Bone is a hierarchical material formed by an organic extracellular matrix and mineral where each component and their physical relationship with each other contribute to fracture resistance. Bone ...quality can be affected by nutrition, and dietary supplements that are marketed to improve overall health may improve the fracture resistance of bone. To test this, 11 week old female C57BL/6 mice were fed either collagen, chondroitin sulfate, glucosamine sulfate, or fish oil 5 times a week for 8 weeks. Femurs, tibiae, and vertebrae were scanned with micro-computed tomography and then mechanically tested. Glucosamine and fish oil lowered elastic modulus, but did not alter the overall strength of the femur. There were no differences in bone mechanics of the tibiae or vertebrae. Overall, the data suggest that dietary supplements did little to improve bone quality in young, healthy mice. These supplements may be more effective in diseased or aged mice.
The long neck of an adult sauropod has been found structurally unsuitable for high browsing while standing on all four feet. Some juveniles might have used a tripodal stance, but an analysis of the ...motion of the centre of mass shows a large adult sauropod could not. We propose here that sauropods could have browsed high by sitting, squatting or even kneeling on their hind legs to elevate their heads without a sharp bend at the base of the neck. A large sauropod needs a way to deal with very high blood pressure when high browsing. Arterial pumping is suggested here as a means of avoiding the need for high blood pressure.
Mountain yellow-legged frogs (Rana muscosa and Rana sierrae) of California's Sierra Nevada have been extirpated from over 90% of their historic range, initially by introduced trout predators, and ...more recently by the emergence of the lethal amphibian chytrid fungus (Batrachochytrium dendrobatidis). Formerly widespread and abundant, mountain yellow-legged frogs are grazers and highly connected high level predators, living in low diversity, low productivity high elevation lakes. Here, I examine the extent to which frog extinctions impact Sierra Nevada lake communities. First, in a study that combined surveys of benthic macroinvertebrates in 22 lakes over 5 years with a reanalysis of benthic macroinvertebrate community data from over 150 lakes, I found no strong differences in benthic macroinvertebrate community diversity or composition between lakes with frogs vs. lakes without frogs. I also conducted experiments to evaluate the impact of tadpoles as grazers on benthic algae, and found that tadpoles do reduce algal biomass in artificial habitats, but that the effect can be small and may not outweigh the influence that abiotic variability has on algal biomass in lakes. Lastly, while I documented that large and periodic tadpole aggregations create biogeochemical hotspots of dissolved nitrogen, the phenomena may not be widespread enough to drive differences in diatom diversity in lakes with vs. without tadpoles. Within lakes, I found little indication that diatom community diversity and composition were responding to tadpole generated nitrogen hotspots as a fluctuation-dependent mechanism with potential to enhance diatom coexistence. While none of the ecological effects of mountain yellow-legged frogs and tadpoles that I observed suggests that their extinctions are having large impacts on Sierra Nevada lake communities, they should not be discounted as expendable, because there are many other ways in which these amphibians could be important in their communities.
We present measurements of the in situ, microscopic architecture of a self- assembled bilayer at the interface between a regularly nanopatterned surface and an aqueous sub-phase using neutron ...reflectometry. The substrate is patterned with a rectangular array of nanoscale holes. Because of the high quality of the pattern, using neutron reflectometry, we are able to map the surface-normal density distribution of the patterned silicon, the penetration of water into the pattern, and the distribution of a deposited film inside and outside of the etched holes. In this stud; 1,2-dilauroyl-sn-glycero-3-phosphocholine （DLPC） single bilayers were deposited on the hydrophilic patterned surface. For bilayers deposited either by vesicle fusion （VF） or by the Langmuir-Schaefer （L-S） technique, the most consistent model found to fit the data shows that the lipids form bilayer coatings on top of the substrate as well as the bottoms of the holes in an essentially conformal fashion. However, while there is a single bilayer on the unetched silicon surface, the lipids coating the bottoms of the holes form a complex bimodal structure consistent with a rough surface produced by the etching process. This study provides insight into film transfer both outside and inside regular nanopatterned features.
