Hypoxic repeat sprint training improves rugby player's repeated sprint but not endurance performance

This study aims to investigate the performance changes in 19 well-trained male rugby players after repeat-sprint training (six sessions of four sets of 5 × 5 s sprints with 25 s and 5 min of active recovery between reps and sets, respectively) in either normobaric hypoxia (HYP; n = 9; F₁O₂ = 14.5%) or normobaric normoxia (NORM; n = 10; F₁O₂ = 20.9%). Three weeks after the intervention, 2 additional repeat-sprint training sessions in hypoxia (F₁O₂ = 14.5%) was investigated in both groups to gauge the efficacy of using "top-up" sessions for previously hypoxic-trained subjects and whether a small hypoxic dose would be beneficial for the previously normoxic-trained group. Repeated sprint (8 × 20 m) and Yo-Yo Intermittent Recovery Level 1 (YYIR1) performances were tested twice at baseline (Pre 1 and Pre 2) and weekly after (Post 1-3) the initial intervention (intervention 1) and again weekly after the second "top-up" intervention (Post 4-5). After each training set, heart rate, oxygen saturation, and rate of perceived exertion were recorded. Compared to baseline (mean of Pre 1 and Pre 2), both the hypoxic and normoxic groups similarly lowered fatigue over the 8 sprints 1 week after the intervention (Post 1: -1.8 ± 1.6%, -1.5 ± 1.4%, mean change ± 90% CI in HYP and NORM groups, respectively). However, from Post 2 onwards, only the hypoxic group maintained the performance improvement compared to baseline (Post 2: -2.1 ± 1.8%, Post 3: -2.3 ± 1.7%, Post 4: -1.9 ± 1.8%, and Post 5: -1.2 ± 1.7%). Compared to the normoxic group, the hypoxic group was likely to have substantially less fatigue at Post 3-5 (-2.0 ± 2.4%, -2.2 ± 2.4%, -1.6 ± 2.4% Post 3, Post 4, Post 5, respectively). YYIR1 performances improved throughout the recovery period in both groups (13-37% compared to baseline) with unclear differences found between groups. The addition of two sessions of "top-up" training after intervention 1, had little effect on either group. Repeat-sprint training in hypoxia for six sessions increases repeat sprint ability but not YYIR1 performance in well-trained rugby players

The addition of an organosilicone surfactant to Agrobacterium suspensions enables efficient transient transformation of in vitro grapevine leaf tissue at ambient pressure

Transient Agrobacterium-mediated transformation of plant tissue has become a standard technique for rapid in vivo analysis of gene expression and function. In grapevine, the efficacy of transient leaf transformation is limited by the ability of bacterial suspensions to penetrate into the tissue. Current protocols therefore use the temporary application of a vacuum or site-specific syringe infiltration to improve transformation efficiencies. We show that supplementing Agrobacterium suspensions with a commercially available organosilicone surfactant (Pulse® penetrant) elevates transformation efficiency at ambient pressure. The transformation efficiency of leaf tissue of in vitro grown Vitis vinifera ‘Sauvignon blanc’ plantlets submerged in Agrobacterium suspension was increased 65-fold by the addition of Pulse® penetrant at low concentration (0.03 % v/v). A quick and precise determination of transformation efficiency was achieved by measuring red pigmentation of cells transiently transformed with the transcriptional activator of anthocyanin biosynthesis, VvMYBA1. A variable increase in transformation efficiency was also observed in eight commercial wine grape varieties and one rootstock variety. Pulse® penetrant can therefore be used to achieve transient transformation of grapevine by simply dipping in vitro leaf material into bacterial suspension culture

Genome-wide epigenetic changes during and following grapevine somatic embryogenesis

Somaclonal variation is a proven source of genetic diversity and is of particular interest in cases where breeding is not a suitable route for crop improvement. Novel sequencing techniques can enhance this approach by enabling the rapid genotypic characterisation of large populations of regenerated plants before phenotypes are expressed. We have been producing novel grapevine somaclones using somatic embryogenesis. However, the stress of tissue culture can alter the epigenetic state of plant cells in a way that may persist in regenerated plants. To study the epigenetic changes induced by this process, we performed bisulphite sequencing on embryogenic callus (EC) and plants regenerated from EC. Compared with leaf material, we found that EC had increased cytosine methylation, particularly in the asymmetrical CHH context, which is indicative of de novo methylation. However, genes and transposable elements (TEs) within genes showed reduced TEspecific CHG methylation. Plants regenerated from EC showed hypermethylation across all cytosine contexts three years after tissue culture. Interestingly, when EC were treated with the demethylating compound 5-Azacytidine, regenerated plants showed higher methylation than those from untreated callus, particularly in CG and CHG contexts. These data suggest that demethylation of TEs during somatic embryogenesis triggers de novo hypermethylation that is stabilised across symmetric cytosine contexts, and which persists years into the future. Based on these results, nanopore-based genotyping efforts are being adapted to include methylation calling, so that the functional impact of epigenetic changes can be determined in somaclone

