501 research outputs found

    Whole genome sequencing of experimental hybrids supports meiosis-like sexual recombination in Leishmania

    Get PDF
    Hybrid genotypes have been repeatedly described among natural isolates of Leishmania, and the recovery of experimental hybrids from sand flies co-infected with different strains or species of Leishmania has formally demonstrated that members of the genus possess the machinery for genetic exchange. As neither gamete stages nor cell fusion events have been directly observed during parasite development in the vector, we have relied on a classical genetic analysis to determine if Leishmania has a true sexual cycle. Here, we used whole genome sequencing to follow the chromosomal inheritance patterns of experimental hybrids generated within and between different strains of L. major and L. infantum. We also generated and sequenced the first experimental hybrids in L. tropica. We found that in each case the parental somy and allele contributions matched the inheritance patterns expected under meiosis 97–99% of the time. The hybrids were equivalent to F1 progeny, heterozygous throughout most of the genome for the markers that were homozygous and different between the parents. Rare, non-Mendelian patterns of chromosomal inheritance were observed, including a gain or loss of somy, and loss of heterozygosity, that likely arose during meiosis or during mitotic divisions of the progeny clones in the fly or culture. While the interspecies hybrids appeared to be sterile, the intraspecies hybrids were able to produce backcross and outcross progeny. Analysis of 5 backcross and outcross progeny clones generated from an L. major F1 hybrid, as well as 17 progeny clones generated from backcrosses involving a natural hybrid of L. tropica, revealed genome wide patterns of recombination, demonstrating that classical crossing over occurs at meiosis, and allowed us to construct the first physical and genetic maps in Leishmania. Altogether, the findings provide strong evidence for meiosis-like sexual recombination in Leishmania, presenting clear opportunities for forward genetic analysis and positional cloning of important genes.</div

    Bench behaviour of ice hockey coaches: Psychophysiological and verbal responses to critical game incidents

    Get PDF
    The purpose of this study was to examine coaches’ psychophysiological and verbal responses to different game situations. The in-game heart rate and verbal responses of three elite ice hockey coaches to four critical game incidents (Goals For/Against; Penalties Taken/Drawn) over four university women’s games were assessed. Verbal comments were categorised using the Coach Behaviour Assessment System, and then comments and heart rate were sequenced to critical incidents recorded on video review. Overall, in-game heart rate was greater than rest and coaches were rarely silent. General encouragement and general commentary were the most common verbal comments. Two hundred and eight critical incident comments were recorded (Goals For/Against 34.6 %; Penalties Taken/Drawn 65.4%) associated with a 10 bpm greater heart rate. Most common verbal responses to critical incidents were general commentary, silence and organisation. The type of comment was affected by the type of critical incident. In 78% of critical incidents, the type of comment made before incidents differed to type of comment after the incident, coaches rarely talked at the same time and silence was common. These novel findings are limited to ice hockey coaches given the small sample size. However, these results should encourage more research into the psychophysiological and verbal responses of coaches in other team sports real game situations to better understand in game coaching behaviour

    A comparison of two anaerobic test measurement systems using an upper body Wingate test

    Get PDF
    This study aimed to compare performance measures acquired by two different Wingate Anaerobic Test systems; Cranlea and Monark. Twenty participants undertook 58 Wingate tests against a 4% body mass resistive load on a cycle ergometer adapted for arm cranking. Corrected peak power output (PP; W) was recorded using 1 rev min–1, 0.5, 1 and 5 s averages and mean power output (MP; W). The Cranlea system recorded the greatest PP (589 ± 267 W) compared with the Monark (546 ± 267 W; P < 0.001). The PP using all other methods was also greater for the Cranlea compared with the Monark system (P < 0.001) with mean differences of 55 ± 18 W for 1 s averages and 22 ± 18 W for MP. Correlations between all PPs were strong (r = 0.99 – 0.97; P < 0.001). In conclusion, although the Cranlea system provides a consistently greater corrected PP it may not be enough to substantially differentiate between systems

    Characterising the application of the “progressive overload” principle of exercise training within cardiac rehabilitation: A United Kingdom-based community programme

