Characterization of the active site and calcium binding in cytochromecnitrite reductases

The decahaem homodimeric cytochrome c nitrite reductase (NrfA) is expressed within the periplasm of a wide range of Gamma-, Delta- and Epsilon-proteobacteria and is responsible for the six-electron reduction of nitrite to ammonia. This allows nitrite to be used as a terminal electron acceptor, facilitating anaerobic respiration while allowing nitrogen to remain in a biologically available form. NrfA has also been reported to reduce nitric oxide (a reaction intermediate) and sulfite to ammonia and sulfide respectively, suggesting a potential secondary role as a detoxification enzyme. The protein sequences and crystal structures of NrfA from different bacteria and the closely related octahaem nitrite reductase from Thioalkalivibrio nitratireducens (TvNir) reveal that these enzymes are homologous. The NrfA proteins contain five covalently attached haem groups, four of which are bis-histidine-co-ordinated, with the proximal histidine being provided by the highly conserved CXXCH motif. These haems are responsible for intraprotein electron transfer. The remaining haem is the site for nitrite reduction, which is ligated by a novel lysine residue provided by a CXXCK haem-binding motif. The TvNir nitrite reductase has five haems that are structurally similar to those of NrfA and three extra bis-histidine-coordinated haems that precede the NrfA conserved region. The present review compares the protein sequences and structures of NrfA and TvNir and discusses the subtle differences related to active-site architecture and Ca2+ binding that may have an impact on substrate reduction

The Challenges of Sport Psychology Delivery in Elite and Professional Sport: Reflections From Experienced Sport Psychologists

The challenges encountered by sport psychologists operating within elite and professional sports teams have arguably been inadequately considered (Nesti, 2010). It has been suggested that this may be due to the inaccessibility of elite team environments (Eubank, Nesti, & Cruickshank, 2014; Nesti, 2010). The purpose of this research was to examine the chal- lenges facing practitioners who operate in elite environments and to illuminate how these were experienced. Qualitative interviews with six experienced applied sport psychologists were conducted and a narrative themed analysis undertaken. Four main themes emerged as most prevalent and meaningful: challenges to congruence, a broader role: managing multiple relationships, the influence of elite sport cultures, and surviving and thriving were presented in narrative form. Practitio- ners provided experiential insight into how specific challenges were understood and dealt with, and how they are able to provide an effective service while managing themselves and the demands of the environment

MicroRNA-184 and its lncRNA sponge uca1 are induced in wounded keratinocytes in a store-operated calcium entry-dependent manner.

There remains a significant need for therapeutic interventions for wound healing as the clinical and socioeconomic challenges presented by the ageing population and associated rise in non-healing wounds persist, exerting enormous pressure on health services. MicroRNAs (miRNAs) are short ≈22 nucleotide non-coding RNA molecules that fine-tune gene expression by degradation of mRNA targets. Several miRNAs promote keratinocyte migration, including miR-21, miR-31 and miR-132 (reviewed in 3 ), hence miRNA-dependent migration is emerging as a framework for wound healing. This article is protected by copyright. All rights reserved

Redox linked flavin sites in extracellular decaheme proteins involved in microbe-mineral electron transfer

Extracellular microbe-mineral electron transfer is a major driving force for the oxidation of organic carbon in many subsurface environments. Extracellular multi-heme cytochromes of the Shewenella genus play a major role in this process but the mechanism of electron exchange at the interface between cytochrome and acceptor is widely debated. The 1.8 Å x-ray crystal structure of the decaheme MtrC revealed a highly conserved CX8C disulfide that, when substituted for AX8A, severely compromised the ability of S. oneidensis to grow under aerobic conditions. Reductive cleavage of the disulfide in the presence of flavin mononucleotide (FMN) resulted in the reversible formation of a stable flavocytochrome. Similar results were also observed with other decaheme cytochromes, OmcA, MtrF and UndA. The data suggest that these decaheme cytochromes can transition between highly reactive flavocytochromes or less reactive cytochromes, and that this transition is controlled by a redox active disulfide that responds to the presence of oxygen

InP-based comb-locked optical super channel transmitter

We demonstrate a comb-based transmitter with a potential to be integrated on a single InP photonic chip. Nyquist-shaped polarization-multiplexed 16QAM/64QAM signals are generated and transmitted over 300-km of SMF-28

eNOS plays essential roles in the developing heart and aorta linked to disruption of Notch signalling

\ua9 2024. Published by The Company of Biologists Ltd. eNOS (NOS3) is the enzyme that generates nitric oxide, a signalling molecule and regulator of vascular tone. Loss of eNOS function is associated with increased susceptibility to atherosclerosis, hypertension, thrombosis and stroke. Aortopathy and cardiac hypertrophy have also been found in eNOS null mice, but their aetiology is unclear. We evaluated eNOS nulls before and around birth for cardiac defects, revealing severe abnormalities in the ventricular myocardium and pharyngeal arch arteries. Moreover, in the aortic arch, there were fewer baroreceptors, which sense changes in blood pressure. Adult eNOS null survivors showed evidence of cardiac hypertrophy, aortopathy and cartilaginous metaplasia in the periductal region of the aortic arch. Notch1 and neuregulin were dysregulated in the forming pharyngeal arch arteries and ventricles, suggesting that these pathways may be relevant to the defects observed. Dysregulation of eNOS leads to embryonic and perinatal death, suggesting mutations in eNOS are candidates for causing congenital heart defects in humans. Surviving eNOS mutants have a deficiency of baroreceptors that likely contributes to high blood pressure and may have relevance to human patients who suffer from hypertension associated with aortic arch abnormalities

Dynamic Limits on Planar Libration-Orbit Coupling Around an Oblate Primary

This paper explores the dynamic properties of the planar system of an ellipsoidal satellite in an equatorial orbit about an oblate primary. In particular, we investigate the conditions for which the satellite is bound in librational motion or when the satellite will circulate with respect to the primary. We find the existence of stable equilibrium points about which the satellite can librate, and explore both the linearized and non-linear dynamics around these points. Absolute bounds are placed on the phase space of the libration-orbit coupling through the use of zero-velocity curves that exist in the system. These zero-velocity curves are used to derive a sufficient condition for when the satellite's libration is bound to less than 90 degrees. When this condition is not satisfied so that circulation of the satellite is possible, the initial conditions at zero libration angle are determined which lead to circulation of the satellite. Exact analytical conditions for circulation and the maximum libration angle are derived for the case of a small satellite in orbits of any eccentricity.Comment: Submitted to Celestial Mechanics and Dynamical Astronom

Primary teachers’ recommendations for the development of a teacher-oriented movement assessment tool for 4-7 year children

To inform the development of a teacher-oriented movement assessment tool, this study aimed to explore primary school teachers’ perceptions of assessing fundamental movement skills (FMS) within physical education (PE) lessons. Thirty-nine primary school teachers of PE, located in the United Kingdom, participated in an individual or group semi-structured interview. Findings signify that teachers perceive a need for an appropriate and effective movement assessment tool that is simple to use, quick to administer, and that provides valuable feedback to guide future teaching and learning. This is vital as teachers indicated that a lack of appropriate resources and a shortage of curriculum time restricts their use of assessment within PE. A movement assessment tool that aligned to the curriculum would be beneficial to teachers to better support children’s learning and acquisition of FMS, as well as to enhance the teachers’ own understanding of the process of assessing FMS