Small-angle X-ray scattering studies of the structure of nucleosome core histone complexes in solution

The nucleosome core histone complex in solution at 2 M NaCl and pH 7 has a radius of gyration R_s, of 3.48 nm and a maximum dimension, L, of 12 nm. Its shape is disc-like with a mean thickness of 3 nm. The radius of gyration determined by us is of the same value as the radius of gyration of the complex in intact core particles (Braddock) et al., Biopolymers 1981, 20, 327). Thus, we conclude that the basic histone tails of the protein complex project about 2 nm from its central part.     

Drought affects the rate and duration of organ growth but not inter-organ growth coordination

Drought at flowering and grain filling greatly reduces maize (Zea mays) yield. Climate change is causing earlier and longer-lasting periods of drought, which affect the growth of multiple maize organs throughout development. To study how long periods of water deficit impact the dynamic nature of growth, and to determine how these relate to reproductive drought, we employed a high-throughput phenotyping platform featuring precise irrigation, imaging systems, and image-based biomass estimations. Prolonged drought resulted in a reduction of growth rate of individual organs—though an extension of growth duration partially compensated for this—culminating in lower biomass and delayed flowering. However, long periods of drought did not affect the highly organized succession of maximal growth rates of the distinct organs, i.e. leaves, stems, and ears. Two drought treatments negatively affected distinct seed yield components: Prolonged drought mainly reduced the number of spikelets, and drought during the reproductive period increased the anthesis-silking interval. The identification of these divergent biomass and yield components, which were affected by the shift in duration and intensity of drought, will facilitate trait-specific breeding toward future climate-resilient crops.

When affected by drought, the plant responds by adjusting the growth of individual organs but not the coordination between the organs.     

Isolation and characterization of microsatellite loci in the ground beetle Carabus problematicus (Coleoptera,Carabidae)

Six microsatellite loci were isolated from the ground beetle Carabus problematicus. The polymorphism ranged from two to 17 alleles and observed and expected heterozygosities ranged from 0.137 to 0.676 and 0.147 to 0.710, respectively.     

Physical and chemical limnology of alpine lakes and pools in the Rwenzori Mountains (Uganda–DR Congo)

This study describes the physical and chemical properties of 17 Afroalpine lakes (>2 m deep) and 11 pools (<2 m deep) in the Rwenzori mountains, Uganda-DR Congo, with the aim to establish the baseline conditions against which to evaluate future environmental and biological changes in these unique tropical ecosystems, and to provide the foundation for lake-based paleoenvironmental studies. Most Rwenzori lakes are located above 3,500 m elevation, and dilute (5–52 μS/cm specific conductance at 25°C) open systems with surface in- and outflow. Multivariate ordination and pairwise correlations between environmental variables mainly differentiate between (1) lakes located near or above 4,000 m (3,890–4,487 m), with at least some direct input of glacial meltwater and surrounded by rocky catchments or alpine vegetation; and (2) lakes located mostly below 4,000 m (2,990–4,054 m), remote from glaciers and surrounded by Ericaceous vegetation and/or bogs. The former group are mildly acidic to neutral clear-water lakes (surface pH: 5.80–7.82; Secchi depth: 120–280 cm) with often above-average dissolved ion concentrations (18–52 μS/cm). These lakes are (ultra-) oligotrophic to mesotrophic (TP: 3.1–12.4 μg/l; Chl-a: 0.3–10.9 μg/l) and phosphorus-limited (mass TN/TP: 22.9–81.4). The latter group are mildly to strongly acidic (pH: 4.30–6.69) waters stained by dissolved organic carbon (DOC: 6.8–13.6 mg/l) and more modest transparency (Secchi-disk depth: 60–132 cm). Ratios of particulate carbon, particulate nitrogen and chlorophyll a in these lakes indicate that organic matter in suspension is primarily derived from the lakes’ catchments rather than aquatic primary productivity. Since key features in the Rwenzori lakes’ abiotic environment are strongly tied to temperature and catchment hydrology, these Afroalpine lake ecosystems can be expected to respond sensitively to climate change and glacier melting. Electronic supplementary material The online version of this article (doi: ) contains supplementary material, which is available to authorized users.     

The Effect of Weight Loss on Sleep‐disordered Breathing in Obese Teenagers

The objective of this study was to assess the effect of weight loss on sleep‐disordered breathing (SDB) in obese teenagers attending a residential treatment center. We also assessed whether the presence of SDB at the start of the weight management therapy was correlated with the amount of weight loss achieved. Obese teenagers were recruited and underwent anthropometry and sleep screening. Subjects with SDB (apnea hypopnea index (AHI) ≥ 2) received a follow‐up screening after weight loss therapy. Sixty‐one obese subjects were included (age = 14.8 ± 2.3; BMI z score = 2.7 ± 0.4). Thirty‐one subjects were diagnosed with SDB with 38% continuing to have residual SDB after a median weight loss of 24.0 kg. Subjects with SDB had a higher median relative decrease in BMI z score compared to subjects without SDB which was 30.5, 33.6, and 50.4% in the group with AHI of the baseline screening study < 2, 2 ≤ AHI < 5, and AHI ≥ 5, respectively (P = 0.02). AHI of the baseline screening study correlated significantly with the relative decrease in BMI z score (partial r = 0.37; P = 0.003), controlling for gender, age, initial BMI z score, and time between both studies. In conclusion, weight loss was successful in treating SDB in obese teenagers. In addition, there was a positive association between the severity of SDB at the start of the treatment and the amount of weight loss achieved. These findings are in favor of considering weight loss as a first‐line treatment for SDB in obese children and adolescents.