitochondrial reactive oxygen species (ROS) production and induce apoptosis. Trophoblast cells supplemented with 100 nM NaSel and 500 nM SeMet exhibited significantly enhanced expression and activity of both GPx and Thx-Red. Antimycin and rotenone were found to generate ROS when measured by 2′,7′-dichlorofluorescein diacetate (DCFDA) assay, and selenium supplementation was shown to reduce ROS production in a dose-dependent manner. Rotenone, 100 μM treatment for 4 h, caused trophoblast cell apoptosis as evidenced by increased Annexin V binding and decreased expression of Bcl-2. In both assays of apoptosis, selenium supplementation was able to prevent apoptosis, preserve Bcl-2 expression and protect trophoblast cells from mitochondrial oxidative stress. This data suggests that selenoproteins such as GPx and Thx-Red have an important role in protecting trophoblast cells from mitochondrial oxidative stress and that selenium supplementation may be important in treating some placental pathologies.Griffith Health, School of Medical ScienceNo Full Tex