Dietary restriction increases skeletal muscle mitochondrial respiration but not mitochondrial content in C57BL/6 mice

Dietary restriction (DR) is suggested to induce mitochondrial biogenesis, although recently this has been challenged. Here we determined the impact of 1, 9 and 18 months of 30% DR in male C57BL/6 mice on key mitochondrial factors and on mitochondrial function in skeletal muscle, relative to age-matched ad libitum (AL) controls. We examined proteins and mRNAs associated with mitochondrial biogenesis and measured mitochondrial respiration in permeabilised myofibres using high resolution respirometry. 30% DR, irrespective of duration, had no effect on citrate synthase activity. In contrast, total and nuclear protein levels of PGC-1?, mRNA levels of several mitochondrial associated proteins (Pgc-1?, Nrf1, Core 1, Cox IV, Atps) and cytochrome c oxidase content were increased in skeletal muscle of DR mice. Furthermore, a range of mitochondrial respiration rates were increased significantly by DR, with DR partially attenuating the age-related decline in respiration observed in AL controls. Therefore, DR did not increase mitochondrial content, as determined by citrate synthase, in mouse skeletal muscle. However, it did induce a PGC-1? adaptive response and increased mitochondrial respiration. Thus, we suggest that a functionally ‘efficient’ mitochondrial electron transport chain may be a critical mechanism underlying DR, rather than any net increase in mitochondrial content per se

Risk-enhancing behaviors associated with human injuries from bison encounters at Yellowstone National Park, 2000–2015

Yellowstone National Park is home to the largest bison population on public land in the United States. Although Yellowstone regulations require visitors to remain at least 23 m from bison, since 1980, bison have injured more visitors to Yellowstone than any other animal. We examined a series of bison-related injuries at Yellowstone to evaluate the circumstances of these injuries and to identify common risk-enhancing behaviors that lead to injury. To do this, we analyzed narrative case incident records from law enforcement regarding bison-human encounters in Yellowstone during 2000–2015. Data regarding demographics, preencounter ac- tivities, number of persons involved, type of injury, and acknowledgement of appropriate viewing distance were extracted from the records. Bison encounters resulted in injury to 25 persons (21 visitors and 4 employees). Age range for injured persons was 7–68 years (median: 49 years), and 13 were female. All injuries occurred in areas of high visitor concentration. Mean visitor distance from bison before injury was 3.4 m (range: 0.3–6.1 m). Twenty persons (80%) actively approached bison before their injuries; 5 (20%) failed to retreat when bison approached. Fifteen persons (60%) were injured when in a group of ≥3 persons approaching bison. Twelve persons (48%) sustained injuries while photographing bison. Six persons (24%) acknowledged they were too close to bison. Education alone might not be sufficient to reduce bison-related injuries. Effective injury pre- vention campaigns for national parks require an understanding of the behaviors and motivations of persons who approach bison. Including behavioral science and behavior change techniques in bison injury prevention cam- paigns might reduce injuries at Yellowstone

Effect of color, size, and density of Sarracenia purpurea on prey capture

General EcologyOur objective was to study physical characteristics of the purple pitcher plant (Sarracenia purpurea) in northern Michigan to determine an effect on the amount (biomass) and richness of insect prey capture. We examined pitcher density, amount of red venation, and pitcher size (length, mouth diameter, and keel width) of 40 pitchers. The catch contained individuals from eleven different insect Orders, the most abundant being Hymenoptera and Diptera. Higher species richness was positively correlated to high-density pitcher groups and mouth diameter. The highest density of pitchers in a plant was 38 pitchers, one of which had 4 different species inside. The highest species richness in a pitcher was 7 different species and the largest mouth diameter was approx. 35mm. Biomass was also positively correlated to mouth diameter, but not to density, pitcher length or keel width. Color showed to be insignificant in determining prey capture. Morphological variation may hold some responsibility in attracting insect prey, but future studies examining an exhaustive scope of pitcher physical traits and their cumulative effect may be valuable in finding the exact mechanism of prey capture.http://deepblue.lib.umich.edu/bitstream/2027.42/61499/1/Wallen_Meg_2008.pd

Complex Contact-Based Dynamics of Microsphere Monolayers Revealed by Resonant Attenuation of Surface Acoustic Waves

Contact-based vibrations play an essential role in the dynamics of granular materials. Significant insights into vibrational granular dynamics have previously been obtained with reduced-dimensional systems containing macroscale particles. We study contact-based vibrations of a two-dimensional monolayer of micron-sized spheres on a solid substrate that forms a microscale granular crystal. Measurements of the resonant attenuation of laser-generated surface acoustic waves reveal three collective vibrational modes that involve displacements and rotations of the microspheres, as well as interparticle and particle-substrate interactions. To identify the modes, we tune the interparticle stiffness, which shifts the frequency of the horizontal-rotational resonances while leaving the vertical resonance unaffected. From the measured contact resonance frequencies we determine both particle-substrate and interparticle contact stiffnesses and find that the former is an order of magnitude larger than the latter. This study paves the way for investigating complex contact-based dynamics of microscale granular crystals and yields a new approach to studying micro- to nanoscale contact mechanics in multiparticle networks.National Science Foundation (U.S.) (Grant CMMI-1333858)United States. Army Research Office (Grant W911NF-15-1-0030)University of Washington. Royalty Research FoundationNational Science Foundation (U.S.) (Grant CHE-1111557

Can exhaled volatile organic compounds differentiate high and low responders to resistance exercise?

Participation in resistance training improves muscle strength and size, as well as reduced risk of chronic disease and frailty. However, the exercise response to resistance training is highly variable. In part this may be attributed to individual physiological differences. Identification of biomarkers that can distinguish between high and low responders to exercise are therefore of interest. Exhaled volatile organic compounds may provide a non-invasive method of monitoring the physiological response to resistance training. However, the relationship between exhaled organic compounds and the acute response to resistance exercise is not fully understood. Therefore, this research will investigate exhaled volatile organic compounds in acute response to resistance exercise with an aim to discover a common group of compounds that can predict high and low responders to standardised resistance training. © 2022 Elsevier Lt