Acclimation to fluctuating light impacts the rapidity and diurnal rhythm of stomatal conductance.

Plant acclimation to growth light environment has been studied extensively, however, the majority of these studies have focused on light intensity and photo-acclimation, with few studies exploring the impact of dynamic growth light on stomatal acclimation and behavior. In order to assess the impact of growth light regime on stomatal acclimation, we grew plants in three different lighting regimes (with the same average daily intensity); fluctuating with a fixed pattern of light, fluctuating with a randomized pattern of light (sinusoidal), and non-fluctuating (square wave), to assess the effect of light regime dynamics on gas exchange. We demonstrated that gs acclimation is influenced by both intensity and light pattern, modifying the stomatal kinetics at different times of the day resulting in differences in the rapidity and magnitude of the gs response. We also describe and quantify response to an internal signal that uncouples variation in A and gs over the majority of the diurnal period, and represents 25% of the total diurnal gs. This gs response can be characterized by a Gaussian element and when incorporated into the widely used Ball-Berry Model greatly improved the prediction of gs in a dynamic environment. From these findings we conclude that acclimation of gs to growth light could be an important strategy for maintaining carbon fixation and overall plant water status, and should be considered when inferring responses in the field from laboratory based experiments

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Diurnal Variation in Gas Exchange: The Balance between Carbon Fixation and Water Loss

Stomatal control of transpiration is critical for maintaining important processes, such as plant water status, leaf temperature, as well as permitting sufficient CO2 diffusion into the leaf to maintain photosynthetic rates (A). Stomatal conductance often closely correlates with A and is thought to control the balance between water loss and carbon gain. It has been suggested that a mesophyll-driven signal coordinates A and stomatal conductance responses to maintain this relationship; however, the signal has yet to be fully elucidated. Despite this correlation under stable environmental conditions, the responses of both parameters vary spatially and temporally and are dependent on species, environment, and plant water status. Most current models neglect these aspects of gas exchange, although it is clear that they play a vital role in the balance of carbon fixation and water loss. Future efforts should consider the dynamic nature of whole-plant gas exchange and how it represents much more than the sum of its individual leaf-level components, and they should take into consideration the long-term effect on gas exchange over time

Dehydration Reduces Posterior Leg and Trunk Flexibility and Increases Stiffness in Male Collegiate Age Runners

Dehydration reduces flexibility and increases stiffness in male collegiate age runners. Dehydration has been shown to negatively affect collagen in vitro; however the literature lacks works exploring the in vivo effects of dehydration on collagenous tissue. This study addresses this gap in the literature, by exploring the effects of dehydration on the muscles and connective tissues of the posterior leg. It was hypothesized that when dehydrated, the collagen within these tissues would become stiffer, decreasing flexibility and increasing stiffness. A cross-over cohort design was conducted to evaluate nineteen male collegiate runners. Each subject attended three sessions: baseline, dehydration and euhydration. The order of testing was randomly assigned and the PI was blinded throughout. Mean sit and reach (MSnR), mean terminal straight leg raise (MTSLR) and mean posterior leg stiffness (MPLS) scores for each testing condition were analyzed using a repeated measures ANOVA. Dehydrated, subjects demonstrated statistically significant decreases in MSnR scores, p\u3c0.001, d=0.469 (MSnR dehydrated 26.83 ± 7.53 cm and MSnR euhydrated 30.36 ± 7.53 cm) and MTSLR, p\u3c0.001, d=1.068 (MTSLR dehydrated 51.38 ± 9.39 and MTSLR euhydrated 60.58 ± 7.74), with a concurrent increase in MPLS, p=0.005, d=1.023 (MPLS dehydrated 0.899 ± 0.357 and MPLS euhydrated 0.508 ± 0.409), as compared to when they were euhydrated. The large effect size for MPLS and MTSLR and moderate for MSnR indicates that when dehydrated subjects became stiffer and has less flexibility as compared to when they are euhydrated. These changes may impede performance and increase the risk of injury in dehydrated individuals

Exploiting natural variation and genetic manipulation of stomatal conductance for crop improvement

Rising global temperatures and more frequent episodes of drought are expected to drive reductions in crop yield, therefore new avenues for improving crop productivity must be exploited. Stomatal conductance (gs) balances plant CO2 uptake and water loss, therefore, greatly impacting the cumulative rate of photosynthesis and water use over the growing season, which are key determinants of crop yield and productivity. Considerable natural variation exists in stomatal anatomy, biochemistry and behavioural characteristics that impact on the kinetics and magnitude of gs and thus gaseous exchange between the plant and atmosphere. Exploiting these differences in stomatal traits could provide novel breeding targets for new crop varieties that are potentially more water use efficient and have the ability to maintain and/or maximize yield in a range of diverse environments. Here we provide an overview of variation in stomatal traits and the impact these have on gs behaviour, as well as the potential to exploit such variation and genetic manipulation for crop improvement

Should we scale-up? A mixed methods process evaluation of an intervention targeting sedentary office workers using the RE-AIM QuEST framework

Background: Interventions targeting a reduction in sedentary behaviour in office workers need to be scaled-up to have impact. In this study, the RE-AIM QuEST framework was used to evaluate the potential for further implementation and scale-up of a consultation based workplace intervention which targeted both the reduction, and breaking up of sitting time.  Methods: To evaluate the Springfield College sedentary behaviour intervention across multiple RE-AIM QuEST indicators; intervention participant, non-participant (employees who did not participate) and key informant (consultation delivery team; members of the research team and stakeholders in workplace health promotion) data were collected using interviews, focus groups and questionnaires. Questionnaires were summarized using descriptive statistics and interviews and focus groups were transcribed verbatim, and thematically analysed.  Results: Barriers to scale-up were: participant burden of activity monitoring; lack of management support; influence of policy; flexibility (scheduling/locations); time and cost. Facilitators to scale up were: visible leadership; social and cultural changes in the workplace; high acceptability; existing health and wellbeing programmes; culture and philosophy of the participating college.  Conclusion: There is potential for scale-up, however adaptations will need to be made to address the barriers to scale-up. Future interventions in office workers should evaluate for scalability during the pilot phases of research

Improved induction of anti-melanoma T cells by adenovirus-5/3 fiber modification to target human DCs

To mount a strong anti-tumor immune response, non T cell inflamed (cold) tumors may require combination treatment encompassing vaccine strategies preceding checkpoint inhibition. In vivo targeted delivery of tumor-associated antigens (TAA) to dendritic cells (DCs), relying on the natural functions of primary DCs in situ, represents an attractive vaccination strategy. In this study we made use of a full-length MART-1 expressing C/B-chimeric adenoviral vector, consisting of the Ad5 capsid and the Ad3 knob (Ad5/3), which we previously showed to selectively transduce DCs in human skin and lymph nodes. Our data demonstrate that chimeric Ad5/3 vectors encoding TAA, and able to target human DCs in situ, can be used to efficiently induce expansion of functional tumor-specific CD8⁺ effector T cells, either from a naïve T cell pool or from previously primed T cells residing in the melanoma-draining sentinel lymph nodes (SLN). These data support the use of Ad3-knob containing viruses as vaccine vehicles for in vivo delivery. "Off-the-shelf" DC-targeted Ad vaccines encoding TAA could clearly benefit future immunotherapeutic approaches

Temporal Dynamics of Stomatal Behavior: Modeling and Implications for Photosynthesis and Water Use.

An analysis of stomatal behavior reveals the importance of modeling slow stomatal responses and the impacts on photosynthesis under dynamic light environments