Thermodynamic Aspects of Flagellar Activity

1. The frequencies of the beat of cilia and flagella from various organisms have been determined at temperatures in the range 5-35°C. 2. Values of the activation enthalpy (ΔH{ddagger}, kcal./mole) and activation entropy (ΔS{ddagger}, e.u.) derived from the thermal dependence of frequency show a linear correlation of the form, ΔS{ddagger} = 3.25 ΔH{ddagger}-50.75. 3. The corresponding isokinetic activation free energy is 15.6 kcal./mole. 4. The results support a hypothesis that the breakdown of an ATP-ATPase complex could be the common rate-limiting reaction for flagellar activity. 5. Values of ΔH{ddagger} and ΔS{ddagger} for the decay of length or tension in striated muscles also fall on the same regression line but some smooth muscles show deviations

GABAergic compensation in connexin36 knock-out mice evident during low-magnesium seizure-like event activity

Gap junctions within the cerebral cortex may facilitate cortical seizure formation by their ability to synchronize electrical activity. To investigate this, one option is to compare wild-type (WT) animals with those lacking the gene for connexin36 (Cx36 KO); the protein that forms neuronal gap junctions between cortical inhibitory cells. However, genetically modified knock-out animals may exhibit compensatory effects; with the risk that observed differences between WT and Cx36 KO animals could be erroneously attributed to Cx36 gap junction effects. In this study we investigated the effect of GABAA-receptor modulation (augmentation with 16 μM etomidate and blockade with 100 μM picrotoxin) on low-magnesium seizure-like events (SLEs) in mouse cortical slices. In WT slices, picrotoxin enhanced both the amplitude (49% increase, p = 0.0006) and frequency (37% increase, p = 0.005) of SLEs; etomidate also enhanced SLE amplitude (18% increase, p = 0.003) but reduced event frequency (25% decrease, p < 0.0001). In Cx36 KO slices, the frequency effects of etomidate and picrotoxin were preserved, but the amplitude responses were abolished. Pre-treatment with the gap junction blocker mefloquin in WT slices did not significantly alter the drug responses, indicating that the reduction in amplitude seen in the Cx36 KO mice was not primarily mediated by their lack of interneuronal gap junctions, but was rather due to pre-existing compensatory changes in these animals. Conclusions from studies comparing seizure characteristics between WT and Cx36 KO mice must be viewed with a degree of caution because of the possible confounding effect of compensatory neurophysiological changes in the genetically modified animals

Antisense oligonucleotides and other genetic therapies made simple

Many genetic neurological diseases result from the dysfunction of single proteins. Genetic therapies aim to modify these disease-associated proteins by targeting the RNA and DNA precursors. This review provides a brief overview of the main types of genetic therapies, with a focus on antisense oligonucleotides (ASOs) and RNA interference (RNAi). We use examples of new genetic therapies for spinal muscular atrophy, Duchenne muscular dystrophy and familial amyloid polyneuropathy to highlight the different mechanisms of action of ASOs and RNAi

Collective beating of artificial microcilia

We combine technical, experimental and theoretical efforts to investigate the collective dynamics of artificial microcilia in a viscous fluid. We take advantage of soft-lithography and colloidal self-assembly to devise microcapets made of hundreds of slender magnetic rods. This novel experimental setup is used to investigate the dynamics of extended cilia arrays driven by a precessing magnetic field. Whereas the dynamics of an isolated cilium is a rigid body rotation, collective beating results in a symmetry breaking of the precession patterns. The trajectories of the cilia are anisotropic and experience a significant structural evolution as the actuation frequency increases. We present a minimal model to account for our experimental findings and demonstrate how the global geometry of the array imposes the shape of the trajectories via long range hydrodynamic interactions.Comment: 5 pages, 3 figure

The Influence of Floodplain Restoration on Flow and Sediment Dynamics in an Urban River

