פרסומים

A review. The most prominent feature of surfactants is their ability to self-assoc. and form discrete aggregates in aq. dispersions. Among the various self-assembled structures that are produced (vesicles, membranes, liq. crystals, etc.), micelles represent the simplest class of assocn. colloids, and are widely used as nano-architectures for different applications. In spite of the vast literature, a complete understanding of all the exptl. evidences related to the micellization process is still a work in progress. In particular, the thermodn. and kinetics of micellization provide the crucial concepts for the control of dissocn. and reconstruction of micelles, such as in the solubilization, stabilization and delivery of active ingredients, and in cosmetics, detergents, food technol., and in pharmaceutical formulations. In this contribution, we offer an overview of the various structures formed by self-assembling amphiphilic mols. in water. The basic thermodn. involved in self-assembly is described, and an overview of the exptl. techniques used in the characterization of the structure and properties of these nanostructures is given. [on SciFinder(R)]

A review. Microemulsions are considered excellent delivery vehicles for bioactives, food additives and food supplements. They offer the advantages of spontaneous formation, ease of manuf., thermodn. stability, very low viscosity and Newtonian properties, full transparency (clear solns.) and improved solubilization capacities of bioactive materials. This chapter explores some of the new trends in microemulsion research, including many carried out in our lab, through anal. of some representative studies. The solubilization of different food additives such as flavoring agents, aromas, antioxidants, and colorants, as well as peptides and nutraceuticals, in various microemulsion compns. and microstructures are reviewed. [on SciFinder(R)]

Honey bee workers care for (’’nurse’’) the brood around the clock without circadian rhythmicity, but then they forage outside with strong circadian rhythms and a consolidated nightly rest. This chronobiological plasticity is associated with variation in the expression of the canonical ‘‘clock genes’’ that regulate the circadian clock: nurse bees show no brain rhythms of expression, while foragers do. These results suggest that the circadian system is organized differently in nurses and foragers. Nurses switch to activity with circadian rhythms shortly after being removed from the hive, suggesting that at least some clock cells in their brain continue to measure time while in the hive. We performed a microarray genome-wide survey to determine general patterns of brain gene expression in nurses and foragers sampled around the clock. We found 160 and 541 transcripts that exhibited significant sinusoidal oscillations in nurses and foragers, respectively, with peaks of expression distributed throughout the day in both task groups. Consistent with earlier studies, transcripts of genes involved in circadian rhythms, including Clockwork Orange that has not been studied before in bees, oscillated in foragers but not in nurses. The oscillating transcripts also were enriched for genes involved in the visual system, ‘‘development’’ and ‘‘response to stimuli’’ (foragers), ‘‘muscle contraction’’ and ‘‘microfilament motor gene expression’’ (nurses), and ‘‘generation of precursor metabolites’’ and ‘‘energy’’ (both). Transcripts of genes encoding P450 enzymes oscillated in both nurses and foragers but with a different phase. This study identified new putative clock-controlled genes in the honey bee and suggests that some brain functions show circadian rhythmicity even in nurse bees that are active around the clock.

A review. First the definition of microemulsions is referred. The differences between microemulsions, emulsions and nanoemulsions are demonstrated. A simple presentation of the mechanism of microemulsion stability is then given., followed by a discussion of microstructures, a characterization of microemulsions,and a brief description of their phase behavior. After that, applications of. microemulsions are discussed, with a focus on the important topic of solubilization of bioactives. Obviously the description of this application was not meant to be all-inclusive. Rather, it was delved into selected microemulsion systems which mainly were investigated in the authors' lab. [on SciFinder(R)]

We examine the time-dependent dynamics of ion crystals in radiofrequency traps. The problem of stable trapping of general three-dimensional crystals is considered and the validity of the pseudopotential approximation is discussed. We analytically derive the micromotion amplitude of the ions, rigorously proving well-known experimental observations. We use a recently proposed method to find the modes that diagonalize the linearized time-dependent dynamical problem. This allows one to obtain explicitly the ('Floquet–Lyapunov') transformation to coordinates of decoupled linear oscillators. We demonstrate the utility of the method by analyzing the modes of a small 'peculiar' crystal in a linear Paul trap. The calculations can be readily generalized to multispecies ion crystals in general multipole traps, and time-dependent quantum wavefunctions of ion oscillations in such traps can be obtained.

