FRET characterisation for cross-bridge dynamics in single-skinned rigor muscle fibres

In this work we demonstrate for the first time the use of Förster resonance energy transfer (FRET) as an assay to monitor the dynamics of cross-bridge conformational changes directly in single muscle fibres. The advantage of FRET imaging is its ability to measure distances in the nanometre range, relevant for structural changes in actomyosin cross-bridges. To reach this goal we have used several FRET couples to investigate different locations in the actomyosin complex. We exchanged the native essential light chain of myosin with a recombinant essential light chain labelled with various thiol-reactive chromophores. The second fluorophore of the FRET couple was introduced by three approaches: labelling actin, labelling SH1 cysteine and binding an adenosine triphosphate (ATP) analogue. We characterise FRET in rigor cross-bridges: in this condition muscle fibres are well described by a single FRET population model which allows us to evaluate the true FRET efficiency for a single couple and the consequent donor–acceptor distance. The results obtained are in good agreement with the distances expected from crystallographic data. The FRET characterisation presented herein is essential before moving onto dynamic measurements, as the FRET efficiency differences to be detected in an active muscle fibre are on the order of 10–15% of the FRET efficiencies evaluated here. This means that, to obtain reliable results to monitor the dynamics of cross-bridge conformational changes, we had to fully characterise the system in a steady-state condition, demonstrating firstly the possibility to detect FRET and secondly the viability of the present approach to distinguish small FRET variations

Psychosocial Conditions of Quality of Life Among Undergraduate Students: A Cross Sectional Survey

Quality of life (QOL) in the context of education is an understudied topic and research related to its’ relation to the sense of coherence (SOC), level of optimism (LOO) and self-efficacy (SE) among students seems to be missing. The rationale for this survey was to fill this gap in knowledge and therefore, the aim of the study is to examine the relationship between students’ QOL and psychological variables such as SOC, LOO and SE, and social ones such as type of faculty, students’ social background and sex. The quantitative cross sectional survey has been conducted at three higher education institutions in Poland in January 2006. The random sample of 396 undergraduate students (average age was 20.5 years) representing 5 different faculties namely physiotherapy, physical education, tourism and recreation, English and Polish philology has been selected and participated in the study. Four reliable and validated research tools have been used to collect the data. These included the SF-36, SOC-29, Seligman’s scale, and GSES. The results have shown to indicate that different variables had a significant effect on particular subscales of the QOL outcomes. For example, among social variables faculty had a significant effect on physical functioning, role limitation due to physical functioning, and changes in health. Sex had a significant effect on role limitation due to emotional problems, social functioning, and energy vitality. Social background had a significant effect on general health. Among psychological variables the sense of coherence was significantly related to all subscales of QOL. A significant effect was noted by self-efficacy on physical and social functioning. Level of optimism had a significant effect on energy-vitality and general health. This research survey has suggested that changes in academic curriculum might be implemented to improve students QOL