Direct Selection Strategy Research Articles

The Effects of Power on Consumer Decision Strategies: The Mediating Role of Behavioral Approach-Inhibition Tendency and the Moderating Role of Gender.

Previous studies on consumer decision strategies have focused on the process or outcomes of decision-making using different decision strategies. Relatively little is known about the factors (especially decision makers' characteristics) influencing the use of different decision strategies. This study examined the effects of power on consumer decision strategies and the underlying mechanisms. Studies 1 (N = 128) and 2 (N = 130) examined multiple- and binary-option situations, respectively. Participants' power was manipulated with a writing task and their consumer decision strategies were assessed through the selection tasks of restaurants and beach resorts. Study 3 (N = 326) further explored the mediator of approach-inhibition tendency and the moderator of gender in the relationship between power and consumer decision strategies. Participants' chronic sense of power, approach-inhibition tendency, and purchasing strategies were measured using questionnaires. Powerful (vs powerless) individuals prefer to use a direct selection (vs exclusion) strategy, regardless of whether they face multiple or binary choices. An increased approach (vs inhibition) tendency explains why elevated power promotes the use of the direct selection strategy. Moreover, gender plays a moderating role. Specifically, the mediation effect of approach (vs inhibition) tendency on the relationship between power and the preference for the direct selection (vs exclusion) strategy is stronger for males than for females. This study extends previous research on power and consumer decision strategies by clarifying that the effects of power on consumer decision strategies are primarily driven by high power (but not by low power). Furthermore, by examining the mediator of approach-inhibition tendency and the moderator of gender, this study promotes a deeper understanding of how power affects consumer decision strategies and for whom the effect is more salient. Besides, the present research has contributions to the approach-inhibition theory of power and the literature on gender differences in consumer behavior, and has practical implications for business marketing.

Direct Selection Strategy for Isolating Aptamers with pH-Sensitive Binding Activity.

An aptamer reagent that can switch its binding affinity in a pH-responsive manner would be highly valuable for many biomedical applications including imaging and drug delivery. Unfortunately, the discovery of such aptamers is difficult and only a few have been reported to date. Here we report the first experimental strategy for generating pH-responsive aptamers through direct selection. As an exemplar, we report streptavidin-binding aptamers that retain nanomolar affinity at pH 7.4 but exhibit a ∼100-fold decrease in affinity at pH 5.2. These aptamers were generated by incorporating a known streptavidin-binding DNA motif into an aptamer library and performing FACS-based screening at multiple pH conditions. Upon structural analysis, we found that one aptamer’s affinity-switching behavior is driven by a noncanonical G-A base-pair that controls its folding in a highly pH-dependent manner. We believe our strategy could be readily extended to other aptamer-target systems because it does not require a priori structural knowledge of the aptamer or the target.

Genetic parameters and characterization of egg content spreading area in White Leghorn chickens.

Uncharacteristically large spreading area on a flat surface of broken egg negatively affects egg quality assessment and reduces eggs' economic value. In this study, we investigated the heredity of the egg content spreading area as well as the relationships between the egg content spreading area and egg quality traits and properties. We measured the total egg content spreading area (TECA), outer thin albumen area (OTAA), inner thick albumen area (ITAA), yolk area (YA), and egg quality traits for 1414 newly laid eggs from 487 27-wk-old White Leghorn pure line pullets. The genetic parameters of egg content spreading areas were estimated. The phenotypic and genetic correlations between egg content spreading area and egg quality traits were analyzed. The differences in the properties of eggs with similar egg weight but markedly different TECA were also analyzed. The heritability estimates for TECA, OTAA, ITAA, and YA were low to moderate, with values of 0.214, 0.176, 0.340, and 0.280, respectively. Egg weight was related to TECA with a phenotypic correlation of 0.450 (P<0.01) and a genetic correlation of 0.349. A high genetic correlation (-0.731) was found between TECA and Haugh unit. In eggs with larger TECA, the weight and total solid content of outer thin albumen (OTA) and moisture content of inner thick albumen (ITA) were significantly higher, whereas the weight and total solid content of ITA was markedly lower, but no differences (P>0.05) were found in the pH of OTA and ITA, moisture content of OTA, as well as the eggshell strength, thickness, and non-destruction and fracture deformation between eggs with similar egg weight but markedly different TECA. These results suggest that the egg content spreading area can be regulated via the direct selection strategy or indirect selection of the ratio of OTA to ITA in the breeding program.

Catch the Best: Novel Screening Strategy to Select Stress Protecting Agents for Crop Plants

Climate change increases stress levels for crops and affects the economic and environmental aspects of agricultural management systems. The application of stress tolerance-mediating microorganisms is an auspicious strategy for improving crop protection, and as such, we developed a direct selection strategy to obtain cultivable microorganisms from promising bioresources using the bait plants, maize, oilseed rape, sorghum and sugar beet. Alpine mosses, lichens and primrose were selected as bioresources, as each is adapted to adverse environmental conditions. A 10% crop-specific selection was found for bait plant rhizosphere communities using cultivation-independent fingerprints, and their potential role as stress protecting agents (SPA) was evaluated following the cultivation of captured bacteria. In addition to assays identifying phytopathogen antagonism and plant growth promotion capacities, our evaluation included those that test the ability to allocate nutrients. Moreover, we developed new assays to measure tolerance in diverse stress conditions. A score scheme was applied to select SPAs with desired properties, and three Pseudomonas species with pronounced antagonistic activity that showed elevated tolerance to desiccation and an improved seed germination rate were subsequently chosen. Screening for environmentally-conditioned and host-adapted microorganisms provides a novel tool for target-oriented exploitation of microbial bioresources for the management of ecofriendly crops facing biotic and abiotic stresses.