    Get PDF
    Background: Recent concerns have cast doubt over the effectiveness of cardiac rehabilitation [CR] programmes for improving cardiorespiratory fitness [CRF] in patients with a history of cardiac disease in the United Kingdom [UK]. We aimed to characterise the weekly progression of exercise training dose over an 8-week Phase III CR programme as we felt this may be partly responsible for the lack of improvement in CRF reported in previous studies. Design: Observational study. Methods: We evaluated a community-based Phase III CR programme in the UK. During each training session, patients wore an Apple Watch and the weekly progression of exercise training dose/load was quantified. The analysis was based on 332 individual training sessions. Exercise intensity [% heart rate reserve] during the cardiovascular [CV] exercise training component [%HRR-CV], CV training duration; estimated changes in cardiorespiratory fitness [change in estimated metabolic equivalents (METs)]; session rating of perceived exertion [sRPE], sRPE training load [sRPE-TL], and exercise training impulse [TRIMP] were evaluated. Results: Thirty cardiac patients [83% male; age [SD] 67.0 [10.0] years; body mass index [SD] 28.3 [4.6] kg∙m-2] were recruited to an 8-week programme [16 sessions in total]. Bayesian repeated-measures ANOVA indicated anecdotal evidence for the alternative hypothesis for changes in %HRR-CV (BF10 = 0.61), sRPE (BF10 = 1.1), and change in estimated METs (BF10 = 1.2) during CR. Conversely, Bayesian repeated-measures ANOVA showed extreme evidence for changes in CV training duration (BF10 = 2.438e+26), TRIMP (BF10 = 71436), and sRPE-TL (BF10 = 779570). Conclusion: The key exercise training principle of progressive overload was only partially applied. Increases observed in exercise dose were due to increases in the duration of CV training, rather than combined with increases in exercise intensity [%HRR-CV and sRPE]. Accordingly, allied health professionals must ensure that exercise intensity is more consistently progressed to optimise the exercise stimulus and improvements in CRF and patient outcomes

    Defective Resection at DNA Double-Strand Breaks Leads to De Novo Telomere Formation and Enhances Gene Targeting

    Get PDF
    The formation of single-stranded DNA (ssDNA) at double-strand break (DSB) ends is essential in repair by homologous recombination and is mediated by DNA helicases and nucleases. Here we estimated the length of ssDNA generated during DSB repair and analyzed the consequences of elimination of processive resection pathways mediated by Sgs1 helicase and Exo1 nuclease on DSB repair fidelity. In wild-type cells during allelic gene conversion, an average of 2–4 kb of ssDNA accumulates at each side of the break. Longer ssDNA is formed during ectopic recombination or break-induced replication (BIR), reflecting much slower repair kinetics. This relatively extensive resection may help determine sequences involved in homology search and prevent recombination within short DNA repeats next to the break. In sgs1Δ exo1Δ mutants that form only very short ssDNA, allelic gene conversion decreases 5-fold and DSBs are repaired by BIR or de novo telomere formation resulting in loss of heterozygosity. The absence of the telomerase inhibitor, PIF1, increases de novo telomere pathway usage to about 50%. Accumulation of Cdc13, a protein recruiting telomerase, at the break site increases in sgs1Δ exo1Δ, and the requirement of the Ku complex for new telomere formation is partially bypassed. In contrast to this decreased and alternative DSB repair, the efficiency and accuracy of gene targeting increases dramatically in sgs1Δ exo1Δ cells, suggesting that transformed DNA is very stable in these mutants. Altogether these data establish a new role for processive resection in the fidelity of DSB repair

    Thermography and thermoregulation of the face

    Get PDF
    BACKGROUND: Although clinical diagnosis of thermoregulation is gaining in importance there is no consistent evidence on the value of thermography of the facial region. In particular there are no reference values established with standardised methods. METHODS: Skin temperatures were measured in the facial area at 32 fixed measuring sites in 26 health subjects (7–72 years) with the aid of a contact thermograph (Eidatherm). A total of 6 measurements were performed separately for the two sides of the face at intervals of equal lengths (4 hours) over a period of 24 hours. Thermoregulation was triggered by application of a cold stimulus in the region of the ipsilateral ear lobe. RESULTS: Comparison of the sides revealed significant asymmetry of face temperature. The left side of the face showed a temperature that was on the average 0.1°C lower than on the right. No increase in temperature was found following application of the cold stimulus. However, a significant circadian rhythm with mean temperature differences of 0.7°C was observed. CONCLUSION: The results obtained should be seen as an initial basis for compiling an exact thermoprofile of the surface temperature of the facial region that takes into account the circadian rhythm, thus closing gaps in studies on physiological changes in the temperature of the skin of the face
    corecore