Neurospora from natural populations: Population genomics insights into the Life history of a model microbial Eukaryote

The ascomycete filamentous fungus Neurospora crassa played a historic role in experimental biology and became a model system for genetic research. Stimulated by a systematic effort to collect wild strains initiated by Stanford geneticist David Perkins, the genus Neurospora has also become a basic model for the study of evolutionary processes, speciation, and population biology. In this chapter, we will first trace the history that brought Neurospora into the era of population genomics. We will then cover the major contributions of population genomic investigations using Neurospora to our understanding of microbial biogeography and speciation, and review recent work using population genomics and genome-wide association mapping that illustrates the unique potential of Neurospora as a model for identifying the genetic basis of (potentially adaptive) phenotypes in filamentous fungi. The advent of population genomics has contributed to firmly establish Neurospora as a complete model system and we hope our review will entice biologists to include Neurospora in their research

The Effects of Time Varying Curvature on Species Transport in Coronary Arteries

Alterations in mass transport patterns of low-density lipoproteins (LDL) and oxygen are known to cause atherosclerosis in larger arteries. We hypothesise that the species transport processes in coronary arteries may be affected by their physiological motion, a factor which has not been considered widely in mass transfer studies. Hence, we numerically simulated the mass transport of LDL and oxygen in an idealized moving coronary artery model under both steady and pulsatile flow conditions. A physiological inlet velocity and a sinusoidal curvature waveform were specified as velocity and wall motion boundary conditions. The results predicted elevation of LDL flux, impaired oxygen flux and low wall shear stress (WSS) along the inner wall of curvature, a predilection site for atherosclerosis. The wall motion induced changes in the velocity and WSS patterns were only secondary to the pulsatile flow effects. The temporal variations in flow and WSS due to the flow pulsation and wall motion did not affect temporal changes in the species wall flux. However, the wall motion did alter the time-averaged oxygen and LDL flux in the order of 26% and 12% respectively. Taken together, these results suggest that the wall motion may play an important role in coronary arterial transport processes and emphasise the need for further investigation

Examination of a pre-exercise, high energy supplement on exercise performance

<p>Abstract</p> <p>Background</p> <p>The purpose of this study was to examine the effect of a pre-exercise high energy drink on reaction time and anaerobic power in competitive strength/power athletes. In addition, the effect of the pre-exercise drink on subjective feelings of energy, fatigue, alertness and focus was also explored.</p> <p>Methods</p> <p>Twelve male strength/power athletes (21.1 ± 1.3 y; 179.8 ± 7.1 cm; 88.6 ± 12.1 kg; 17.6 ± 3.3% body fat) underwent two testing sessions administered in a randomized and double-blind fashion. During each session, subjects reported to the Human Performance Laboratory and were provided with either 120 ml of a high energy drink (SUP), commercially marketed as Redline Extreme^®or 120 ml of a placebo (PL) that was similar in taste and appearance but contained no active ingredients. Following consumption of the supplement or placebo subjects rested quietly for 10-minutes prior to completing a survey and commencing exercise. The survey consisted of 4 questions asking each subject to describe their feelings of energy, fatigue, alertness and focus for that moment. Following the completion of the questionnaire subjects performed a 2-minute quickness and reaction test on the Makoto testing device (Makoto USA, Centennial CO) and a 20-second Wingate Anaerobic Power test. Following a 10-minute rest subjects repeated the testing sequence and after a similar rest period a third and final testing sequence was performed. The Makoto testing device consisted of subjects reacting to both a visual and auditory stimulus and striking one out of 30 potential targets on three towers.</p> <p>Results</p> <p>Significant difference in reaction performance was seen between SUP and PL in both average number of targets struck (55.8 ± 7.4 versus 51.9 ± 7.4, respectively) and percent of targets struck (71.9 ± 10.5% versus 66.8 ± 10.9%, respectively). No significant differences between trials were seen in any anaerobic power measure. Subjective feelings of energy (3.5 ± 0.5 versus 3.1 ± 0.5) and focus (3.8 ± 0.5 versus 3.3 ± 0.7) were significantly higher during SUP compared to PL, respectively. In addition, a trend towards an increase in average alertness (p = 0.06) was seen in SUP compared to P.</p> <p>Conclusion</p> <p>Results indicate a significant increase in reaction performance, with no effect on anaerobic power performance. In addition, ingestion of this supplement significantly improves subjective feelings of focus and energy in male strength/power athletes.</p

Children’s coping with in vivo peer rejection: An experimental investigation

We examined children's behavioral coping in response to an in vivo peer rejection manipulation. Participants (N=186) ranging between 10 and 13 years of age, played a computer game based on the television show Survivor and were randomized to either peer rejection (i.e., being voted out of the game) or non-rejection control. During a five-min. post-feedback waiting period children's use of several behavioral coping strategies was assessed. Rejection elicited a marked shift toward more negative affect, but higher levels of perceived social competence attenuated the negative mood shift. Children higher in depressive symptoms were more likely to engage in passive and avoidant coping behavior. Types of coping were largely unaffected by gender and perceived social competence. Implications are discussed. © 2006 Springer Science+Business Media, LLC

Development of aggression subtypes from childhood to adolescence:a group-based multi-trajectory modelling perspective

