Calcium binding activity of the epidermal growth factor-like domains of the apicomplexan microneme protein EtMIC4

Microneme proteins are secreted from apicomplexan parasites during invasion of host cells and they play crucial roles in parasite-host cell adhesion. EtMIC4 is a 240 kDa transmembrane protein from Eimeria tenella that contains 31 tandemly arranged epidermal growth factor (EGF), like repeats within its extracellular domain. The majority of these repeats have calcium binding (cb) consensus sequences. Little is known about cbEGFs in apicomplexan parasites but their presence in microneme proteins suggests that they may contribute to parasite-host interactions. To investigate the potential role of cbEGFs we have expressed and correctly refolded a cbEGF triplet from EtMIC4 (cbEGF7-9) and demonstrated that this triplet binds calcium. Circular dichroism spectroscopic analysis of cbEGF7-9 demonstrates that the molecule undergoes a gradual change in conformation with increasing levels of calcium. In the presence of calcium, the triplet becomes resistant to proteolytic degradation by a variety of proteases, a characteristic feature of cbEGF repeats from higher eukaryotic proteins, such as fibrillin, suggesting that calcium binding induces the formation of a rigid conformation. Moreover, mass spectrometric mapping of the cleavage sites that are protected by calcium shows that these sites are located both close to and distant from the calcium binding sites, indicating that protection is not due to steric hindrance by calcium ions, but rather due to the overall conformation adopted by the triplet in the presence of calcium. Thus, the tandemly-arranged cbEGF repeats within EtMIC4 provide a mechanism whereby, in the calcium-rich extracellular environment, the molecule could adopt a protease-resistant, rigid structure that could favour its interaction with host cell ligands

VCE early acoustic test results of General Electric's high-radius ratio coannular plug nozzle

Results of variable cycle engine (VCE) early acoustic engine and model scale tests are presented. A summary of an extensive series of far field acoustic, advanced acoustic, and exhaust plume velocity measurements with a laser velocimeter of inverted velocity and temperature profile, high radius ratio coannular plug nozzles on a YJ101 VCE static engine test vehicle are reviewed. Select model scale simulated flight acoustic measurements for an unsuppressed and a mechanical suppressed coannular plug nozzle are also discussed. The engine acoustic nozzle tests verify previous model scale noise reduction measurements. The engine measurements show 4 to 6 PNdB aft quadrant jet noise reduction and up to 7 PNdB forward quadrant shock noise reduction relative to a fully mixed conical nozzle at the same specific thrust and mixed pressure ratio. The influences of outer nozzle radius ratio, inner stream velocity ratio, and area ratio are discussed. Also, laser velocimeter measurements of mean velocity and turbulent velocity of the YJ101 engine are illustrated. Select model scale static and simulated flight acoustic measurements are shown which corroborate that coannular suppression is maintained in forward speed

Prehistoric landslides: significance, recognition, examples

Prehistoric landslides with a wide range of ages and sizes exist worldwide in both rock and soil. Many are thought to have occurred during Pleistocene time when climates in some areas were harsher and wetter. Subsequent weathering and erosion have subdued topography and other features of prehistoric landslides, often making them difficult to recognize. Recognition is the key to dealing with prehistoric and other old landslides. Old slide masses are usually only marginally stable because past movements reduced available shear strength on their failure surfaces to residual levels. These masses are susceptible to reactivation by construction activities, heavy precipitation, and earthquakes. If prehistoric landslides are recognized, they can be avoided or steps taken to minimize interference with them. Where they cannot be avoided, they must be stabilized or lived with. Stabilization typically involves robust retaining structures, large buttress fills, or excavation of most of the slide mass - all of which are expensive. Living with old landslides may involve continuing maintenance for distress caused by creep or other movements; this can also be expensive. Problems arise when prehistoric and other old landslides are unrecognized, then reactivated during or after construction. Then, unexpected ground movements cause damage, increase costs, set back construction schedules, and disrupt partially completed or completed facilities and operations. Geologic considerations, features of prehistoric and old landslides, and guidance for recognizing them are presented. Then examples of prehistoric landslides in the United States, Papua New Guinea, and Australia are given

Crimea referendum – our experts react

Yesterday Crimean voters backed a proposal to secede from Ukraine and join the Russian Federation. We asked a number of experts for their reactions to the referendum and their views on what might happen next

RNF17 blocks promiscuous activity of PIWI proteins in mouse testes

PIWI proteins and their associated piRNAs protect germ cells from the activity of mobile genetic elements. Two classes of piRNAs-primary and secondary-are defined by their mechanisms of biogenesis. Primary piRNAs are processed directly from transcripts of piRNA cluster loci, whereas secondary piRNAs are generated in an adaptive amplification loop, termed the ping-pong cycle. In mammals, piRNA populations are dynamic, shifting as male germ cells develop. Embryonic piRNAs consist of both primary and secondary species and are mainly directed toward transposons. In meiotic cells, the piRNA population is transposon-poor and largely restricted to primary piRNAs derived from pachytene piRNA clusters. The transition from the embryonic to the adult piRNA pathway is not well understood. Here we show that RNF17 shapes adult meiotic piRNA content by suppressing the production of secondary piRNAs. In the absence of RNF17, ping-pong occurs inappropriately in meiotic cells. Ping-pong initiates piRNA responses against not only transposons but also protein-coding genes and long noncoding RNAs, including genes essential for germ cell development. Thus, the sterility of Rnf17 mutants may be a manifestation of a small RNA-based autoimmune reaction

