Reversal of genetic homeostasis in laboratory populations of Drosophila melanogaster under long-term selection for geotaxis and estimates of gene correlates: evolution of behavior-genetic systems

Among Drosophila melanogaster, divergently selected for geotaxis intermittently over 600 generations (28 years), about 80,000 animals have been analyzed behavior-genetically. Each major chromosome pair from two lines was isogenized on an unselected isogenic background. Measurement of their behavioral effects revealed the relative magnitudes II greater than III greater than X for the negatively geotactic (high) line and X greater than III greater than II for the positively geotactic (low) line. When reversing selection for the now phenotypically stable high and low lines and then repeatedly relaxing the reversals, a new genetic homeostasis in the low line was indicated by the return of the reversed-line average scores towards the low extreme; that is, the low line has attained a stable equilibrium for positive geotaxis, an uncharacteristic behavior and an effect not seen before 1979. This change suggests the recent evolution of a new coadaptation among genes. Although not as conclusive, a similar genetic interpretation is suggested for the high line.     

Re-examining the home disadvantage in professional ice hockey

Occurrence of the home disadvantage in professional ice hockey was examined by analyzing shootout data from 2005 through 2008. Results indicated that teams involved in shootouts playing at their home arenas did not lose significantly more games at home than on the road. Results did not support the hypotheses that emphasize the roles of physical contact and diffusion of responsibility in accounting for past failures to find the home disadvantage in professional ice hockey.     

Prospective Associations Between Peer Victimization and Internalizing Symptoms in Adolescence: The Protective Role of Hope

Youth who experience aggression at the hands of peers are at an increased risk for a variety of adjustment difficulties, including depressive and anxiety symptoms and lower self-esteem. The links between peer victimization and internalizing problems are robust, but less work has been done to identify individual-level protective factors that might mitigate these outcomes. The current study investigated whether hope served as a moderator of the prospective links from peer victimization to depressive and anxiety symptoms and self-esteem during adolescence. Participants included 166 high school students (64% female; 88% Black/African American). Youth completed self-report measures at three different time points across the Spring semester of an academic year. As predicted, hope interacted with peer victimization to predict changes in depressive and anxiety symptoms over the course of the semester. That is, for youth with low levels of hope, peer victimization predicted more stable patterns of depressive and anxiety symptoms. For adolescents with average levels of hope, however, peer victimization did not influence anxiety and depressive symptoms over time. Finally, for adolescents with high levels of hope, peer victimization predicted greater decreases in anxiety symptoms over time. Hope did not interact with peer victimization to predict self-esteem. Rather, hope uniquely predicted higher levels of self-esteem, whereas peer victimization uniquely predicted lower levels of self-esteem. The current study provides initial support for the notion that hope can serve as a protective factor among youth who are victims of peer aggression.

     

If We Build It … Will They Come? – Establishing a Cancer Genetics Services Clinic for an Underserved Predominantly Latina Cohort

Background: Cancer genetic counseling and testing is a standard of care option for appropriate families and can identify individuals at increased risk prior to diagnosis, when prevention or detection strategies are most effective. Despite documented efficacy of cancer risk reduction in high-risk individuals, underserved and minority individuals have a disproportionate cancer burden and limited access to genetic counseling. Methods: A needs assessment survey documented gaps in knowledge and interest in prevention. Satellite clinics were established at two indigent healthcare systems. Cancer genetics CME lectures were conducted and referral guidelines disseminated to clinicians who referred patients for counseling. Results: An increase in clinician knowledge was demonstrated post-CME and reflected by quality referrals. Eighty-eight percent of patients kept their appointments. In the predominantly Latina⁶ (n=77) clinic population, 71.4% were affected with cancer, and 17 mutation positive families were identified. Preliminary data shows a positive impact on patients' motivation and behavior. The majority has expressed satisfaction and reduction in anxiety. Conclusions: This study demonstrates feasibility and acceptability of cancer genetics services in this population, suggesting the potential to reduce cancer morbidity in underserved, high-risk families.“Latino” is the most common census term for individuals of Spanish, Mexican, Central and South American, Cuban, or Puerto Rican descent, referring to ethnicity, and is generally considered a more ethnically/culturally based term for individuals of the aforementioned groups. As this cohort is female the feminine noun “Latina” is used     

