Setting the biological time in central and peripheral clocks during ontogenesis

In mammals, the principal circadian clock within the suprachiasmatic nucleus (SCN) entrains the phase of clocks in numerous peripheral tissues and controls the rhythmicity in various body functions. During ontogenesis, the molecular mechanism responsible for generating circadian rhythmicity develops gradually from the prenatal to the postnatal period. In the beginning, the maternal signals set the phase of the newly developing fetal and early postnatal clocks, whereas the external light-dark cycle starts to entrain the clocks only later. This minireview discusses the complexity of signaling pathways from mothers and the outside world to the fetal and newborn animals' circadian clocks.     

Conservation of pBuM–2 satellite DNA sequences among geographically isolated Drosophila gouveai populations from Brazil

In this study, we have compared 34 repetition units of pBuM-2 satellite DNA of individuals from six isolated populations of Drosophila gouveai, a cactophilic member of Drosophila buzzatii cluster (repleta group). In contrast to the results of previous morphological and molecular data, which suggest differentiation among the D. gouveai populations, the sequences and the cluster analysis of pBuM-2 monomers showed that this repetitive element is highly conserved among the six D. gouveai populations (97.8% similarity), indicating a slow rate of evolution of pBuM-2 sequences at the population level. Probably, some homogenization mechanisms of tandem sequences, such as unequal crossing or gene conversion, have maintained the sequence similarity of pBuM-2 among D. gouveai populations. Alternatively, such a result may be associated with a functional role of pBuM-2 sequences, although it is not understood at present.     

Detection of competitive enzyme inhibition with end point progress curve data

A model for a dimensionless factor, the inhibition detection limit (IDL), which describes the limit of detection of competitive inhibition for end point assays as a function of the proportion of substrate converted into product, has been developed. For a given end point enzymatic assay, the IDL function has a maximum that is dependent on the error structure parameters (four parameters) of the assay, the value of [S]o/K(ms), and the extent of product inhibition (K(ms)/K(mp)). Accordingly, the substrate conversion level that maximized the ability to detect samples with high Ki/[I] ratios was predicted for each member of a population of simulated assays. Furthermore, we identified a consensus substrate conversion level where the probability of a near-optimal robustness and detection limit for all the members of the assay population is maximal. Unlike the optimal substrate conversion level for individual assays, this consensus substrate conversion level was dependent only on [S]o/K(m), K(ms)/K(mp), and whether the signal increases or decreases during the course of the reaction. Consensus substrate conversion levels were beyond the initial velocity range for almost all the analyzed assay populations. It was shown that the IDL factor was a more informative indicator of assay quality than the popular Z' factor.     

Occurrence of 1-Glyceryl-1-myo-Inosityl Phosphate in Hyperthermophiles

The accumulation of compatible solutes was studied in the hyperthermophilic bacterium Aquifex pyrophilus as a function of the temperature and the NaCl concentration of the growth medium. Nuclear magnetic resonance analysis of cell extracts revealed the presence of α- and β-glutamate, di-mannosyl-di-myo-inositol phosphate, di-myo-inositol phosphate, and an additional compound here identified as 1-glyceryl-1-myo-inosityl phosphate. All solutes accumulated by A. pyrophilus are negatively charged at physiological pH. The intracellular levels of di-myo-inositol phosphate increased in response to supraoptimal growth temperature, while α- and β-glutamate accumulated in response to osmotic stress, especially at growth temperatures below the optimum. The newly discovered compound, 1-glyceryl-1-myo-inosityl phosphate, appears to play a double role in osmo- and thermoprotection, since its intracellular pool increased primarily in response to a combination of osmotic and heat stresses. This work also uncovered the nature of the unknown compound, previously detected in Archaeoglobus fulgidus (L. O. Martins et al., Appl. Environ. Microbiol. 63:896-902, 1997). The curious structural relationship between diglycerol phosphate (found only in Archaeoglobus species), di-myo-inositol phosphate (a canonical solute of hyperthermophiles), and the newly identified solute is highlighted. This is the first report on the occurrence of 1-glyceryl-1-myo-inosityl phosphate in living systems.     

