A vector for double epitope tagging with a recyclable marker

Multimeric protein complexes play diverse and vital roles in the cell, but following the composition of these complexes under varying growth conditions can be challenging. Toward that goal, we have designed a vector that permits the double epitope tagging of a protein at its carboxy terminus. One 'universal' tag, a triple repeat of the HA1 epitope, is fused with every protein to be studied, allowing the composition and stoichiometry of the proteins in a complex to be detected with a single antibody. Each protein also can be tagged with a second epitope specific for that protein. This 'specific' tag can be used to immunoprecipitate complexes containing that protein of interest. Any epitope to which a specific antibody is available can be used for this second tag. Because there are a limited number of selection markers for cloning in yeast, the kanamycin cassette, flanked by loxP sites, was incorporated into the vector to permit marker recycling using Cre-lox recombinase. This vector was used to tag 4 proteins involved in ribosome biogenesis-Ytm1, Cic1, Brx1 and Drs1. An anti-HA1 antibody could detect all four proteins in crude lysates and yielded the relative abundance of these four proteins, of which Drs1 is reproducibly less abundant than any of the others, which may have implications for the control of ribosome biogenesis. The Ytm1 protein was also tagged with the VSV epitope and can be specifically detected using an anti-VSV antibody. This vector may prove useful for exploring other protein complexes.     

Families and risk: prospective analyses of familial and social influences on adolescent substance use.

Parental, peer, and older siblings' contributions to adolescents' substance use were investigated with 2 waves of panel data from 225 African American families. Structural equation modeling showed that older siblings' behavioral willingness (BW) to use substances at Time 1 (T1) predicted target adolescents' Time 2 (T2) use, controlling for other T1 variables. Regression analyses revealed an interaction between targets' and siblings' BW, such that targets were more likely to use at T2 if both they and their siblings reported BW at T1. This interaction was stronger for families living in high-risk neighborhoods. Finally, siblings' willingness buffered the impact of peer use on targets' later use: Low sibling BW was associated with less evidence of peer influence. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A randomized trial of cognitive therapy and imaginal exposure in the treatment of chronic posttraumatic stress disorder.

A randomized trial was performed in which imaginal exposure (IE) and cognitive therapy (CT) were compared in the treatment of chronic posttraumatic stress disorder (PTSD). Patients who continued to meet PTSD caseness at the end of a 4-week symptom-monitoring baseline period (n?=?72) were randomly allocated to either IE or CT. There was a significant improvement in all measures over treatment and at follow-up, although there were no significant differences between the 2 treatments at any assessment. A significantly greater number of patients who showed worsening over treatment received IE, although this effect was not found at follow-up. Patients who worsened showed a greater tendency to miss treatment sessions, rated therapy as less credible, and were rated as less motivated by the therapist. It was concluded that either exposure or a challenge to cognition can result in symptom reduction, although neither resulted in complete improvement. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Adolescent smoking trajectories and nicotine dependence.

The present study correlates empirically constructed prospective adolescent smoking trajectories with indicators of nicotine dependence assessed in adolescence and in adulthood. Excluding individuals who reported no smoking during repeat assessment (nonadopters), we identified five smoking trajectory groups: experimenters (n=116, 48.5%), late increasers (n=39, 16.3%), early increasers (n=37, 15.5%), quitters (n=22, 9.2%), and persistent smokers (n=25, 10.5%). Higher frequency of nicotine dependence symptoms in adolescence occurred in the quitters and persistent smokers groups, who smoked at higher levels relative to the experimenters, late increasers, and early increasers groups, who reported a similar frequency of nicotine dependence symptoms and smoked at low levels. Lifetime nicotine dependence was assessed in adulthood in lifetime daily smokers using the Fagerstr?m Test for Nicotine Dependence (FTND) and the Nicotine Dependence Scale (NDS). Lifetime FTND levels were similar across trajectory groups. Relative to experimenters, all remaining smoking trajectory groups had higher NDS levels that were similar to one another. These results suggest that higher levels of adolescent nicotine dependence were associated with heavier smoking trajectory groups, and that regardless of trajectory group membership, smoking more than a few cigarettes per week throughout adolescence resulted in similar levels of lifetime nicotine dependence as measured by the FTND and NDS.     

Spatial unmasking of birdsong in zebra finches (Taeniopygia guttata) and budgerigars (Melopsittacus undulatus).

Budgerigars and zebra finches were tested, using operant conditioning techniques, on their ability to identify a zebra finch song in the presence of a background masker emitted from either the same or a different location as the signal. Identification thresholds were obtained for three masker types differing in their spectrotemporal characteristics (noise, modulated noise, and a song chorus). Both bird species exhibited similar amounts of spatial unmasking across the three masker types. The amount of unmasking was greater when the masker was played continuously compared to when the target and masker were presented simultaneously. These results suggest that spatial factors are important for birds in the identification of natural signals in noisy environments. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Activity Dependent Brain Plasticity: Does Singing Increase the Volume of a Song System Nucleus? Theoretical Comment on Sartor and Ball (2005).

The avian telencephalic song system, including nucleus high vocal center (HVC), is an important model for the study of brain plasticity. J. J. Sartor and G. F. Ball (2004) asked whether song activity itself could increase HVC volume (see record 2005-01705-022). They report that male starlings that sang more, motivated by gaining possession of a nest box in competition with another male, had larger HVCs than males that sang less. These results are suggestive but correlational. A more direct experimental approach will be required to establish that HVC size is activity dependent. Their experiment is an important first step, however. The song activity hypothesis merits continued investigation because of its potential to produce unique insights into naturally occurring brain plasticity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)