A three dimensional model of the photosynthetic membranes of Ectothiorhodospira halochloris

The three dimensional organization of the complete photosynthetic apparatus of the extremely halophilic, bacteriochlorophyll b containing Ectothiorhodospira halochloris has been elaborated by several techniques of electron microscopy. Essentially all thylakoidal sacs are disc shaped and connected to the cytoplasmic membrane by small membraneous ldquobridgesrdquo. In sum, the lumina of all thylakoids (intrathylakoidal space) form one common periplasmic space. Thin sections confirm a paracrystalline arrangement of the photosynthetic complexes in situ. The ontogenic development of the photosynthetic apparatus is discussed based on a structural model derived from serial thin sections

Selective glucose sensing in complex media using a biomimetic receptor

Glucose is a key biomedical analyte, especially relevant to the management of diabetes. Current methods for glucose determination rely on the enzyme glucose oxidase, requiring specialist instrumentation and suffering from redox-active interferents. In a new approach, a powerful and highly selective achiral glucose receptor is mixed with a sample, l-glucose is added, and the induced CD spectrum is measured. The CD signal results from competition between the enantiomers, and is used to determine the d-glucose content. The involvement of l-glucose doubles the signal range from the CD spectrometer and allows sensitivity to be adjusted over a wide dynamic range. It also negates medium effects, which must be equal for both enantiomers. The method has been demonstrated with human serum, pre-filtered to remove proteins, giving results which closely match the standard biochemical procedures, as well as a cell culture medium and a beer sample containing high (70 mM) and low (0.4 mM) glucose concentrations respectively

Transient peak-strain matching partially recovers the age-impaired mechanoadaptive cortical bone response

Mechanoadaptation maintains bone mass and architecture; its failure underlies age-related decline in bone strength. It is unclear whether this is due to failure of osteocytes to sense strain, osteoblasts to form bone or insufficient mechanical stimulus. Mechanoadaptation can be restored to aged bone by surgical neurectomy, suggesting that changes in loading history can rescue mechanoadaptation. We use non-biased, whole-bone tibial analyses, along with characterisation of surface strains and ensuing mechanoadaptive responses in mice at a range of ages, to explore whether sufficient load magnitude can activate mechanoadaptation in aged bone. We find that younger mice adapt when imposed strains are lower than in mature and aged bone. Intriguingly, imposition of short-term, high magnitude loading effectively primes cortical but not trabecular bone of aged mice to respond. This response was regionally-matched to highest strains measured by digital image correlation and to osteocytic mechanoactivation. These data indicate that aged bone’s loading response can be partially recovered, non-invasively by transient, focal high strain regions. Our results indicate that old murine bone does respond to load when the loading is of sufficient magnitude, and bones’ age-related adaptation failure may be due to insufficient mechanical stimulus to trigger mechanoadaptation

Preventing childhood obesity: what works?

Rates of overweight in North American children and adolescents have increased dramatically since the 1970s. Childhood obesity has reached epidemic proportions and calls for prevention and treatment programs to reverse this trend have been made. However, the evidence base needed for effective action is still incomplete, especially for childhood obesity prevention programs. This paper focuses on primary prevention of childhood obesity and has three aims: (1) to briefly describe current primary prevention approaches for childhood obesity and the evidence for their impact; (2) to elucidate promising, but untested intervention strategies using an ecological framework and evidence from experimental and epidemiological research on factors influencing children\u27s eating and weight status; and (3) to introduce a multiphase strategy for screening intervention components and building and evaluating potent interventions for childhood obesity. Most childhood obesity prevention programs have focused on school-aged children and have had little success. We suggest that, given these findings, prevention efforts should be expanded to explore other contexts in which children live as possible settings for intervention efforts, including the family and childcare settings. Given that 25% of preschool children are already overweight, intervening with children before school entry should be a priority. A review of experimental research on the developing controls of food intake in infancy and childhood suggests possible intervention strategies, focusing on parenting and aspects of the feeding environment. Epidemiological findings point to even earlier modifiable risk factors, including gestational weight gain, maternal prepregnancy weight, and formula feeding. However, the potential impact of altering these risk factors remains to be evaluated. In response to this problem, we suggest a new, multiphase method for accomplishing this, including screening intervention components, refining intervention designs and confirming component efficacy to build and evaluate potent, optimized interventions

Migraine headaches among university students using id migraine test as a screening tool

