Protein aggregation induced during glass bead lysis of yeast

Yeast cell lysates produced by mechanical glass bead disruption are widely used in a variety of applications, including for the analysis of native function, e.g. protein–protein interaction, enzyme assays and membrane fractionations. Below, we report a striking case of protein denaturation and aggregation that is induced by this lysis protocol. Most of this analysis focuses on the type 1 casein kinase Yck2, which normally tethers to the plasma membrane through C‐terminal palmitoylation. Surprisingly, when cells are subjected to glass bead disruption, non‐palmitoylated, cytosolic forms of the kinase denature and aggregate, while membrane‐associated forms, whether attached through their native palmitoyl tethers or through a variety of artificial membrane‐tethering sequences, are wholly protected from denaturation and aggregation. A wider look at the yeast proteome finds that, while the majority of proteins resist glass bead‐induced aggregation, a significant subset does, in fact, succumb to such denaturation. Thus, yeast researchers should be aware of this potential artifact when embarking on biochemical analyses that employ glass bead lysates to look at native protein function. Finally, we demonstrate an experimental utility for glass bead‐induced aggregation, using its fine discrimination of membrane‐associated from non‐associated Yck2 forms to discern fractional palmitoylation states of Yck2 mutants that are partially defective for palmitoylation. Copyright © 2010 John Wiley & Sons, Ltd.     

Mineralization of a sorbed polycyclic aromatic hydrocarbon in two soils using catalyzed hydrogen peroxide

Hydrogen peroxide (H2O2) catalyzed by soluble iron or naturally occurring soil minerals, (i.e., modified Fenton's reagent) was investigated as a basis for mineralizing sorbed and NAPL-phase benzo[a]pyrene (BaP), a hydrophobic and toxic polycyclic aromatic hydrocarbon, in two soils of different complexity. 14C-Benzo[a]pyrene was added to silica sand and a silt loam soil, and mineralization was investigated using three-level central composite rotatable experimental designs. The effects of H2O2 concentration, slurry volume, and iron(II) amendment were investigated in the silica sand systems. In a Palouse loess silt loam soil, the variables included H2O2 concentration, slurry volume, and pH, with H2O2 catalyzed by naturally occurring iron oxyhydroxides. Regression equations generated from the data were used to develop three-dimensional response surfaces describing BaP mineralization. Based on the recovery of 14C-CO2, 70% BaP mineralization was achieved in the sand within 24 h using 15 M H2O2 and an iron(II) concentration of 6.6 mM with a slurry volume of 0.3 x the field capacity of the sand. For the silt loam soil, 85% mineralization of BaP was observed using 15 M H2O2, no iron amendment, and a slurry volume of 20 x the soil field capacity. The balance of the radiolabeled carbon remained as unreacted BaP in the soil fraction. Gas-purge measurements over 5 d confirmed negligible desorption under nontreatment conditions. However, oxidation reactions were complete within 24 h and promoted up to 85% BaP mineralization, documenting that the natural rate of desorption/dissolution did not control the rate of oxidation and mineralization of the BaP. The results show that catalyzed H2O2 has the ability to rapidly mineralize sorbed/NAPL-phase BaP and that partitioning, which is often the rate-limiting factor in soil remediation, does not appear to limit the rate of vigorous Fenton-like treatment.     

Fabrication of microchannel structures in fluorinated ethylene propylene

A new technique for fabrication of channel structures with diameters down to 13 microm in fluorinated ethylene propylene (also known as poly(tetrafluoroethylene-co-hexafluoropropylene), FEP) is described. The technique is based on the unique property of a dual-layer fluoropolymer tubing consisting of an outer layer of poly(tetrafluoroethylene) (PTFE) and an inner layer of FEP. When heated (>350 degrees C), the outer PTFE layer shrinks while the inner FEP layer melts, resulting in filling of all empty space inside the tubing with FEP. The channel structures are formed using tungsten wires as templates that are pulled out after completion of the shrinking and melting process. While several analytical devices have been reproducibly prepared and shown to function, this report describes a single example. A microreactor coupled to an electrochemical flow cell detects the biuret complex of the natively electroinactive peptide des-Tyr-Leu-enkephalin.     

Déjà vu all over again: Re-revisiting the conceptual status of early word learning: Comment on Smith and Samuelson (2006).

The authors assert that L. B. Smith and L. Samuelson's (2006; see record 2006-20488-029) most recent critique of A. E. Booth, S. R. Waxman, and Y. T. Huang's (2005; see record 2005-05098-004) work missed its mark, deflecting attention from the important theoretical difference between the two sets of authors' positions and focusing instead on imagined differences and minor expositional complaints. The authors' goal in this response is twofold. First, they aim to redirect attention to the 1 clear difference between the 2 theoretical positions regarding word learning, a difference that is focused on the role of conceptual (in conjunction with perceptual) information in word learning. Second, they place L. B. Smith and L. Samuelson's (2006) current critique in the context of previous exchanges. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Reconceptualizing feeding and feeding disorders in interpersonal context: The case for a relational disorder.

