Lipid Composition Affects the Efficiency in the Functional Reconstitution of the Cytochrome c Oxidase

The transmembrane protein cytochrome c oxidase (CcO) is the terminal oxidase in the respiratory chain of many aerobic organisms and catalyzes the reduction of dioxygen to water. This process maintains an electrochemical proton gradient across the membrane hosting the oxidase. CcO is a well-established model enzyme in bioenergetics to study the proton-coupled electron transfer reactions and protonation dynamics involved in these processes. Its catalytic mechanism is subject to ongoing intense research. Previous research, however, was mainly focused on the turnover of oxygen and electrons in CcO, while studies reporting proton turnover rates of CcO, that is the rate of proton uptake by the enzyme, are scarce. Here, we reconstitute CcO from R. sphaeroides into liposomes containing a pH sensitive dye and probe changes of the pH value inside single proteoliposomes using fluorescence microscopy. CcO proton turnover rates are quantified at the single-enzyme level. In addition, we recorded the distribution of the number of functionally reconstituted CcOs across the proteoliposome population. Studies are performed using proteoliposomes made of native lipid sources, such as a crude extract of soybean lipids and the polar lipid extract of E. coli, as well as purified lipid fractions, such as phosphatidylcholine extracted from soybean lipids. It is shown that these lipid compositions have only minor effects on the CcO proton turnover rate, but can have a strong impact on the reconstitution efficiency of functionally active CcOs. In particular, our experiments indicate that efficient functional reconstitution of CcO is strongly promoted by the addition of anionic lipids like phosphatidylglycerol and cardiolipin

Improving parsing of spontaneous speech with the help of prosodic boundaries

Parsing can be improved in automatic speech understanding if prosodic boundary marking is taken into account, because syntactic boundaries are often marked by prosodic means. Because large databases are needed for the training of statistical models for prosodic boundaries, we developed a labeling scheme for syntactic-prosodic boundaries within the German VERBMOBIL project (automatic speech-to-speech translation). We compare the results of classifiers (multi-layer perceptrons and language models) trained on these syntactic-prosodic boundary labels with classifiers trained on perceptual-prosodic and purely syntactic labels. Recognition rates of up to 96% were achieved. The turns that we need to parse consist of 20 words on the average and frequently contain sequences of partial sentence equivalents due to restarts, ellipsis, etc. For this material, the boundary scores computed by our classifiers can successfully be integrated into the syntactic parsing of word graphs; currently, they improve the parse time by 92% and reduce the number of parse trees by 96%. This is achieved by introducing a special Prosodic Syntactic Clause Boundary symbol (PSCB) into our grammar and guiding the search for the best word chain with the prosodic boundary scores

Формирование проектных команд на основе анализа социальных сетей

Цель исследования – разработка социальной технологии равномерного разделения сложившегося коллектива на проектные группы. В процессе исследования проводилось разделение группы, состоящей из 20 студентов, на четыре мини-группы по 5 человек для реализации проектов, ранжирование полученных мини-групп по уровню сложности выполняемых задач и статистическая оценка эффективности разделения. В результате исследования учебная группа из 20 студентов была разделена на четыре мини-группы по 5 человек с коэффициентом модулярности кластеризации 0,284, проведено ранжирование полученных мини-групп по уровню сложности выполняемых задач, статистически оценено положительное влияние взаимодействия внутри мини-групп на индивидуальную академическую успеваемость студентов.The purpose of study is a development of social technology of uniform division of the existing staff in the project groups. During the study, there were conducted division of the group consisting of 20 students into four mini-groups of 5 people for the projects' realization, ranking of received mini-groups by the level of the task complexity to perform, and statistical evaluation of the division efficiency. As a result, the group of 20 students was divided into four mini-groups of 5 people with modularity coefficient of clustering equals to 0.284, ranking of received mini-groups by the level of the task complexity to perform was conducted, positive influence of interaction within mini-groups on individual academic performance of students was statistically estimated

On the predicaments of the English L1 language learner: a conceptual article

The unparalleled rise of English has led native speakers (L1) to becoming increasingly outnumbered by L2 speakers; English as global commodity has stimulated much research into the learning and teaching of English. Meanwhile, fewer and fewer L1 English speakers are choosing to learn languages; a phenomenon which has received less attention. This article investigates both phenomena in the light of two recent theoretical developments in Applied Linguistics and second language acquisition (SLA), namely dynamic system theory and the multilingual turn in SLA, scrutinising the effects of the re-positioning of L1 English language learners. The conclusion suggests a conceptualisation of this learner group alongside, and yet very different to, other linguistically disadvantaged group. Pedagogical pathways to best support this learner group are also discussed

Allometric scaling of maximum metabolic rate: the influence of temperature

1. Maximum aerobic metabolic rate, measured in terms of rate of oxygen consumption during exercise (Vo2max ), is well known to scale to body mass (M) with an exponent greater than the value of 0•75 predicted by models based on the geometry of systems that supply nutrients. 2. Recently, the observed scaling for Vo2max (∞M0•872) has been hypothesized to arise because of the temperature dependence of biological processes, and because large species show a greater increase in muscle temperature when exercising than do small species. 3. Based on this hypothesis, we predicted that Vo2max will be positively related to ambient temperature, because heat loss is restricted at high temperatures and body temperature is likely to be elevated to a greater extent than during exercise in the cold. 4. This prediction was tested using a comparative phylogenetic generalized least-squares (PGLS) approach, and 34 measurements of six species of rodent (20•5–939 g) maximally exercising at temperatures from –16 to 30°C. 5. Vo2max is unrelated to testing temperature, but is negatively related to acclimation temperature. We conclude that prolonged cold exposure increases exercise-induced Vo2max by acting as a form of aerobic training in mammals, and that elevated muscle temperatures of large species do not explain the scaling of Vo2max across taxa.Centre of Excellence for Invasion Biolog

Iron Behaving Badly: Inappropriate Iron Chelation as a Major Contributor to the Aetiology of Vascular and Other Progressive Inflammatory and Degenerative Diseases

The production of peroxide and superoxide is an inevitable consequence of aerobic metabolism, and while these particular "reactive oxygen species" (ROSs) can exhibit a number of biological effects, they are not of themselves excessively reactive and thus they are not especially damaging at physiological concentrations. However, their reactions with poorly liganded iron species can lead to the catalytic production of the very reactive and dangerous hydroxyl radical, which is exceptionally damaging, and a major cause of chronic inflammation. We review the considerable and wide-ranging evidence for the involvement of this combination of (su)peroxide and poorly liganded iron in a large number of physiological and indeed pathological processes and inflammatory disorders, especially those involving the progressive degradation of cellular and organismal performance. These diseases share a great many similarities and thus might be considered to have a common cause (i.e. iron-catalysed free radical and especially hydroxyl radical generation). The studies reviewed include those focused on a series of cardiovascular, metabolic and neurological diseases, where iron can be found at the sites of plaques and lesions, as well as studies showing the significance of iron to aging and longevity. The effective chelation of iron by natural or synthetic ligands is thus of major physiological (and potentially therapeutic) importance. As systems properties, we need to recognise that physiological observables have multiple molecular causes, and studying them in isolation leads to inconsistent patterns of apparent causality when it is the simultaneous combination of multiple factors that is responsible. This explains, for instance, the decidedly mixed effects of antioxidants that have been observed, etc...Comment: 159 pages, including 9 Figs and 2184 reference