Graphical representation of the salient conformational features of protein residues.

A composite plot for depicting in two dimensions the conformation and the secondary structural features of protein residues has been developed. Instead of presenting the exact values of the main- and side-chain torsion angles (φ, psi and chi(1)), it indicates the region in the three-dimensional conformational space to which a residue belongs. Other structural aspects, like the presence of a cis peptide bond and disulfide linkages, are also displayed. The plot may be used to recognize patterns in the backbone and side-chain conformation along a polypeptide chain and to compare protein structures derived from X-ray crystallography, NMR spectroscopy or molecular modelling studies and also to highlight the effect of mutation on structure.     

Simulation of protein misfolding using a lattice model

The structure of the tightly bound complex of the globular myosin head with F-actin is the key to understanding important details of the mechanism of how the actin-myosin motor functions. The current notion on this complex is based on the docking of known atomic structures of constituent proteins into low-resolution electron-density maps. The atomic structure of the complex was refined by the molecular mechanics method, which consists in minimizing the energy of molecular interaction and which makes it possible to optimize not only the relative position of protein backbones as rigid bodies, but also the position of side chains on the protein interface. The structure calculated using ICM-Pro software, on the one hand, is close to the model obtained using electron microscopy; on the other hand, it ensures the best calculated interaction energy and accounts for the results of mutagenesis experiments. On the basis of the structure obtained, we can suggest the molecular mechanisms underlying the actin-activated release of ATP hydrolysis products from myosin and the decrease in the affinity of myosin for actin upon binding of nucleotides.     

Promoting Smoke-Free Homes: A Novel Behavioral Intervention Using Real-Time Audio-Visual Feedback on Airborne Particle Levels

Interventions are needed to protect the health of children who live with smokers. We pilot-tested a real-time intervention for promoting behavior change in homes that reduces second hand tobacco smoke (SHS) levels. The intervention uses a monitor and feedback system to provide immediate auditory and visual signals triggered at defined thresholds of fine particle concentration. Dynamic graphs of real-time particle levels are also shown on a computer screen. We experimentally evaluated the system, field-tested it in homes with smokers, and conducted focus groups to obtain general opinions. Laboratory tests of the monitor demonstrated SHS sensitivity, stability, precision equivalent to at least 1 µg/m³, and low noise. A linear relationship (R² = 0.98) was observed between the monitor and average SHS mass concentrations up to 150 µg/m³. Focus groups and interviews with intervention participants showed in-home use to be acceptable and feasible. The intervention was evaluated in 3 homes with combined baseline and intervention periods lasting 9 to 15 full days. Two families modified their behavior by opening windows or doors, smoking outdoors, or smoking less. We observed evidence of lower SHS levels in these homes. The remaining household voiced reluctance to changing their smoking activity and did not exhibit lower SHS levels in main smoking areas or clear behavior change; however, family members expressed receptivity to smoking outdoors. This study established the feasibility of the real-time intervention, laying the groundwork for controlled trials with larger sample sizes. Visual and auditory cues may prompt family members to take immediate action to reduce SHS levels. Dynamic graphs of SHS levels may help families make decisions about specific mitigation approaches.     

Occurrence of poly-3-hydroxybutyrate inAzospirillum sp.

Azospirillum strains isolated from the roots and rhizosphere of some plants growing in West Bengal were subjected to qualitative and quantitative evaluation for poly-3-hydroxybutyrate (PHB) production. Out of the total 49 isolates, 13 (26%) were confirmed as PHB producers according to staining and chemical assay methods. The majority of these strains belonged toAzospirillum brasilense butA. amazonense andA. lipoferum were also present. When grown in the presence of NH₄Cl in the medium, the PHB content of the strains ranged from 1 to 14% of cell dry mass. The identity of the PHB extracted fromAzospirillum strain 24P-N-72 was confirmed by the characteristic UV and IR absorption peaks at 235 nm and 1730 cm⁻¹, respectively.     