<p>Abstract</p> <p>Background</p> <p>Migraine is a significant health problem, especially for the young people, due to its frequency and accompanying morbidity, causing disability and loss of performance. In this study, our aim was to determine the prevalence of migraine headaches among university students in Edirne, a Turkish city.</p> <p>Methods</p> <p>In this cross-sectional and descriptive study, study population was composed of students registered to Trakya University in the academic year of 2008-2009. Out of these, 3694 of them accepted to participate. Participants who had two or more headaches in the last 3 months formed the headache group. Afterwards, two preliminary questions were applied to the headache group and participants with at least one affirmative response were asked to perform the validated ID-Migraine™ test.</p> <p>Results</p> <p>The mean age of 3694 students participated in the study was 19.23 ± 1.84 (17-39 years), with adolescents:adult ratio being 2.5:1. 1613 students (43.7%) did have at least two headaches in the last three months. Migraine-type headache was detected in 266 subjects (7.2%) based on the ID-Migraine™ test. Of the migraine group, 72 were male (27.1%) and 194 were female (72.9%). There was no significant difference in migraine prevalence between adolescent and adult age groups.</p> <p>Conclusions</p> <p>With a prevalence similar to adults, primary care physicians should be aware of the probability of migraine headaches in university students in order to maintain a successful school performance.</p

Proportions of Convective and Stratiform Precipitation Revealed in Water Isotope Ratios

Tropical and midlatitude precipitation is fundamentally of two types, spatially-limited and high-intensity convective or widespread and lower-intensity stratiform, owing to differences in vertical air motions and microphysical processes governing rain formation. These processes are difficult to observe or model and precipitation partitioning into rain types is critical for understanding how the water cycle responds to climate changes. Here, we combine two independent data sets – convective and stratiform precipitation fractions, derived from the Tropical Rainfall Measuring Mission satellite or synoptic cloud observations, and stable isotope and tritium compositions of surface precipitation, derived from a global network – to show that isotope ratios reflect rain type proportions and are negatively correlated with stratiform fractions. Condensation and riming associated with boundary layer moisture produces higher isotope ratios in convective rain, along with higher tritium when riming in deep convection occurs with entrained air at higher altitudes. Based on our data, stable isotope ratios can be used to monitor changes in the character of precipitation in response to periodic variability or changes in climate. Our results also provide observational constraints for an improved simulation of convection in climate models and a better understanding of isotope variations in proxy archives, such as speleothems and tropical ice

Differential Patterns of Food Appreciation during Consumption of a Simple Food in Congenitally Anosmic Individuals: An Explorative Study

Food is evaluated for various attributes. One of the key food evaluation domains is hedonicity. As food is consumed, its hedonic valence decreases (due to prolonged sensory stimulation) and hedonic habituation results. The aim of the present study was to investigate changes in food pleasantness ratings during consumption of a simple food by individuals without olfactory experience with food as compared to normosmics. 15 congenital anosmics and 15 normosmic controls were each presented with ten 10 g banana slices. Each was visually inspected, then smelled and chewed for ten seconds and subsequently rated for hedonicity on a 21-point scale. There was a significant difference in pleasantness ratings between congenital anosmics and controls (F(1, 26) = 6.71, p = .02) with the anosmics exhibiting higher ratings than the controls, a significant main repeated-measures effect on the ratings (F(1.85, 48) = 12.15, p<.001), which showed a decreasing trend over the course of consumption, as well as a significant portion*group interaction (F(1.85, 48) = 3.54, p = .04), with the anosmic participants experiencing a less pronounced decline. The results of the present explorative study suggest that over the course of consumption of a simple food, congenitally anosmic individuals experience differential patterns of appreciation of food as compared to normosmics. In this particular case, the decrease of hedonic valence was less pronounced in congenital anosmics

Uncoupling of sexual reproduction from homologous recombination in homozygous Oenothera species

Salient features of the first meiotic division are independent segregation of chromosomes and homologous recombination (HR). In non-sexually reproducing, homozygous species studied to date HR is absent. In this study, we constructed the first linkage maps of homozygous, bivalent-forming Oenothera species and provide evidence that HR was exclusively confined to the chromosome ends of all linkage groups in our population. Co-segregation of complementary DNA-based markers with the major group of AFLP markers indicates that HR has only a minor role in generating genetic diversity of this taxon despite its efficient adaptation capability. Uneven chromosome condensation during meiosis in Oenothera may account for restriction of HR. The use of plants with ancient chromosomal arm arrangement demonstrates that limitation of HR occurred before and independent from species hybridizations and reciprocal translocations of chromosome arms—a phenomenon, which is widespread in the genus. We propose that consecutive loss of HR favored the evolution of reciprocal translocations, beneficial superlinkage groups and ultimately permanent translocation heterozygosity