High-resolution characterization of antibody fragment/antigen interactions using Biacore T100

A Biacore T100 optical biosensor was used to characterize the binding kinetics of a panel of antigen binding fragments (Fabs) directed against the PcrV protein from Pseudomonas aeruginosa. PcrV protein forms part of the type III secretion system complex of this opportunistic pathogen. We demonstrate that the biosensor response data for each Fab collected from three different surface densities of the antigen could be fit globally to a simple 1:1 interaction model. Importantly, we found that the Fabs with the slowest dissociation rate provided the best protection in cell cytotoxicity studies. To further characterize the Fab interactions, binding data were automatically acquired at different temperatures and under different buffer conditions. The comprehensive characterization of these Fabs shows how Biacore T100 can be used to complement protein therapeutic discovery programs from basic research to the selection of therapeutic candidates.     

Subunit architecture of multimeric complexes isolated directly from cells

Recent developments in purification strategies, together with mass spectrometry (MS)-based proteomics, have identified numerous in vivo protein complexes and suggest the existence of many others. Standard proteomics techniques are, however, unable to describe the overall stoichiometry, subunit interactions and organization of these assemblies, because many are heterogeneous, are present at relatively low cellular abundance and are frequently difficult to isolate. We combine two existing methodologies to tackle these challenges: tandem affinity purification to isolate sufficient quantities of highly pure native complexes, and MS of the intact assemblies and subcomplexes to determine their structural organization. We optimized our protocol with two protein assemblies from Saccharomyces cerevisiae (scavenger decapping and nuclear cap-binding complexes), establishing subunit stoichiometry and identifying substoichiometric binding. We then targeted the yeast exosome, a nuclease with ten different subunits, and found that by generating subcomplexes, a three-dimensional interaction map could be derived, demonstrating the utility of our approach for large, heterogeneous cellular complexes.     

Evaluation of experimental cleanser solution of Ricinus communis: effect on soft denture liner properties

doi: 10.1111/j.1741‐2358.2010.00438.x Evaluation of experimental cleanser solution of Ricinus communis: effect on soft denture liner properties Objective: This study evaluated colour stability, hardness and roughness of soft denture liners after immersion in various cleansers. Materials and methods: Thirty specimens (14 mm × 4 mm) of Elite Soft Relining (ES) and Mucopren Soft (MS) were randomly immersed in distilled water at 37°C, sodium hypochlorite 1%, and an experimental Ricinus communis solution (RC) for 7, 15 and 183 continuous days. Results: anova (p < 0.05) and Tukey’s test indicated that after T7 (μ =8.79 ± 7.36); T15 (μ = 4.23 ± 2.62) and T183 (μ = 8.78 ± 3.16), MS presented a higher increase in hardness than ES. After T7, MS underwent an increase in roughness (μ = 0.09 ± 0.80); ES underwent a decrease (μ = ?0.08 ± 0.16). RC caused the smallest variation in roughness. After T15, both materials presented an increase in roughness. After T183, ES (μ = ?0.30 ± 0.48) presented a higher roughness variation than MS (μ = ?0.07 ± 0.32). Hypochlorite caused an increase in roughness (μ = 0.02 ± 0.19). Conclusion: After all periods ES presented higher colour alteration than MS; highest colour alteration was caused by hypochlorite. Both materials were more stable after immersion in RC.     

Oral health related quality of life of edentulous patients after denture relining with a silicone-based soft liner

doi: 10.1111/j.1741‐2358.2011.00503.x Oral health related quality of life of edentulous patients after denture relining with a silicone‐based soft liner Background: Knowledge of benefits caused by a treatment on quality of life is very relevant. Despite the wide use and acceptance of soft denture liners, it is necessary to evaluate the patient’s response about the use of these materials with regard to improvement in oral health related quality of life (OHRQoL). Objectives: The aim of this study was to evaluate the influence of denture relining in the OHRQoL of edentulous patients. Materials and methods: Thirty‐two complete denture wearers had their lower dentures relined with a silicone‐based material (Mucopren soft, Kettenbach, Germany) according to chairside procedures. OHRQoL was assessed before and after 3 months of relining by means of OHIP‐EDENT, and the median scores were compared by Wilcoxon test (p ≤ 0.05). Results: After 3 months of relining, participants reported significant improvement of their OHRQoL (p ≤ 0.01). Conclusion: Denture relining with a soft liner may have a positive impact on the perceived oral health of edentulous patients.