Metabolic Syndrome Is Associated with Increased Oxo-Nitrative Stress and Asthma-Like Changes in Lungs

Epidemiological studies have shown an increased obesity-related risk of asthma. In support, obese mice develop airway hyperresponsiveness (AHR). However, it remains unclear whether the increased risk is a consequence of obesity, adipogenic diet, or the metabolic syndrome (MetS). Altered L-arginine and nitric oxide (NO) metabolism is a common feature between asthma and metabolic syndrome that appears independent of body mass. Increased asthma risk resulting from such metabolic changes would have important consequences in global health. Since high-sugar diets can induce MetS, without necessarily causing obesity, studies of their effect on arginine/NO metabolism and airway function could clarify this aspect. We investigated whether normal-weight mice with MetS, due to high-fructose diet, had dysfunctional arginine/NO metabolism and features of asthma. Mice were fed chow-diet, high-fat-diet, or high-fructose-diet for 18 weeks. Only the high-fat-diet group developed obesity or adiposity. Hyperinsulinemia, hyperglycaemia, and hyperlipidaemia were common to both high-fat-diet and high-fructose-diet groups and the high-fructose-diet group additionally developed hypertension. At 18 weeks, airway hyperresponsiveness (AHR) could be seen in obese high-fat-diet mice as well as non-obese high-fructose-diet mice, when compared to standard chow-diet mice. No inflammatory cell infiltrate or goblet cell metaplasia was seen in either high-fat-diet or high-fructose-diet mice. Exhaled NO was reduced in both these groups. This reduction in exhaled NO correlated with reduced arginine bioavailability in lungs. In summary, mice with normal weight but metabolic obesity show reduced arginine bioavailability, reduced NO production, and asthma-like features. Reduced NO related bronchodilation and increased oxo-nitrosative stress may contribute to the pathogenesis.     

Fine structure of reproductive glands in two primitive marine pulmonates (Basommatophora: Siphonariidae)

Within the clade Euthyneura the marine basommatophorans are particularly neglected. More morphological and molecular studies are needed because their phylogenetic relationships with other pulmonates remain unresolved. The present study examines the most conspicuous reproductive gland, the glandular complex in two marine limpets, Siphonaria capensis and S. serrata (Pulmonata: Basommatophora) at both gross and fine structural levels. These two sympatric species with different developmental modes were selected to compare the structure and function of this enormous glandular structure. In both S. capensis and S. serrata, the glandular complex shows an undifferentiated state composed of an acidophilic albumen gland and a basophilic mucous gland. The glands contain secretory cells and supporting cells (= ciliated cells) that are highly ciliated. When the histochemical properties of the glandular complex were compared with those of siphonariid egg masses (of each species) it could be established that the albumen gland was responsible for the production of perivitelline fluid whereas the mucous gland secreted substances that help in the assembly of mucous layers surrounding the egg capsules. We suggest that the presence of a single glandular complex comprised of two glands is the most primitive organization of reproductive glands in pulmonates. Furthermore, the histology, fine structure and histochemistry of these glands are very similar to those of the reproductive glands of opisthobranchs.     

Differentials of fertility between polygynous and monogamous marriages in rural Bangladesh

This paper discusses polygynous marriages in rural Bangladesh, using marital status and birth registration data from the Demographic Surveillance System (DSS) of the International Center for Diarrheal Disease Research, for the period 1975-79. Of all the marriages recorded during this period about 5% were polygynous. To identify the women polygynously married, 1974 census data of the DSS area were used. The difference in age at marriage between the polygynous groom and his subsequent wife was 15 years on average. The socioeconomic indicators studied were education, occupation and area of dwelling space. In general, these indicators between women in monogamous marriages were significantly higher than between the women in polygynous unions. During the period 1976-79, 863 polygynous marriages were recorded (4.9% of all marriages in the study area). Polygynous marriages were found to be less frequent among men with 2ndary and higher levels of education. The highest proportion of polygynous marriages occurred among husbands with no schooling or Koranic education. The general fertility rate of women in monogamous marriages was significantly higher than for women in polygynous marriages, overall and in all age groups except 20-24. During the period 1975-79, the mean number of liveborn children for monogamous women was higher than that of polygynous women.