Cattle show several responses to heat load, including spending more time standing. Little is known about what benefit this may provide for the animals. Data from 3 separate cooling management trials ...were analyzed to investigate the relationship between behavioral patterns in lactating dairy cows experiencing mild to moderate heat stress and their body temperature. Cows (n=157) were each fitted with a leg data logger that measured position and an intravaginal data logger that measures core body temperature (CBT). Ambient conditions were also collected. All data were standardized to 5-min intervals, and information was divided into several categories: when standing and lying bouts were initiated and the continuance of each bout (7,963 lying and 6,276 standing bouts). In one location, cows were continuously subjected to heat-stress levels according to temperature–humidity index (THI) range (THI≥72). The THI range for the other 2 locations was below and above a heat-stress threshold of 72 THI. Overall and regardless of period of day, cows stood up at greater CBT compared with continuing to stand or switching to a lying position. In contrast, cows lay down at lower CBT compared with continuing to lie or switching to a standing position, and lying bouts lasted longer when cows had lower CBT. Standing bouts also lasted longer when cattle had greater CBT, and they were less likely to lie down (less than 50% of lying bouts initiated) when their body temperature was over 38.8°C. Also, cow standing behavior was affected once THI reached 68. Increasing CBT decreased lying duration and increased standing duration. A CBT of 38.93°C marked a 50% likelihood a cow would be standing. This is the first physiological evidence that standing may help cool cows and provides insight into a communally observed behavioral response to heat.
Schizophrenia is a highly heritable, neuropsychiatric disorder characterized by episodic psychosis and altered cognitive function. Despite success in identifying genetic variants associated with ...schizophrenia, there remains uncertainty about the causal genes involved in disease pathogenesis and how their function is regulated.
We performed a multi-stage epigenome-wide association study, quantifying genome-wide patterns of DNA methylation in a total of 1714 individuals from three independent sample cohorts. We have identified multiple differentially methylated positions and regions consistently associated with schizophrenia across the three cohorts; these effects are independent of important confounders such as smoking. We also show that epigenetic variation at multiple loci across the genome contributes to the polygenic nature of schizophrenia. Finally, we show how DNA methylation quantitative trait loci in combination with Bayesian co-localization analyses can be used to annotate extended genomic regions nominated by studies of schizophrenia, and to identify potential regulatory variation causally involved in disease.
This study represents the first systematic integrated analysis of genetic and epigenetic variation in schizophrenia, introducing a methodological approach that can be used to inform epigenome-wide association study analyses of other complex traits and diseases. We demonstrate the utility of using a polygenic risk score to identify molecular variation associated with etiological variation, and of using DNA methylation quantitative trait loci to refine the functional and regulatory variation associated with schizophrenia risk variants. Finally, we present strong evidence for the co-localization of genetic associations for schizophrenia and differential DNA methylation.
Background. Human immunodeficiency virus (HIV)-associated neurocognitive disorders (HAND) can show variable clinical trajectories. Previous longitudinal studies of HAND typically have been brief, did ...not use adequate normative standards, or were conducted in the context of a clinical trial, thereby limiting our understanding of incident neurocognitive (NC) decline and recovery. Methods. We investigated the incidence and predictors of NC change over 16–72 (mean, 35) months in 436 HIV-infected participants in the CNS HIV Anti-Retroviral Therapy Effects Research Cohort. Comprehensive laboratory, neuromedical, and NC assessments were obtained every 6 months. Published, regression-based norms for NC change were used to generate overall change status (decline vs stable vs improved) at each study visit. Survival analysis was used to examine the predictors of time to NC change. Results. Ninety-nine participants (22.7%) declined, 265 (60.8%) remained stable, and 72 (16.5%) improved. In multivariable analyses, predictors of NC improvements or declines included time-dependent treatment status and indicators of disease severity (current hematocrit, albumin, total protein, aspartate aminotransferase), and baseline demographics and estimated premorbid intelligence quotient, non-HIV-related comorbidities, current depressive symptoms, and lifetime psychiatric diagnoses (overall model P < .0001). Conclusions. NC change is common in HIV infection and appears to be driven by a complex set of risk factors involving HIV disease, its treatment, and comorbid conditions.
Current sampling of genomic sequence data from eukaryotes is relatively poor, biased, and inadequate to address important questions about their biology, evolution, and ecology; this Community Page ...describes a resource of 700 transcriptomes from marine microbial eukaryotes to help understand their role in the world's oceans.
Abstract
We present seven new transiting hot Jupiters from the WASP-South survey. The planets are all typical hot Jupiters orbiting stars from F4 to K0 with magnitudes of V = 10.3-12.5. The orbital ...periods are all in the range of 3.9-4.6 d, the planetary masses range from 0.4 to 2.3 M
Jup and the radii from 1.1 to 1.4 R
Jup. In line with known hot Jupiters, the planetary densities range from Jupiter-like to inflated (ρ = 0.13-1.07ρJup). We use the increasing numbers of known hot Jupiters to investigate the distribution of their orbital periods and the 3-4 d 'pile-up'.
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