The molecular basis of the interaction between mitochondrial carrier homologue 2 (MTCH2) and truncated BID (tBID) was characterized. These proteins participate in the apoptotic pathway, and the interaction between them may serve as a target for anticancer lead compounds. In response to apoptotic signals, MTCH2 recruits tBID to the mitochondria, where it activates apoptosis. A combination of peptide arrays screening with biochemical and biophysical techniques was used to characterize the mechanism of the interaction between tBID and MTCH2 at the structural and molecular levels. The regions that mediate the interaction between the proteins were identified. The two specific binding sites between the proteins were determined to be tBID residues 59–73 that bind MTCH2 residues 140–161, and tBID residues 111–125 that bind MTCH2 residues 240–290. Peptides derived from tBID residues 111–125 and 59–73 induced cell death in osteosarcoma cells. These peptides may serve as lead compounds for anticancer drugs that act by targeting the tBID-MTCH2 interaction.

The circadian clock is a core molecular mechanism that allows organisms to anticipate daily environmental changes and adapt the timing of behaviors to maximize efficiency. In social insects, the ability to maintain the appropriate temporal order is thought to improve colony efficiency and fitness. We used the newly sequenced fire ant (Solenopsis invicta) genome to characterize the first ant circadian clock. Our results reveal that the fire ant clock is similar to the clock of the honeybee, a social insect with an independent evolutionary origin of sociality. Gene trees for the eight core clock genes, period, cycle, clock, cryptochrome-m, timeout, vrille, par domain protein 1 & clockwork orange, show ant species grouping closely with honeybees and Nasonia wasps as an outgroup to the social Hymenoptera. Expression patterns for these genes suggest that the ant clock functions similar to the honeybee clock, with period and cry-m mRNA levels increasing during the night and cycle and clockwork orange mRNAs cycling approximately anti-phase to period. Gene models for five of these genes also parallel honeybee models. In particular, the single ant cryptochrome is an ortholog of the mammalian-type (cry-m), rather than Drosophila-like protein (cry-d). Additionally, we find a conserved VPIFAL C-tail region in clockwork orange shared by insects but absent in vertebrates. Overall, our characterization of the ant clock demonstrates that two social insect lineages, ants and bees, share a similar, mammalian-like circadian clock. This study represents the first characterization of clock genes in an ant and is a key step towards understanding socially-regulated plasticity in circadian rhythms by facilitating comparative studies on the organization of circadian clockwork.

The goal of the present work is to study theor. the structure of water inside the water cylinder of the inverse hexagonal mesophase (HII) of glyceryl monooleate (monoolein, GMO), using the method of mol. dynamics. To simplify the computational model, a fixed structure of the GMO tube is maintained. The nonstd. cylindrical geometry of the system required the development and application of a novel method for obtaining the starting distribution of water mols. A predictor-corrector schema is employed for generation of the initial d. of water. Mol. dynamics calcns. are performed at const. vol. and temp. (NVT ensemble) with 1-dimensional periodic boundary conditions applied. During the simulations the lipid structure is kept fixed, while the dynamics of water is unrestrained. Distribution of hydrogen bonds and d. as well as radial distribution of water mols. across the water cylinder show water structure deep in the cylinder (∼6 \AA below the GMO heads). The obtained results may help understanding the role of water structure in the processes of insertion of external mols. inside the GMO/water system. The present work has a semi-quant. character and it should be considered as the initial stage of more comprehensive future theor. studies. (c) 2012 American Institute of Physics. [on SciFinder(R)]