The persistence of elevated subtypes of aggression beginning in childhood have been associated with long-term maladaptive outcomes. Yet it remains unclear to what extent there are clusters of individuals following similar developmental trajectories across forms (i.e., physical and indirect) and functions (i.e., proactive and reactive) of aggression. We aimed to identify groups of children with distinct profiles of the joint development of forms and functions of aggression and to identify risk factors for group membership. A sample of 787 children was followed from birth to adolescence. Parent and teacher reports, and standardised assessments were used to measure two forms and two functions of aggressive behaviour, between six and 13 years of age along with preceding child, maternal, and family-level risk-factors. Analyses were conducted using a group-based multi-trajectory modelling approach. Five trajectory groups emerged: non-aggressors, low-stable, moderate-engagers, high-desisting, and high-chronic. Coercive parenting increased membership risk in the moderate-engagers and high-chronic groups. Lower maternal IQ increased membership risk in both high-desisting and high-chronic groups, whereas maternal depression increased membership risk in the high-desisting group only. Never being breastfed increased membership risk in the moderate-engagers group. Boys were at greater risk for belonging to groups displaying elevated aggression. Individuals with chronic aggression problems use all subtypes of aggression. Risk factors suggest that prevention programs should start early in life and target mothers with lower IQ. Strategies to deal with maternal depression and enhance positive parenting while replacing coercive parenting tactics should be highlighted in programming efforts

Magnesium induces neuronal apoptosis by suppressing excitability

In clinical obstetrics, magnesium sulfate (MgSO4) use is widespread, but effects on brain development are unknown. Many agents that depress neuronal excitability increase developmental neuroapoptosis. In this study, we used dissociated cultures of rodent hippocampus to examine the effects of Mg++ on excitability and survival. Mg++-induced caspase-3-associated cell loss at clinically relevant concentrations. Whole-cell patch-clamp techniques measured Mg++ effects on action potential threshold, action potential peak amplitude, spike number and changes in resting membrane potential. Mg++ depolarized action potential threshold, presumably from surface charge screening effects on voltage-gated sodium channels. Mg++ also decreased the number of action potentials in response to fixed current injection without affecting action potential peak amplitude. Surprisingly, Mg++ also depolarized neuronal resting potential in a concentration-dependent manner with a +5.2 mV shift at 10 mM. Voltage ramps suggested that Mg++ blocked a potassium conductance contributing to the resting potential. In spite of this depolarizing effect of Mg++, the net inhibitory effect of Mg++ nearly completely silenced neuronal network activity measured with multielectrode array recordings. We conclude that although Mg++ has complex effects on cellular excitability, the overall inhibitory influence of Mg++ decreases neuronal survival. Taken together with recent in vivo evidence, our results suggest that caution may be warranted in the use of Mg++ in clinical obstetrics and neonatology

First Measurement of Transferred Polarization in the Exclusive e p --> e' K+ Lambda Reaction

The first measurements of the transferred polarization for the exclusive ep --> e'K+ Lambda reaction have been performed in Hall B at the Thomas Jefferson National Accelerator Facility using the CLAS spectrometer. A 2.567 GeV electron beam was used to measure the hyperon polarization over a range of Q2 from 0.3 to 1.5 (GeV/c)2, W from 1.6 to 2.15 GeV, and over the full center-of-mass angular range of the K+ meson. Comparison with predictions of hadrodynamic models indicates strong sensitivity to the underlying resonance contributions. A non-relativistic quark model interpretation of our data suggests that the s-sbar quark pair is produced with spins predominantly anti-aligned. Implications for the validity of the widely used 3P0 quark-pair creation operator are discussed.Comment: 6 pages, 4 figure

Survey of A_LT' asymmetries in semi-exclusive electron scattering on He4 and C12

Single spin azimuthal asymmetries A_LT' were measured at Jefferson Lab using 2.2 and 4.4 GeV longitudinally polarized electrons incident on He4 and C12 targets in the CLAS detector. A_LT' is related to the imaginary part of the longitudinal-transverse interference and in quasifree nucleon knockout it provides an unambiguous signature for final state interactions (FSI). Experimental values of A_LT' were found to be below 5%, typically |A_LT'| < 3% for data with good statistical precision. Optical Model in Eikonal Approximation (OMEA) and Relativistic Multiple-Scattering Glauber Approximation (RMSGA) calculations are shown to be consistent with the measured asymmetries.Comment: 9 pages, 5 figure

Observation of an Exotic Baryon with S=+1 in Photoproduction from the Proton

The reaction $\gamma p \to \pi^+K^-K^+n$ was studied at Jefferson Lab using a tagged photon beam with an energy range of 3-5.47 GeV. A narrow baryon state with strangeness S=+1 and mass $M=1555\pm 10$ MeV/c$^2$ was observed in the $nK^+$ invariant mass spectrum. The peak's width is consistent with the CLAS resolution (FWHM=26 MeV/c$^2$), and its statistical significance is 7.8 $\pm$ 1.0 ~$\sigma$. A baryon with positive strangeness has exotic structure and cannot be described in the framework of the naive constituent quark model. The mass of the observed state is consistent with the mass predicted by a chiral soliton model for the $\Theta^+$ baryon. In addition, the $pK^+$ invariant mass distribution was analyzed in the reaction $\gamma p\to K^-K^+p$ with high statistics in search of doubly-charged exotic baryon states. No resonance structures were found in this spectrum.Comment: 5 pages, 5 figures, add reference