M13-102: A vector for facilitating construction and improving quality of M13 shotgun libraries

A modified vector, M13-102, is described which utilizes the previously reported M13-100 direct selection strategy for shotgun cloning [Guilfoyle and Smith, Nucleic Acids Res. 22 (1994) 100–107]. In these vectors, direct selection replaces the need for phosphatase treatment of vector DNA and is achieved by insertional inactivation of M13 gene X. When not inactivated, the engineered overproduction of the M13 gene X product mediates phage replication repression. M13-102 contains two new additions: (1) a sequence enabling triple-helix-mediated affinity capture (TAC) for purification of linearized vector DNA, and (2) universal primer sequences for wider compatibility with commercial instruments that support fluorescence-based sequencing. Using a biotinylated homopyrimidine oligodeoxyribonucleotide as thirdstrand probe, TAC is performed on streptavidin-coated magnetic beads [Ji et al., Genetics Analysis: Techniques and Applications 11 (1994) 43–47], and serves as a rapid and efficient alternative to gel purification. To reduce tandem insertions, phosphatase treatment of insert DNA was easily invoked without sacrificing cloning efficiency. The combined capabilities of direct selection, TAC purification and phosphatase treatment of inserts should facilitate library construction and improve overall library quality.

Isolation and characterization of a novel gene deleted in DiGeorge syndrome.

The region commonly deleted in DiGeorge syndrome (DGS) has been localized at 22q11.1-q11.2 with the aid of a high resolution banding technique. A 22q11 specific plasmid library was constructed with a microdissection and microcloning method. Dosage analysis proved three of 144 randomly selected microclones to detect hemizygosity in two patients with DGS. Two of the clones were found to contain independent low-copy-number repetitive sequences, all of which were included in the region deleted in the DGS patients. Screening of the cosmid library and subsequent cosmid walking allowed us to obtain two cosmid contigs corresponding to the microclones within the deletion (contig 1 and contig 2), whose order fluorescence in situ hybridization identified as centromere-contig 1-contig 2-telomere on 22q. By direct selection strategy using one of the cosmids of contig 1, a 4.3 kb cDNA was obtained from fetal brain cDNA library. Sequence analysis of the cDNA revealed an open reading frame encoding 552 amino acids which had several characteristics of DNA-binding proteins. The gene, designated LZTR-1, which was transcribed in several essential fetal organs, proved to be hemizygously deleted in seven of eight DGS patients or its variants, but not in one DGS patient and GM00980. Although LZTR-1 does not locate in the shortest region of overlap, several of its structural characteristics identifying it as transcriptional regulator suggest that it plays a crucial role in embryogenesis and that haploinsufficiency of this gene may be partly related to the development of DGS.

A direct selection strategy for shotgun cloning and sequencing in the bacteriophage M13.

A new cloning strategy is described which utilizes direct selection of recombinants for shotgun sequencing in the filamentous bacteriophage M13. Direct selection is accomplished by insertional inactivation of the M13 gene X protein, a powerful inhibitor of phage-specific DNA synthesis when overproduced. An extra copy of gene X was inserted into the intergenic region of M13 and placed under the control of the bacteriophage T7 gene 10 promoter and RBS. Random fragments are cloned into the EcoRV cloning site of the new gene X cistron and recombinants are selected in an E. coli male strain producing T7 RNA polymerase. Cloning efficiencies obtained with M13-100 or phosphatase-treated M13mp19 vector are comparable. The direct selection capability of M13-100 was demonstrated to have the following advantages: (a) consistently achieved high ratios of recombinants to religated vector in the libraries, averaging about 500:1 (0.2% background), and (b) the elimination of the need for phosphatase treatment of the vector to reduce background. The direct selection strategy significantly improves the efficiency of shotgun library construction in M13, and should therefore facilitate the cloning aspects of large scale sequencing projects.

Direct selection: a method for the isolation of cDNAs encoded by large genomic regions.

We have developed a strategy for the rapid enrichment and identification of cDNAs encoded by large genomic regions. The basis of this "direct selection" scheme is the hybridization of an entire library of cDNAs to an immobilized genomic clone. Nonspecific hybrids are eliminated and selected cDNAs are eluted. These molecules are then amplified and are either cloned or subjected to further selection/amplification cycles. This scheme was tested using a 550-kilobase yeast artificial chromosome clone that contains the EPO gene. Using this clone and a fetal kidney cDNA library, we have achieved a 1000-fold enrichment of EPO cDNAs in one cycle of enrichment. More significantly, we have further investigated one of the "anonymous" cDNAs that was selectively enriched. We confirmed that this cDNA was encoded by the yeast artificial chromosome. Its frequency in the starting library was 1 in 1 x 10(5) cDNAs and after selection comprised 2% of the selected library. DNA sequence analysis of this cDNA and of the yeast artificial chromosome clone revealed that this gene encodes the beta 2 subunit of the human guanine nucleotide-binding regulatory proteins. Restriction mapping and hybridization data position this gene (GNB2) to within 30-70 kilobases of the EPO gene. The selective isolation and mapping of GNB2 confirms the feasibility of this direct selection strategy and suggests that it will be useful for the rapid isolation of cDNAs, including disease-related genes, across extensive portions of the human genome.