The feeding of young children is fundamentally a relational and multisystemic process. Successful treatment of clinically significant feeding problems involves careful assessment of the full range of influences on the feeding relationship and integrated treatment approaches. However, current diagnostic approaches to feeding disorders tend to be reductionistic, exclusively focused on the child as an individual, and overly concerned with exclusionary criteria. Criteria are proposed for "Feeding Disorder Between Parent and Child" that address these limitations and embrace the complexity of feeding problems. A multiaxial diagnosis that describes the child (including medical, developmental, and behavioral characteristics); the parent; the parent-child relationship; and the social and nutritional context of feeding will more accurately speak to treatment planning in this population. The proposed diagnostic criteria were developed and refined on the basis of the available literature and many years of treatment experience across the authors of this article. The proposed diagnosis will support the development and evaluation of treatment packages with components specifically targeted to issues of the child, parent, parent-child interaction, and the broader environment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Contingency management for smoking cessation in adolescent smokers.

This pilot study evaluated the use of contingency management (CM) procedures in combination with cognitive-behavioral therapy (CBT) for smoking cessation in adolescents. Twenty-eight treatment-seeking adolescent smokers participated in a 1-month, school-based smoking cessation program and were randomly assigned to receive either CM with weekly CBT or CBT alone. In the CM+CBT group, biochemical verification of abstinence was obtained twice daily during the first 2 weeks, followed by daily appointments during the 3rd week and once every other day during the 4th week. Participants were monetarily reinforced for abstinence on an escalating magnitude schedule with a reset contingency. At the end of 1 week and 1 month of treatment, abstinence verified using quantitative urine cotinine levels was higher in participants in the CM+CBT group (1 week: 76.7%; 1 month: 53.0%) when compared with the CBT-alone group (1 week: 7.2%; 4 weeks: 0%). These preliminary results provide a strong initial signal supporting the utility of CM techniques for smoking cessation in adolescents and demonstrate the feasibility of implementing such a program in a school setting. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

High-maintenance interaction: Inefficient social coordination impairs self-regulation.

Tasks requiring interpersonal coordination permeate all spheres of life. Although social coordination is sometimes efficient and effortless (low maintenance), at other times it is inefficient and effortful (high maintenance). Across 5 studies, participants experienced either a high- or a low-maintenance interaction with a confederate before engaging in an individual-level task requiring self-regulation. Self-regulation was operationalized with measures of (a) preferences for a challenging task with high reward potential over an easy task with low reward potential (Study 1) and (b) task performance (anagram performance in Study 1, Graduate Record Exam performance in Studies 2 and 3, physical stamina in Study 4, and fine motor control in Study 5). Results uniformly supported the hypothesis that experiencing high-maintenance interaction impairs one's self-regulatory success on subsequent, unrelated tasks. These effects were not mediated through participants' conscious processes and emerged even with a nonconscious manipulation of high-maintenance interaction. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Character of Organic Matter in Soil-Aquifer Treatment Systems

The objective of this study was to investigate the character and fate of bulk organics in reclaimed water used for groundwater recharge via soil-aquifer treatment (SAT). The study design followed a watershed guided approach considering hydraulically corresponding samples of drinking water sources, SAT-applied wastewater effluents, and subsequent post-SAT samples representing a series of different travel times in the subsurface. Water samples were fractionated into hydrophobic acids, transphilic acids, and hydrophilic carbon using a XAD resin-based protocol. Extensive characterization of organic carbon in the different samples was performed using state-of-the-art analytical techniques including excitation–emission matrix fluorescence spectroscopy, size exclusion chromatography, carbon-13 nuclear magnetic resonance spectroscopy (13C-NMR), Fourier transform infrared spectroscopy (FTIR), and elemental analysis. During SAT, transphilic and hydrophilic organic matter were preferentially removed. The results generally demonstrated that naturally derived (NOM) and effluent-derived organic matter after SAT overlap extensively in molecular weight distribution, amount and distribution of hydrophobic and hydrophilic carbon fractions, and chemical characteristics based on elemental analysis and 13C-NMR and FTIR spectroscopy. However, the residual portion of the dissolved organic carbon contained both effluent-derived organic matter and NOM.     

Smell, think and act: A cognitive robot discriminating odours

In this paper, we explore the integration of an electronic nose and its odour discrimination functionalities into a multi-sensing robotic system which works over an extended period of time. The robot patrols an office environment, collecting odour samples of objects and performing user requested tasks. By considering an experimental platforms which operates over an extended period of time, a number of issues related to odour discrimination arise such as the drift in the sensor data, online learning of new odours, and the correct association of odour properties related to objects. In addition to an electronic nose our robotic system consists of other sensing modalities (vision and sonar), behaviour-based control and a high level symbolic planner.