The use of resting heart rate and heart rate variability to monitor stress and predict performance following hypoxic repeated sprint training in rugby players

Heart rate variability (HRV) is a non-invasive, low-cost measure of autonomic nervous system balance that is associated with training stress. While HRV has been used previously to monitor training stress in endurance athletes during live high altitude training protocols, little research exists on the use of HRV to monitor stress in team sport players during repetitive sprint training in normobaric hypoxic conditions. The aim of this research was to investigate whether heart measures such as HRV and resting heart rate could detect changes in training stress due to hypoxia. A secondary aim was to then investigate whether such measures could predict performance change post-training

Using neopterin to monitor stress in hypoxic and normoxic repeated sprint training in rugby players

Objectives: Neopterin has been used as a stress marker in team sport athletes, but its use in monitoring stress in hypoxic training requires further investigation. The objective of this study was to determine whether neopterin measures could detect differences between hypoxic and normoxic training stress and whether such levels could predict subsequent performance. Methods: Nineteen amateur club rugby players completed two repeated sprint (cycling) sessions per week for 3 weeks in either hypoxic (RSH, n = 9, FIO2 = 0.145) or normoxic (RSN, n = 10, FIO2 = 0.209) conditions. Repeated sprint ability (RSA, running), and the Yo-Yo Intermittent Recovery Level 1 test (YYIR1) were assessed pre- and post- intervention. Resting neopterin, total neopterin, and the difference between resting and post-exercise neopterin and total neopterin levels (acute change) were monitored during training. Results: Neopterin and total neopterin measurements demonstrated high individual variability in all participants. Neopterin and total neopterin were likely and very likely elevated respectively in RSH vs RSN between weeks 1 and 3 (neopterin, 56.4 %, ± 55.6, p = 0.10; percent change, ± 90% confidence interval, p value; total neopterin, 42.2 %, ± 23.5, p = 0.02). Aside from a moderate correlation between the acute change in total neopterin with YYIR1 (r = -0.38) there were no substantial correlations between neopterin and total neopterin measures and post-intervention performance. Conclusions: Neopterin or total neopterin can distinguish between hypoxic and normoxic training. However, high individual variability and limited predictive ability of subsequent performance may restrict the practical application of this stress marker

Arcobacter cryaerophilus isolated from New Zealand mussels harbor a putative virulence plasmid

A wide range of Arcobacter species have been described from shellfish in various countries but their presence has not been investigated in Australasia, in which shellfish are a popular delicacy. Since several arcobacters are considered to be emerging pathogens, we undertook a small study to evaluate their presence in several different shellfish, including greenshell mussels, oysters, and abalone (paua) in New Zealand. Arcobacter cryaerophilus, a species associated with human gastroenteritis, was the only species isolated, from greenshell mussels. Whole-genome sequencing revealed a range of genomic traits in these strains that were known or associated virulence factors. Furthermore, we describe the first putative virulence plasmid in Arcobacter, containing lytic, immunoavoidance, adhesion, antibiotic resistance, and gene transfer traits, among others. Complete genome sequence determination using a combination of long- and short-read genome sequencing strategies, was needed to identify the plasmid, clearly identifying its benefits. The potential for plasmids to disseminate virulence traits among Arcobacter and other species warrants further consideration by researchers interested in the risks to public health from these organisms

The effect of sleep quality and quantity on athlete's health and perceived training quality

University athletes are unique because they not only have to cope with the normal psycho-physiological stress of training and playing sport, but they also need to accommodate the stress associated with their academic studies along with considerable stress from their social environment. The ability to manage and adapt to stress ultimately helps improve athletic performance, but when stress becomes too much for the athlete, it can result in maladaptation's including sleep disruption which is associated with performance loss, negative mood changes, and even injury or illness. This research aimed to determine if sleep quantity and quality were associated with maladaptation in university athletes. We examined subjective measures of sleep duration and sleep quality along with measures of mood state, energy levels, academic stress, training quality and quantity, and frequency of illness and injury in 82 young (18–23 years) elite athletes over a 1 year period in 2020. Results indicate sleep duration and quality decreased in the first few weeks of the academic year which coincided with increased training, academic and social stress. Regression analysis indicated increased levels of perceived mood (1.3, 1.1–1.5, Odds Ratio and 95% confidence limits), sleep quality (2.9, 2.5–3.3), energy levels (1.2, 1.0–1.4), training quality (1.3, 1.1–1.5), and improved academic stress (1.1, 1.0–1.3) were associated with ≥8 h sleep. Athletes that slept ≥8 h or had higher sleep quality levels were less likely to suffer injury/illness (0.8, 0.7–0.9, and 0.6, 0.5–0.7 for sleep duration and quality, respectively). In conclusion, university athletes who maintain good sleep habits (sleep duration ≥8 h/night and high sleep quality scores) are less likely to suffer problems associated with elevated stress levels. Educating athletes, coaches, and trainers of the signs and symptoms of excessive stress (including sleep deprivation) may help reduce maladaptation and improve athlete's outcomes