Explanatory factors for health inequalities across different ethnic and gender groups: data from a national survey in England

BACKGROUND: The objective of this study was to examine the relative contribution of factors explaining ethnic health inequalities (EHI) in poor self-reported health (pSRH) and limiting long-standing illness (LLI) between Health Survey for England (HSE) participants. METHOD: Using HSE 2003-2006 data, the odds of reporting pSRH or of LLI in 8573 Bangladeshi, Black African, Black Caribbean, Chinese, Indian, Irish and Pakistani participants was compared with 28,470 White British participants. The effects of demographics, socioeconomic position (SEP), psychosocial variables, community characteristics and health behaviours were assessed using separate regression models. RESULTS: Compared with White British men, age-adjusted odds (OR, 95% CI) of pSRH were higher among Bangladeshi (2.05, 1.34 to 3.14), Pakistani (1.77, 1.34 to 2.33) and Black Caribbean (1.60, 1.18 to 2.18) men, but these became non-significant following adjustment for SEP and health behaviours. Unlike Black Caribbean men, Black African men exhibited a lower risk of age-adjusted pSRH (0.66, 0.43 to 1.00 (p=0.048)) and LLI (0.45, 0.28 to 0.72), which were significant in every model. Likewise, Chinese men had a lower risk of age-adjusted pSRH (0.51, 0.26 to 1.00 (p=0.048)) and LLI (0.22, 0.10 to 0.48). Except in Black Caribbean women, adjustment for SEP rendered raised age-adjusted associations for pSRH among Pakistani (2.51, 1.99 to 3.17), Bangladeshi (1.85, 1.08 to 3.16), Black Caribbean (1.78, 1.44 to 2.21) and Indian women (1.37, 1.13 to 1.66) insignificant. Adjustment for health behaviours had the largest effect for South Asian women. By contrast, Irish women reported better age-adjusted SRH (0.70, 1.51 to 0.96). CONCLUSIONS: SEP and health behaviours were major contributors explaining EHI. Policies to improve health equity need to monitor these pathways and be informed by them

The Effects of Arousal and Attention on Emotional False Memory Formation

Previous research has shown that with reduced attention at encoding, false recognition of critical lures for negative arousing DRM lists were higher than positive arousing lists. The current study extends this research to examine the role of attention for both arousing and nonarousing valenced false memory formation. Further, due to contradictory findings in past research, we examined attention at encoding using both within- (Experiment 1) and between-(Experiment 2) participants design. Participants were exposed to high and low arousing, valenced DRM lists under full and reduced attention conditions. Experiment 1 revealed that only negative arousing false memories were not affected by reduced attention at study, all other false memories decreased. In Experiment 2, although recognition of negative high arousing critical lures was higher, false memories increased in the reduced attention condition for all list types. Differences in attention during encoding affect the retrieval of emotional stimuli dependent on arousal and valence, however, our decision strategies can override the impact of this when it comes to retrieval

Practical quantum metrology with large precision gains in the low photon number regime

Quantum metrology exploits quantum correlations to make precise measurements with limited particle numbers. By utilizing inter- and intra- mode correlations in an optical interferometer, we find a state that combines entanglement and squeezing to give a 7-fold enhancement in the quantum Fisher information (QFI) - a metric related to the precision - over the shot noise limit, for low photon numbers. Motivated by practicality we then look at the squeezed cat-state, which has recently been made experimentally, and shows further precision gains over the shot noise limit and a 3-fold improvement in the QFI over the optimal Gaussian state. We present a conceptually simple measurement scheme that saturates the QFI, and we demonstrate a robustness to loss for small photon numbers. The squeezed cat-state can therefore give a significant precision enhancement in optical quantum metrology in practical and realistic conditions

Coined quantum walks on percolation graphs

Quantum walks, both discrete (coined) and continuous time, form the basis of several quantum algorithms and have been used to model processes such as transport in spin chains and quantum chemistry. The enhanced spreading and mixing properties of quantum walks compared with their classical counterparts have been well-studied on regular structures and also shown to be sensitive to defects and imperfections in the lattice. As a simple example of a disordered system, we consider percolation lattices, in which edges or sites are randomly missing, interrupting the progress of the quantum walk. We use numerical simulation to study the properties of coined quantum walks on these percolation lattices in one and two dimensions. In one dimension (the line) we introduce a simple notion of quantum tunneling and determine how this affects the properties of the quantum walk as it spreads. On two-dimensional percolation lattices, we show how the spreading rate varies from linear in the number of steps down to zero, as the percolation probability decreases to the critical point. This provides an example of fractional scaling in quantum walk dynamics.Comment: 25 pages, 14 figures; v2 expanded and improved presentation after referee comments, added extra figur