A study of floodplain sedimentation on a recently restored floodplain is presented. This study uses a two-dimensional hydro-morphodynamic model for predicting flow and suspended sediment dynamics in the downstream of Johnson Creek, the East Lents reach, where the bank of the river has been reconfigured to reconnect to a restored floodplain on a 0.26 km2 (26-ha) site. The simulation scenarios include event-based (10, 50, 100, and 500 year floods) deposition modelling of flood events and long-term modelling using the 64 historical flood events between 1941 and 2014. Simulation results showed that the restored floodplain significantly attenuates the upstream flood peak by up to 25% at the downstream. Results also indicated that approximately 20-30% of sediment from the upstream is deposited on the East Lents floodplain. Further, deposited sediment over the simulated period (1941-2014) is approximately 0.1% of the basin’s flood storage capacity, however the reduction in the storage does not offset the overall flood resilience impact of the flood basin. The sediment conservation at the East Lents flood basin as predicted by the model reduces the annual sediment loading of the Johnson Creek by 1% at the confluence with Willamette River, providing both water quality and flood resilience benefits further downstream

Modelling Formal and Informal Domestic Water Consumption in Accra

Urban utilities in developing countries are often unwilling to extend coverage or improve services for fear that not enough water is available. This study used modelling to project the city-level water demand implications of slum water improvements in Accra (Ghana). The research collated existing data around water use patterns and also used purpose-designed surveys to explore usage and demand in slum communities in more depth

Connexin36 knockout mice display increased sensitivity to pentylenetetrazol-induced seizure-like behaviors

Large-scale synchronous firing of neurons during seizures is modulated by electrotonic coupling between neurons via gap junctions. To explore roles for connexin36 (Cx36) gap junctions in seizures, we examined the seizure threshold of connexin36 knockout (Cx36KO) mice using a pentylenetetrazol (PTZ) model

Predictors of Motivation to Coach in High School Students and Adult Coaches

We conducted two studies to investigate predictors of coaching motivation. In Study One, we focused on variables linked to coaching motivation and burnout in adult sports coaches. We examined high school extracurricular experiences, and coaching engagement. Positive interpersonal events experienced during high school predicted coaching motivation and a motivation. Positive interpersonal and performance events in high school predicted feelings of reduced accomplishment, while negative interpersonal and performance events in high school predicted physical exhaustion. Two aspects of coaching engagement, vigor and absorption predicted coaching motivation. Thus, coaches’ motivation was predicted by both high school and current coaching events. In Study Two, we examined whether the same high school events predicted a desire to coach in recent high school graduates. Participants retrospectively reported participation in high school sports or heavy investment in alternate activities (e.g., marching band). For both groups, identification with the activity and dedication to the activity predicted a desire to coach. A desire to coach was not predicted by high school extracurricular events. Our findings indicate that high school experiences exerted differential effects on recent graduates versus adult coaches in terms of attitudes toward coaching

Effects of water source accessibility and reliability improvements on water consumption in eastern Nairobi

Under the commitments of the UN Sustainable Development targets, there is increasing pressure on water utility providers in developing countries to improve their levels of service to consumers, especially for the rapidly growing numbers of people with lower incomes who reside in urban informal settlements. However, pressure on water resources in many regions is simultaneously increasing owing to factors such as pollution, agricultural needs, and climate change. It is therefore important to assess the impacts of improving water services on city-wide water resources. This study examines consumption data from the East African city of Nairobi, collected from households of a variety of residential neighbourhoods. The study suggests that average per capita water consumption is closely related to water source choice (i.e. tap in the dwelling, yard tap, or water vendor kiosks). Within categories of water source type, variables such as household wealth, cost of water, and education do not have significant effects on per capita consumption. It is noted that increased accessibility of water causes the upper bound of consumption to rise, but not the lower. It may therefore be theorized that having a tap in a dwelling is necessary but not sufficient to increase per capita consumption. Within the sample examined, there is no statistically significant difference in per capita consumption between water source types other than a tap in a dwelling, and it is therefore suggested that providing a yard tap to those currently without any form of water connection may have negligible impact on city-wide water consumption