Genetic and Biochemical Analysis of the Activation Mechanism of the Saccharomyces Cerevisiae Pheromone Receptor

Activation mechanism of the α-factor pheromone receptor of Saccharomyces cerevisiae was analyzed using biochemical and genetic techniques. An in vitro partial proteolysis assay was developed to determine the conformational change of the receptor that occurs upon binding of agonist. The activation specific cleavages were established by comparing cleavage products with antagonist versus agonist occupied receptor. Of the changes in peptide pattern that were revealed by trypsinization, the fragment resulting from the exposure of the third loop to the protease was found to be agonist specific and to be G-protein independent. A low-affinity binding receptor mutant was isolated which failed to undergo this agonist induced conformational change. Four intra-allelic suppressors of this receptor mutant were isolated and all were mapped to the ends of transmembrane helices 4, 5, 6 and 7; all were found to be replacements of non-polar residues by polar ones. The role of the suppressor mutations in conformational change was analyzed

Transcriptional regulation of Bacillus subtilis glucose starvation-inducible genes: control of gsiA by the ComP-ComA signal transduction system.

The Bacillus subtilis glucose starvation-inducible transcription units, gsiA and gsiB, were characterized by DNA sequencing, transcriptional mapping, mutational analysis, and expression in response to changes in environmental conditions. The gsiA operon was shown to consist of two genes, gsiAA and gsiAB, predicted to encode 44.9- and 4.8-kDa polypeptides, respectively. The gsiB locus contains a single cistron which encodes a protein of unusual structure; most of its amino acids are arranged in five highly conserved, tandemly repeated units of 20 amino acids. The 5' ends of gsiA and gsiB mRNAs were located by primer extension analysis; their locations suggest that both are transcribed by RNA polymerase containing sigma A. Expression of both gsiA and gsiB was induced by starvation for glucose or phosphate or by addition of decoyinine, but only gsiA was induced by exhaustion of nutrient broth or by amino acid starvation. Regulation of gsiA expression was shown to be dependent upon the two-component signal transduction system ComP-ComA, which also controls expression of genetic competence genes. Mutations in mecA bypassed the dependency of gsiA expression on ComA. Disruption of gsiA relieved glucose repression of sporulation but did not otherwise interfere with sporulation, development of competence, motility, or glucose starvation survival. We propose that gsiA and gsiB are members of an adaptive pathway of genes whose products are involved in responses to nutrient deprivation other than sporulation

The mental health of young workers: A pilot study

The aim of the study was to evaluate the distribution of psychological symptoms in young workers, and the relationship with regard to sociodemographic characteristics using the Brief Symptom Inventory (BSI; Derogatis, 1992), in İzmir Apprenticeship Training Center, Turkey, with 203 randomly selected apprentices aged 15-21, 31 (15.3%) females and 172 (84.7%) males. The mean age was 17.48± 1.24 years. The apprentices were from four different occupational groups: Metalwork (21.7%), Auto repair (29.6%), Electric repair (20.7%) and Hairdressing (28.1%). Results showed that apprentices who are female, who come from single-parent families, who reported low socioeconomic status, who had lost one of their parents or siblings, whose fathers had no stable job, and who work in hairdressing are at risk for psychological problems. In conclusion, those "at risk" apprentices should receive psychosocial support and counseling for coping with problems. © Society for Personality Research (Inc.)

A Practical Guide to the Preparation of Liquid Crystal-Templated Microparticles

We provide a practical guide to methods and protocols that use polymer networks templated from droplets of liquid crystal (LC) to synthesize micrometer-sized polymeric particles that are chemically patchy, are anisometric in shape, possess anisotropic optical properties, and/or are mesoporous. We describe a range of methods that permit the preparation of LC droplets (containing reactive monomers) as templates for polymerization, including formation of LC-in-water emulsions by mechanical methods (e.g., vortexing), encapsulation in polymeric shells, or microfluidics. The relative merits of the methods, including ease of use and potential pitfalls, and the resulting droplet size distributions, are described. We also report a menu of approaches that can be used to control the internal configurations of the LC droplets, including changes in composition of the continuous solvent phases (e.g., addition of glycerol) and adsorption of surfactants or colloids at the interfaces of the LC droplets. Photopolymerization of the LC droplets in bipolar, radial, axial, or preradial configurations and subsequent extraction of the nonreactive mesogens generates polymeric particles that have spindle, spherical, spherocylindrical, or tear shapes, respectively. Finally, we describe how to characterize these polymeric particles, including their shape, internal structure, optical properties, and porosity. The methods described in this paper, which provide access to complex microparticles with properties relevant to separation processes, drug delivery, and optical devices, are general and versatile and can be readily developed further (e.g., by changing the choice of LC) to create an even greater diversity of microparticles