Recognition Decisions From Visual Working Memory Are Mediated by Continuous Latent Strengths

Making recognition decisions often requires us to reference the contents of working memory, the information available for ongoing cognitive processing. As such, understanding how recognition decisions are made when based on the contents of working memory is of critical importance. In this work we examine whether recognition decisions based on the contents of visual working memory follow a continuous decision process of graded information about the correct choice or a discrete decision process reflecting only knowing and guessing. We find a clear pattern in favor of a continuous latent strength model of visual working memory–based decision making, supporting the notion that visual recognition decision processes are impacted by the degree of matching between the contents of working memory and the choices given. Relation to relevant findings and the implications for human information processing more generally are discussed.     

Evolution of an instinct under long-term divergent selection for geotaxis in domesticated populations of Drosophila melanogaster

Long-term divergent selection for geotaxis in lines of Drosophila melanogaster (the fruit fly) is described. After 26 years (600+ generations) of intermittent selection, the mean geotactic scores now remain stable upon relaxed selection, a result suggesting that evolutionary changes have occurred in these lines. Because the stability is not due to genetic fixation (homozygosity) of the lines, it must be due to either close linkage of genes associated with geotaxis (which would not result in enduring change) or the development of new coadapted gene complexes utilizing genes associated with extreme geotaxis expression (which should result in enduring change). Better evidence for the latter hypothesis is obtained from the low, than from the high, line. The notions of coadaptation and genetic homeostasis are considered, as well as the prospective use of the geotaxis lines to study such concepts experimentally. The geotactic behavior expressed in each line is defined as "instinctive": It increases reproductive success and is characteristic of a population.     

Coupling of Eye,Finger, Elbow,and Shoulder Movements During Manual Aiming

Temporal and spatial coupling of point of gaze (PG) and movements of the finger, elbow, and shoulder during a speeded aiming task were examined. Ten participants completed 40-cm aiming movements with the right arm, in a situation that allowed free movement of the eyes, head, arm, and trunk. On the majority of trials, a large initial saccade undershot the target slightly, and 1 or more smaller corrective saccades brought the eyes to the target position. The finger, elbow, and shoulder exhibited a similar pattern of undershooting their final positions, followed by small corrective movements. Eye movements usually preceded limb movements, and the eyes always arrived at the target well in advance of the finger. There was a clear temporal coupling between primary saccade completion and peak acceleration of the finger, elbow, and shoulder. The initiation of limb-segment movement usually occurred in a proximal-to-distal pattern. Increased variability in elbow and shoulder position as the movement progressed may have served to reduce variability in finger position. The spatial-temporal coupling of PG with the 3 limb segments was optimal for the pick up of visual information about the position of the finger and the target late in the movement.     

Goal-Directed Aiming: Correcting a Force-Specification Error With the Right and Left Hands

In 2 experiments, the authors examined manual aiming asymmetries as well as the ability of participants to adjust their aiming trajectories following an unexpected change to the inertial resistance to movement. In Experiment 1, participants (N = 11) were able to rapidly adjust their movement trajectories to conform to the new movement requirements. They were faster and more consistent when aiming with their right hand than with their left hand, regardless of whether or not the movement was perturbed. In Experiment 2, participants' (N = 11) vision of the hand was manipulated so that the role of visual feedback in the corrective process could be examined. Vision had an impact not only on performance but also on the characteristics of the movement trajectories. Manual asymmetries in aiming were associated with a right hand superiority during the final corrective stages of the movement.