Self-reporting and self-regulating liquid crystals

Liquid crystals (LCs) are anisotropic fluids that combine the long-range order of crystals with the mobility of liquids(1,2). This combination of properties has been widely used to create reconfigurable materials that optically report information about their environment, such as changes in electric fields (smart-phone displays)(3), temperature (thermometers)(4) or mechanical shear(5), and the arrival of chemical and biological stimuli (sensors)(6,7). An unmet need exists, however, for responsive materials that not only report their environment but also transform it through self-regulated chemical interactions. Here we show that a range of stimuli can trigger pulsatile (transient) or continuous release of microcargo (aqueous microdroplets or solid microparticles and their chemical contents) that is trapped initially within LCs. The resulting LC materials self-report and self-regulate their chemical response to targeted physical, chemical and biological events in ways that can be preprogrammed through an interplay of elastic, electrical double-layer, buoyant and shear forces in diverse geometries (such as wells, films and emulsion droplets). These LC materials can carry out complex functions that go beyond the capabilities of conventional materials used for controlled microcargo release, such as optically reporting a stimulus (for example, mechanical shear stresses generated by motile bacteria) and then responding in a self-regulated manner via a feedback loop (for example, to release the minimum amount of biocidal agent required to cause bacterial cell death).11Nsciescopu

Is obesity a risk factor for psychopathology among adolescents?

WOS: 000221304600008PubMed ID: 15151546Background: Although several studies have documented the existence of psychopathology in obese adolescents, disagreement remains regarding the extent and nature of this psychopathology. The aim of the present study was to explore the type and frequency of psychopathology in a clinical as well as a non-clinical sample of obese adolescents, and in a normal weight control group. Methods: The study sample consisted of a clinical study group of 30 obese adolescents, a non-clinical obese group of 30 obese adolescents, and a control group of 30 normal weight adolescents. Psychological assessment was performed using a non-structured psychiatric interview, the Child Behavior Checklist (CBCL), Children Depression Inventory (CDI), Rosenberg Self-esteem scale (SES) and the Eating Attitude Test (EAT). Results: More than half of the clinical obese adolescents (16/30) had a DSM-IV diagnosis, often involving major depressive disorder (n = 10). The mean scores of anxiety-depression, social problems, social withdrawal and total problem in the CBCL scale of the clinical obese group were significantly higher than the non-clinical obese group and the normal weight control group. The mean total scores of the SES and the CDI of the clinical obese group were higher than the normal weight control group. The mean total score of EAT of the clinical obese group was significantly higher than the normal weight control group, and the mean score of EAT of the non-clinical obese group was significantly higher than the normal weight control group. Conclusions: The results support previously published reports which show a higher ratio of psychopathology (depression, behavioral problems, low-esteem) among clinical obese adolescents than among non-clinical obese adolescents. Findings provided evidence for a psychosocial at-risk population in a subgroup of obese adolescents

Experimental Insights into the Nanostructure of the Cores of Topological Defects in Liquid Crystals

The nanoscopic structure of the cores of topological defects in anisotropic condensed matter is an unresolved issue, although a number of theoretical predictions have been reported. In the experimental study reported in this Letter, we template the assembly of amphiphilic molecules from the cores of defects in liquid crystals and thereby provide the first experimental evidence that the cores of singular defects that appear optically to be points (with strength m = +1) are nanometer-sized closed-loop, disclination lines. We also analyze this result in the context of a model that describes the influence of amphiphilic assemblies on the free energy and stability of the defects. Overall, our experimental results and theoretical predictions reveal that the cores of defects with opposite strengths (e.g., m = +1 vs m = -1) differ in ways that profoundly influence processes of molecular self-assembly.11Nsciescopu